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As a prelude to using zeolites as supports for electrocatalysts, the voltammetric behavior of various analytes was examined at zeolite‐modified electrodes in aqueous solution. The following parameters were studied: preparation and characterization of electrodes, ability to concentrate or exclude analytes from dilute solution, linearity of response to concentration of analytes in solution, selectivity toward analytes of various sizes and charges, and the role of electrolyte cations in determining the response. The following analytes were used: methyl viologen dication (N,N′‐dimethyl‐4,4′bipyridyl), heptyl viologen, hexammineruthenium (III), hexacyanoferrate (III), and copper (II). Zeolites mixed with carbon paste gave more reproducible and robust electrodes than did films of zeolite/polystyrene on platinum or glassy carbon electrodes. Electrodes modified with zeolite Y concentrated methyl viologen, hexammineruthenium (III), and Cu(II) from dilute solution (0.1–10 mM), and cyclic voltammetric peak current was linear as a function of solution concentration after an equilibration period of 1h. Ferricyanide and heptyl viologen were excluded from the zeolite based on charge and size, respectively, and were therefore not concentrated from solution. The smaller pore zeolite A accommodated only Cu(II). Selectivity and competition among pairs of analytes were also examined. The peak current in cyclic voltammetry was also correlated with the mobility of electrolyte cations within the zeolite matrix, based on their charge, and their size relative to the size of the zeolite channels. Enhancement factors (defined as peak current at a modified electrode divided by that at an unmodified electrode) reached values in the range of 50, despite the loss of active surface area of the electrode caused by the modification.

ChemInform Abstract is investigated using the following analytes: methyl viologen dication (I), heptyl viologen (II), Ru(NH3)63+ (III), Fe(CN)63-(IV) and Cu2+. It is found that zeolites mixed with carbon paste give more reproducible and robust electrodes than films of zeolite/polystyrene on Pt or glassy carbon. Electrodes modified with zeolite Y concentrate (I), (III), and Cu2+ from dilute solutions, whereas (II) and (IV) are excluded from the zeolite (due to charge and size, resp.). The zeolite A, having smaller pore size, accommodates only Cu2+. Enhancement factors (ratio of faradaic peak current at the zeolite modified, electrode to that of the unmodified electrode), selectivity and competition among pairs of analytes are investigated and the electroanalytical applicability is discussed.

The consumption of poppy seeds in various foods may lead to a positive opiate result in urine subjected to testing for drugs of abuse. As a natural constituent of poppy seeds, thebaine was investigated as a possible marker for poppy seed consumption. Poppy seeds were examined for opiate content by gas chromatography-ion trap mass spectrometry (GC-MS) after extraction with methanol. Urine samples spiked with thebaine and urine from subjects given 11 g of poppy seeds were tested for the presence of thebaine, codeine, and morphine. Street heroin, one morphine and one codeine tablet, and urine from individuals who had used heroin were also examined for thebaine. Urine specimens were screened by enzyme immunoassay (EMIT) and confirmed for thebaine by GC-MS using a solid-phase extraction method. The GC-MS assay showed a linear response over a range of 1-100 ng/mL and a limit of detection of 0.5 ng/mL. Thebaine was detectable in the urine of poppy seed eaters in concentrations ranging from 2 to 81 ng/mL. Because thebaine was absent in powdered drugs and the urine of true opiate drug users, thebaine is proposed as a direct marker for poppy seed use.