In these tests, there's something called the "limit of quantitation" or "LOQ," which is the lowest level at which a lab can really determine the concentration of something, Amesbury says.
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The paper, with the appetizing title of "Insights into the Key Compounds of Durian (Durio zibethinus L. 'Monthong') Pulp Odor by Odorant Quantitation and Aroma Simulation Experiments," breaks down the durian's signature stench into 16 distinct compounds.
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In an article entitled "Quantitation of Key Tastants and Re-engineering the Taste of Parmesan Cheese"—which doesn't exactly roll off the tongue—Hedda Hillmann and Thomas Hofmann of the Technical University of Munich describe what makes good Parmesan taste great.
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In recent years, research in human DNA quantitation has focused on new "real-time" quantitative PCR (qPCR) techniques. Quantitative PCR methods enable automated, precise, and high-throughput measurements. Inter-laboratory studies have demonstrated the importance of human DNA quantitation on achieving reliable interpretation of STR typing and obtaining consistent results across laboratories.
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Quantitation by indirect calorimetry, as opposed to the Harris-Benedict equation, is needed to accurately measure REE in cancer patients.
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Image Studio™ Lite is free image processing software used for quantitation of Western blot images and images from related experiments.
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Brendel, A., et al., Cerebrospinal shunt flow in adults: radionuclide quantitation with emphasis on patient position. Radiology, 1983. 149: p. 815-818.Pitteti R. 2007.
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Harris, Daniel C. Quantitative Chemical Analysis, W.H. Freeman and Company ,2007. This chemical is also used in the quantitation of magnesium in the clinical laboratory.
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LAESI technology allows high throughput analysis of these sample types and the use of internal standards and calibration curves permit the absolute quantitation of targeted biomolecules.
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Br J Ophthalmol. 2001 May;85(5):563-5. 9\. Berger JW, Yoken J. Computer-assisted quantitation of choroidal neovascularization for clinical trials. Invest Ophthalmol Vis Sci.
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A human proteome detection and quantitation project. 2009 May;8(5):883–6. A variety of MS instrument types have been used for quantitation of the enriched peptides, including most frequently triple quadrupole mass spectrometers implementing the “multiple reaction monitoring” (MRM) method (a format sometimes referred to as “immuno-MRM”Zhao L, Whiteaker JR, Voytovich UJ, Ivey RG, Paulovich AG. Antibody-Coupled Magnetic Beads Can Be Reused in Immuno-MRM Assays To Reduce Cost and Extend Antibody Supply. J Proteome Res.
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In January 2017, NEB released Luna universal quantitative real-time polymerase chain reaction (qPCR) and reverse-transcription quantitative polymerase chain reaction (RT-qPCR) kits. The Luna kits are used for DNA or RNA quantitation.
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An alternative method to assess DNA and RNA concentration is to tag the sample with a Fluorescent tag, which is a fluorescent dye used to measure the intensity of the dyes that bind to nucleic acids and selectively fluoresce when bound (e.g. Ethidium bromide). This method is useful for cases where concentration is too low to accurately assess with spectrophotometry and in cases where contaminants absorbing at 260 nm make accurate quantitation by that method impossible. The benefit of fluorescence quantitation of DNA and RNA is the improved sensitivity over spectrophotometric analysis.
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There are several methods of DNA extraction possible including organic (phenol-chloroform) extraction, Chelex extraction, and differential extraction. Quantitation is commonly conducted using a form of the polymerase chain reaction, known as real-time PCR, quantitative PCR, or qPCR. qPCR is the preferred method of DNA quantitation for forensic cases because it is very precise, human-specific, qualitative, and quantitative. This technique analyses changes in fluorescence signals of amplified DNA fragments between each PCR cycle without needing to pause the reaction or open the temperature- sensitive PCR tubes.
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Coinfections sometimes can epitomize a zero sum game of bodily resources, and precise viral quantitation demonstrates children co-infected with rhinovirus and respiratory syncytial virus, metapneumovirus or parainfluenza virus have lower nasal viral loads than those with rhinovirus alone.
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Meinert was raised in rural Minnesota. He earned a doctor of philosophy in statistics at University of Minnesota in 1964. His dissertation was titled Quantitation of the isotope displacement of immunoassay of insulin. His advisor was Richard B. McHugh.
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Pearson developed methods for high-resolution analysis of complex protein mixtures using multiple two-dimensional gel electrophoresis and monoclonal antibodies with Dr. N. Leigh Anderson. In 2004, Pearson, Anderson and their colleagues developed Stable Isotope Standards and Capture by Anti-Peptide Antibodies (SISCAPA), that allows quantitation of biomarkers in complex molecular mixtures such as human plasma. This has allowed a new mass spectrometric approach to longitudinal biomarker quantitation that is receiving attention worldwide as a diagnostic tool in health and disease. Pearson is the Chief Scientific Officer and co-founder, with Dr. N. Leigh Anderson and Constance Seniff, of SISCAPA Assay Technologies, Inc.
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SISCAPA is an extension of the well-known gold-standard methods of stable-isotope dilution for quantitation of small molecules by mass spectrometry (MS). Rather than measure an intact protein directly by mass spectrometry, SISCAPA makes use of proteolytic digestion (e.g., with the enzyme trypsin) to cleave sample proteins into smaller peptides ideally suited to quantitation by mass spectrometry. By selecting a target peptide whose sequence occurs only in the selected target protein (a so-called “proteotypic” peptide), the target peptide can serve as a direct quantitative surrogate for the target protein (assuming the digestion process is complete, or at least reproducible).
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A convenient quantitation of the effect of a solute additive on the solubility of another solute may be obtained by the Setschetow equation:Singhai, A., 1992. Studies on solubilization, formulation and evaluation of some drugs, Dept. of Pharm. Sci. Dr. H. S. Gaur vishwavidhyalaya.
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Epimerisation may happen. Phloroglucinolysis can be used for instance for proanthocyanidins characterisation in wine or in the grape seed and skin tissues. Thioglycolysis can be used to study proanthocyanidins or the oxidation of condensed tannins. It is also used for lignin quantitation.
