A dynamic reaction cell ICP-MS was used as a CE detector for the speciation analysis of arsenic and selenium. Samples containing arsenite, arsenate, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, selenite, selenate, selenocysteine, selenomethione, and Se-methylselenocysteine were subjected to electrophoretic separation before being introduced into the microconcentric nebulizer (CEI-100) for their determination by ICP-MS. The separation has been achieved in a 60 cm length x 75 microm id fused-silica capillary. The electrophoretic buffer used was 25 mmol/L CAPS, and 0.5 mmol/L SDS at pH 9.5, whereas the applied voltage was set at 25 kV. The potentially interfering (38)Ar(40)Ar(+) and (40)Ar(40)Ar(+) at the selenium masses m/z 78 and 80 were reduced in intensity by approximately three orders of magnitude by using 1.4 mL/min CH(4) as reactive cell gas in the dynamic reaction cell. Arsenic was determined as the adduct ion (75)As(12)CH(2) (+) at m/z 89. The LOD for arsenic and selenium was in the range of 0.6-1.8 ng/mL, and 0.5-1.4 ng/mL, respectively, based on peak height. This method has been applied to determine various arsenic and selenium compounds in NIST SRM 1633a Coal Fly Ash and NRCC DOLT-3 Dogfish Liver reference materials and a selenium dietary supplement. The arsenic and selenium compounds were extracted from fish liver and dietary supplement by using Protease XIV and Lipase, and from coal fly ash with HF solution. The spike recoveries were in the range 91-103% for all the species studied.

A CE-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for iodine and bromine speciation analysis is described. Samples containing ionic iodine (I(-) and IO(3)(-)) and bromine (Br(-) and BrO(3)(-)) species are subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100). The separation has been achieved in a 50 cm length x 75 microm id fused-silica capillary. The electrophoretic buffer used is 10 mmol/L Tris (pH 8.0), while the applied voltage is set at -8 kV. Detection limits are 1 and 20-50 ng/mL for various I and Br compounds, respectively, based on peak height. The RSD of the peak areas for seven injections of 0.1 microg/mL I(-), IO(3)(-) and 1 microg/mL Br(-), BrO(3)(-) mixture is in the range of 3-5%. This method has been applied to determine various iodine and bromine species in NIST SRM 1573a Tomato Leaves reference material and a salt and seaweed samples obtained locally. A microwave-assisted extraction method is used for the extraction of these compounds. Over 87% of the total iodine and 83% of the total bromine are extracted using a 10% m/v tetramethylammonium hydroxide (TMAH) solution in a focused microwave field within a period of 10 min. The spike recoveries are in the range of 94-105% for all the determinations. The major species of iodine and bromine in tomato leaves, salt, and seaweed are Br(-), IO(3)(-), I(-), and Br(-), respectively.

A capillary electrophoresis-inductively coupled plasma mass spectrometric (CE-ICP-MS) method for the determination of cobalamin is described. Samples of cobalt-containing compounds were subjected to electrophoretic separation before injection into the microconcentric nebulizer (CEI-100) of ICP-MS. The Co-containing compounds studied include cyanocobalamin (CN-Cbl, vitamin B12), hydroxocobalamin (OH-Cbl), and Co(II). The species studied were well separated using a 70 cm lengthx75 microm i.d. fused silica capillary with the applied voltage set at +20 kV. A 25 mM Tris buffer (pH 9.0) containing 15 mM sodium dodecyl sulfate (SDS) was used as the electrophoretic buffer. The CE-ICP-MS detection limits were 0.3, 0.2, and 1.7 ng of Co mL(-1) for CN-Cbl, OH-Cbl, and Co(II), respectively. The concentrations of cobalamin compounds were determined in selected nutritive supplements and chlorella samples. A microwave-assisted extraction method was used for the extraction of these compounds. Over 92% of the total cobalt species was extracted using a 5% v/v HNO3 solution in a focused microwave field within a period of 10 min; spike recovery was in the range of 94-105% for various species. The major cobalt species in nutritive supplements and chlorella samples was cyanocobalamin.