PARENT SESSION
68 - State of the Art in Analytical Chemistry
8:00 AM to 6:30 PM, Wednesday, 15 May 2002
Exhibition Area

(68-06) Determination of trace concentrations of hexavalent chromium in water.

Comber, Sean^*,1, Gardner, Mike¹, ¹ WRc-NSF, Henley Road, Medmenham, Marlow, Bucks

ABSTRACT- Metal speciation is usually the key to the fate and behaviour of metals. In the case of chromium, the important issue is the relative proportions of the trivalent (CrIII) and hexavalent (CrVI) forms. The biological effects of the metal in the two oxidation states are markedly different. The trivalent form is relatively non-toxic and is regarded as an essential trace element, whilst CrVI is of relatively high toxicity and has been shown to be a carcinogen in animal studies. A simple and sensitive solvent extraction-atomic spectrometric technique has been developed for the determination of hexavalent chromium in fresh and saline waters. The technique is based on the reaction of chromium with diphenylcarbazide. The method has been tested on a variety of water samples over an analytical range of 0 to 2 g l^-1. A limit of detection of 0.024 g l^-1 was achieved. Spiking recoveries in the range 87 to 115% were achieved in river water, drinking water and marine waters. The methodology was applied to assessing the levels of chromium (VI) in UK tap waters and also to investigate the seasonal variation in the speciation of chromium in a major UK river (Thames).

Key words: chromium, speciation, hexavalent, water