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A relative quantitation can be obtained with a variety of differential isotope labeling technologies. There are also several quantitative protein phosphorylation methods, including fluorescence immunoassays, Microscale thermophoresis, FRET, TRF, fluorescence polarization, fluorescence-quenching, mobility shift, bead-based detection, and cell-based formats.
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Shin DS, Javornik NB, Berger JW. Computer-assisted, interactive fundus image processing for macular drusen quantitation. Ophthalmology. 1999 Jun;106(6):1119-25. 18\. Berger JW. Quantitative image sequence analysis of fundus fluorescein angiography. Ophthalmic Surg Lasers. 1999 Jan;30(1):72-3. 19\.
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Q-tof mass spectrometer combines TOF and quadrupole instruments, which cause high mass accuracy for product ions, accurate quantitation capability, and fragmentation experiment applicability. This is a method of mass spectrometry that ion fragmentation (m/z) ratio determined through a time of flight measurement.
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F.J. Heinrich, and D.E. Newbury eds., Electron probe quantitation, Plenum Press, 1991) to yield quantitative chemical compositions. The resulting chemical information is gathered in textural context. Variations in chemical composition within a material (zoning), such as a mineral grain or metal, can be readily determined.
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In clinical microbiology labs, the quantitation of microbial burden is considered a routine function as it is associated with the severity and progression of the disease. To achieve a good quantitation a high sensitivity of the technique is needed. A key limitation of metagenomic next- generation sequencing (mNGS) is its decreased sensitivity with high background as these can be clinically relevant as the pathogen load in infections can be very low. Whereas interfering substances represent a common problem to clinical chemistry or to PCR diagnostics, the degree of interference from host (for example, in tissue biopsies) or nonpathogen nucleic acids (for example, in stool) in metagenomics is a new twist.
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M. "Expression of Stable Isotopically Labeled Proteins for Use as Internal Standards for Mass Spectrometric Quantitation of Clinical Protein Biomarkers." NIST, material measurement laboratory. The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce, 30 Mar 2009. Web. 19 Nov 2011.
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In 1983, Perstorp, a Sweden-based chemical company, purchased Pierce. Perstorp was a manufacturer of chemicals, resins, plastics, and laminates. In 1985, researchers at Pierce Chemical Company, led by Paul K. Smith, published a method detailing the use of bicinchoninic acid (BCA) as a protein quantitation reagent.Smith, P.K., et al. 1985.
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There are two types of isobaric tags commercially available: tandem mass tags (TMT) and isobaric tags for relative and absolute quantitation (iTRAQ). Amine-reactive TMT are available in duplex, 6-plex and 10-plex and now 11-plex sets. Amine-reactive iTRAQ are available in 4-plex and 8-plex forms.
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H. isora is a rich source of antioxidants, carbohydrates, proteins, fibre, calcium, phosphorus, and iron.Gayathri, P., Gayathri Devi, S., & Sivagami Srinivasan, S. S. (2010). Screening and Quantitation of Phytochemicals and Nutritional Components of the Fruit and Bark of Helicteres isora. Hygeia journal for drugs and medicines, 2(1), 57-62.
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Recent usage of kava has been documented in forensic investigations by quantitation of kavain in blood specimens. The principal urinary metabolite, conjugated 4'-OH-kavain, is generally detectable for up to 48 hours.R. Baselt, Disposition of Toxic Drugs and Chemicals in Man, 8th edition, Biomedical Publications, Foster City, CA, 2008, pp. 803–804.
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Sometimes an internal standard is added at a known concentration directly to an analytical sample to aid in quantitation. The amount of analyte present is then determined relative to the internal standard as a calibrant. An ideal internal standard is isotopically-enriched analyte which gives rise to the method of isotope dilution.
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Development of a stable isotope dilution assay for the quantitation of glycidamide and its application to foods and model systems. Journal of agricultural and food chemistry, 56(15), 6087-6092. The first experiments on glycidamide formation were done by Murray and Cloke (1934). They tried to form glycidamides from α,β-ethylenic nitriles.
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Ocaña MF, Neubert H. An immunoaffinity liquid chromatography-tandem mass spectrometry assay for the quantitation of matrix metalloproteinase 9 in mouse serum. Anal Biochem. 2010 Apr 15;399(2):202–10. Addition of this specific capture step provides two primary advantages in comparison with a conventional workflow analyzing an unfractionated sample digest: sensitivity and throughput.
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Equilibrium gel is made from a synthetic clay. Unlike other gels, it maintains the same consistency throughout its structure and is stable, which means it does not separate into sections of solid mass and those of more liquid mass. Equilibrium gel filtration liquid chromatography is a technique used for the quantitation of ligand binding.
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8plex iTRAQ kit Isobaric tags for relative and absolute quantitation (iTRAQ) is an isobaric labeling method used in quantitative proteomics by tandem mass spectrometry to determine the amount of proteins from different sources in a single experiment. It uses stable isotope labeled molecules that can be covalent bonded to the N-terminus and side chain amines of proteins.
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Quantitative Mass Spectrometry. Multiple methods allow for the quantitation of proteins by mass spectrometry (quantitative proteomics), and recent advances have enabled quantifying thousands of proteins in single cells. Typically, stable (e.g. non- radioactive) heavier isotopes of carbon (13C) or nitrogen (15N) are incorporated into one sample while the other one is labeled with corresponding light isotopes (e.g.
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Recently EThcD has been developed combining electron-transfer and higher-energy collision dissociation. Compared to the usual fragmentation methods, EThcD scheme provides more informative MS/MS spectra for unambiguous phosphosite localization. A detailed characterization of the sites of phosphorylation is very difficult, and the quantitation of protein phosphorylation by mass spectrometry requires isotopic internal standard approaches.
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Optical density of ribosome sample. The important wavelengths of 260nm and 280nm are labeled. In molecular biology, quantitation of nucleic acids is commonly performed to determine the average concentrations of DNA or RNA present in a mixture, as well as their purity. Reactions that use nucleic acids often require particular amounts and purity for optimum performance.
