تسجيل الدخول

تسجيل

Reference standards

المؤلف:  Sue Jickells , Adam Negrusz (Editors)

المصدر:  Clarkes Analytical Forensic Toxicology

الجزء والصفحة:  410

2026-11-09

44

Reference standards

If an acceptable reference standard of the drug is available, and if the calibration graph passes through zero, measurement of replicates of the standard (at a comparable concentration) and of the test solutions are performed in bracketing sequence (i.e. each group of samples is preceded and followed by the standard), under identical conditions of solvent and temperature and using the same pair of matched cells. Each result should be corrected for the cell constant. The concentration of the test sample is then found by reference to the results from the standards.

Where UV-visible is coupled to liquid chromatography, it is more usual to run a series of calibration standards where the concentration of the standards covers a known but varying range. The calibration standards are analysed first, then the test samples. Where large sample batches are analysed, it is good practice to analyse one of the standards after every 10 samples. A calibration line is plotted and the values for the samples are interpolated from the calibration line.