Validity checking of oral fluid should include:
(1) measurement of IgG concentration
(2) check for an unusual color
(3) check for unusual texture or semi-solid characteristics
(4) check for an unusual odor
(5) review of analytical results for evidence of an adulterant (failure to recover internal standards, unusual test reactions, damage to laboratory equipment)
(6) screening for and identification of an interfering substance or adulterant
A specimen is considered substituted if:
(1) IgG concentration is < 0.10 µg/mL (unless the patient has hypogammaglobulinemia)
A specimen is considered adulterated if:
(1) an adulterant is identified at a level above the threshold concentration
A specimen is considered invalid if:
(1) a problem is found with the specimen
(1a) tube A has a different physical appearance than tube B
(1b) there is interference with an immunoassay for drugs on two separate aliquots
(1c) there is interference with a confirmatory test on at least two separate aliquots
(1d) there is an interfering substance that may damage laboratory equipment
(2) the interfering compound is not positively identified