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Negative chemical ionization (NCI), charge-exchange chemical ionization and atmospheric-pressure chemical ionization (APCI) are some of the common variations of this technique. CI has several important applications in identification, structure elucidation and quantitation of organic compounds. Beside the applications in analytical chemistry, the usefulness in chemical ionization extends toward biochemical, biological and medicinal fields as well.
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Platelet aggregation studies are optional. Serum protein electrophoresis results indicate evidence of a monoclonal spike but cannot establish the spike as IgM. An M component with beta-to-gamma mobility is highly suggestive of Waldenström's macroglobulinemia. Immunoelectrophoresis and immunofixation studies help identify the type of immunoglobulin, the clonality of the light chain, and the monoclonality and quantitation of the paraprotein.
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Fremy's salt, being a long-lived free radical, is used as a standard in electron paramagnetic resonance (EPR) spectroscopy, e.g. for quantitation of radicals. It intense EPR spectrum is dominated by three lines of equal intensity with a spacing of about 13 G (= 1.3 mT). \- See page 463 for information on intensity measurements and page 86 for an EPR spectrum of Fremy's salt.
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High-Throughput SISCAPA Quantitation of Peptides from Human Plasma Digests by Ultrafast, Liquid Chromatography-Free Mass Spectrometry. J Proteome Res. 2012 Nov 19;:121119143208008–8.Razavi M, Johnson LDS, Lum JJ, Kruppa G, Anderson NL, Pearson TW. Quantification of a Proteotypic Peptide from Protein C Inhibitor by Liquid Chromatography-Free SISCAPA-MALDI Mass Spectrometry: Application to Identification of Recurrence of Prostate Cancer.
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KHP is also a useful standard for total organic carbon (TOC) testing. Most TOC analyzers are based on the oxidation of organics to carbon dioxide and water, with subsequent quantitation of the carbon dioxide. Many TOC analysts suggest testing their instruments with two standards: one typically easy for the instrument to oxidize (KHP), and one more difficult to oxidize. For the latter, benzoquinone is suggested.
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Bromopyrogallol red is designed to be a hydrogen donor for peroxidase. Instead of an indicator, bromopyrogallol red is now used as a catalyst, and its reaction rate depends upon enzyme and substrate concentrations. With the HRP-H2O2-BPR catalytic system, the bromopyrogallol red is determined to be an efficient reagent and quantitation of HRP can be performed. It will increase the reaction rate of H2O2 and glucose.
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Simultaneous detection of potato viruses, PLRV, PVA, PVX and PVY from dormant potato tubers by TaqMan(R) real-time RT-PCR. J Virol Methods 142, 1-9. and discrimination of PVYO and PVYN isolatesBalme-Sinibaldi, V., Tribodet, M., Croizat, F., Lefeuvre, P., Kerlan, C., Jacquot, E., 2006. Improvement of Potato virus Y (PVY) detection and quantitation using PVYN- and PVYO-specific real-time RT-PCR assays.
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Similarly, the company's PathAlert technology was selected to monitor Yersinia pestis, the causative agent of the plague, at the Torino Winter Games in 2006. Their Qubit platform for RNA, DNA, and protein quantitation was awarded an R&D; 100 Award as being a "Top 100 Technologically Significant New Product" by R&D; Magazine.Invitrogen's Qubit Platform Wins 2007 R&D; 100 Award . Invitrogen developed and introduced stem cell products.
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Allyl propyl disulfide is an organosulfur compound with the chemical formula C3H5S2C3H7. It is a volatile pale-yellow liquid with a strong odor. It is a major component of onion oil and is used in food additives and flavors.Lawson, Larry D.; Wang, Zhen Yu J.; Hughes, Bronwyn G. "Identification and HPLC quantitation of the sulfides and dialk(en)yl thiosulfinates in commercial garlic products" Planta Medica 1991, vol.
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In 2004, Mike Hunkapiller retired and Cathy Burzik replaced him as President of Applied Biosystems. Applera collaborated with General Electric, Abbott Laboratories, Seattle Genetics, and Merck in diagnostics development. Applied Biosystmes also teamed with Northrop Grumman and Cepheid of Sunnyvale, California, to detect Bacillus anthracis during the anthrax contamination case of the U.S. Postal Service. In 2005, the company released new tools for small molecule quantitation in pharmaceutical drug development.
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Serotonin, and consequently 5-HIAA, are produced in excess by most carcinoid tumors, especially those producing the carcinoid syndrome of flushing, hepatomegaly (enlarged liver), diarrhea, bronchospasm, and heart disease. Quantitation of urinary 5-HIAA is the best test for carcinoid, but scrupulous care must be taken that specimen collection and patient preparation have been correct. Carcinoid tumors may cause increased excretion of tryptophan, 5-hydroxytryptophan and histamine as well as serotonin.
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Protein deamidation has been commonly analyzed by reverse-phase liquid chromatography (RPLC) through peptide mapping. Recently reported novel ERLIC-MS/MS method would enhance the separation of deamidated and non-deamidated peptides with increased identification and quantitation quantification. Mass spectrometry is commonly used to characterize deamidation states of proteins, including therapeutic monoclonal antibodies. The technique is especially useful for deamidation analysis due to its high sensitivity, speed, and specificity.
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"Advancing Parallel Solution Phase Library Synthesis through Efficient Purification, Quantitation, and Characterization Techniques" Journal of Laboratory Automation, 48 (1992) 3789. In order to handle the vast number of structural possibilities, researchers often create a 'virtual library', a computational enumeration of all possible structures of a given pharmacophore with all available reactants.E. V.Gordeeva et al. "COMPASS program - an original semi-empirical approach to computer-assisted synthesis" Tetrahedron, 48 (1992) 3789.
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It may cause allergic skin reactions in humans. Excessive exposure can cause nausea, headache, muscle weakness, salivation, shortness of breath and seizures. In humans, cypermethrin is deactivated by enzymatic hydrolysis to several carboxylic acid metabolites, which are eliminated in the urine. Worker exposure to the chemical can be monitored by measurement of the urinary metabolites, while severe overdosage may be confirmed by quantitation of cypermethrin in blood or plasma.
