Routine Analysis of Toxic Arsenic Species in Urine Using Agilent HPLC with 7500 Series ICP-MS

摘要

A new method using HPLC coupled to ICP-MS has been developed that is capable of separating all five important arsenic compounds in human urine within 12 minutes with detection limits ranging from 0.05 to 0.1 (mu)g/L (50 (mu)L injection). Furthermore, by using 5 (mu)L injections, it is possible to achieve similar performance on undiluted urine samples, thereby significantly simplifying sample preparation and handling. Arsenic exposure may lead to cancer or other adverse effects, but the toxicity is strongly dependent on the species. Of the five As species most commonly found in human urine, the order of toxicity is: As(III) (arsenite) > As(V) (arsenate) > DMA (dimethylarsenic acid) >= MMA (monomethylarsonic acid) AB (arsenobetaine). While HPLC-ICP-MS is well accepted as the analytical technique of choice for As speciation in urine, some remaining difficulties have prevented the technique from becoming routine. These are: 1) Finding chromatographic conditions that will separate the five most important species as well as inorganic chloride in a reasonable time, with good retention time reproducibility, dynamic range, and sensitivity. 2) Resolving or eliminating the ArCl interference on As formed as a result of the high NaCl concentration in urine samples. 3) Avoiding clogging of the ICP-MS interface from total dissolved solids (TDS) contained in the urine and HPLC buffers.