[Chemiluminescence determination of 6-mercaptopurine in the luminol-potassium ferricyanide system]

A novel chemiluminescence (CL) method to determine 6-mercaptopurine (6-MP) is described, based on the catalytic effect of 6-MP on the CL reaction of luminol with K3Fe(C-N)6 in a flow system. Under optimal experimental conditions, the calibration graph is linear in the range of 1.02 x 10(-7) to 1.02 x 10(-9) mol x L(-1) 6-MP. The linear regression equation was Y = 36.315c + 140.72, where Y is the relative emission intensity and c is the concentration of 6-MP expressed in 10(-8) mol x L(-1) and the correlation coefficient is 0. 998 2 with the detection limits of 6. 33 X 10(-10) mol x L(-1) (S/N = 3). CL peak-height precision is 3.54% of RSD (n = 12) for a level of 2.0 x 10(-9) mol x L(-1). This method satisfactorily provides a fast, simple, sensible and favorable technique for the determination of 6-MP in synthesized samples in implementation. Moreover, the possible mechanism of CL enhancement was briefly discussed. Obviously, the reaction was related to the formation of free radicals. Thus, the CL emission could preliminarily be attributed to the process of energy transfer due to O2. radical and * OH radical resulting from the oxidation product of 6-MP by K3Fe(CN)6, which acts as an active intermediate that reacts with luminol, leading to the formation of excited luminol molecule, which gives out an emission when it returns to its ground state.