Determination of tarce water in non-polar organic solvents with a flow-injection system and tin tetrachloride or antimony pentachloride

Low levels of water (limit of detection 2-5 mg kg^1?)can be determined in a non-polar organic solvents such as benzene, 1,2-dichloroethane (DCE) and n-hexane by utilizing the reaction of water with SnCl₄ or SbCl₅. The reaction results of hydrolysis in halide and is accompanied by a decrease in optical absorption. With SnSl₄, the reaction is monitored near 300 nm and with SbCl₅ it is monitored at lower wavelengths (350-420). Niether reactons proceeds well in media containing only DCE and n-hexane. For this reason, the arrangemens involves a halide reagent dissolved in benzene which is merged with a benzene/n-hexane/DCE carrier stream into which samlpe is injected. A configuration in which only 2μl of a concentrated halide reagent solution is injected into the flowing sample stream is also shown to be viable for the determination of water in benzene. A membrane-permeation-based calibration method for preparing trace water standards is described.