A simple lab on chip (LOC) for quantitation of sugar contents was proposed. It is based on migration of sucrose solution along a channel filled with water. The migration time, which is the time period that the sample travels, starting from at the injection moment to the point of detection, is related to the sugar content. By taking the benefits due to the Schlieren effect, the migration time can be monitored by using a fiber optic spectrophotometer. In another simple LOC system, addition of a bromothymol blue indicator in the water channel, the migration time was be able to be monitored via naked eyes and with a stop watch. Calibration equations were : y = 0.430 x + 9.500, R2 = 0.957 (for 800nm), and y = 1.12 x + 43.33, R2 = 0.993 for the LOC with fiber optic spectrophotometer and for the LOC with naked eyes detection, respectively. The results obtained by the proposed methods for determination of sugar contents in concentrates of syrup samples and samples of pharmaceutical preparations for cough syrup, agree with that using a refractometer which is normally used. This is an approach for green analytical chemistry.

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A flow injection analysis (FIA) for boron determination was studied using a compact and simple two-channel manifold. This method is based on the chromogenic reaction of borate with azomethine-H to form a yellow complex. The absorbance of the complex was measured at 405 nm. The chemical factors and FIA variables influencing the color development were examined. When a 0.5% (w/v) azomethine-H solution (pH 6.5) containing 1.5 % (w/v) ascorbic acid and 10 % (w/v) ammonium acetate was used as a reagent solution, the constant and maximum absorbance was obtained at a flow rate of 1.2 mL min^-1 and a reaction temperature of 40 °C. Under optimum conditions with 200 μL sample injection, the calibration graph was linear from 0.01 to 1.2 mg L^-1 of boron. The relative standard deviation was 0.99 % (n = 9) at the 0.2 mg L^-1 level. The detection limit and the determination limit were 0.011 (3σ) and 0.037 (10σ) mg L^-1, respectively. The sampling rate was 20 h^-1. The proposed FIA promises a simple and rapid method with high sensibility and precision for boron determination in aqueous samples.

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