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Fentanyl may be measured in blood or urine to monitor for abuse, confirm a diagnosis of poisoning, or assist in a medicolegal death investigation. Commercially available immunoassays are often used as initial screening tests, but chromatographic techniques are generally used for confirmation and quantitation. The Marquis Color test may also be used to detect the presence of fentanyl. Using formaldehyde and sulfuric acid, the solution will turn purple when introduced to opium drugs.
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Ion trap EI MS can be incorporated for the identification and quantitation of nonylphenol polyethoxylate (NPEO) residues and their degradation products such as nonylphenol polyethoxy carboxylates and carboxyalkylphenol ethoxy carboxylates, in the samples of river water and sewage effluent. Form this research, they have found out that the ion trap GC- MS is a reliable and convenient analytical approach with variety of ionization methods including EI, for the determination of target compounds in environmental samples.
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Tests The HI test is frequently used for detection and quantitation of humoral antibody for PPV. Antibody sometimes can be detected as early as 5 days after swine are exposed to live virus, and it may persist for years. Sera examined by the HI test are usually pretreated by heat inactivation (56?C, 30 minutes) and by adsorption with erythrocytes (to remove naturally occurring hemagglutinins) and kaolin (to remove or reduce nonantibody inhibitors of HA).
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To evaluate peripheral lymphocyte function, T and B cell quantitation and in vitro responses to three nonspecific mitogens were studied in 34 persons with highest PBB levels (mean: 787 ppb), and in 56 with low levels (mean: 2.8 ppb). Again, no statistically significant differences in lymphocyte function were noted. However, these studies are ongoing and adverse reproductive-system effects continue to be found in the grandchildren of those who consumed tainted farm products.
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The amount of radioactivity can be quantified and serves as an indicator of the metabolic activity of the gland. A normal quantitation of radioiodine uptake demonstrates that about 8-35% of the administered dose can be detected in the thyroid 24 hours later. Overactivity or underactivity of the gland, as may occur with hyperthyroidism or hypothyroidism, is usually reflected in increased or decreased radioiodine uptake. Different patterns may occur with different causes of hypo- or hyperthyroidism.
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In this respect, several research works have explored the potential of PALM to perform a quantitation of the number of fluorophores (and therefore proteins of interest) present in a sample by counting the activated fluorophores. The approach used to treat the fluorescent dynamics of the fluorescent label used in the experiments will determine the final appearance of the super-resolution image, and the possibility of determining an unambiguous correspondence between a localization event and a protein in the sample.
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Diazepam may be quantified in blood or plasma to confirm a diagnosis of poisoning in hospitalized patients, provide evidence in an impaired driving arrest, or to assist in a medicolegal death investigation. Blood or plasma diazepam concentrations are usually in a range of 0.1–1.0 mg/l in persons receiving the drug therapeutically. Most commercial immunoassays for the benzodiazepine class of drugs cross-react with diazepam, but confirmation and quantitation are usually performed using chromatographic techniques.
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Trypsin also has been used to remove nonantibody inhibitors of HA. Parameters of the HI test have been studied in detail. The SN test is occasionally used for detection and quantitation of humoral antibody for PPV. Neutralization of infectivity is usually confirmed by the absence or reduction either of intranuclear inclusions or fluorescent cells in cultures or of viral hemagglutinin in the culture medium. The SN test has been reported to be more sensitive than the HI test.
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The most popular methods for isotope labeling are SILAC (stable isotope labeling by amino acids in cell culture), trypsin-catalyzed 18O labeling, ICAT (isotope coded affinity tagging), iTRAQ (isobaric tags for relative and absolute quantitation). “Semi- quantitative” mass spectrometry can be performed without labeling of samples. Typically, this is done with MALDI analysis (in linear mode). The peak intensity, or the peak area, from individual molecules (typically proteins) is here correlated to the amount of protein in the sample.
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Causes of increased foetal-maternal haemorrhage are seen as a result of trauma, placental abruption or may be spontaneous with no cause found. Up to 30 mL of foetal- maternal transfusion may take place with no significant signs or symptoms seen in either mother or foetus.Polesky HF Sebring ES. Evaluation of methods of detection and quantitation of fetal cells and their effects on Rh Ig usage. American Journal of Clinical Pathology 198 1; 76(suppl):525-529.
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This clearance is based on the CLSI/NCCLS-17A Limits of Detection and Limits of Quantitation, October 2004 guideline. The guidelines for diagnosis and management of food allergy issues by the National Institute of Health state that: In 2010 the United States National Institute of Allergy and Infectious Diseases recommended that the RAST measurements of specific immunoglobulin E for the diagnosis of allergy be abandoned in favor of testing with more sensitive fluorescence enzyme-labeled assays.
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Measurement of protein using bicinchoninic acid. Anal. Biochem. 150, 76-85 The BCA protein assay method maintains the high sensitivity and low variability among proteins associated with the Lowry protein assay, while providing increased tolerance to the presence of non-ionic detergents and buffer salts. The BCA assay has since become one of the most widely used methods of protein quantitation. Pierce was recognized for its international marketing efforts in 1990 when it received the US President's "E" Award for success in exporting.
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Methods: Strands can be purified by denaturing gel electrophoresis if needed,Methods: and precise concentrations determined via any of several nucleic acid quantitation methods using ultraviolet absorbance spectroscopy.Methods: The fully formed target structures can be verified using native gel electrophoresis, which gives size and shape information for the nucleic acid complexes. An electrophoretic mobility shift assay can assess whether a structure incorporates all desired strands.Methods: Fluorescent labeling and Förster resonance energy transfer (FRET) are sometimes used to characterize the structure of the complexes.
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The proper arsenic MCL continues to be debated. Some have argued that the 10 ppb federal standard is still too high, while others have argued that 10 ppb is needlessly strict. Individual states can establish lower arsenic limits; New Jersey has done so, setting a maximum of 0.005 mg/L (5 ppb) for arsenic in drinking water.Megan A. Ferguson and others, Lowering the detection limit for arsenic: implications for a future practical quantitation limit, American Water Works Association Journal, Aug.
