| The chromium in the environment can exist steadily as chromium (Ⅲ) and chromium (Ⅵ). Chromium (Ⅲ) is the essential trace element of human body and foundation of protein, and it is also the essential element of mammal glucose and fat metabolism. However, chromium (Ⅳ) is generally known as carcinogen. Therefore, it is very important to carry on speciation analysis of the chromium in the environment.Since 1978, flow extraction technique is widely used owning to its characteristics of high enrichment efficiency, ease of automation and little reagent-consuming. Used as a windowless optical cell, a single drop can be free of contamination from deposition on the window. In addition, as the most general and popular photography sensor, charge coupled device (CCD) has been leaned to the microminiaturization and integration. Therefore, it has been used as the detector for the spectral instruments.The aim of this work is to couple the continuous flow extraction (CFE) with the liquid drop techniques. By using a T-tube with two open-ends as a prolonged liquid drop device, a laboratory-constructed glass tube as a automated phase separator, the automated liquid-liquid extraction system was developed in this laboratory and for the chromium speciation analysis in water samples. Under optimal conditions, calibration curve was linear in the range of 7.5350 μg L-1, with a correlation coefficient of 0.9993. The limit of detection (3a) was 7.5 μg L-1. The method issimple, cost-effective and labor-effective. It takes the advantages of CFE and liquid drop techniques, and is potentially useful in chromium speciation of water samples. |
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