The ESTD procedure is the basic quantitation procedure in which both calibration and unknown samples are analyzed under the same conditions. The results from the unknown sample are then compared with those of the calibration sample to calculate the amount in the unknown.
The ESTD procedure uses absolute response factors unlike the ISTD procedure. The response factors are obtained from a calibration and then stored. In following sample runs, compound amounts are calculated by applying these response factors to the measured sample responses. Make sure that the sample injection size is reproducible from run to run, since there is no standard in the sample to correct for variations in injection size or sample preparation.
When preparing an ESTD analysis, the calculation of the amount of a particular compound in an unknown sample occurs in two steps:
An equation for the curve through the calibration points for this compound is calculated using the type of fit specified in the Mode and Origin settings in the compound table.
The amount of the compound in the unknown is calculated using the equation described above. This amount may appear in the report or it may be used in additional calculations called for by sample multiplier, compound multiplier, or dilution factor values before being reported.