There has been substantial interest in the use of saliva as a diagnostic medium for drugs of abuse because it can be obtained noninvasively. Although drugs of abuse have been investigated in saliva for more than a decade, the role of saliva remains uncertain. A clear picture is difficult to obtain because of variations in (1) the analytical methods used; (2) the dose regimen of subjects, which was either unknown or differed between studies; and (3) the elapsed time between drug intake and sample collection. This communication summarizes the studies on the quantitative determination of different drugs of abuse in saliva to elucidate the current status in this area. Marijuana, cocaine, phencyclidine, opiates, barbiturates, amphetamines, and diazepines (or their metabolites) have all been detected in saliva by various analytical methods, including immunoassay, gas chromatography/mass spectrometry, and thin layer chromatography. Initial studies with cocaine and phencyclidine suggest a correlation between saliva and plasma concentrations of these drugs, indicating a dynamic equilibrium between saliva and blood. Tetrahydrocannabinol, the active component in marijuana, on the other hand, does not appear to be transferred from plasma to saliva. However, tetrahydrocannabinol is sequestered in the buccal cavity during smoking and can be detected in saliva. These findings point to the potential role of saliva in the analysis of many illicit drugs. To clearly identify the role of saliva as a diagnostic medium for drugs of abuse, research efforts should be directed towards (1) performing systematic studies on correlations between saliva, blood, and urine and (2) determining the concentrations of drugs and their metabolites in saliva as a function of dose and time after intake.

Drugs of abuse in saliva: a review.

Publisher Summary This chapter discusses the newer approaches to the isolation, identification, and quantitation of steroids in biological materials. Progress in steroid analysis has been remarkable in the last 15 years. Much of present knowledge in steroid endocrinology could not have been acquired without the development of radioimmunoassay and other competitive protein-binding methods. These methods have provided the sensitivity and speed required for measurement of physiological concentrations of steroid hormones in large series of samples. Parallel with this development, both liquid and gas-liquid chromatographic methods have been markedly improved and mass spectrometers have become available for routine use. The most important advancement in this area has been the successful combination of gas chromatography and mass spectrometry (GC-MS) for analysis of molecules as large as steroids. Immunoassay and GC-MS are complementary methods. GC-MS is important as a reference method to test and validate the specificity of an immunoassay. The steroid composition of biological samples taken under different physiological and pathological conditions can be characterized by GC-MS, and immunoassays may then be developed for detailed studies of selected steroids in larger numbers of samples.

Newer approaches to the isolation, identification, and quantitation of steroids in biological materials.

Revue comprenant 37 references: les principes, appareillages, techniques, precision, utilisation, developpement futur

Isotope dilution mass spectrometry of inorganic and organic substances

Calculations of flux rates for stable isotope tracer studies are based upon enrichment values of an infused tracer. We propose the determination of enrichment values by gas chromatography/mass spectrometry, which is based on tracer mole fraction and mass spectrometer signals, normalized over the total signal of an ion fragment isotopomer distribution. The method accounts for overlap of the signals of one or two tracers and the tracee, high tracer mole fraction and incomplete labelling of the (infused) tracer. For the single and multiple tracer case a linear relationship between tracer mole fraction (from zero to one) and all normalized mass spectrometer signals is derived. This linearity over the entire range is demonstrated with a single (1-13C)glucose tracer and for mixtures of (1-13C)- and (3,3-2H2)tyrosine tracers. The linearity allows determination of the tracer mole fraction for two tracers, using multiple linear regression. The corresponding calibration can rely on measurements of the pure tracer and tracee compound, without weighing or check for chemical purity. This is compared with a calibration based on tracer/tracee mixtures. Estimates for the tracer mole fraction are slightly better if based on a calibration, using standard mixtures. In all cases the tracer mole fraction can be determined with high precision (coefficient of variation smaller than 5%) and high accuracy. For tyrosine it is demonstrated that the measurement of seven channels rather than three, for the main isotopomers, does not reduce the precision in the prediction of the tracer mole fraction. Equations are also derived to use the tracer mole fraction to estimate the endogenous production of the tracee under study conditions, assuming a steady state of the host metabolism.

Determination of the isotope enrichment of one or a mixture of two stable labelled tracers of the same compound using the complete isotopomer distribution of an ion fragment; theory and application to in vivo human tracer studies

Isotopic analyses of inorganic and organic substances by mass spectrometry

Isotopic dilution analysis in connection with “selected ion monitoring” as well as mass fragmentography in a broad sense, allow quantitative determinations of small quantities of substances with mass spectrometry. The presence of peaks of more than one substance at the (m/e) points of the spectra necessitates the use of a careful mathematical analysis, which is introduced in this work. Examples are considered.

Quantitative estimates for isotopic dilution analysis in mass spectrometry

The use of a model developed by the authors for the simultaneous quantitative determination of several isotopically labelled substances of the same chemical structure is described in detail for a two substance system. A computational flow chart is included. An example using natural estradiol and 4-[14C] labelled estradiol with manifold deuterated estradiol as an internal standard is presented. The basis of the model is discussed.

Simultaneous quantitative estimates of several isotopically labelled substances in the picogram range with selected ion monitoring.

A method is proposed for the quantitative estimation of a substance and its labelled analogue using the selected ion monitoring technique of gas chromatography mass spectrometry, in which estimation is achieved without a third labelled analogue as internal standard. In a first measurement the ratio of natural to labelled substance is established. Then a known amount of either labelled or natural compound is added, the isotope ratio is determined a second time and from these two measurements the mass amounts can be calculated. When applied to the heptafluorobutyrates of androstenedione and progesterone about 10 pg of 14C labeled compounds can be determined in the presence of 1 ng of the natural substances.

An application of gas chromatography mass spectrometry to the quantitation of substances and their labelled variants

Estradiol-17β and [4-14C]estradiol-17β in total mass amounts of 0, 10 and 20 pg per analysis in the presence of 1000 pg [2H8]estradiol as an internal standard were simultaneously quantitatively determined by gas chromatography mass spectrometry using the selected ion monitoring technique. The experiment (a nested three way analysis of variance) was designed to investigate the two-dimensional error structure which facilitates the study and comparison of the variances: (1) the variance originating in the device, including gas chromatograph, mass spectrometer and computer system with its interfaces; (2) the variance originating from titration, pipetting and derivatization of the samples. The study revealed that in this concentration range the variance due to sample preparation is smaller than that due to the device. The deviations due to the device were shown to have a two-dimensional normal distribution.

A two‐dimensional analysis of variance for the simultaneous quantitative determination of estradiol and its 4‐14C isotopically labelled analogue with selected ion monitoring

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Quantitative estimates for isotopic dilution analysis in mass spectrometry

Simultaneous quantitative estimates of several isotopically labelled substances in the picogram range with selected ion monitoring.

An application of gas chromatography mass spectrometry to the quantitation of substances and their labelled variants

A two‐dimensional analysis of variance for the simultaneous quantitative determination of estradiol and its 4‐14C isotopically labelled analogue with selected ion monitoring