VESICLE-MEDIATED HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY COUPLED TO HYDRIDE GENERATION INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY FOR SPECIATION OF TOXICOLOGICALLY IMPORTANT ARSENIC SPECIES

The use of vesicles as mobile phases can provide a synergic combinatio n for high-performance liquid chromatographic (HPLC) separation when c oupled to hydride generation inductively coupled plasma atomic emissio n spectrometric (HG-ICP-AES) detection, as illustrated here for arseni c speciation. The more toxic arsenic species including arseneous, arse nic, monomethylarsonic and dimethylarsinic acids can be separated with in 10 min by using didodecyldimethylammonium bromide (DDAB) vesicles i n phosphate buffer containing 0.5% methanol and a C18 reversed-phase c olumn, which had previously been modified by DDAB soluton. In addition , the sensitivity of detection on-line by HG-ICP-AES of the four separ ated arsenic species was enhanced by the presence of DDAB vesicles. Th e normalized detection limits for arsenic with the proposed speciation method were down to the sub-ng level and the observed precisions were always better than +/- 5% for the four forms of arsenic at the 10 ng level of the element in water. Arsenic recoveries (full procedure) wer e found to range from 93 to 108% for tap water and human urine samples by this vesicle-mediated HPLC-HG-ICP-AES technique for arsenic specia tion.