The Study On Direct Determination Of Sodium Formaldehyde Sulfoxylate In Foods

Sodium formaldehyde sulfoxylate is non-food raw materials, and harmful to human. At present, there are the following three types of methods for testing the Sodium formaldehyde in foods. (1) Determination of formaldehyde to project content of sodium formaldehyde sulfoxylate:this method is obviously incorrect. For the sample which only adds formaldehyde, this inference is not established. (2) Determination of formaldehyde and sulfur dioxide, respectively, then according to the ratio of two to determine whether add Sodium formaldehyde sulfoxylate. This method, do the following six experimental operation:1) distill sample according to the distillation method of determination of formaldehyde sample; 2) the calibration standard solution of formaldehyde; 3) Determination of formaldehyde content in the sample; 4) Calibration standard solution of sulfur dioxide; 5) re-treatment samples by determination of sulfite; 6) determine the content of sulfur dioxide in liquid sample. This determination consumes a lot of time and effort, and their recovery rate of two determinations of formaldehyde and sulfur dioxide are also inconsistent, it is difficult to make an accurate determination on the amount of Sodium formaldehyde sulfoxylate. (3) Determination formaldehyde hydrogen sulfate using ion chromatography. This method can only detect Sodium formaldehyde sulfoxylate residues, and Sodium formaldehyde sulfoxylate will decompose under acid or high temperature. In the production process of food, Sodium formaldehyde sulfoxylate will be part or all of the decomposition of formaldehyde and sulfur dioxide. So this method is not accurate. These three methods are not rigorous obvious, and the operation are all cumbersome. Therefore, we established an accurate, specific, sensitive and simple detection method, especially for the study.ObjectiveThis study aimed to explore a specific, accurate, sensitive, simple, widely used method in the direct determination of sodium formaldehyde sulfoxylate in various foods. To improve those less strict, cumbersome methods, attempt to establish a scientific method, as an effective national standard testing method to test sodium formaldehyde sulfoxylate.MethodsFirst, the sample was distillated by water vapor under acidic conditions followed by the-addition of sodium hydroxide which produced sulfur dioxide and formaldehyde. Second, acting with pararosaniline hydrochloride, which generate a purple substance. Third, determining its absorbance at 560 nm, or by Quantitative comparison with the standard series solution; or directly measured by HPLC.ResultsDetermined by spectrophotometry, the content of sodium formaldehyde sulfoxylate was 0.02-0.7 mg, the response value (absorbance) and the content of sodium formaldehyde sulfoxylate was a good linearity of r=0.9996, lowest determination limit of 0.005 mg and higher recovery of 93.5%-107.3%. HPLC linear range of 0.02-0.6 mg, the correlation coefficient r= 0.9995; the detection limit was 0.003 mg, if the sample weight 10.00 g, the minimum detectable concentration was 3 mg/kg; relative standard deviations of 3.1%; the recovery rate was 93.5%-102.2%.ConclusionsIn this study, whether by the spectrophotometric determination or by high performance liquid chromatography, the sample is directly measured the sodium formaldehyde sulfoxylate. This method can avoid the wrong results caused by speculation from the content of formaldehyde. It also simplified the sample treatment, not only can detect the determination of sodium formaldehyde sulfoxylate as residue in the food, but also can detect the determination of formaldehyde and sulfur dioxide. This simple and accurate method is suitable for the direct determination of sodium formaldehyde sulfoxylate in foods.