Methods of Saliva Analysis and the Relationship between Saliva and Blood Concentration

Immunologic analysis, originally developed for urine, is also effective for saliva. Using fluorescence polarization immunoassay (FPIA), we analyzed saliva directly (without former extraction) for barbiturates, opiates, cannabinoides, amphetamines, and cocaine. By using calibration standards, cut-off limits were established. The presence of benzodiazipines was tested using radioimmunoassay. Substance concentration in saliva, given some conditions, is equivalent to the nonprotein-linked serum concentration. In a series of analyses with codeine and cyclobarbital, we showed that an essential prerequisite is a certain ph-value in saliva. Thus, we determined the following saliva/plasma ratios: amphetamine, 2.4; barbiturates, up to 0.5; cannabinoides, 1 to 2; cocaine, 1 to 2; morphine, 0.2; codeine, 1 to 3; benzodiazepines, 0.03. In addition, saliva was tested for aliphatic alcohols by head space gas chromatography. Studies with subjects showed that the dynamics of elimination, and thereby the concentration ratio between saliva and blood, are strongly interdependent. Thus, the saliva method proved to be an efficient tool for epidemiologic studies dealing with psychoactive substances, including alcohol and licit and illicit drugs.