TABLE OF CONTENTS

To establish useful bioremediation techniques for mineralizing harmful organoarsenic compounds, environmental factors such as arsenic concentrations and bacterial biomass in the soils of Ohkunoshima Island were investigated. The distribution of contamination levels of arsenic compounds was different in the various areas of the Island. Among the isolates of arsenate-resistant bacteria from the soils, a few isolates have remarkable reduction activities for monomethylarsonic acid, and the two isolates with strong activities belonged to the group of Pseudomonas putida strains.

The water-soluble arsenic in marine sponges were analyzed using high-performance liquid chromatography with an inductively coupled plasma mass spectrometer serving as an arsenic-specific detector(HPLC/ICP/MS, see Fig). All sponges contained arsenobetaine(peak I) and two arseno-sugar (2,3-dihydroxypropyl 5-deoxy-5-(dimethylarsinoyl)--ribofuranoside(peak II) and 3-glyceroposphosphoryl-2-hydroxy-1-[5-deoxy-5-(dimetylarsinoyl)--ribofuranosyloxy] propane) (peak III). A linear relationship existed between total water-soluble arsenic and arsenobetaine.

Cysteine (Cys) reacts with MMAs^V or DMAs^V and forms MMAs^IIIDC or DMAs^IIIC in vitro. MMAs^IIIDC or DMAs^IIIC may exert cytolethality by separating into MMAs^III or DMAs^III and Cys, probably becoming MMAs^III(OH)₂ or DMAs^IIIOH, before being transported into the cells.

The major route of human exposure to arsenic is via ingestion. Seafoods contain large amounts of various arsenic compounds. Recently, people have been advised not to eat Hijiki seaweed (Hijikia fusiforme) in the Unitedingdom because of its high content of inorganic arsenic (iAs). To clarify the risks of Hijiki ingestion, a 42-year-old male volunteer ingested 825 µg of iAs compounds contained in 8 servings of commercial Hijiki food, after refraining from eating seafood for three months. In order to determine the distribution of arsenic species in his urine, arsenic compounds were analyzed using HPLC-ICP-MS. The maximum concentrations of arsenate (AsV), arsenite (AsIII), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were found at 4, 6.5, 13, and 17.5 hours after ingestion, respectively. Asrsenobetaine concentration was very low, and almost constant throughout the observation period. A total of 28% of ingested arsenic was excreted in urine. The total amounts of AsV, AsIII, MMA, and DMA excreted in urine over 50 hours were 11.2, 31.8, 40.9, and 104.0 µg, respectively. After eating one serving of Hijiki, arsenic intake and urinary excretion were at levels similar to those in individuals affected by arsenic poisoning. Long-term ingestion of Hijiki might thus have the potential to cause arsenic poisoning.

The sensitivity and behavior of arseno-betaine on ICP-MS and ICP-AES analysis were investigated using the BCR arsenobetaine. The behavior and analytical sensitivity of arsenobetaine using ICP-MS and ICP-AES were also investigated using a commercially available synthetic arsenobetaine, and were compared with results for BCR-AB based on a JCSS arsenic standard solution. In the results, arsenic determined directly in arsenobetaine showed about 15% greater sensitivity in analysis by ICP-MS and ICP-AES than did inorganic (JCSS) arsenic.

We have developed the LC/MS/MS analysis method for chemical warfare agents related compounds in environmental samples. 2-Chloro-vinylarsonic acid (CVAOA), Phenylarsonic acid (PAA), Thiodigricol (TDG), Phenylmethylarsinic acid (PMAA), 2-Chlorovinylarsine oxide (CVAO), Phenylarsine oxide (PAO), Diphenylarsinic acid (DPAA), Bis(2-Chlorovinyl)arsinous acid (BCVAA) and Bis(diphenylarsine)oxide (BDPAO) were simultaeously able to be measured by LC/MS/MS equipped with a C8 column and ESI. The LODs of CVAOA, PAA, PMAA, DPAA and other compounds were 0.5 µg/mL, 0.05 µg/mL, 0.001 µg/mL, 0.0001 µg/mL and 0.01 µg/mL respectively.

The unsymmetrically substituted arsinic acid ethylphenylarsinic acid, when dissolved in metha- nol-d₄ or ethanol-d₆, formed esters in which the chiral nature of the arsenic atom was clearly revealed by the diastereotopicity and resulting anisochrony of the protons of the methylene component of the ethyl group attached to arsenic.

A type of edible brown algae, Hijikia fusiforme, contains a high amount of inorganic arsenic. The arsenic compound in Hijiki was removed by the Japanese cooking method, and the excretion of arsenic in Hijiki was also examined with mice. The speciation analysis of arsenic was measured by HPLC/ICP-MS system.

A method for determination of 2-chlorovinylarsenous acid (CVAA) and 2-chlorovinylarsonic acid (CVAOA), which are degradation compounds of the chemical warfare agent Lewisite, was examined by high performance liquid chromatography/inductively coupled plasma-mass spectrometry (HPLC/ICP-MS). Inertsil C₈ was suitable as the column and the mobile phase was consisted of 0.1% formic acid-acetonitrile (80:20). These compounds were detected sensitively in a short time and separated from inorganic arsenicals and diphenylarsinic acid (DPAA) and phenylarsonic acid (PAA), which are degradation compounds of diphenylchloroarsine and phenyldichloroarsine, respectively. The detection limits of CVAA and CVAOA were 0.2 and 0.1 ngAs/ml, respectively. In addition, a dynamic reaction cell and oxygen as the reaction gas were applied, and then arsenic was detected as AsO⁺ (m/z 91) in order to prevent interference by ArCl⁺ (m/z 75). This method was applied to the analysis of urine obtained from a CVAA-administered mouse and CVAOA was detected as the main metabolite. Thus, the speciation analysis of arsenic compounds derived from chemical warfare agents was achieved by HPLC/ICP-MS.