Semi-micro column high-performance liquid chromatography with UV detection for quantification of aspirin and salicylic acid and its application to patients' sera administered with low-dose enteric-coated aspirin.

A simultaneous determination of aspirin (ASA) and its metabolite, salicylic acid (SA), in human serum by a semi-micro column HPLC-UV was developed. A relatively small size of serum sample (100 microL) containing ASA and SA was cleaned up by a simple solid phase extraction. A good separation of ASA and SA could be achieved within 25 min using a semi-micro ODS column with an eluent of MeOH/0.7 mm phosphoric acid solution (pH 2.5) = 50:50 (v/v). The calibration curves for ASA and SA showed good linearity (r = 0.999) with the detection limits 114 and 38 ng/mL at a signal-to-noise ratio of 3, respectively. ASA and SA in patients' sera administered with low-dose enteric-coated aspirin were determined, and the concentration ranges obtained for ASA and SA were 1.2-2.2 and 0.5-57.3 microg/mL, respectively.