Determination and pharmacokinetic properties of arsenic speciation in Xiao-Er-Zhi-Bao-Wan by high-performance liquid chromatography with inductively coupled plasma mass spectrometry.

A method of high performance liquid chromatography with a Hamilton PRP-X100 ion-exchange column (250 × 4.1 mm id, 10 µm) coupled to inductively coupled plasma mass spectrometry was employed to generate a full concentration-time profile of arsenic speciation after oral administration. The results exhibited good linearity and revealed that, in the pills, the average arsenic concentration was 10105.4 ± 380.7 mg/kg, and in the water extraction solution, the inorganic As(III) and As(V) concentrations were 220.1 ± 12.6 and 45.5 ± 2.3 mg/kg, respectively. No trace of monomethyl arsenic acid was detected in any of the plasma samples. We then successfully applied the established methodology to examine the pharmacokinetics of arsenic speciation. The resulting data revealed that, after oral administration in rats, the plasma concentration of each arsenic species reached Cmax shortly after initial dosing, and that the distribution and elimination of As(V) was faster than that of As(III) and dimethyl arsenic acid. Additionally, the t1/2 values of As(V), As(III), and dimethyl arsenic acid were 3.4 ± 1.6, 14.3 ± 4.0, and 19.9 ± 1.6 h, respectively. This study provides references for the determination of arsenic speciation in mineral-containing medicines and could serve as a useful tool in measuring the true toxicity in traditional medicines that contain them.