Table 4.

Determination of Cr(III) and Cr(VI) in different types of waters (three parallel determinations).

Sample	Cr(III), µg/L Mean ± SD	Cr(VI), µg/L Mean ± SD	Recovery for Cr(VI), %
River water	2.3 ± 0.2	<DL
River water + 0.5 µg/L Cr(VI)	2.2 ± 0.2	0.49 ± 0.02	94 ± 2
Seawater	0.52 ± 0.04	<DL
Seawater + 0.2 µg/L Cr(VI)	0.54 ± 0.04	0.21 ± 0.02	95 ± 4
Groundwater	1.3 ± 0.1	0.25± 0.02
Groundwater + 0.4 µg/L Cr(VI)	1.2 ± 0.1	0.63 ± 0.03	93 ± 4