On-line coupling of microdialysis sampling with high performance liquid chromatography and hydride generation atomic absorption spectrometry for continuous in vivo monitoring of arsenic species in the blood of living rabbits

An automated on-line method has been developed for the continuous in vivo monitoring of arsenic species, including arsenite (AsIII), arsenate (AsV), monomethvlarsonic acid (MMA) and dimethvlarsinic acid (DMA), in the blood of living rabbits. The method is based on microdialysis sampling, high performance liquid chromatography (HPLC) separation and hydride generation atomic absorption spectrometry (HGAAS) detection. Dialysates perfused through an implanted microdialysis probe were collected in the sample loop of an on-line injector for direct and automated injection into an HPLC system hyphenated with HGAAS. Operating under optimal conditions, the detection limit was found to be 2.0, 2.9, 2.4 and 4.2 ng/ml for AsIII, MMA, DMA and AsV, respectively. Typical precision values of 7.0% (AsIII), 7.0% (MMA), 5.1% (DMA) and 8.7% (AsV) were obtained, respectively at a concentration level of 10 ng/ml. Spike recoveries close to 100%, relative to an aqueous standard, were obtained for each species. The average in vivo recoveries of AsIII, MMA, DMA and AsV in the blood of living rabbits were 5.7, 12.4, 8.9, and 11.0%, respectively. The use of an on-line microdialysis-HPLC-HGAAS system permitted the continuous monitoring, with a temporal resolution of 20 min sampling, of four arsenic species in the blood of living rabbits treated with arsenic trioxide. Based on our results, we present here the first finding, to the best of our knowledge of the distribution of arsenite in the blood of a living organism after administration of arsenic trioxide.