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Pharmacokinetics is often studied using mass spectrometry because of the complex nature of the matrix (often plasma or urine) and the need for high sensitivity to observe concentrations after a low dose and a long time period. The most common instrumentation used in this application is LC-MS with a triple quadrupole mass spectrometer. Tandem mass spectrometry is usually employed for added specificity. Standard curves and internal standards are used for quantitation of usually a single pharmaceutical in the samples.
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In alternative fashion, the primers or probe can be designed without methylation specificity if discrimination is needed between the CpG pairs within the involved sequences. Quantitation is made in reference to a methylated reference DNA. A modification to this protocol to increase the specificity of the PCR for successfully bisulfite-converted DNA (ConLight-MSP) uses an additional probe to bisulfite-unconverted DNA to quantify this non-specific amplification. Further methodology using MSP-amplified DNA analyzes the products using melting curve analysis (Mc-MSP).
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Furanylfentanyl may be measured in blood or urine to monitor for use, confirm a diagnosis of poisoning, or assist in a medicolegal death investigation. Commercially available immunoassays are often used as initial screening tests, but chromatographic techniques are generally used for confirmation and quantitation. Blood furanylfentanyl concentrations are expected to be in a range of 1-45 μg/L in victims of fatal overdosage.Baselt, R. (2017) Disposition of Toxic Drugs and Chemicals in Man, 11th edition, Biomedical Publications, Foster City, CA, p. 2315.
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Validation of analytical procedures is imperative in demonstrating that a drug substance is suitable for a particular purpose.VALIDATION OF ANALYTICAL PROCEDURES: TEXT AND METHODOLOGY Common validation characteristics include: accuracy, precision (repeatability and intermediate precision), specificity, detection limit, quantitation limit, linearity, range, and robustness. In cases such as changes in synthesis of the drug substance, changes in composition of the finished product, and changes in the analytical procedure, revalidation is necessary to ensure quality control. All analytical procedures should be validated.
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When using fluorescent antibodies to image proteins in western blots, normalization requires that the user define the upper and lower limits of quantitation and characterize the linear relationship between signal intensity and the sample mass volume for each antigen. Both the target protein and the normalization control need to fluoresce within the dynamic range of detection. Many HKPs are expressed at high levels and are preferred for use with highly-expressed target proteins. Lower expressing proteins are difficult to detect on the same blot.
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Thioglycolysis can be used to study proanthocyanidins or the oxidation of condensed tannins., It is also used for lignin quantitation. Reaction on condensed tannins from Douglas fir bark produces epicatechin and catechin thioglycolates.Douglas-Fir Bark: Characterization of a Condensed Tannin Extract, by Hong-Keun Song, A thesis submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science, December 13, 1984 Condensed tannins from Lithocarpus glaber leaves have been analysed through acid- catalyzed degradation in the presence of cysteamine.
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Gene and exon read counts may be calculated quite easily using HTSeq, for example. Quantitation at the transcript level is more complicated and requires probabilistic methods to estimate transcript isoform abundance from short read information; for example, using cufflinks software. Reads that align equally well to multiple locations must be identified and either removed, aligned to one of the possible locations, or aligned to the most probable location. Some quantification methods can circumvent the need for an exact alignment of a read to a reference sequence altogether.
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Zeng's main focus is on proteomics and the dynamic behavior of proteins. She leads a research team at the Institute of Biochemistry and Cell Biology at the Shanghai Institute for Biological Sciences to make progress in methodology development, application of quantitative proteomics, and regulation mechanism of protein dynamic behavior. Her team developed novel methods for proteomics research including multi-dimensional LC-MS/MS that can aid protein profiling, phosphopeptide enrichment, and multiplex quantitation. They applied quantitative proteomics in cell signaling and biomarker discovery of diabetes.
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Thioglycolysis can be used to study procyanidins or the oxidation of condensed tannins. It is also used for lignin quantitation. Reaction on condensed tannins from Douglas fir bark produces epicatechin and catechin thioglycolates.Douglas-Fir Bark: Characterization of a Condensed Tannin Extract, by Hong-Keun Song, A thesis submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science, December 13, 1984 Condensed tannins from Lithocarpus glaber leaves have been analysed through acid-catalyzed degradation in the presence of cysteamine.
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VUV detectors complement mass spectrometry, which struggles with characterizing constitutional isomers and compounds with low mass quantitation ions. VUV spectra can also be used to deconvolve analyte co- elution, resulting in an accurate quantitative representation of individual analyte contribution to the original response.H. Fan, J. Smuts, L. Bai, P. Walsh, D.W. Armstrong, K.A. Schug, Gas chromatography–vacuum ultraviolet spectroscopy for analysis of fatty acid methyl esters, Food Chem. 2016, 194, 265–271 This characteristically lends itself to significantly reducing GC runtimes through flow rate-enhanced chromatographic compression.
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The use of only heavy amino acids eliminates the need for 100% incorporation of amino acids needed for SILAC. The increased multiplexing capability of NeuCode amino acids is from the use of mass defects from extra neutrons in the stable isotopes. These small mass differences however need to be resolved on high resolution mass spectrometers. One of the main benefits of SILAC is the level of quantitation bias from processing errors is low because heavy and light samples are combined before sample preparation for MS analysis.
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When interpreting the results of a test, it is important to consider the diamorphine usage history of the individual, since a chronic user can develop tolerance to doses that would incapacitate an opiate-naive individual, and the chronic user often has high baseline values of these metabolites in his system. Furthermore, some testing procedures employ a hydrolysis step before quantitation that converts many of the metabolic products to morphine, yielding a result that may be 2 times larger than with a method that examines each product individually.
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The triple quadrupole mass spectrometer allows for increased sensitivity and specificity yielding lower detection and quantitation limits. For these reasons, employment of the TQMS is a vital asset in the fields of drug metabolism, pharmacokinetics, environmental studies, and biological analyses. In most drug and pharmacokinetic studies, animals like rats, are subjected to a new drug in order to probe how the substance metabolizes in the body. By analyzing the rat’s urine or plasma with a triple quadrupole coupled to liquid chromatography, the concentration and fragmentation pattern of the new drug can be determined.
