BackgroundMethamphetamine has an adverse effect on the ability to drive safely. Police need to quickly screen potentially impaired drivers therefore a rapid disposable test for methamphetamine is highly desirable. This is the first proof-of-concept report of a disposable electrochemical test for methamphetamine in undiluted saliva.ResultsA screen printed carbon electrode is used for the N,N′-(1,4-phenylene)-dibenzenesulfonamide mediated detection of methamphetamine in saliva buffer and saliva. The oxidized mediator reacts with methamphetamine to give an electrochemically active adduct which can undergo electrochemical reduction. Galvanostatic oxidation in combination with a double square wave reduction technique resulted in detection of methamphetamine in undiluted saliva with a response time of 55 s and lower detection limit of 400 ng/mL.ConclusionsUsing a double square wave voltammetry technique, rapid detection of methamphetamine in undiluted saliva can be achieved, however there is significant donor variation in response and the detection limit is significantly higher than desired. Further optimization of the assay and sensor format is required to improve the detection limit and reduce donor effects.Electronic supplementary materialThe online version of this article (doi:10.1186/s13065-016-0147-2) contains supplementary material, which is available to authorized users.
SummaryThe solvents acetonitrile, methanol, N,N-dimethylformamide, dimethyl sulfoxide, formamide, and deionized water were investigated for their ability to support current flow without added electrolyte. Using open tubular capillary electro horesis, currents were measured to be in the nanoampere (10 A) range for all solvents but formamide (lo4 A). Comparisons with flow data showed no clear relationship between current and electroosmotic flow. Packed capillary columns (3-pm ODs) were used for separations using both pure solvent and hydroorganic mixtures as mobile phases. Separation of four hydrophobic dyes showed mild retention in pure ACN. A 16 polynuclear aromatic hydrocarbon (PAH) standard solution was separated in 80/20 ACNlHzO with reduced plate heights (h) between 2.8 and 3.1 for retained species. A separation of nine androstenediones was achieved using a 70130 MeOWHzO mobile phase.
Abstract. Samples of regular and decaffeinated varieties of green coffee beans, instant coffee, and "roast & grind" coffee have been examined by micellar electrokinetic capillary chromatography (MECC). The separation conditions affecting the reproducibility of the determination of caffeine in these samples are presented. Sodium dodecyl sulfate (SDS) and cetyltrimethylammonium chloride (CTAC) were employed to demonstrate the role of the surfactant system in reproducibility. The use of NaOH and HC1 was explored for column rinsing to enhance the stability of the electroosmotic flow. The levels of caffeine ranged from 3.95% (by weight) for regular coffee to 0.07% for decaffeinated coffee. The relative standard deviation (RSD) for the migration time of the peak corresponding to caffeine in coffee samples was 0.74 % . The RSDs for the peak areas and heights were 1.04 and 2.07%, respectively. The results of the quantitation of caffeine by MECC are compared to levels determined by high-performance liquid chromatography (HPLC).
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