Research And Analysis The Methods For Determination The SO₂ Content In White Granulated Sugar

One of the most important qualitative indexes about white granulated sugaris the SO₂ content. At present, the national standard method for determinationthe SO₂ content in white granulated sugar is pararosaniline hydrochloridemethod. This method is brief and accurate; meanwhile this method has severaldisadvantages: Firstly, the oxious reagent HgCl₂ is used, which will causeenvironmental pollution and endanger the safety of analyst. Secondly, the SO₂standard solution is unstable and the chromomeric agent is uncertain, which willstraight influence the precision, the accuracy, the sensitivity and the uncertaintyof this method. So, the pararosaniline hydrochloride (without mercury salt)spectrophotometries and other methods which are innoxious or harmfulless,stable, better repeatability must be researched.This paper studied these methods: pararosaniline hydrochloride method(improved chromomeric agent), formaldehyde sampling-pararosanilinehydrochloride spectrophotometry, triethanolamine sampling-pararosanilinehydrochloride spectrophotometry, chromatography of ions, and theseapplications in determination the SO₂ content in white granulated sugar. Themain research contents were as follows:1. The analysis of the national standard method and the research ofpararosaniline hydrochloride method (improved chromomeric agent). 2. The research of pararosaniline hydrochloride (without mercury salt)spectrophotometries: (1)the process of formaldehyde sampling-pararosanilinehydrochloride spectrophotometry was: 5mL sugar solution+5mL formaldehydesolution+1mL sodium sulfamate+0.5mL sodium hydroxide+1mLpararosaniline hydrochloride, ambient temperature, 20min, 10mm cuvette,590nm wavelength; (2)the process of triethanolamine-sampling pararosanilinehydrochloride spectrophotometry was: 5mL sugar solution+5mLtriethanolamine solution+2mL formaldehyde+1 mL pararosanilinehydrochloride, ambient temperature, 20min, 10mm cuvette, 590nm wavelength.3. The research of chromatography of ions: IonPac AS11 splitter; NaOH aseluent, gradient elution, 1.00mL/min; suppressed conductively detection;qualitative analysis with retaining time, quantitative analysis with externalreference method.4. The comparison of these methods (the precision, the accuracy, thesensitivity and the uncertainty) and making comprehensive evaluation of them.The results indicated that these methods were more applicative than the nationalstandard method, and the method which had the best applicative prospect wasformaldehyde sampling-pararosaniline hydrochloride spectrophotometry.Comparing with the experimental results by the national standard method,these methods had no significant differences and could be applied indetermination the SO₂ content in white granulated sugar preliminarily.