Development of a Potential-Modulated Electrochemiluminescence Measurement System for Selective and Sensitive Determination of the Controlled Drug Codeine.

Codeine is a common analgesic drug that is a pro-drug of morphine. It also has a high risk of abuse as a recreational drug because of its extensive distribution as an OTC drug. Therefore, sensitive and selective screening methods for codeine are crucial in forensic analytical chemistry.

Sensitive screening of methamphetamine stimulant using potential-modulated electrochemiluminescence.

Methamphetamine (MA) is one of the most commonly abused recreational stimulants; thus, rapid and sensitive screening methods for MA are of great importance in forensic analytical chemistry. In the present work, potential modulation was combined with electrochemiluminescence (ECL) for the sensitive determination of MA. The potential modulated (PM) technique involved applying a signal to electrodes by superimposing an alternating current potential on the direct current potential.

Electrochemiluminescence of Tris(2,2'-bipyridine)ruthenium(II)/Tri-n-propylamine with an Electric Contactless Power Transfer System.

An electrochemiluminescence (ECL) analytical device was developed using an electric contactless power transfer system. A mutually induced electromotive voltage was generated by wrapping an enameled wire around a commercial contactless charger. There was no electrical contact between the power supply and the electrochemical cell.

Potential-modulated electrochemiluminescence of a tris(2,2'-bipyridine)ruthenium(II) / lidocaine system under 430 kHz ultrasound irradiation.

The electrochemiluminescence (ECL) of tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)) in the presence of lidocaine was investigated under ultrasound (US) irradiation. The sonoelectrochemical experiments are conducted by indirect irradiation of ultrasound with a piezoelectric transducer operating at 430 kHz. In a supporting electrolyte at pH 11, the Ru(bpy)/lidocaine system gave weak ECL peaks around +1.

High-Frequency Heating Extraction Method for Sensitive Drug Analysis in Human Nails.

A simple, sensitive, and rapid extraction method based on high-frequency (H-F) heating was developed for drug analysis in human nails. A human nail was placed in a glass tube with an extraction solvent (methanol and 0.1% formic acid; 7:3, /), and a ferromagnetic alloy (pyrofoil) was wrapped in a spiral around the glass tube.

Sonochemical preparation of gold nanoparticles for sensitive colorimetric determination of nereistoxin insecticides in environmental samples.

A simple colorimetric method using gold nanoparticles (AuNPs) was developed as an efficient strategy for specific and sensitive detection of insecticides that are analogs of nereistoxin (NRT). The AuNPs were synthesized by a surfactant-free sonochemical reaction with ultrasonication at 430 kHz. A color change occurred in the presence of NRT because the AuNPs aggregated if they were coated with a small amount of thioctic acid (TA).

Electrochemical Determination of Chromium(VI) in River Water with Gold Nanoparticles-Graphene Nanocomposites Modified Electrodes.

In this study, nanocomposites of ligand-free gold nanoparticles that are anchored onto the graphene surface (Graphene/AuNPs) were synthesized by a sonochemical method in a single reaction step. A highly sensitive amperometric sensor using Graphene/AuNPs is proposed for the determination of trace hexavalent chromium Cr(VI) in environmental water samples. Compared with a gold electrode, a glassy carbon electrode and a AuNPs modified glassy carbon electrode, the Graphene/AuNPs modified glassy carbon electrode exhibits the highest electrocatalytic activity and stability towards the reduction of Cr(VI), based on the results by cyclic voltammetry and electrochemical AC impedance studies.

Development and application of ultrasound-assisted microextraction to analysis of fenitrothion in environmental samples.

A microextraction technique based on ultrasonic emulsification and demulsification was developed for detecting pesticides at trace levels in environmental water samples. In this ultrasound-assisted microextraction (UAME), chloroform was emulsified with an aqueous sample solution containing trace fenitrothion (MEP) by ultrasonic irradiation (48 kHz) for 5 min. The emulsion was then demulsified by ultrasonic irradiation (2.

Electrochemiluminescence of Tris(2,2'-bipyridyl)ruthenium(II) with Ascorbic Acid and Dehydroascorbic Acid in Aqueous and Non-aqueous Solutions.

The electrochemiluminescence (ECL) of tris(2,2'-bipyridyl)ruthenium(II) (Ru(bpy)3(2+)) is studied in non-aqueous media using dehydroascorbic acid (DHA) as coreactant to validate the evidence for the mechanism of the ascorbic acid (H2A)/Ru(bpy)3(2+) ECL system in an aqueous media. DHA is electrochemically reduced around -1.2 V vs.

Enzymatic flow injection method for rapid determination of choline in urine with electrochemiluminescence detection.

In order to determine trace choline in human urine, a flow injection analysis (FIA) system has been developed by coupling an enzyme reactor with an electrochemiluminescence (ECL) detector. The enzyme reactor is prepared by covalently immobilizing choline oxidase (ChOx) onto the aminopropyl-controlled pore glass beads, which are then carefully packed into a micro column. The enzyme reactor catalyzes the production of hydrogen peroxide that is in direct proportion to the concentration of choline.

Rapid determination of ascorbic acid, dehydroascorbic acid, and total vitamin C by electrochemiluminescence with a thin-layer electrochemical cell.

This paper reports on a rapid and sensitive method for the simultaneous determination of ascorbic acid (H(2)A), dehydroascorbic acid (DHA), and total vitamin C by electrochemiluminescence (ECL) using a thin-layer electrochemical cell. Significant ECL signals can be generated by the anodic oxidation of Ru(bpy)(3) (2+) in the presence of H(2)A or DHA in pH 8.8 phosphate buffer solution.

Self-quenching in the electrochemiluminescence of Ru(bpy)3 2+ using ascorbic acid as co-reactant.

In this study, electrochemiluminescence (ECL) of Ru(bpy)(3)(2+) (bpy = 2,2'-bipyridyl) using ascorbic acid (H(2)A) as co-reactant was investigated in an aqueous solution. When H(2)A was co-existent in a Ru(bpy)(3)(2+)-containing buffer solution, ECL peaks were observed at a potential corresponding to the oxidation of Ru(bpy)(3)(2+), and the intensity was proportional to H(2)A concentration at lower concentration levels. The formation of the excited state *Ru(bpy)(3)(2+) was confirmed to result from the co-reaction between Ru(bpy)(3)(3+)and the intermediate of ascorbate anion radical (A(-)*), which showed the maximum ECL at pH = 8.