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CAS Number: 149-44-0 - 6035-47-8
EC Number : 205-739-4
Rongalite = sodium hydroxymethylsulfinate = sodium formaldehyde sulfoxylate
Rongalite is a chemical compound with the molecular formula Na+HOCH2SO2−.
This salt has many additional names, including Rongalit, sodium hydroxymethylsulfinate, sodium formaldehyde sulfoxylate, and Bruggolite.
sodium hydroxymethylsulfinate is listed in the European Cosmetics Directive as sodium oxymethylene sulfoxylate (INCI).
sodium hydroxymethylsulfinate is water-soluble and generally sold as the dihydrate.
Sodium hydroxymethylsulfinate compound and its derivatives are widely used in the dye industry.
Although available commercially, the salt can be prepared from sodium dithionite and formaldehyde:
Na2S2O4 + 2 CH2O + H2O → HO-CH2-SO3Na + HO-CH2-SO2Na
This reaction proceeds quantitatively, such that dithionite can be determined by its conversion to Rongalite, which is far less O2-sensitive and thus easier to handle.
The hydroxymethanesulfinate ion is unstable in solution towards decomposition to formaldehyde and sulfite.
Addition of at least one equivalent of formaldehyde pushes the equilibrium towards the side of the adduct and reacts further to give the bis-(hydroxymethyl)sulfone.
Such solutions are shelf-stable indefinitely.
Sodium hydroxymethanesulfinate was originally developed in the early 20th century for the textile industry as a shelf-stable source of sulfoxylate ion, where the latter can be generated at will.
Sodium hydroxymethylsulfinate In use, when sodium hydroxymethanesulfinate is made acidic, the reducing sulfoxylate ion and formaldehyde are released in equimolar amounts.
For safety reasons the generation of formaldehyde must be taken into consideration when used industrially.
NaHOCH2SO2 can essentially be considered to be a source of SO22−.
As such it is used both as a reducing agent and as a reagent to introduce SO2 groups into organic molecules.
Treatment of elemental Se and Te with NaHOCH2SO2 gives solutions containing the corresponding Na2Sex and Na2Tex, where x is approximately 2.
As a nucleophile, NaHOCH2SO2 reacts with alkylating agents to give sulfones.
HO-CH2-SO2Na + 2 C6H5CH2Br → [C6H5CH2]2SO2 + NaBr + CH2O + HBr
Occasionally, alkylation will occur also at oxygen, thus α,α'-dibromoxylene gives both the sulfone and the isomeric sulfinate ester.
Use
The original use of the compound was as industrial bleaching agent and as a reducing agent for vat dyeing.
Another large-scale use is as a reducing agent in redox-initiator systems for emulsion polymerization.
One of the typical redox pair examples is t-butyl peroxide.
A niche use is its use as water conditioner for aquaria as it rapidly reduces chlorine and chloramine and reacts with ammonia to form the innocuous aminomethylsulfinate ion.
Sodium hydroxymethylsulfinate is also used as an antioxidant in pharmaceutical formulation.
The compound has been used increasingly in commercial cosmetic hair dye colour removers despite the generation of formaldehyde, a known human carcinogen.
Sodium hydroxymethylsulfinate has a variety of specialized applications in organic synthesis.
Related compounds
Sodium hydroxymethylsulfinate zinc complex Zn(HOCH2SO2)2 is marketed under the trademarks Decroline, Decolin, and Safolin. This compound is an additive in polymers and textiles.[5]
Sodium hydroxymethanesulfinate is called Rongalite C. Calcium hydroxymethanesulfinate is called Rongalite H.
