In:
Аналитика и контроль, Ural Federal University, Vol. 25, No. 2 ( 2021), p. 146-154
Abstract:
Different algorithms for processing the quantitative gas chromatographic analysis data using the double standard addition method are compared for their accuracy. Three principal approaches are possible for such processing: I – simple comparison of values determined by single and double standard additions, II – approximation of «peak area of analyte» (S) – «mass of standard addition» (madd) dependence by the least squares method [linear regression, m(S)], and III – independent quantification of analyte with both standard additions followed by the linear extrapolation of two sub-results on the so-called «zero standard addition», mx(madd ® 0). It is concluded that the quantitation results obtained using the various modes of the method are comparable in accuracy, but somewhat underestimated relative to the specified amounts of analytes. The principal reason of such systematic errors is the evaporation of the solvent during the successive injecting of the same samples into the gas chromatograph. Due to this reason the peak areas, measured after the standard addition, appear to be slightly increased and this leads to the systematic underestimation of the results. The second (less important) factor is the small increase of the sample volumes due to the addition of the components to be determined. It is confirmed that the systematic errors of different modes of standard addition are not exceeding the values of their random uncertainties. The optimal results (considering their signs of deviations) are provided using the double standard addition method with extrapolation of sub-results on «zero standard addition». In order to exclude the possible influence of «human factor» (increasing the results precision during the series of analyses of similar samples due to the rising experience of analytical chemists) all parallel measurements have been performed by bachelor students of the Chemistry Institute of the St. Petersburg State University in the course of their laboratory practical works in chromatography. Such organization of experiments increases their credibility as it excluded the dependence of the results on the qualification of chemists.
Type of Medium:
Online Resource
ISSN:
2073-1442
,
2073-1450
DOI:
10.15826/analitika.2021.25.2.010
Language:
Unknown
Publisher:
Ural Federal University
Publication Date:
2021
detail.hit.zdb_id:
2915076-0
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