Valve switching device and method for online pretreatment of sample for determining hexavalent chromium

Abstract

The invention discloses a valve switching device and method for online pretreatment of a sample for determining hexavalent chromium. The device comprises a six-way valve, a ten-way valve, two infusion pumps, a sample injector and a waste liquid bottle, wherein the six-way valve is connected with the sample injector, the infusion pumps and a pretreatment column respectively, and the ten-way valve serves as a switcher to be connected with a receiving ring and is connected with the pretreatment column, the infusion pumps and a separation column respectively. The device has high integrity, can achieve the detection on hexavalent chromium ions in the complex sample after being connected with a chromatographic column, a derivation device and a detection device, instrument dismounting or erection is not needed during sample detection, and the valve switching device is convenient and good in practicability.

Description

technical field [0001] The invention relates to a valve switching device, in particular to a valve switching device used for on-line pretreatment of samples for determination of hexavalent chromium. Background technique [0002] Chromium exists widely in nature, usually in two forms of Cr(Ⅲ) and Cr(Ⅵ). The two have completely different properties, among which Cr(Ⅲ) is an essential trace element for the human body, while Cr(Ⅵ) has certain toxic and side effects on the human body, and even causes death in high concentrations. For this reason, it is particularly important to develop methods for different valence states of chromium. [0003] At present, there are redox method, spectrophotometry, atomic absorption spectrometry and other detection methods for chromium in different valence states in the sample. Several methods are compared. The redox method is simple in principle and low in cost, but the reaction time is long, and the solution needs to be strictly controlled. Aci...

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Problems solved by technology

[0003] At present, there are redox method, spectrophotometry, atomic absorption spectrometry and other detection methods for chromium in different valence states in the sample. Several methods are compared. The redox method is simple in principle and low in cost, but the reaction time is long, and the solution needs to be strictly controlled. Acidity prevents the mutual transformation of Cr(Ⅵ) and Cr(Ⅲ), which can easily make the detection results inaccurate; spectrophotometry and atomic absorption spectrometry develop rapidly and are more and more widely used, among which spectrophotometry is prone to exist in the determination Matrix interference leads to wrong results, and atomic absorption spectroscopy itself cannot distinguish Cr(Ⅲ) and Cr(Ⅵ). It needs to use silica gel and other media to elute separately after adsorption for detection. The operation is complicated and the cost is high.

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