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Interactions are measured in real time, providing the ability to monitor binding specificity, rates of association and dissociation, or concentration, with high precision and accuracy. Only molecules binding to or dissociating from the biosensor can shift the interference pattern and generate a response profile. Unbound molecules, changes in the refractive index of the surrounding medium, or changes in flow rate do not affect the interference pattern. This is a unique characteristic of bio-layer interferometry and extends its capability to perform in crude samples used in applications for protein-protein interactions, quantitation, affinity, and kinetics.
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The sequences are deconvoluted to find the frequency of each tag. The tag frequency can be used to report on transcription of the gene that the tag came from. Serial analysis of gene expression (SAGE) was a development of EST methodology to increase the throughput of the tags generated and allow some quantitation of transcript abundance. cDNA is generated from the RNA but is then digested into 11 bp "tag" fragments using restriction enzymes that cut DNA at a specific sequence, and 11 base pairs along from that sequence.
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Quantitative PCR can also be applied to the detection and quantification of DNA in samples to determine the presence and abundance of a particular DNA sequence in these samples. This measurement is made after each amplification cycle, and this is the reason why this method is called real time PCR (that is, immediate or simultaneous PCR). In the case of RNA quantitation, the template is complementary DNA (cDNA), which is obtained by reverse transcription of ribonucleic acid (RNA). In this instance the technique used is quantitative RT-PCR or Q-RT-PCR.
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The OpenMS Proteomics Pipeline (TOPP) is a set of computational tools that can be chained together to tailor problem-specific analysis pipelines for HPLC-MS data. It transforms most of the OpenMS functionality into small command line tools that are the building blocks for more complex analysis pipelines. The functionality of the tools ranges from data preprocessing (file format conversion, baseline reduction, noise reduction, peak picking, map alignment,...) over quantitation (isotope-labeled and label-free) to identification (wrapper tools for Mascot, Sequest, InsPecT and OMSSA). TOPP is developed in the groups of Prof.
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CATAI developed the Videophone network in the Canary Islands in 1991 for distant support. At the present it includes the best practice implementation pilots in phone medicine (oncology, particularly home care, and psychiatry, particularly childhood psychiatry), Tele-ECG and Tele-ultrasounds, particularly obstetrics and gynaecology. The first in the world to carry out distant DNA quantitation (in 1991), it was applied to image analysis for prognostic factors in breast cancer. Objective image analysis and prognostic factors have been incorporated into the regional breast cancer registry of over 3000 patients (see above).
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Therefore, a number of label free detection methods are available, such as surface plasmon resonance (SPR), carbon nanotubes, carbon nanowire sensors (where detection occurs via changes in conductance) and microelectromechanical system (MEMS) cantilevers. All these label free detection methods are relatively new and are not yet suitable for high-throughput protein interaction detection; however, they do offer much promise for the future. Immunoassays on thiol-ene "synthetic paper" micropillar scaffolds have shown to generate a superior fluorescence signal. Protein quantitation on nitrocellulose coated glass slides can use near-IR fluorescent detection.
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Protein quantitation is accomplished by comparing the intensities of the reporter ions in the MS/MS spectra. Three types of tandem mass tags are available with different reactivity: (1) reactive NHS ester which provides high-efficiency, amine-specific labeling (TMTduplex, TMTsixplex, TMT10plex and TMT11plex), (2) reactive iodacetyl function group which labels sulfhydryl-(-SH) groups (iodoTMT) and (3) reactive alkoxyamine functional group which provides covalent labeling of carbonyl-containing compounds (aminoxyTMT). A key benefit of isobaric labeling over other quantification techniques (e.g. SILAC, ICAT, Label-free) is the increased multiplex capabilities and thus increased throughput potential.
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Isobaric labeling for tandem mass spectrometry: proteins are extracted from cells, digested, and labeled with tags of the same mass. When fragmented during MS/MS, the reporter ions show the relative amount of the peptides in the samples. An isobaric tag for relative and absolute quantitation (iTRAQ) is a reagent for tandem mass spectrometry that is used to determine the amount of proteins from different sources in a single experiment. It uses stable isotope labeled molecules that can form a covalent bond with the N-terminus and side chain amines of proteins.
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Researchers began using pumps and injectors to make a rudimentary design of an HPLC system. Gas amplifier pumps were ideal because they operated at constant pressure and did not require leak-free seals or check valves for steady flow and good quantitation. Hardware milestones were made at Dupont IPD (Industrial Polymers Division) such as a low-dwell-volume gradient device being utilized as well as replacing the septum injector with a loop injection valve. While instrumentational developments were important, the history of HPLC is primarily about the history and evolution of particle technology.
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Use of alcian blue has historically been a popular staining method in histology especially for light microscopy in paraffin embedded sections and in semithin resin sections. The tissue parts that specifically stain by this dye become blue to bluish-green after staining and are called "Alcianophilic" (comparable to "eosinophilic" or "sudanophilic"). Alcian blue staining can be combined with H&E; staining, PAS staining and van Gieson staining methods. Alcian blue can be used to quantitate acidic glycans both in microspectrophotometric quantitation in solution or for staining glycoproteins in polyacrylamide gels or on western blots.
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Tyrosine Beyond the identification of physical clinical symptoms outlined above, the definitive criterion for diagnostic assessment of Tyrosinemia Type I is elevated succinylacetone (SA) in blood and urine. Elevated SA levels are not associated with any other known medical condition, so there is minimal risk of misdiagnosis. Quantitation of tyrosine levels is also used as a diagnostic but is less reliable due to high false positive and false negative rates. Newborns are not generally screened for HT1 due to rarity of the condition and lack of apparent symptoms at time of birth.
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Signal of unknowns can be compared to that of standards allowing quantitation of the target antigen. To aid in the diagnosis of infectious diseases, immunoassays can detect or measure antigens from either infectious agents or proteins generated by an infected organism in response to a foreign agent. For example, immunoassay A may detect the presence of a surface protein from a virus particle. Immunoassay B on the other hand may detect or measure antibodies produced by an organism's immune system that are made to neutralize and allow the destruction of the virus.
