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NADP+ is reduced by glucose-6-phosphate dehydrogenase enzyme (G-6-PD) in the presence of glucose-6-phosphate, and the rate of formation of NADPH is proportional to the G-6-PD activity, and is determined fluorometrically.
It is an enzymatic method for the quantitative determination of glucose-6-phosphate dehydrogenase activity from dried blood spots, with fluorometric detection.