A Teflon tube of 1.5 m in length and 0.5 mm in inner diameter was used to extract Cu(II) after complexation with oxine-5-sulfonate in in-tube solid-phase microextraction/electrothermal atomic absorption spectrometry. Prior to extraction, Zephiramine was loaded onto the inner wall of the Teflon tube, the sample solution was adjusted to pH 5.6, and then placed in a ca. 1 or 2-ml sample vessel. Subsequently, extraction was carried out in such a way that the sample solution was sucked into the Teflon tube and discharged to the original vessel with a syringe pump included in the auto-sampler. The suction and discharge actions were repeated several times to attain equilibrium and to improve the amounts of copper extracted. The percent extraction after equilibrium was 79 for a 200-µl sample solution. The effect of the sample volume was examined in the range of 0.5 2.0 ml. The suction and discharge actions were repeated 7 times with 295 µl of the sample solution, which was the inner volume of the Teflon tube. The results showed that the amounts of copper extracted increased with increasing volume of the sample solution up to 1.0 ml, although the percent extraction decreased with the sample volume. When copper extracted from 1.0 ml of a 0.3 ng ml 1 sample solution was eluted by 30 µl of methyl acetate (10 methanol), a reasonable repeatability with a relative standard deviation of 2.8 (n 3) was obtained. A linaer calibration graph was also obtained in the range of 0 0.5 ng ml 1 Cu(II). The detection limit(3σ ) was 0.01 ng ml 1 . The slope of the calibration graph was 14.2-times greater than that obtained by injecting 20 µl of standard solutions into the atomization furnace.
A new method for the indirect spectrophotometic determination of arsenic was developed. This method is based on the extraction of arsenic(III) from a solution of pH 1.5 on a finely divided anion-exchange resin as a complex with ammonium pyrrolidinedithiocarbamate(APDC), separation of the resin fixing the As(III)-APDC complex from the bulk solution on a membrane filter, re-dispersion of the resin in a solution containing copper(II) and conversion of a coloreless As(III)-APDC complex to a yellow Cu(II)-APDC complex, collection of the rsin on a membrane filter and measurement of the absorbance of the resulting Cu(II)-APDC complex in the resin phase by a spectrophotometer or a dennsitometer. The effects of interfering ions were successfully suppressed with the combined use of diethyldithiocarbamate (DDTC) and EDTA. The method was applied to a standard river water sample. Good results were obtained for the detemination of arsenic(III, V) at the ppb level in 40 ml of the sample.
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