Speciation of organotin compounds by capillary electrophoresis using indirect ultraviolet absorbance detection.

Capillary electrophoresis (CE) with indirect photometric detection was investigated for the separation of organotin species. Compounds such as dimethyltin (DMT), dibutyltin (DBT), and tributyltin (TBT) are important pollutants in the aqueous environment and techniques are needed to analyze directly aqueous environmental samples quickly and economically. By adjusting the mobile phase to pH 2.65 by HCl, tributyltin, dibutyltin and dimethyltin in aqueous solutions were separated by capillary electrophoresis using indirect ultraviolet (UV) absorbance detection. Pyridine was used as the UV absorption additive at 254 nm and separation was achieved in 6 min. Peak tailing obtained at higher pH suggests strong interaction between the dimethyltin cation and the negatively charged capillary wall. Cetyltrimethylammonium bromide (CTAB) was added to the mobile phase to improve the peak shapes when the pH of the mobile phase was greater than 3.5. Separations of organotin species in mobile phases with or without CTAB were compared. The change of electrophoretic mobility in mobile phases with different pH values indicates that DMT and DBT start to undergo hydrolysis at a pH 3.0. It was also found that the choice of the buffer anions is critical in the separation of the tin compounds as complexes appear to form with DMT and DBT in the presence of oxalate and citrate.

Separation and determination of arsenic(V) and arsenic(III) in sea-water by solvent extraction and atomic-absorption spectrophotometry by the hydride-generation technique.

Arsenic(V) and arsenic(III) in sea-water have been separated by complexing the arsenic(III) with ammonium pyrrolidinedithiocarbamate (APDC) in the range 4.0-4.5 and extracting the complex with chloroform. The organic phase is then wet-ashed with a 1:1 mixture of concentrated nitric acid and perchloric acid to get rid of all organics, and the arsenic(III) is determined by hydride generation and atomic-absorption spectrophotometry. Total arsenic is determined by first reducing arsenic(V) to arsenic(III) with potassium iodide and then applying the method used for arsenic(III). The arsenic(V) content is determined by difference. The low detection limit of 0.031 ng ml and the high sensitivity and precision make the method suitable for analysis of open ocean waters.

Analysis of whole blood by neutron activation: a search for a biochemical indicator of neoplasia.

We determined a total of 13 elements in the whole blood of cancer patients and controls by using instrumental neutron activation analysis. The samples were spotted as whole blood on small filter paper disks, allowed to dry at room temperature, and sealed between two polyethylene disks. They were then irradiated and counted. Eleven elements were determined by this method. Sodium and chlorine were measured by irradiating whole blood in polyethylene vials. Statistical analysis of the data predicts that, with a very hgih probability, cobalt and iron are lower, adn sodium, tantalum, lanthanum and chlorine are higher in the cancer patients than in the normal persons tested. Chromium, zinc, and bromine also show differences between the two groups at a probability exceeding 0.95. Variations are indicated in scandium and cesium also, but are less strongly supported. Hafnium and selenium show no significant differences.