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Immunoanalytical techniques based on an indirect competitive ELISA to determine cocaine in the gas phase are described. A test-gas generator was developed and evaluated by determining saturation vapour pressures and the sublimation enthalpy of cocaine base. To achieve quantitative recovery of the drug, the saturated air stream was sucked through a retention fluid. For validation of the test gas generator, samples were analysed with a microtitre plate cocaine-ELISA based on monoclonal antibodies. To simplify the sampling and analysis procedures by analysing the retention fluid directly in the sampling vessel, particle-based immunoassay formats were developed. According to the ELISA format, avidin was immobilized on the particles. The application of various solid particles consisting of different materials with a wide range of diameters (0.5-550 microns) to the analysis of cocaine standards and gas samples showed good correlation with the results obtained with the microtitre plate ELISA with an average IC50 value (end-point of the test; concentration at 50% binding) of 9.7 ng ml-1. The particle-based assays showed IC50 values in the range of 5-54 ng ml-1 and signal background ratios ranging from 2 to 11. The application of particle-based assays for direct analysis of cocaine in the sample fluid was successfully performed with glass beads, precoated with avidin and a biotin-cocaine conjugate. Recovery of cocaine from the gas phase depended on the volume of sample fluid and on the geometry of the sample tube.

The interaction of triazine aldehydes with the aldehyde binding site of bacterial luciferases was investigated using a series of triazine aldehydes with different aldehyde chain length, and substituents on the s-triazine ring. Substrate activity was determined using luciferase from Photobacterium fischeri and Vibrio harveyi in a dithionite-based luciferases assay. The chain length optimum was determined for two triazine aldehyde classes to be C-10 and C-11, respectively. Only the substrate activity of 10-(4-chloro-6-methylthio-s-triazine-2-yl)aminodecanal (5) was as high as n-decanal, the reference aldehyde. All other triazine derivatives reduced light emission, probably by hindered binding of the substrates. The degree of activity reduction correlated with the volume of the triazine ring moiety. The triazine moiety volume of compound 5 was estimated to be 200 x 10(-30) m3. Triazine aldehydes which showed reduced light emission had an estimated volume of 228 x 10(-30) m3 or greater. All triazine aldehydes showed approximately 10-fold lower activities for Vibrio harveyi than for Photobacterium fischeri luciferase. Substrate specificity was the same for both luciferases. A schematic superposition of quinone aldehydes and triazine aldehydes which showed substrate activities equivalent to n-decanal, indicated potential interaction sites of aldehyde substrates with the aldehyde binding site of bacterial luciferases. The in vivo relevance of the results is discussed.

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