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Chromatography separation of arsenic compounds is important for chemical speciation studies; yet a complete separation of several biologically and environmentally important arsenic compounds has been difficult to achieve on a single column. We report here baseline resolution for arsenate, arsenite, monomethylarsonic acid, dimethylarsinic acid, arsenobetaine, arsenocholine, and tetramethylarsonium ion, by using mixed ion-pair reagents containing 10 mMhexanesulfonate and 1 mMtetraethylammonium hydroxide, as mobile phase. The complete separation of these anionic, cationic and neutral arsenic species on a reversed-phase C18column took only 12 min. Inductively coupled plasma mass spectrometry, hydride generation atomic absorption spectrometry and atomic fluorescence spectrometry systems were used for element-specific detection. The speciation technique was successfully applied to studies of urinary excretion of arsenic compounds following one-time ingestion of shrimp. Arsenobetaine ingested from the consumption of shrimp was excreted into urine in its original form; and approximately 70% of the total arsenobetaine ingested was excreted into urine within 37 h after ingestion.

Capillary electrophoresis with laser-induced fluorescence detection was used to monitor biosynthetic transformations of a labeled derivative of N-acetyllactosamine (β Gal(1 → 4)βGlcNAc, LacNAc) in crude microsomal extracts. For this purpose, six authentic standards including LacNAc-O-TMR itself (-TMR, a linker arm attached to tetramethylrhodamine), the tri-and tetrasaccharides that would form by either α(1 → 2) or α(1 → 3) fucosylation of LacNAc or both (i.e,, H-type 2, LeX and LeY sequences) were chemically synthesized. The potential degradation products produced by galactosidase and hexosaminidase were also prepared. All of the standards were kinetically competent substrates for the enzymes present in HT-29 cells and could be baseline separated in a single run requiring 11 min. The action of competing enzymes acting on the common LacNAc sequence could thus be monitored in a single run with sensitivity routinely as low as a few thousand molecules.Copyright 1995, 1999 Academic Press, Inc.