Application of a Molecularly Imprinted Polymer for Pipette Tip Micro Solid Phase Extraction of 6-Mercaptopurine in Seawater and Body Fluids samples before its Spectrophotometric Analysis

This research investigates the usage of pipette tip micro solid phase extraction for the separation of 6-mercaptopurine of complicated matrices before its spectrophotometric detection. To overcome the non-selectivity of spectrophotometry, an ethylene glycol dimethacrylate-based molecularly imprinted polymer was prepared and applied as an adsorbent, which enabled selective and fast extraction of the analyte. To improve the transfer of the analyte to the adsorbent, salting-out effect was employed by the addition of 300 mg of NaCl to the sample before performing microextraction. Variables affecting the microextraction of the protocol were investigated utilizing two ways of one-factor-at-a-time and response surface methodology, which showed good consistency with each other. Extraction parameters were optimized as pH of sample = 9.0, sample volume = 10 mL, amount of adsorbent = 2.0 mg, eluent = 250 µL of methanol:acetonitrile (1:5 v/v), and extraction and elution cycles of 10 and 12 times, respectively. The dynamic linear range of the protocol was 1.0–1000.0 µg L-1, with a limit of detection of 0.25 µg L-1. The method was compared with extraction by a non-imprinted polymer. The extraction efficiency of the analyte obtained from 96.0% to 99.8%, by relative standard deviations better than 5.3%. The suggested technique was employed to determine 6-mercaptopurine in seawater and body fluid samples, and the results were validated by comparing them to a standard HPLC method. The whole analysis time, including microextraction, was about 25 minutes and to perform this method, the sole instrument required is a conventional spectrophotometer.