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A flow injection system with anion exchange resin minicolumns was coupled with dynamic reaction cell (DRCtrade mark) ICP-MS for the determination and speciation of selenite and selenate at sub mugL(-1) levels. The charged selenate and uncharged selenite were separated on the first resin column in which only selenate was retained. The unretained selenite was then deprotonated with alkaline solution, and the resulting anionic selenite species was collected on the second column serially connected downstream. By setting a sample loop, total selenium can be determined together with selenite and selenate. The selenium species was eluted by nitric acid and carried to DRCtrade mark ICP-MS for their detection. Using ammonia as reaction gas, the detection of (78)Se was improved. The enrichment factor was 20 for 10mL of sample. The standard deviations (n=5) of peak heights were 4.9%, 4.1%, and 7.0% for a 5.0x10(-2)mugL(-1) selenite and selenate, and total Se, respectively. The calibration graphs were linear from 2.0x10(-2) to 1.0mugL(-1) selenite and selenate. And, the linearity for total selenium was good in the range of 10.0x10(-2) to 1.0mugL(-1). The proposed method has been demonstrated for the application to natural and bottled drinking water samples.

A novel and simple flow-based method was developed for the simultaneous determination of As(III) and As(V) in freshwater samples. Two miniature columns with a solid phase anion exchange resin, placed on two 6-way valves were utilized for the solid-phase collection/concentration of arsenic(III) and arsenic(V), respectively. As(III) could be retained on the column after its oxidation to As(V) species with an oxidizing agent. The collected analytes were then sequentially eluted by 2M nitric acid and introduced into ICP-AES. Potassium permanganate was examined as potential oxidizing agent for conversion of As(III) to As(V). The standard deviation of the analytical signals (peak height) for the replicate analysis (n=5) of 0.5mugl(-1) solution were 3 and 5% for As(III) and As(V), respectively. The limit of detection (3sigma) for both As(III) and As(V) were 0.1mugl(-1). The proposed system produced satisfactory results on the application to the direct analysis of inorganic arsenic species in freshwater samples.

A simple and low cost flow injection (FI) system with bead injection (BI) was developed for determination of low concentration (mumol l(-1)) of iron in water samples. Chelex-100 chelating resin beads, trapped in a jet ring cell, were employed. The intensity of red complex of 1,10-phenanthroline with Fe(2+) was monitored using colorimetric detector with a LED green light source. Amount of total Fe (Fe(2+) and Fe(3+)) and Fe(2+) can be evaluated by with and without reduction of Fe(3+) using ascorbic acid. Lowest detectable levels of Fe(2+) were 0.90 and 0.45 mumol l(-1) for sample loading time of 3 and 5 min, respectively. Working range was up to 3.90 mumol l(-1) using 0.3% w/v 1, 10-phenanthroline. Percent recoveries of spiked water samples (0.90-2.33 mumol l(-1) of Fe(2+)) were 100-110%.