Quantitative standardization

Adequate precision and accuracy are only likely to be achieved if some standardization procedure is employed and the nature of this, internal or external standards or the method of standard additions, needs to be chosen carefully. If internal standardization procedures are adopted then appropriate compound(s) must be chosen and their effect on the chromatographic and mass spectrometry methods assessed. The ideal internal standard is an isotopically labelled analogue of the analyte but, although there are a number of commercial companies who produce a range of such molecules, these are not always readily available. An analytical laboratory is then faced with the choice of carrying out the synthesis of the internal standard themselves or choosing a less appropriate alternative with implications on the accuracy and precision of the method to be developed. 

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The quantitation of HCV RNA in serum may be important in predicting and monitoring response to antiviral therapy (Davis, 1994). A variety of methods have been used to quantitate HCV RNA, including endpoint dilution RT-PCR, competitive PCR, multicyclic RT-PCR, nucleic acid sequence-based amplification, RT-PCR with a single internal quantitation standard, and bDNA (Chazouilleres et al, 1994 Detmer et al., 1996 Ishiyama et al, 1992 Kaneko et al., 1992 Klevits et al., 1991 Kobayashi etal., 1993 Miskovsky etal., 1996). 

All quantitation standards are easily observed under these conditions, including the 0.05% LOD standard. 

In this procedure, two templates—an experimental one and a control quantitation standard of roughly the same size—compete for a chimeric primer that contains portions homologous to each. After gel electrophoresis, the accumulation of amplitied products from the control template is compared with that from the... 

For quantitative estimation, a sealed reusable capillary tube, with a known quantity of sodium salt of trimethylsilyl propionic acid (TSP) dissolved in 35 pi of D20, is inserted into the NMR tube while obtaining NMR spectra. The internal standard TSP is used as a chemical shift reference as well as a quantitative standard for the estimation of metabolites, and D20 is used as the field-frequency-lock . Spectra are acquired at room temperature. Typical spectra acquired at room temperature of human bile and standard glycine- and taurine-conjugated BAs are shown in Fig. 5.4.16. 

Talmage S. B., 1925, Quantitative standards for hardness of the ore minerals, Econ Geol., 20, 531-553. 

The value of the theory is to be assessed exclusively by its capacity for experimental test. Model experiments give quantitative standards by means of which the probability of each stage in the emergence of life may be estimated. 

The PARCC parameters are meaningful only if compared to certain standards as a means to determine their acceptability. The EPA gives the following definition to these qualitative and quantitative standards, which are called acceptance criteria (EPA, 1997a) ... 

The zeolite products with the highest XRD intensities and with the lowest amorphous material impurities were used as the quantitative standards for both Na-ZSM-5 and mordenite. The degree of crystallization was estimated by comparing the sum of the respective XRD peak areas (around 20 = 20-30°) with those of the standard. 

Same laser for Raman and one optical tweezers 785 nm 2,6-pyridine dicarboxylic acid (Ca-DPA) in bacteria spores Ca-DPA at 1,017 cm Raman spectra of the Ca-DPA peak can be used as quantitative standard measure to reveal concentration and characteristic spore information... 

An indirect enzyme-linked immunosorbent assay (ELISA) was developed for maduramicin in poultry feed. The assay utilized polyclonal anti-maduramicin antibody raised in rabbits, maduramicin monoamide with 1,6-hexane diamine-conjugated ovalbumin as the coating antigen, horseradish peroxidase conjugated goat anti-rabbit IgG and 2,2 azinobis(3-ethylbenzthiazoline) sulfonic acid (ABTS) for quantitation. Standard curves ranging from 0 to 80 ng/mL maduramicin were constructed. The assay did not cross-react with monensin, lasalocid, salinomycin, lincomycin, narasin, chlortetracycline or roxarsone. Broiler feed fortified at 4 to 7 ppm maduramicin were shown to be quantifiable by ELISA at an average recovery of 98.1%. This ELISA method for maduramicin in poultry feed is comparable to the established HPLC-F method. 

Choice of quantitative standard - IS (isotopically labeled of not), external standard, or standard addition.154... 

Figure 2. High resolution gas chromatograms of Aroclor 1242 and Aroclor 1254. QS refers to quantitation standard, IS refers to Internal standard, and numbers are lUFAC numbers for chlorobiphenyls. ...

All GCMS data files were examined with a general search procedure developed for scanning GCMS data for anthropogenic chemicals at trace levels. Hard copies of the mass spectral data were examined manually to verify computer matches and Identify compounds not selected by the computer program. Identified compounds were then quantitated by multiplying their peak area with appropriate response factors obtained from analyses of quantitative standards under Identical Instrumental tunes and... 

Sample set or sequence method Controls and documents parameters of autosampler and sample/standard information Injection sequence vial, inject volume, injections, run time Functions inject samples, equilibrate, calibrate, quantitate Standard/sample info name, amount, sample weight, label claim, level... 

Once the pellets were air-dried, the 3 and 5 extended A9 DNA templates were resuspended in 20 pL of ddH20. After resuspension, 1 pL of the DNA samples were mixed with 1 pL of 6x Orange dye and quantitated against 1 pL of 100-bp and 200-bp double-stranded DNA quantitation standards. 

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