Arsenic compounds in a marine food chain

A three-organism food chain within a rock pool at Rosedale, NSW, Australia, was investigated with respect to arsenic compounds by high performance liquid chromatography – hydraulic high pressure nebulization – inductively coupled plasma mass spectrometry (HPLC-HHPN-ICP-MS). Total arsenic concentration was determined in the seaweed Hormosira banksii (27.2 μg/g dry mass), in the gastropod Austrocochlea constricta (74.4 μg/g dry mass), which consumes the seaweed, and in the gastropod Morula marginalba (233 μg/g dry mass), which eats Austrocochlea constricta. The major arsenic compounds in the seaweed were (2′R)-dimethyl[1-O-(2′,3′-dihydroxypropyl)-5-deoxy-β-d-ribofuranos-5-yl]arsine oxide and an unidentified compound. The herbivorous gastropod Austrocochlea constricta transformed most of the arsenic taken up with the seaweed to arsenobetaine. Traces of arsenite, arsenate, dimethylarsinic acid, arsenocholine, the tetramethylarsonium cation, and several unknown arsenic compounds were detected. Arsenobetaine accounted for 95% of the arsenic in the carnivorous gastropod Morula marginalba. In Morula marginalba the concentration of arsenocholine was higher, and the concentrations of the minor arsenic compounds lower than in the herbivorous gastropod Austrocochlea constricta.     

Determination of total arsenic by use of a zinc-column arsine generator

A method for the measurement of total arsenic in extracts of environmental materials is described. Arsenic is reduced to arsine with a zinc reductor column, the evolved arsine is decomposed in a heated carbon-tube furnace, and arsenic determined by measurement of its atomic-absorption at 193.7 nm. The detection limit is 0.002 mug/ml and the coefficient of variation is 1.4% at 0.01 mug/ml.     

Solochrome Violet R als Reagens zur spektrophotometrischen Bestimmung von Mikrogrammengen Molybd?n

Zusammenfassung In der vorliegenden Arbeit wird eine rasche und genaue spektrophotometrische Bestimmung von Mikrogrammengen MolybdÄn beschrieben. Als Reagens wird der Azofarbstoff Solochrome Violet R verwendet. Dieser bildet mit MolybdÄn in sehwach salzsaurem Medium einen rotgefÄrbten Komplex, der selbst bei Anwesenheit von ÄDTA bestÄndig ist. Dadurch ist es möglich, den störenden Einflu\ anderer Ionen, z. B. den des Zirkoniums, auszuschalten. Mit dieser Methode lassen sich noch 2,0 g MolybdÄn/10 ml Me\lösung mit relativ hoher Genauigkeit bestimmen.Wir danken Herrn Prof. Dr. F. Hecht für seine Unterstützung, die für das Zustandekommen dieser Arbeit von gro\em Nutzen war.