Søren N. Pedersen

Liquid chromatography electrospray mass spectrometry with variable fragmentor voltages gives simultaneous elemental and molecular detection of arsenic compounds

A single quadrupole high performance liquid chromatography electrospray mass spectrometry system with a variable fragmentor voltage facility was used in the positive ion mode for simultaneous recording of elemental and molecular mass spectral data for arsenic compounds. The method was applicable to the seven organoarsenic compounds tested: four arsenic-containing carbohydrates (arsenosugars), a quaternary arsonium compound (arsenobetaine), dimethylarsinic acid, and dimethylarsinoylacetic acid. It was not suitable for the two inorganic arsenic species arsenite and arsenate. In the case of arsenosugars, qualifying ion data for a characteristic common fragment (m/z 237) was also simultaneously obtained. The method was used to identify and quantify the major arsenosugars in crude extracts of two brown algae.

Estrogenic effect of dietary 4-tert-octylphenol in rainbow trout (Oncorhynchus mykiss)

The estrogenic effect of dietary 4-tert-octylphenol (octylphenol) in rainbow trout Oncorhynchus mykiss was investigated. Octylphenol was administered orally to sexually immature rainbow trout every second day for 11 days in doses between 0.4 and 50 mgkg(-1)2 d(-1). Plasma vitellogenin was measured at day 0, 6 and 11 and at the end of the experiments, the amounts of octylphenol retained in liver and muscle were determined. Increases in average plasma vitellogenin levels were seen at exposure to 40 mg octylphenol kg(-1) every second day; the most sensitive fish responded to 30 mgkg(-1). Doses below 20 mg octylphenol kg(-1)2 d(-1) had no effect. The ED(50) value for induction of vitellogenin synthesis was 35 mg octylphenol kg(-1)2 d(-1). Only 1 to 2 per thousand of the total amount of octylphenol administered orally over the 11 days experimental period was retained in muscle and liver at the end of the experiment. A clear dose-related increase was observed for concentrations of octylphenol in both liver and muscle of fish exposed to doses between 0.4 and 50 mgkg(-1)2 d(-1). A significant correlation was found between the concentrations of octylphenol in the liver and vitellogenin level in plasma.

A new arsenobetaine from marine organisms identified by liquid chromatography–mass spectrometry

A new arsenic-containing betaine, trimethyl(2-carboxy- ethyl)arsonium inner salt 2, has been identified in fish muscle tissue by liquid chromatography–mass spectrometry.

Orally administered bisphenol a in rainbow trout (Oncorhynchus mykiss): Estrogenicity, metabolism, and retention

The estrogenic effect of orally administered bisphenol A (BPA) was investigated in a rainbow trout (Oncorhynchus mykiss) test system. Bisphenol A was administered orally to sexually immature rainbow trout every second day for up to 12 d in doses between 1.8 and 258 mg/kg every second day (/2d). Plasma vitellogenin was measured before and during the exposures, and the concentrations of BPA in plasma, liver, and muscle and the plasma concentrations of BPA glucuronic acid (BPAGA) were determined at the end of the experiments. Increases in average plasma vitellogenin levels were seen at oral exposure to 24 mg BPA/kg/2d; the most sensitive fish responded to 9.3 mg/kg/2d. At day 12, the 10, 50, and 90% effective doses for increase in vitellogenin synthesis were 13, 19, and 25 mg/kg/2d, respectively. Bisphenol A could be detected in liver, muscle, and plasma at the end of the exposure, generally in increasing concentrations with increasing doses; liver concentrations generally were higher than muscle concentrations. Four to five hours after the last feeding of doses between 3.6 and 24 mg BPA/kg, plasma BPA concentrations ranged between 400 and 1,200 nM, whereas BPAGA concentrations were between 2- and 10-fold higher. The difference between BPA and BPAGA concentrations increased with increasing BPA dose. Bisphenol A showed little tendency to bioaccumulate in rainbow trout; less than 1% of the total amount of BPA administered orally at doses between 1.8 and 258 mg/ kg/2d over the 10- or 12-d experimental period was retained in muscle and liver at 5 or 24 h after the end of the experiments.