IUPAC name:
Sodium hydroxymethanesulfinate
Other names:
Sodium formaldehydesulfoxylate, sodium oxymethylene sulfoxylate, Brüggolit
Identifiers
CAS Number : 149-44-0
6035-47-8 (dihydrate)
ChEMBL : ChEMBL2107242
ChemSpider : 8649
ECHA InfoCard: 100.005.219
EC Number:205-739-4
PubChem CID : 23689980
RTECS number :PB0380000
UNII : X4ZGP7K714
SQ4705447D (dihydrate)
CompTox Dashboard (EPA) : DTXSID7027120
Properties
Chemical formula: CH3NaO3S
Molar mass: 118.10 g/mol
154.14 g/mol, dihydrate
Appearance: colorless crystals
Density :1.75 g/cm3, dihydrate
Melting point: 64.5 °C (148.1 °F; 337.6 K) dihydrate
Solubility in water: 600 g/L, dihydrate (approximate)
Acidity (pKa): decomposes at low pH
Structure
Molecular shape: pyramidal at S
Hazards
GHS pictograms GHS08: Health hazard
GHS Signal word :Warning
GHS hazard statements: H341
GHS precautionary statements: P201, P202, P281, P308+313, P405, P501
Related compounds
Related compounds: SO32−, CH2O
Synonyms:
Sodium formaldehyde sulfoxylate
6035-47-8
Hydroxymethanesulfinic acid monosodium salt dihydrate
NCGC00166400-01
DSSTox_CID_28956
DSSTox_RID_83221
DSSTox_GSID_49030
CHEMBL3188745
DTXSID4049030
sodium;sulfinomethanolate;dihydrate
Tox21_113558
CAS-6035-47-8
Sodium formaldehyde sulfoxylate
149-44-0
205-739-4
Formaldehydesulfoxylic acid sodium salt
Hydroxyméthanesulfinate de sodium
Hydroxymethanesulfinic acid sodium salt
Methanesulfinic acid, 1-hydroxy-, sodium salt
MONOSODIUM HYDROXYMETHANESULFINATE
Natriumhydroxymethansulfinat
Oxymethansulfinsaeuren natrium
Rongalit
Sodium (hydroxymethyl)sulfinate
sodium formaldehyde sulphoxylate
Sodium formaldehydesulfoxylate
Sodium hydroxymethanesulfinate
sodium hydroxymethanesulfinate
Sodium hydroxymethanesulphinate
Sodium hydroxymethanesulphonate
sodium oxymethylene sulfoxylate
UNII-X4ZGP7K714
X4ZGP7K714
Aldanil
Bleachit D
C.I. Reducing Agent 2
Discolite
Formaldehyde sodium sulfoxylate
formaldehyde sodium sulphoxylate
Formapon
Formopan
Hydrolit
Hydroxymethanesulfinic acid monosodium salt
Hydroxymethansulfinsaeure, natriumsalz
Leptacid
Leptacit
Methanesulfinic acid, hydroxy-, monosodium salt
Rongalite, also called Rongalit (registered trademark of BASF), is sodium hydroxymethylsulfinate, or Na+HOCH2SO2-.
The salt has many names, including also sodium formaldehyde sulfoxylate, and Bruggolite.
Sodium hydroxymethylsulfinate is listed in the European Cosmetics Directive as sodium oxymethylene sulfoxylate (INCI).
Sodium hydroxymethylsulfinate is water-soluble and generally sold as the dihydrate.
Sodium formaldehydesulfoxylate (SFS) is a long name for a rather small molecule.
Sodium hydroxymethylsulfinate also goes by the name sodium hydroxymethanesulfinate or, most commonly, its trade name Rongalite.
Sodium hydroxymethylsulfinate is usually marketed as the dihydrate.
SFS has a long history:
Sodium hydroxymethylsulfinate In a short 1908 US patent assigned to Heyden Chemical Works (New York), Bruno R. Seifert and Otto W. Meves reduced formaldehyde and sulfur dioxide with zinc dust to a paste containing a zinc formaldehydesulfoxylate that could be converted to the sodium salt with sodium hydroxide or carbonate.
In a 1922 article, Frederick W. Heyl and Frank E. Greer of Upjohn1 (Kalamazoo, MI) reported an improved synthesis of a method described in a 1913 German patent.
Sodium hydroxymethylsulfinate mixture of formaldehyde and sodium hydrogen sulfite is treated with a mixture of zinc dust and zinc oxide.
Sodium hydroxymethylsulfinate convoluted purification process leads to acceptably pure SFS.
A 1935 patent by Frederick W. Binns at the Virginia Smelting Co.2 (Portland, ME) describes a similar synthesis that starts from zinc, sulfur dioxide, and formaldehyde.
Today SFS is manufactured from sodium dithionite (Na2S2O4) and formaldehyde.
Sodium hydroxymethylsulfinate was originally developed as a treatment for mercury poisoning (hence its pharmaceutical origin), but that was of limited value.
Sodium hydroxymethylsulfinate current uses are in vat dyeing as a reducing agent, in redox polymerization initiator systems, and for aquarium water conditioning.
Earlier this month, Scientific Update, a Mayfield, UK–based firm that holds conferences and training courses for industrial chemists and chemical engineers, featured Rongalite as its Reagent of the Month. The article focuses on the uses of the reagent in organic chemical synthesis.
