Acta Medica Okayama 68 2 2005 Determination of trace amounts of bromide by flow injection/stopped-flow detection technique using kinetic-spectrophotometric method 274 280 EN K. Uraisin D. Nacapricha S. Lapanantnoppakhun K. Grudpan Shoji Motomizu <p>A simple, sensitive and selective method for the determination of bromide in seawater by using a flow injection/stopped-flow detection technique was examined. The detection system was developed for a new kinetic-spectrophotometric determination of bromide in the presence of chloride matrix without any extraction and/or separation. The detection was based on the kinetic effect of bromide on the oxidation of methylene blue (MB) with hydrogen peroxide in a strongly acidic solution. Large amounts of chloride could enhance the sensitivity of the method as an activator. The decolorisation of the blue color of MB was used for the spectrophotometric determination of bromide at 746 nm. A stopped-flow approach was used to improve the sensitivity of the measurement and provide good linearity of the calibration over the range of 0-3.2 p,g ml(-1) of bromide. The relative standard deviation was 0.74% for the determination of 2.4 jig ml(-1) bromide (n=5). The detection limit (3 sigma) was 0.1 mu g ml(-1) with a sampling frequency of 12 h(-1). The influence of potential interfering ions was studied. The proposed method was applied to the determination of bromide in seawater samples and provided satisfactory results. </p> No potential conflict of interest relevant to this article was reported.

Elsevier Science B.V. Acta Medica Okayama 0003-2670 579 1 2006 A membraneless gas diffusion unit: Design and its application to determination of ethanol in liquors by spectrophotometric flow injection 33 37 EN N. Choengchan T. Mantim P. Wilairat P. K. Dasgupta Shoji Motomizu D. Nacapricha This work presents new design of a gas diffusion unit, called 'membraneless gas diffusion (MGD) unit', which, unlike a conventional gas diffusion (GD) unit, allows selective detection of volatile compounds to be made without the need of a hydrophobic membrane. A flow injection method was developed employing the MGD unit to determine ethanol in alcoholic drinks based on the reduction of dichromate by ethanol vapor. Results clearly demonstrated that the MGD unit was suitable for determination of ethanol in beer, wine and distilled liquors. Detection limit (3S/N) of MGD unit was lower than the GD unit (GD: 0.68%, v/v; MGD: 0.27%, v/v). The MGD design makes the system more sensitive as mass transfer is more efficient than that of GD and thus, MGD can perfectly replace membrane-based designs. No potential conflict of interest relevant to this article was reported.