[Determination of azathiopurine concentration in human serum by second derivative spectra method]

A sensitive and rapid method for the determination of azathiopurine concentration in human serum was established. By using ultraviolet second derivative spectra, the method eliminated background interference of biological sample and coexisting drugs. The serum sample was extracted with ethyl acetate, the extract was evaporated to dryness with a gentle N2 stream, and 0.25 ml of methanol was added to dissolve the residue. Quantitative calculation was made with analytical wavelength of 274 nm and 293 nm, and peak- to- valley method. The minimum detectable concentration of AZP in serum was 25 ng.ml-1 and average recovery was 99.3% +/- 5.9%.