Chemiluminescent Determination of 6-Mercaptopurine in Pharmaceutical Preparation

Abstract

A new chemiluminescence method is described for the determination of 6-mercaptopurine.In the presence of tris(2,2'-bipyridine)ruthenium(II), 6-mercaptopurine (6MP) and hydrogen peroxide, upon the addition of hydroxide ion, resulted in intense light emission. The emission intensity is greatly enhanced by the presence of Tween-20. The linear range and detection limit of 6MP are 1.4X10-5 -1.4X10.8 g/ml and 3X10-10 g/ml, respectively. The method was evaluated by carrying out an interference study with common excipients and other coexisting compounds, by a recovery study and by the analysis of commercial formulation. A satisfactory result was obtained. KeywordsChemiluminescence, 6-mercaptopurine, tris(2,2'-bipyridine)ruthenium (II) 6-Mercaptopurine (6MP) is a well-known clinical agent for therapy of human leukemias and an immunosuppressive drug.' Most of the methods described for the determination of 6MP are based on the electrochemical characteristics. But these methods have poor sensitivity and selectivity. Many metal ions and anion radicals interfere with the determination of 6MP.Tris(2,2'-bipyridine)ruthenium(II) (Ru(bpy)32+) is an extremely versatile base reactant for a variety of chemiluminescent processes.2-4 The most elegant ways to obtain chemiluminescence (CL) from Ru(bpy)32+ solution is to produce the oxidized and/or reduced form of the complex "in situ" by electrochemical methods. However, no analytical application that uses Ru(bpy)32+ as CL reagent in solution directly has yet been presented.We report here a solution CL system involving Ru(bpy)32+, 6MP, H2O2 and OH-. In the presence of Tween-20, the linear range and detection limit of 6MP are 1.4X108 -1.4X 10-5 g/ ml and 3.0X10'° g/ ml, respectively.hydroxide and diluting to 100.0 ml with water. This was kept at 4° C in a refregerator.All other reagents were of analytical grade or better and all water used was doubly distilled in a fused-silica apparatus.Procedures A 0.2 ml portion of 0.5 mmol/l Ru(bpy)32+, 0.2 ml of 4.0% Tween-20, 0.2 ml of 5.0 tg 6MP and 0.2 ml of 0.45% hydrogen peroxide were mixed in reaction cuvettes. Then the mixture was moved into a measuring chamber with a constant temperature of 25° C. After the start button was pushed, a 0.2 ml of 0.4 mol/l sodium hydroxide was injected into the reaction cuvettes automatically and the CL produced was measured immediately (see Fig. 1). The calibration graph of emission intensity vs. concentration of 6MP was constructed and the 6MP contents of the samples were determined. Each standard or sample solution was measured five times. Results and Discussion ExperimentalApparatus and reagents LKB 1251 luminometer, dispenser SVD and dispenser controller DC (Pharmacia LKB Biotechnology AB, Sweden), with a Epson LX-800 printer (Seiko Epson Corp. Japan) were used. A 1.0 mmol/ 1 stock solution of [Ru(bpy)3]Br2 (prepared in our laboratory) was prepared by dissolving 745.7 mg [Ru(bpy)3]Br2 in water and diluting with water to 11.A 0.5 mg/ml stock solution of 6MP was preapred by dissolving 50.0 mg of it in 5.0...

Simple Chemiluminescence Method for the Determination of Mercaptopurine

“…11 In this method, the mixing order of the reagents considerably affects the CL signal. Still, a simple and convenient method to measure mercaptopurine would be highly desirable.…”

“…[7][8][9][10] However, only one CL method was reported for the determination of MP, which was based on reactions among tris-(2,2′-bipyridine)ruthenium(II), MP, hydrogen peroxide, Tween 20 and hydroxide ion. 11 In this method, the mixing order of the reagents considerably affects the CL signal. Still, a simple and convenient method to measure mercaptopurine would be highly desirable.…”

On‐line chemical generation of tris(2,2′‐bipyridyl)ruthenium(III) and its application in CE with chemiluminescence detection

“…Despite more than amine-containing analytes [21,30,31], organic acids [22][23][24][25]32] and sulfur-containing analytes [26][27][28][29]33] can be detected, the chemical generation method is still limited for the probable instability of the active Ru(bipy) 3 31 . By far, only a few reports about CE-CL based on chemical generation of Ru(bipy) 3 31 have been published [34,35].…”

“…-cerium(IV) CL system is favorable for the determination of organic acids [23][24][25]32] and sulfurcontaining analytes [26][27][28][29]33], outside of amine-containing analytes. In the proposed scheme, the a-ketocarboxylic acids including oxalic acid, 2-ketoglutaric acid, 2-ketobutyric acid, and sodium pyruvate were used as models to demonstrate the feasibility of the CE-CL approach.…”

Chemiluminescence Determination of Sulfite in Sugar and Sulfur Dioxide in Air Using Ru(bipy)32+-K2S2O8 System

“…20 Ru(bipy) 3 2+ is an extremely versatile base reactant for a variety of electrogenerated CL processes 21,22 , and has also recently become a useful CL reagent. It can be applied to the determination of 6-mercaptopurine 23 in alkaline media and oxalic, tartaric acids etc. 24,25 in sulfuric acid media.…”