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Internal Quality Assurance Requirements for the Analysis of Dioxins in Environmental Samples

List of Figures

Figure 1

The figure shows two chromatograms: First chromatogram is acquired on a DB-5 column and it displays four peaks in elution order corresponding to following isomers: 1,2,3,4-TCDD at 28:11 min, 1,2,3,7-/1,2,3,8-TCDD at 28:17 min, 2,3,7,8-TCDD at 28:25 min and 1,2,3,9-TCDD at 28:37 min. None of the peaks are baseline resolved: The valley between first two peaks is ~ 65%, between second and third peak ~25% and between third and fourth peak ~20%. The ratio between second valley X and the third peak height Y is less than 0.25. Second chromatogram is acquired on a DB-225 column and displays three peak in elution order corresponding to following isomers: 2,3,4,7- TCDF at 19:59 min, 2,3,7,8-TCDF at 20:15 min and 1,2,3,9-TCDF at 20:34 min. These peaks are not baseline resolved. The valley between first and second peak is ~ 15% and between second and third peak ~ 10%. The ratio between first valley X and second peak height Y is less than 0.3.

Figure 2

The picture shows a sequence of the chromatogram and the way how the signal S to noise N for the peak is calculated. S is the peak height and N is estimated by zooming the baseline close to the peak (e.g. 10 times). Ratio S/N must be higher than 3.

Equation 1

Left side of the equation: MDL (is equal to), Right side of the equation: Numerator: 3 multiplied by N multiplied by A/H multiplied by Qs, Denominator: As multiplied by RRF multiplied by S. All terms are explained in the text.

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