Drug assay, electrochemical

Dean et al. [93] used a high performance liquid chromatographic method for the simultaneous determination of primaquine and carboxyprimaquine in plasma with electrochemical detection. After the addition of the internal standard, plasma was deproteinized by the addition of acetonitrile. Nitrogen-dried supernatants, resuspended in mobile phase were analyzed on a C8 reversed-phase column. Limits of detection for primaquine and carboxyprimaquine were 2 and 5 ng/mL with quantitation limits of 5 and 20 ng/mL, respectively. The assay sensitivity and specificity are sufficient to permit quantitation of the drug in plasma for pharmacokinetics following low dose (30 mg, base) oral administration of primaquine, typically used in the treatment of malaria and P. carinii pneumonia. 

Rotshteyn Y, Weingarten B. 1996. A highly sensitive assay for the simultaneous determination of morphine, morphine-3-glucuronide, and morphine-6-glucuronide in human plasma by high-performance liquid chromatography with electrochemical and fluorescence detection. Ther Drug Monit 18(2) 179-188. 

The use of polarographic assays for the determination of drugs in blood is the most demanding on the detection limitations of the technique. Differential pulse polarography, stripping voltammetry, and LCEC are the only electrochemical methods currently available for routine determination of drugs below 1.0 ng/mL of blood. 

Radi [41] used an anodic voltammetric assay method for the analysis of omeprazole and lansoprazole on a carbon paste electrode. The electrochemical oxidations of the drugs have been studied at a carbon paste electrode by cyclic and differential-pulse voltammetry in Britton-Robin-son buffer solutions (0.04 M, pH 6-10). The drug produced a single oxidation step. By differential-pulse voltammetry, a linear response was obtained in Britton-Robinson buffer pH 6 in a concentration range from 2 x 10-7to 5 x 10 5 M for lansoprazole or omeprazole. The detection limits were 1 x 10 8 and 2.5 x 10 8 M for lansoprazole and omeprazole, respectively. The method was applied for the analysis of omeprazole in capsules. The results were comparable to those obtained by spectrophotometry. 

MS/MS) is the standard detector for bioanalytical assays and drug discovery screening, its use for routine assays of drug substances and products is still limited due to its high cost and lower precision. Nevertheless, LC/MS/MS methods are increasingly used for ultra trace analysis or screening of complex samples. Other detection options include conductivity detection for ionic species and electrochemical detection for neuroactive species in biochemical research. 

The minimum uncertainty for simple matrices is achieved with use of electrochemical sensors, especially for the assay of organic cations and organic and inorganic anions in food and clinical analysis. The selectivity and sensitivity of these sensors are adequate to detect numerous pharmaceutical products, without any prior separation. The ability of electrochemical sensors to determine continuously the activity of an ion in solution has made their use possible in in vitro and in vivo dissolution tests of drugs. 

Mesenteric effluents were collected at 1-min intervals up to 10 min during and following periarterial nerve stimulation. Coronary effluents were collected for 3 min at 15-sec intervals. In both cases samples were collected in plastic tubes containing 0.01 N perchloric acid and 0.025% EDTA, and stored at — 70°C until analysis. All samples were analyzed within 3 weeks. NE was determined by high-performance liquid chromatography coupled with electrochemical detection (Imamura et al., 1994). None of the drugs used in our experiments interfered with the NE assay. 

Electrochemical assays for therapeutic drugs, like paracetamol or acetyl-salicylate have been described [35]. Urea can be assayed potentiometrically by a H sensitive ISFET with a Si02 gate insulator covered by a SijN4 Him to which urease (EC 3.5.1.5) is covalently attached [36]. 

Creatinine. Electrophoresis Principles Isoelectric Focusing. Enzymes Enzymes In Physiological Samples Industrial Products and Processes Enzyme Assays. Forensic Sciences Alcohol In Body Fluids DNA Profiling Systematic Drug Identification Thin-Layer Chromatography. Immunoassays Applications Forensic. Microscopy Applications Forensic. Nucleic Acids Electrochemical Methods. Polymerase Chain Reaction. Spectrophotometry Oven/lew Biochemical Applications. 

See also. Chemiluminescence Oven/iew. Derivatiza-tion of Analytes. Electrophoresis Oven/iew. Enzymes Oven/iew Immobiiized Enzymes Enzyme-Based Eiec-trodes Enzymes in Physioiogicai Sampies Industriai Products and Processes Enzyme-Based Assays. Fluorescence Clinical and Drug Applications. Immunoassays Overview Production of Antibodies. Immunoassays, Applications Clinical Food Forensic. Immunoassays, Techniques Radioimmunoassays Enzyme Immunoassays Luminescence Immunoassays. Mass Spectrometry Polymerase Chain Reaction Products. Nucleic Acids Chromatographic and Electrophoretic Methods Electrochemical Methods. Polymerase Chain Reaction. 

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