METHOD DEVELOPMENT OF SINGLE-INTERFACE HOLLOW FIBER MEMBRANE-LIQUID PHASE MICROEXTRACTION FOR DETERMINATION OF METAL IONS AND IONIZABLE ORGANIC COMPOUNDS

Abstract

A concept of single-interface hollow fiber liquid phase microextraction (HF-LPME), where the target analytes was extracted and eluted inside the lumen of the HF membrane was explored. Cr(VI) and salicylic acid (SA) were used as the model for this study. The single-interface HF-LPME was designed. The sample solution was fed into the narrow lumen of the membrane resulting in the increased positive pressure inside the lumen, thus the leakage of organic solvent to the outer of the membrane wall was observed. This problem was overcome by flow balancing pressure. The single-interface HF-LPME behaviors of Cr(VI) and salicylic acid were discussed. The parameters influenced the extraction efficiency on the enrichment factor such as inlet flow rate, elution flow rate, organic solvent and extraction time were optimized. The performance of the method was evaluated under the optimal conditions. For Cr(VI), the working range of 5 to 30 µg L-1 (R2 = 0.9994) and the limits of detection of 1.2 µg L-1 were obtained. For salicylic acid, the working range of 0.25 to 2.00 mg L-1 (R2 = 0.9990) and the limit of detection of 0.2 mg L-1 were obtained. The proposed methods were successfully applied to a various water samples and drug samples. The recoveries of Cr(VI) spiked water samples were in the range 92 to 111% with RSD less than 10%. The recoveries of salicylic acid spiked drug samples were in the range 92 to 103% with RSD less than 3%. The method is simple to operate, cheap and utilizing of less organic solvent, which is environmental friendly.