Objective To develop a quick and accurate method to determine trace glutaraldehyde in water.
Methods Glutaraldehyde reacted with phenol reagent (3-methyl-2-benzothiazolinone hydrazone hydrochloride, MBTH) and produced azine. Azine was oxidized by ferric ions in acid solution to blue-green compounds. A colorimetric assay was conducted because the color of the compound was directly proportional to glutaraldehyde content. The effect of wavelength, phenol reagent concentration, hydrochloric acid, developing temperature, and developing time on the result of test were analyzed, and opt conditions were determined.
Results The optimum absorption wavelength was 604 nm; the optimum dosages of MBTH and ammonium ferric sulfate were 200mg/L and 1800mg/L, respectively. Maintaining 30℃ for 15min, MBTH fully reacted with glutaraldehyde and produced azine. The optimum amount of hydrochloric acid as a colorant's solvent was 0.2 mol/L. The optimum developing temperature and time was 40℃ and 40 min respectively, without disturbing. Under the optimal experimental conditions, the absorbance showed an excellent linear relationship with glutaraldehyde in the range of 0.005-1.00 mg/L, and the detection limit was 0.005 mg/L. The relative standard deviation was 0.34%, and the average recovery was 98.13%.
Conclusion The described method can quickly determine trace glutaraldehyde in water with low limit of detection, high sensitivity and wide linear range, and thus has the potential in practical application.
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