V-1300 formaldehyde buffer solution absorption _ hydrochloric acid para-rosaniline method - Database & Sql Blog Articles

V-1300 formaldehyde buffer solution absorption_hydropenylamine hydrochloride method

Key words: formaldehyde; para-rosaniline hydrochloride; mei analysis ; V-1200; V-1300 I. Reagent 1, sodium tetrachloromercury absorption solution: weigh 13.6 g high-mercury and 6.0 g Sodium, dissolved in water and diluted to 100 00 m L, allowed to stand overnight, filtered and used. 2, sulfamic acid according to the solution (12 g / L), 3 formaldehyde solution (2g / L): draw 0.55 m L of non-polymerized precipitated formaldehyde (36%), diluted with water to 100m L, and mix. 4. Starch indicator solution: Weigh 1g of soluble starch, mix it with a little water to make a paste, slowly pour into 100 ml of boiling water, add with stirring, boil, let cool, and use this solution when it is ready for use. 5. Ferrous potassium solution: Weigh 10.6 g of ferrous iron, add water to dissolve and dilute to 100 ml, 6. Zinc acetate solution: Weigh 22 g of zinc acetate [Zn(CH3000)2·2H20] dissolved in a small amount In water, add 3 ml of glacial acetic acid, dilute with water to 100 ml, 7. Pararosaniline hydrochloride solution: Weigh 0.1 g of pararosaniline hydrochloride in a mortar, add a small amount of water to dissolve and dilute to 100 ml. Take 20 ml, place it in a 100 ml volumetric flask, add hydrochloric acid (1+1), shake well to make the solution turn from red to yellow. If it is not yellow, add a small amount of hydrochloric acid until yellow appears, then dilute to the mark with water. Mix and reserve (if no hydrochloric acid, pararosaniline can be replaced with fuchsin hydrochloride). Method for purifying pararosaniline hydrochloride: Weigh 20g of pararosaniline hydrochloride in 400ml of water, acidify with 50ml of hydrochloric acid ((1+5), stir slowly, add 4g~5g of activated carbon, heat and boil for 2min. Pour the mixture into the large funnel. Filtration (filtered with hot funnel). The filtrate was allowed to stand overnight, crystallized, and then suction filtered with a Buchner funnel. The crystal was resuspended in a mixture of 1 000 ml of monoethanol (10:1) and shaken for 3 min. ~5 min, suction filtration with a Buchner funnel, and repeated washing until the ether layer is not colored, dried in a sulfuric acid drier, and stored in a brown bottle after grinding. 8. Iodine solution [c(I/2I) ₂ g = 0. 100 mol / L]. 9, sodium thiosulfate standard solution [c (Na2S203 · 5H20) = 0.10 0mol / L] 10, sulfur dioxide standard solution: weighed 0. 5 g sodium bisulfite, dissolved In 200 ml of sodium tetramercury absorbing solution, place overnight, and filter the supernatant with a quantitative filter paper. Pipette 10. 0 ml of sodium bisulfite-four sodium sulphate solution in 250 ml iodine volumetric flask, add 100 ml of water, accurate Add 20.0 0m L iodine solution ((0.1 mol/L), 5 ml glacial acetic acid, shake well, place in the dark, after 2 min Speed ​​up with sodium thiosulfate (0.1 00mol / L) standard solution to pale yellow, add 0.5 m L of starch indicator solution, continue to drip until colorless. Also take 100ml water, accurately add iodine solution 20.0 ml (0.1 mol / L), 5ml glacial acetic acid, according to the same method for reagent blank test. The concentration of sulfur dioxide standard solution is calculated according to formula (1). X=[(V ₂ —V ₁ )*C*32.03*1000 ]/MX——sulfur dioxide Standard solution concentration, in milligrams per milliliter (mg/ml); V, - Determination of the volume of sodium thiosulfate standard solution consumed by sodium bisulfite-four sodium sulphate solution, in milliliters (ml); The reagent blank consumes the volume of sodium thiosulfate standard solution in milliliters (ml); C - the molar concentration of sodium thiosulfate standard solution, in moles per liter (mol / L); 32. 03 - per sulphur Sodium sulfate [c (Na2S203. 5 H20) = 1.0 00mol / L] standard solution is equivalent to the quality of sulfur dioxide, the unit is milligrams (mg) 11, sulfur dioxide use liquid: before the use of sulfur dioxide standard solution with four sodium mercury absorption The liquid is diluted to 2 ug of sulfur dioxide per ml. 12. Sodium hydroxide Liquid (20g / L). 13, sulfuric acid (1 + 71), two, analysis steps 1, water-soluble solid samples such as white sugar can be weighed about 10.00 g of uniform sample (depending on the amount of sample content) ), dissolved in a small amount of water, placed in a 100 ml, volumetric flask, add 4 ml of sodium hydroxide solution (20 g / L), 5 minutes later, add 4 ml, sulfuric acid (1 + 71), then add 20 ml of sodium tetrachloromercurate absorption solution, Dilute to the mark with water. 2, other solid samples such as biscuits, fans, etc. can be weighed 5.0 g ~ 10.0 g of evenly ground samples, wet with a small amount of water and transferred into a 100 ml volumetric flask, then add 20ml of sodium tetrazolium absorbing solution, soak for more than 4h If the upper layer solution is not clear, add ferrous iron (3.5) and zinc acetate (2.5 ml each of 2.5 ml, and finally dilute to 100 ml with water. Scale, filter and set aside. 3. Liquid samples such as wine, etc. Can directly absorb 5.0ml - 10.0ml sample, placed in a 100ml volumetric flask, diluted with a small amount of water, add 20ml of four sodium sulphate absorption solution, shake well, and finally add water to the scale, mix, if necessary, filter for use. Measure 0. 50 ml-5.0 ml of the above sample treatment solution in a 25 ml plug colorimetric tube. Also take up 0.20, 0.40, 0.60, 0.80, 1.00, 1.50, 2.00 ml of sulfur dioxide standard use solution (equivalent to 0, 0.4 , 0.8, 1.2, 1.6, 2.0, 3.0, 4.0 fag sulfur dioxide), respectively in a 25ml with a plug colorimetric tube. Add a four-catch sodium sorbate to the sample and standard tube to 10ml. 1ml of iron sulfamate solution (12g / L), 1 ml, formaldehyde solution ((2 g / L) and 1ml of pararosaniline hydrochloride solution Shake well and place for 20 min. Use 1cm cuvette to adjust the zero point with zero tube, measure the absorbance at 550 nm, and compare the standard curve. 3. Calculate the sulfur dioxide content in the sample according to formula (2). X=A*1000/m*v/100*1000*1000X—the content of sulfur dioxide in the sample, in grams per kilogram (g/kg); A—the mass of sulfur dioxide in the sample solution, in micrograms (kg); M - the mass of the sample, the unit is gram (g); V - the volume of the sample solution used, the unit is milliliter (ml) Keywords: formaldehyde; the para-rosaniline hydrochloride method; the analysis of .com;V-1200