Chlorella Vulgaris Microalgae as a Green Packing for the Microextraction by Packed Sorbent of Nitrofurantoin in Urine

A sensitive, relatively selective, and semi-automated microextraction by packed sorbent (MEPS) method was developed for the spectrophotometric determination of nitrofurantoin (NFT) in urine samples using a green sorbent. Chlorella vulgaris, a unicellular green microalgae, was used for the first time, as a biosorbent in the developed MEPS method. Effects of several factors such as sample volume, eluent volume, sample pH and number of extraction cycles (draw-ejects) on the performance of the method were carefully studied. It was found that NFT is quantitatively enriched on the packed syringe from a sample adjusted on pH 8, after 14 draw-eject cycles. This procedure was easily performed by a designed reciprocating apparatus. After washing the sorbent for removing matrix interferences, the analyte was eluted by 30% acetone in water as eluent. Under the optimized conditions, a detection limit of 0.039 mg l-1 and a linear calibration curve with an R2 of 0.997 was obtained for NFT determination. The precision of the method, expressed as the relative standard deviation, was 3.54 for six replicates. The method was successfully applied to the determination of NFT in human urine samples.