A sensitive inhibition chemiluminescence method for the determination of 6-mercaptopurine in tablet and biological fluid using the reaction of luminol–Ag(III) complex in alkaline medium

A sensitive inhibition chemiluminescence (CL) method for the determination of 6-mercaptopurine (6-MP) is developed. The mechanism of the CL reaction between Ag(III) complex {[Ag(HIO6)2]5−} and luminol in alkaline solution was proposed, along with the inhibition mechanism of 6-MP on the CL emission. The inhibition degree of CL emission was proportional to the logarithm of 6-MP concentration. The effects of the reaction conditions on CL emission and inhibition were examined. Under the optimized conditions, the detection limit (s/n=3) was 3.7×10−10 g ml−1. The recoveries of 6-MP were in the range of 97.7–105% with the RSD of 2.1–3.4% (n=5) for tablet samples, 103–106% with the RSDs of 1.1–2.1% for spiked serum sample, and 97.2–101% with the RSD of 2.0–4.5% for spiked urine sample. The accuracy of this method for the tablet analysis was examined by comparing with the pharmacopoeia method. The proposed method was used for the determination of 6-MP at clinically relevant concentrations in real urine and serum samples with satisfactory results.