Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sodium Bisulfite Part 4, Monographs for Reagent Chemicals: General Descriptions, Specifications, and Tests eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
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ABSTRACT This monograph for Sodium Bisulfite provides, in addition to common physical constants, a general description including typical appearance, applications, and aqueous solubility. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Insoluble Matter, Chloride, Heavy Metals, and Iron.
NaHSO3 (sodium bisulfite) Formula Wt 104.06 Na2S2O5 (sodium metabi- Formula Wt 190.10 sulfite)
CAS No. 7631-90-5 CAS No. 7681-57-4
Note: This reagent is usually a mixture of sodium bisulfite and sodium metabisulfite.
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . white solid Applications . . . . . . . . . . . . . . . . . . . . . . . . reducing agent; convenient source of sulfur dioxide Aqueous solubility . . . . . . . . . . . . . . . . . . . . soluble in 3.5 parts water
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥58.5% SO2 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.02% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.002%
© 2017 American Chemical Society
A
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4332 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (Titration of reducing power). Weigh accurately about 0.47 g, and add to a mixture of 100.0 mL of 0.1 N iodine volumetric solution and 5 mL of 10% hydrochloric acid solution. Swirl gently until the sample is dissolved completely. Titrate the excess of iodine with 0.1 N sodium thiosulfate volumetric solution, adding 3 mL of starch indicator solution near the end of the titration. One milliliter of 0.1 N iodine consumed corresponds to 0.003203 g of SO2.
Downloaded by CORNELL UNIV on May 25, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.4332
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in 200 mL of water.
Chloride Dissolve 0.50 g in 100 mL of water, and transfer 10 mL of the well-mixed solution to a platinum dish. Add low-chloride 10% sodium hydroxide reagent solution until the solution is slightly alkaline to litmus paper, making note of the volume of sodium hydroxide added. Prepare a standard containing 0.01 mg of chloride ion (Cl) in 10 mL of water, and add the same volume of low-chloride 10% sodium hydroxide reagent solution as was added to the sample solution. To each solution, add dropwise 2 mL of 30% hydrogen peroxide, and allow to stand at room temperature for 10 min. Evaporate the solutions to dryness on a hot plate (~100 °C), dissolve the residues in 10 mL of water, and add 1 mL of nitric acid and 1 mL of silver nitrate reagent solution to each. Any turbidity in the solution of the sample should not exceed that of the standard.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Dissolve 3.0 g in a solution of 15 mL of water and 8 mL of hydrochloric acid. Evaporate to dryness on a hot plate (~100 °C), dissolve the residue in about 20 mL of water, and dilute with water to 25 mL. For the control, add 0.02 mg of lead ion (Pb) to 1.0 g of sample, and treat exactly as the 3.0 g of sample.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Dissolve 1.0 g in 10 mL of water, add 2 mL of hydrochloric acid, and evaporate to dryness on a hot plate (~100 °C). Dissolve the residue in a mixture of 5 mL of water and 2 mL of hydrochloric acid, and again evaporate to dryness. Dissolve the residue in 4 mL of hydrochloric acid, dilute with water to 100 mL, and use 50 mL of the solution without further acidification.
© 2017 American Chemical Society
B
ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4332 ACS Reagent Chemicals, Part 4
