Cutoff levels for validity testing.

CFR · 2024-01-01 · US · Title 10

(a) (b) (1) Determine the creatinine concentration; (2) Determine the specific gravity of every specimen for which the creatinine concentration is less than 20 mg/dL; (3) Determine the pH; (4) Perform one or more initial validity tests for oxidizing adulterants; and (5) Perform additional validity tests, the choice of which depends on the observed indicators or characteristics below, when the following conditions are observed: (i) Abnormal physical characteristics; (ii) Reactions or responses characteristic of an adulterant obtained during initial or confirmatory drug tests (e.g., non-recovery of internal standards, unusual response); or (iii) Possible unidentified interfering substance or adulterant. (c) (1) The pH is less than 3, or equal to or greater than 11, using either a pH meter or a colorimetric pH test for the initial test on the first aliquot and a pH meter for the confirmatory test on the second aliquot; (2) The nitrite concentration is equal to or greater than 500 mcg/mL using either a nitrite colorimetric test or a general oxidant colorimetric test for the initial test on the first aliquot and a different confirmatory test (e.g., multi-wavelength spectrophotometry, ion chromatography, capillary electrophoresis) on the second aliquot; (3) The presence of chromium (VI) is verified using either a general oxidant colorimetric test (with a cutoff equal to or greater than 50 mcg/mL chromium (VI)-equivalents) or a chromium (VI) colorimetric test (chromium (VI) concentr

official document · source cfr-2024 · id 10:§ 26.161