Determination of sample concentrations

The area of each recorded peak is proportional to the concentration of the substance. The area may therefore be used to determine the concentration of each individual substance. 

In the chromatogram shown in Fig. 41, the relative areas for the different substances are as follows  

The accuracy attainable by gas chromatography depends on the technique used (detector, method of integration and concentration of the sample). 

Even with manual injection, quantitative results are normally accurate to 1 - 2 % (RSD). With the aid of appropriate technology, e.g. electronic integrators or data systems, accuracy may be improved to less than 1 % (RSD). 

The main reason behind the extremely widespread acceptance of gas chromatography is its sensitivity. The simplest version of a thermal-conductivity detector can determine concentrations down to 0.01 % (100 ppm) (depending on the type of carrier gas and the substance to be determined). A flame ionization detection (FID) detects substances whose concentrations are in the ppm to ppb range. 

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The offset concentration after subtraction of the reagent blank (C g) is the nutrient concentration Czero of the ZW. In the formula for the determination of sample concentrations use the nominal standard concentrations plus Cano for Ch and C. ... 

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