Response factors, determination

The water residue level is also determined from the relative responses of the analytes to the internal standards. The sample residue levels are calculated by comparison with an average response factor determined by triplicate analysis of a five-point calibration curve. Samples receive 5ng of each internal standard (0.1 ngmL ) and are concentrated 50-fold by Ci8 SPE before analysis to achieve adequate instrumental sensitivity. The calculations to determine the residue level in water are outlined in Section 7.3.3. 

Famoxadone, IN-JS940, and IN-KZ007 residues are measured in soil (p-g kg ), sediment (p-gkg ), and water (pgL ). Quantification is based on analyte response in calibration standards and sample extract analyses determined as pg mL Calibration standard runs are analyzed before and after every 1 samples in each analytical set. Analyte quantification is based on (1) linear regression analysis of (y-axis) analyte concentration (lagmL Q and (x-axis) analyte peak area response or (2) the average response factor determined from the appropriate calibration standards. The SLOPE and INTERCEPT functions of Microsoft Excel are used to determine slope and intercept. The AVERAGE and STDEV functions of Microsoft Excel are used to determine average response factors and standard deviations. 

Quantification is performed by comparing the sample response with an average response factor determined from the standard analyses. Internal standards are used... 

With care internal normalization can be used where peak size is measured by height instead of area, though this is rare. The response factor is now subject to slight variations in column temperature, injection technique, carrier flow, and the like, all mentioned under peak height measurement previously. This approach requires that the standard mix for response factors to be run as close in time to the unknown as possible and new response factors to be determined each time. Note also that response factors determined from area measurement in no way are the same for those determined from peak height. 

True quantification of pyrazines in the powdered sarples presented seme difficulty. Due to sensitivity problems in sampling reconstituted sairples, the decision was made to purge the powdered NFCM. An internal standard could not be easily added to a dry sample, so quantification was accomplished calculating concentrations relative to response factors determined for external standard solutions. Standardized concentration units were determined using the following relationships ... 

Semiquantitative analysis is carried out by comparing or fitting spectra for elemental ions (based on their natural abundances or response factors determined previously) and molecular ions to the experimental mass spectrum acquired over a wide mass range. Day to day changes in sensitivity and mass bias are corrected by measuring signals for a few elements in a standard solution. The keys to... 

Quantitative results were obtained using response factors determined with n-nonane internal standard. Peak areas were measured with a K and E planimeter. The low boiling fractions, i.e., methane, ethane, ethylene, isobutane, neopentane and neohexane were identified by authentic samples with a 4 x 1/8" Porapak Q Column. Preparative gas chromatography was carried out with a 6 x 1/4" Apiezon L Column. 

The GC-FID analysis is conducted by injection of 1 to 2 fil of FI or F3 into a gas chromatograph equipped with a high resolution capillary column (operated in sphtless injection mode). The injector and detector temperatures are set at 290 and 300°C, respectively. The GC temperature program is selected to achieve near-baseline separation of all of the saturated hydrocarbons. Quantitation of the individual components is performed by the internal standard method. The relative response factor (RRF) for each component is calculated relative to the internal standard. The TPH is also quantified by the internal standard method using the baseline corrected total area of the chromatogram and the average hydrocarbon response factor determined over the entire analytical range. ... 

The purity of pure gas requires to be checked prior to use for response factor determination or prior to linearity check of pure component response factors. Purity of pure gas is checked by consecutive analysis runs of each pure gas. The component area divided by the sum of peak areas recorded with each component, will be used as a measure of the purity of component. 

ID significant peaks by RRT and MW (LC-MS) only, unless more work is necessary for RRF (relative response factor) determination or project needs... 

Response factors determined at two-week intervals were found to deviate. Best results are obtained when response factors were determined just prior to each analysis. 

General—In the routine analysis of samples described in the scope of this procedure, it is possible to obtain all components of interest from a single run. Response factors, determined in duplicate runs on a selected reference standard, are used to convert peak areas (or peak heights) of the unknown sample to mol percent. 

Use the response factor determined for n-nonane for all the nonaromatic hydrocarbon plus benzene peaks. 

Use the response factor determined for o-xylene for all the peaks eluting after ethylbenzene, and the response factor determined for fi-nonane for all the nonaromatic hydrocarbon peaks. 

Calculate the weight percent concentration of the total nonaromatics and each impurity as follows. Use the response factor determined for n-nonane for all nonaromatic components, the factor for oxylene for all xylenes, and the factor for cumene for all aromatic hydrocarlrans containing nine or more carbon atoms as follows ... 

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