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A further method to differentiate converted from unconverted bisulfite-treated DNA is using high-resolution melting analysis (HRM), a quantitative PCR-based technique initially designed to distinguish SNPs. The PCR amplicons are analyzed directly by temperature ramping and resulting liberation of an intercalating fluorescent dye during melting. The degree of methylation, as represented by the C-to-T content in the amplicon, determines the rapidity of melting and consequent release of the dye. This method allows direct quantitation in a single-tube assay, but assesses methylation in the amplified region as a whole rather than at specific CpG sites.
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Isobaric tag labeling enables simultaneous identification and quantification of proteins from multiple samples in a single analysis. To quantify proteins, peptides are labeled with chemical tags that have the same structure and nominal mass, but vary in the distribution of heavy isotopes in their structure. These tags, commonly referred to as tandem mass tags, are designed so that the mass tag is cleaved at a specific linker region upon higher-energy collisional-induced dissociation (HCD) during tandem mass spectrometry yielding reporter ions of different masses. Protein quantitation is accomplished by comparing the intensities of the reporter ions in the MS/MS spectra.
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Although m6A sites could be profiled at high resolution using UV-based methods, the stoichiometry of m6A sites - the methylation status or the ratio m6A+ to m6A- for each individual site within a type of RNA - is still unknown. SCARLET (2013) and m6A-LAIC-seq (2016) allows for the quantitation of stoichiometry at a specific locus and transcriptome-wide, respectively. Bioinformatics methods used to analyze m6A peaks do not make any prior assumptions about the sequence motifs within which m6A sites are usually found, and take into consideration all possible motifs. Therefore, it is less likely to miss sites.
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Rapid scanning became feasible because computers could be used to step the spectrometer from one ion peak to the next. This allowed acquisition and display of data in real-time, and gave operators the potential to interact with the system and modify what was being monitored. A major strength of the instrument was precise quantitation. It could be used to detect trace contaminants in environmental samples, to identify drugs in a case of overdose, and to measure drug metabolites. After the United States Environmental Protection Agency (EPA) was established in 1970, it became a major customer for Finnigan's GC/MS.
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After graduation in chemistry he worked for a year at the Philip R. Park Research Foundation taking care of an animal colony and assisting with growth experiments on synthetic amino acid diets. One of these was the experiment by Geiger that first demonstrated that the essential amino acids must be present simultaneously for growth to occur. He returned to graduate school at the UCLA chemistry department with professor of biochemistry M.S. Dunn to develop microbiological methods for the quantitation of the pyrimidines. The day after graduating on 19 June 1949, he married Elizabeth Furlong and the next day left for New York City and the Rockefeller Institute for Medical Research.
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After proper mixing of the sample and the reagent, the mixture is incubated for 10 minutes at ambient temperature and the absorbance of the solution is read at 440 nm. Flavonoid content is expressed in mg/g of quercetin."Teneurs en principaux flavonoides des fleurs de Cratageus monogyna Jacq et de Cratageus Laevigata (Poiret D.C.) en Fonction de la vegetation". J. L. Lamaison and A. Carnet, Plantes Medicinales Phytotherapie, 1991, XXV, pages 12–16 Quantitation results produced by the means of diode array detector- coupled HPLC are generally given as relative rather than absolute values as there is a lack of commercially available standards for every phenolic molecules.
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These slides are commercially available through Schott AG. Nevertheless, conventional white nitrocellulose films continue to be the dominant surface for many protein microarray applications because the claims above have not proved relevant to end user requirements. Regardless, nitrocellulose slide manufacturers like Grace Bio-Labs continue to develop new nitrocellulose surfaces to further optimize their use in protein microarrays. A method for protein quantitation on nitrocellulose coated glass slides uses near-IR fluorescent detection with quantum dots. Traditional porous nitrocellulose signal to noise is limited by auto-fluorescence of the nitrocellulose at the respective required wavelengths of excitation and emission for standard organic fluorescent detection probes.
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The reactivity of the various antioxidants tested are compared to that of Trolox, which is a vitamin E analog. Other antioxidant capacity assays which use Trolox as a standard include the diphenylpicrylhydrazyl (DPPH), oxygen radical absorbance capacity (ORAC), ferric reducing ability of plasma (FRAP) assays or inhibition of copper-catalyzed in vitro human low- density lipoprotein oxidation. New methods including the use of biosensors can help monitor the content of polyphenols in food. Quantitation results produced by the mean of diode array detector–coupled HPLC are generally given as relative rather than absolute values as there is a lack of commercially available standards for all polyphenolic molecules.
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Their model succeeded in a median 890-fild selectivity for 44 cancer-related DNA SNVs, with a minimum of 200, which represents at least a 30-fold improvement over previous hybridization- based assays. In addition, they applied this technology to assay low VAF sequences from human genomic DNA following PCR, as well as directly to synthetic RNA sequences. Based on the expertise, they developed a new PCR method called Blocker Displacement Amplification (BDA). It is a temperature- robust PCR which selectively amplifies all sequence variants within a roughly 20 nt window by 1000-fold over wildtype sequences, allowing easy detection and quantitation of hundreds of potentials variants originally at ≤ 0.1% allele frequency.
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For example, a B12-deficient state which causes megaloblastic anemia and which may be mistaken for classical PA may be caused by infection with the tapeworm Diphyllobothrium latum, possibly due to the parasite's competition with host for vitamin B12. The classic test for PA, the Schilling test, is no longer widely used, as more efficient methods are available. This historic test consisted, in its first step, of taking an oral dose of radiolabelled vitamin B12, followed by quantitation of the vitamin in the patient's urine over a 24-hour period via measurement of the radioactivity. A second step of the test repeats the regimen and procedure of the first step, with the addition of oral intrinsic factor.
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Affinity capillary electrophoresis (ACE) refers to a number of techniques which rely on specific and nonspecific binding interactions to facilitate separation and detection through a formulary approach in accordance with the theory of electromigration. Using the intermolecular interactions between molecules occurring in free solution or mobilized onto a solid support, ACE allows for the separation and quantitation of analyte concentrations and binding and dissociation constants between molecules. With ACE, scientists hope to develop strong binding drug candidates, understand and measure enzymatic activity, and characterize the charges on proteins. Affinity capillary electrophoresis can be divided into three distinct techniques: non- equilibrium electrophoresis of equilibrated sample mixtures, dynamic equilibrium ACE, and affinity-based ACE.
