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Handbook of Solvents - George Wypych - ChemTech - Ventech!

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1138 Michel Bauer, Christine Barthélémy<br />

Figure 16.2.2. Head-space injection <strong>of</strong> the gaseous sample into the chromatographic system. Typical<br />

chromatogram <strong>of</strong> class 1 solvents using the conditions described for System A (European Pharmacopoeia<br />

method). Flame-ionization detector: calculation <strong>of</strong> H/h for 1,1,1-trichloroethane.<br />

WLOQ = α LOQ<br />

is to calculate the LOQ according to the signal to noise ratio S/N method 63,68 (see Figure<br />

16.2.2) and to repeat this determination independently several times (e.g.,n=6)during the<br />

intermediate precision determination. If LOQ m is the mean value and σ the standard deviation,<br />

a possible definition <strong>of</strong> WLOQ could be the upper limit <strong>of</strong> the one side confidence limit<br />

at a specified risk α (e.g., 0.05).<br />

WLOQ = LOQm + t n−1,<br />

α σ<br />

where t is Student’s coefficient.

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