Odor: characteristic
Use: Sodium formaldehyde sulfoxylate is generally used as an industrial bleaching agent for textiles, molasses, and soaps.
Sodium hydroxymethylsulfinate also has a niche use as a water conditioner, reducing the amount of chlorine, and in pharmaceuticals as an antioxidant.
Sodium hydroxymethanesulfinate hydrate
meets compendial specs of USP
149-44-0
Molecular Formula : CH3NaO3S
Molecular Weight : 118.10
Part A
Storage : 8 to 25°C (Cool & dry area)
Shelf Life : 60 Months
HSN Code : 29309099
IMDG Identification :Not Regulated for Transport (Non-Haz)
Specifications
Appearance (Colour): White
Appearance (Form): Chips
Assay: min. 98%
pH (2% aq. solution): 9.5 - 10.5
Hazard statements
H341 Suspected of causing genetic defects (if exposed)
H361d Suspected of damaging the unborn child (if exposed)
Precautionary statements:
Precautionary statements - prevention:
P201 Obtain special instructions before use.
P260 Do not breathe dust/fume/gas/mist/vapours/spray.
P280 Wear protective gloves/protective clothing/eye protection/face protection.
Precautionary statements - response
P308+P313 IF exposed or concerned: Get medical advice/attention.
For professional users only
Supplemental hazard information
EUH031 Contact with acids liberates toxic gas.
Precautions for safe handling
Provision of sufficient ventilation.
Avoid: Aerosol or mist formation.
Avoid dust formation.
Avoid exposure. Do not mix with acids.
• Measures to prevent fire as well as aerosol and dust generation
Removal of dust deposits.
Advice on general occupational hygiene
Wash hands before breaks and after work.
Keep away from food, drink and animal feedingstuffs.
Conditions for safe storage, including any incompatibilities
Keep container tightly closed.
Store in a dry place.
Protect from sunlight.
Hygroscopic solid.
Conducting polymers such as poly(3,4-ethylenedioxythiophene):poly-(styrenesulfonate) (PEDOT:PSS) have attracted extensive attention for thermoelectric applications due to its solution-processability, mechanical flexibility, low thermal conductivity and tunable electrical conductivity.
This work demonstrated a sequential post-treatment method with formamide and sodium formaldehyde sulfoxylate (SFS) to significantly improve thermoelectric properties of PEDOT:PSS film, particularly its Seebeck coefficients.
Water-soluble and non-toxic SFS is an ionic-type reducing agent, which is used as an environmentally benign chemical reagent for the first time to treat PEDOT:PSS.
First, the PEDOT:PSS film was soaked with formamide (F-PEDOT:PSS), and then was treated with SFS solutions with various molar concentrations (SFS–F-PEDOT).
The Seebeck coefficient of F-PEDOT:PSS film treated with 100 mM SFS was steeply increased from 14.8 to 51.8 μV/K primarily due to the proper control of the doping level and the carrier concentration although the corresponding electrical conductivity of the film was reduced from 2,873 to 693 S/cm.
Sodium hydroxymethylsulfinate The resulting power factor reached its maximum value of 185.8 μW/K2m, which was approximately three times that of formamide-treated film (F-PEDOT:PSS: 63.7 μW/K2m).
The cross-plane thermal conductivity of the pristine PEDOT:PSS film was dropped from 0.59 W/mK for the pristine film to 0.29 W/mK for the SFS-F-PEDOT:PSS film, leading to an estimated ZT value of in the range of ~0.07–~0.14 at 300 K. Also, the stability of SFS-F-PEDOT:PSS film was examined under a harsh environment, and results showed that the film retained its electrical conductivity and Seebeck coefficient of more than 85% after continuous exposure under 70 °C and a humidity of 75% RH for 480 h, revealing the excellent long-term environmental stability.
Flammability Classification: Not flammable; combustible if involved in a fire.
Flash Point: >100°C (>212°F)
Flammability Limits in Air: Not applicable
Autoignition Temperature: No data available
Extinguishing Media: Carbon dioxide, foam, dry chemical, water fog
Unusual Fire and Explosion Hazards: Larger amounts of contained, molten material may
violently decompose above 70°C. Combustion products may include but are not limited to carbon
monoxide, carbond ioxide, sulfur dioxide, some metallic oxides. The product may contain fine dusts
capable of forming explosive dust/air mixtures.
