ErythrocyticGlucose-6-PhosphateDehydrogenaseMeasured by a DifferentialpH Technique

We propose a new quantitative electrochemical method for determining glucose-6-phosphate dehydrogenase (EC 1.1.1.49) activity inpurifiederythrocytesor in whole blood, based on measurement of the pH change caused by oxida-tion of glucose 6-phosphate to 6-phosphogluconic acid, with simultaneous reduction of NADP to NADPH + H. No sample pretreatment (e.g., preparation of hemolysate) is needed, and the automatic correction for sample blanks obviates interference from 6-phosphogluconate dehydrogen-ase (EC 1.1.1.44). The method is simple and fast, and the standard curve is linear to at least 2200 U/L at 37#{176}C.The within-day CV was 3.9 % for actMties in healthy individuals (mean value 1204 U/L), and 10 % for deficient ones (classi-fied as belonging to class II, mean value 407 U/L). Results ( con-elated well with those obtained with the WHO-recom