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In addition, due to the relative size of the human genome in comparison with microbial genomes the interference can occur at low levels of contaminating material. Another challenge for clinical metagenomics in regards to sensitivity is the diagnosis of coinfections where there are present high-titer pathogens that can generate biased results as they may disproportionately soak up reads and make difficult to distinguish the less predominant pathogens. In addition to issues with interfering substances, specially in the diagnosis area, accurate quantitation and sensitivities are essential as a confusion in the results can affect to a third person, the patient. For these reason, practitioners currently have to be keenly aware of the index-swapping issues associated with Illumina sequencing which can lead to trace incorrectly barcoded samples.
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AMS was developed in the late 1970s from two distinct research threads with a common goal: an improvement in radiocarbon dating that would make efficient use of datable material and that would extend the routine and maximum reach of radiocarbon dating. AMS is routinely used in geochronology and archaeology, but biological applications began appearing in 1990 mainly due to the work of scientists at Lawrence Livermore National Laboratory. AMS service is now more accessible for biochemical quantitation from several private companies and non-commercial access to AMS is available at the National Institutes of Health (NIH) Research Resource at Lawrence Livermore National Laboratory, or through the development of smaller affordable spectrometers. AMS does not measure the radioactivity of carbon-14 in microdose samples.
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The current proteomics of microbial community makes use of both gel-based (one-dimensional and two-dimensional) and non-gel liquid chromatography based separation, where both rely on mass spectrometry based peptide identification. While proteomics is largely a discovery-based approach that is followed by other molecular or analytical techniques to provide a full picture of the subject system, it is not limited to simple cataloging of proteins present in a sample. With the combined capabilities of "top-down" and "bottom-up" approaches, proteomics can pursue inquiries ranging from quantitation of gene expression between growth conditions (whether nutritional, spatial, temporal, or chemical) to protein structural information. A metaproteomics study of the human oral microbiome found 50 bacterial genera using shotgun proteomics.
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Secondary-ion mass spectrometry (SIMS) is a technique used to analyze the composition of solid surfaces and thin films by sputtering the surface of the specimen with a focused primary ion beam and collecting and analyzing ejected secondary ions. The mass/charge ratios of these secondary ions are measured with a mass spectrometer to determine the elemental, isotopic, or molecular composition of the surface to a depth of 1 to 2 nm. Due to the large variation in ionization probabilities among different materials, SIMS is generally considered to be a qualitative technique, although quantitation is possible with the use of standards. SIMS is the most sensitive surface analysis technique, with elemental detection limits ranging from parts per million to parts per billion.
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More than a million of different probes can be synthesized on an array with Affymetrix's Genechip technology with a detection limit of one to ten copies of mRNA per well. Optimized microarrays are typically considered to produce repeatable relative quantitation of different targets. Currently, FDA have already approved a number of diagnostics assays utilizing microarrays: Agendia's MammaPrint assays can inform the breast cancer recurrence risk by profiling the expression of 70 genes related to breast cancer; Autogenomics INFNITI CYP2C19 assay can profile genetic polymorphisms, whose impacts on therapeutic response to antidepressants are great; and Affymetrix's CytoScan Dx can evaluate intellectual disabilities and congenital disorders by analyzing chromosomal mutation. In the future, the diagnostic tools for cancer will likely to focus on the Next Generation Sequencing(NGS).
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The isolation of a natural product refers, depending on context, either to the isolation of sufficient quantities of pure chemical matter for chemical structure elucidation, derivitzation/degradation chemistry, biological testing, and other research needs (generally milligrams to grams, but historically, often more), or to the isolation of "analytical quantities" of the substance of interest, where the focus is on identification and quantitation of the substance (e.g. in biological tissue or fluid), and where the quantity isolated depends on the analytical method applied (but is generally always sub-microgram in scale). The ease with which the active agent can be isolated and purified depends on the structure, stability, and quantity of the natural product. The methods of isolation applied toward achieving these two distinct scales of product are likewise distinct, but generally involve extraction, precipitation, adsorptions, chromatography, and sometimes crystallizations.
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Conventional mass spectrometers are often large as well as prohibitively expensive and complex in their operation which has led to the increased attractiveness of miniature mass spectrometers (MMS) for a variety of applications. MMS are optimized towards affordability and simple operation, often forgoing the need for experienced technicians, having a low cost of manufacture, and being small enough in size to allow for the transfer of data collection from the laboratory into the field. These advantages often come at the cost of reduced performance where MMS resolution, as well as the limits of detection and quantitation, are often barely adequate to perform specialized tasks. The integration of DMF with MMS has the potential for significant improvement of MMS systems by increasing throughput, resolution, and automation, while decreasing solvent cost, enabling lab grade analysis at a much reduced cost.
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Little to no parent drug is present in urine, so there is a lot of research to try and identify the major urinary metabolites that could be used as markers of synthetic cannabinoid intake. The major urinary metabolites in most cases are formed by oxidation of the alkyl side-chain to an alcohol and carboxylic acid followed by glucuronide conjugation and also by N-dealkylation and aromatic hydroxylation. For example, the main metabolites of JWH-018, of which there are over 20, include carboxylated, monohydroxylated, dihydroxylated, and trihydroxylated metabolites, but they are mostly excreted in urine as glucuronide conjugates. The presence of synthetic cannabinoids or their metabolites in bodily fluids may be determined using specifically-targeted commercially available immunoassay screening methods (EMIT), while liquid chromatography-mass spectrometry is most often used for confirmation and quantitation. There are commercially available EMIT kits for the screening of the synthetic cannabinoids JWH-018, JWH-073, JWH-398, JWH-200, JWH-019, JWH-122, JWH-081, JWH-250, JWH-203, CP-47,497, CP-47,497-C8, HU-210, HU-211, AM-2201, AM-694, RCS-4, and RCS-8 through companies like NMS Labs, Cayman Chemical, and Immunoanalysis Corporation.
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