Determination of Cr(III) and Cr(VI) at Sub-ppb Levels in Water with Solid-Phase Extraction/Metal Furnace Atomic Absorption Spectrometry

Abstract

determined Cr(III) and Cr(VI) in river water and lake water with cation-and anion-exchange resin in batch experiments by ICP-AES. Sumida et al. 11,12 preconcentrated Cr(III) and Cr(VI) in tap water, river water, wastewater, and seawater with iminodiacetate chelating resin column by ICP-AES. Furusho et al. 13 developed an automated pretreatment system for the determination of Cr(III) and Cr(VI) in tap water, river water, and mineral drinking water with iminodiacetate chelating resin and synthesized chitosan resin columns by ICP-AES. In this way, the iminodiacetate chelating resin was often used for the speciation of Cr in water; however, the chelate-forming reaction 2010 © The Japan Society for Analytical Chemistry † To whom correspondence should be addressed. E-mail: tetsuo@meiji.ac.jp A simple method using solid-phase extraction combined with metal furnace atomic absorption spectrometry was developed for the determination of Cr(III) and Cr(VI) at sub-ppb levels in water. A 500-ml water sample was adjusted to pH 3 with nitric acid and then passed through an iminodiacetate extraction disk placed on a cation-exchange extraction disk at a flow rate of 20 -40 ml min -1 for concentrating Cr(III). The filtrate was adjusted to pH 10 with aqueous ammonia and then passed through an anion-exchange extraction disk at a flow rate of 2 ml min -1 for concentrating Cr(VI). The Cr(III) and Cr(VI) collected were eluted with 40 ml of 3 mol l -1 nitric acid for Cr(III) and 40 ml of 1 g l -1 diphenylcarbazide solution for Cr(VI). Each eluate was diluted to 50 ml with deionized water and injected into a U-type tungsten board on the metal furnace. The calibration curves of Cr(III) and Cr(VI) showed good linearity in the range of 0.1 -0.5 ng. The detection limits corresponding to three times the standard deviation (n = 5) of blank values were 8.1 pg for both Cr(III) and Cr(VI). The analytical value of total Cr (Cr(III) + Cr(VI)) in certified reference material of river water (JSAC 0302-3) was in good agreement with the reference value. The recovery test for 0.50 μg (1.00 μg l -1 ) of Cr(III) and Cr(VI) added to 500 ml of the water samples showed sufficient values (98.1 -106%), except for river water sampled downstream due to relatively higher CODMn value. The relative standard deviations (n = 5) were less than 5% for both Cr(III) and Cr(VI). Determination of Cr(III) and Cr(VI) at Sub-ppb Levels in

Preliminary Characterization of a NADPH Dependent Chromate Reductase from Trichoderma pseudokoningii

“…In nature, chromium exists in two oxidation states: hexavalent and trivalent, of which chromium (III) is considered to be one of the essential trace elements in the human body and is required in metabolism of glucose [1]. On the other hand, chromium (VI) is well known for its higher toxicity and carcinogenicity.…”

Utilization of Modified Corn Silk as a Biosorbent for Solid-phase Extraction of Cr(III) and Chromium Speciation

“…2 Owing to these distinctly different physiological effects, it is particularly important to detect the chromium species and to determine its content. [3][4][5] The use of Cr chemicals in several industrial processes leads to contamination of natural waters mainly due to improper disposal methods. 6 According to the World Health Organization, 7 the US Environmental Protection Agency 8 and the Safe Drinking Water Act of China, 9 the Cr concentration in drinking water must be below 50 μg L -1 .…”

Determination of Diphenylarsinic Acid, Phenylarsonic Acid and Inorganic Arsenic in Drinking Water by Graphite-furnace Atomic-absorption Spectrometry after Simultaneous Separation and Preconcentration with Solid-phase Extraction Disks

“…In particular, membrane disk SPEs have been used to pretreat large-volume water samples because they allow relatively high flow rates, due to their large cross-sectional areas. 16 SPE disks keep their shape during the pretreatment process to assay, so they are useful for wet analyses 17 as well as direct analyses (e.g., X-ray fluorescence (XRF) spectrometry, [18][19][20] γ-ray spectrometry, 21,22 and laser-induced breakdown spectroscopy 23 ). An analytical method using an iminodiacetate extraction disk, followed by direct introduction into GFAAS instrument, has also been reported for determining heavy metals at sub-μg L -1 levels in water.…”