Speciation and bioaccessibility of arsenic in traditional Chinese medicines and assessment of its potential health risk.

Arsenic in traditional Chinese medicines (TCMs) has caused public concerns about its health risk in recent years due to the high toxicity of arsenic and widespread use of those medicines throughout the world. However, in previous studies the arsenic toxicity was usually overestimated by considering the total arsenic concentration only. This work investigated the total concentration, speciation and bioaccessibility of arsenic in 84 commonly used traditional Chinese patent medicines (CPMs) and Chinese herbal medicines (CHMs) to evaluate arsenic's potential health risks to human. Arsenic was found in all the CPMs and 88% of CHMs at concentrations ranging from 0.033 to 91,000mgkg-1 and 0.012 to 6.6mgkg-1, respectively. The bioaccessibility of arsenic varied significantly and was in the range of 0.21%-90% in the CPMs and 15%-96% in the CHMs, with inorganic arsenic as the predominant species. The average daily intake dose (ADD) and hazard quotient (HQ) of arsenic in most of medicines were within the safe limits, while in certain medicines, they exceeded the safe threshold level. These excesses remind us that the potential health risk by consumption of several medicines may not be negligible and more control and monitoring of arsenic in medicines should be carried out.

Efficient interface for online coupling of capillary electrophoresis with inductively coupled plasma-mass spectrometry and its application in simultaneous speciation analysis of arsenic and selenium.

A simple and highly efficient online system coupling of capillary electrophoresis to inductively coupled plasma-mass spectrometry (CE-ICP-MS) for simultaneous separation and determination of arsenic and selenium compounds was developed. CE was coupled to an ICP-MS system by a sprayer with a novel direct-injection high-efficiency nebulizer (DIHEN) chamber as the interface. By using this interface, six arsenic species, including arsenite (As(III), arsenate (As(V)), monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), arsenobetaine (AsB), and arsenocholine (AsC) and five selenium species (such as sodium selenite (Se(IV)), sodium selenate (Se(VI)), selenocysteine (SeCys), selenomethionine (SeMet), and Se-methylselenocysteine (MeSeCys)) were baseline-separated and determined in a single run within 9 min under the optimized conditions. Minimum dead volume, low and steady sheath flow liquid, high nebulization efficiency, and high sample transport efficiency were obtained by using this interface. Detection limits were in the range of 0.11-0.37 µg L(-1) for the six arsenic compounds (determined as (75)As at m/z 75) and 1.33-2.31 µg L(-1) for the five selenium species (determined as (82)Se at m/z 82). Repeatability expressed as the relative standard deviations (RSD, n = 6) of both migration time and peak area were better than 2.68% for arsenic compounds and 3.28% for selenium compounds, respectively. The proposed method had been successfully applied for the determination of arsenic and selenium species in the certified reference materials DORM-3, water, urine, and fish samples.

Speciation analysis of arsenic compounds by capillary electrophoresis on-line coupled with inductively coupled plasma mass spectrometry using a novel interface.

In this work, a capillary electrophoresis (CE) coupled with inductively coupled plasma mass spectrometer (ICP-MS) system was developed for the simultaneous determination of ten arsenic compounds including arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, 3-nitro-4-hydroxyphenylarsonic acid, o-Arsanilic acid, p-ureidophenylarsonic acid, and 4-nitrophenylarsonic acid. The CE-ICP-MS system was hyphenated by a novel and high efficient interface which was directly used as the nebulizer. The separation was achieved on a 100cm length×50µm ID fused-silica capillary. Analytical conditions such as electrophoretic buffer composition, concentration and pH value, separation voltage, methanol concentration in the sheath flow liquid and sample injection time were optimized. Baseline separation of the ten arsenic species was achieved using an electrophoretic buffer consisting of 12mM NaH2PO4 and 8mM HBO3 at pH 9.20 with an applied voltage of +30kV. The detection limits of the ten arsenic compounds ranged from 0.9 to 3.0ngAsg(-1), corresponding to absolute detection limits in the range of 19-65fg As and the relative standard deviations (RSD, n=5) were below 1.5%, 5.7% and 4.8% for migration time, peak height and peak area, respectively. This method was successfully applied to determine various arsenicals in two certified reference materials (TORT-2 and DORM-3) and environmental samples such as ground water samples, herbal plants and chicken meat.