Special Fire Fighting Procedures: Use protective fire fighting clothing and positive pressure selfcontained breathing apparatus to protect against potential harmful and/or irritating fumes. If
containers cannot be cooled, break open to spill material out. Do not use high pressure water jet as
this may craete dusting. Prevent fire runoff water frome ntering sewer drains; collect for appropriate
disposal.
Skin Contact: Wash immediately with plenty of soap and water for at least 15 minutes; get
medical attention if irritaion occurs.
Eye Contact: Flush eyes immediately with plenty of water for at least 15 minutes; get medical
attention if irritation persists.
Ingestion: Do not induce vomiting; give several glasses of water of milk to drink immediately. Get
medical attention.
Inhalation: Move person to fresh air.
Get medical attention if respiration irritation develops or if breathing becomes difficult.
Colour discharge printing agent on cotton and synthetic fabrics
Soluble in water.
Provides a unique versatility of printing on both cotton and synthetics due to the exceptional stability over long periods and high compatibility with various print systems.
Excellent production due to strong reduction power.
Excellent definition of Discharge prints.
Field of application: As a discharge agent in textile printing, as redox catalyst in polymerisation process for manufacturing polymer and as an antioxidant in drug formulations.
Chemical Basis: Sodium Formaldehyde Sulfoxylate
Ionic Character:
Form: Crystalline powder
Abstract : Objective: To establish a method for determination of sodium formaldehyde sulfoxylate in food by high performance liquid chromatography (HPLC).
Methods: Samples were extracted with phosphoric acid solution, then the formaldehyde released from sodium formaldehyde sulfoxylate residues in samples and reacted with 2,4-dinitrophenylhydrazine (DNPH) for generating yellow 2,4-dinitrobenzene, which was separated with Eclipse XDB-C18 column (250 mm × 4.6 mm, 5 µm) with the mobile phase of acetonitrile-water (60:40, V:V) at 35°C, and the flow rate was 1.0 mL/min.
The detection wavelength was set at 355 nm and then determined by HPLC.
Results: The optimization of the experimental conditions was that the concentration of phosphoric acid solution was 2.0%, and the concentration of 2,4-dinitrophenylhydrazine (DNPH) solution was 2.0% with 60°C bathing for 30 min.
Sodium hydroxymethylsulfinate calibration curve of formaldehyde was linear within the range of 0-3 µg/mL (r=1.00).
Sodium hydroxymethylsulfinate recoveries of formaldehyde spiked at 3 levels of 5, 10 and 30 µg were 95.36%-98.20% and RSD were 0.403%-1.05%.
Sodium hydroxymethylsulfinate limit of detection was 0.17 mg/kg.
Conclusion: The method is rapid and accurate, which is suitable for detection of sodium formaldehyde sulfoxylate residues in food.
Sodium Formaldehyde Sulfoxylate also called SFS is a white powder or granules with slight specific odor.
Sodium hydroxymethylsulfinate contains Sodium Hydroxymethane Sulfinate as active ingredient and is used as reducing agent in initiator systems for the main or post polymerization of emulsion polymers.
Sodium formaldehyde sulfoxylate is a white solid chemical, soluble in water.
Sodium formaldehyde sulfoxylate is generally used as an industrial bleaching agent for textiles, molasses, and soaps.
Sodium hydroxymethylsulfinate also has a niche use as a water conditioner, reducing the amount of chlorine, and in pharmaceuticals as an antioxidant.
We have helped multiple customers, from small end users to large Fortune 500 customers, with their Sodium formaldehyde sulfoxylate supply requirements and can ship bulk and various packaged products to meet such needs.
A method of treatment for acute mercury poisoning utilizing sodium formaldehyde sulfoxylate and based on the work of Rosenthal is outlined.
It consists of:
1. Immediate gastric lavage with sodium formaldehyde sulfoxylate.
2. Intravenous injection of sodium formaldehyde sulfoxylate.
3. High colonic irrigations with the same drug twice daily.
4. Gastric lavage twice daily for two days.
5. Daily intravenous glucose in saline.
6. Mouthwash with sodium formaldehyde sulfoxylate for stomatitis.
7. Supportive measures as needed.
8. Fluids and soft diet.
The findings and results in 20 cases treated by this method are presented.
Four fatal cases are presented and the causes of death are analyzed.
Sodium hydroxymethylsulfinate significance of early treatment, physiologic supportive measures, high colonic irrigations, and individual management are stressed.
Sodium hydroxymethylsulfinate method is not considered to be ideal, but it is felt that it should be used in all cases of acute mercury poisoning until a more efficient routine is discovered.
Spectrum Chemical manufactures and distributes fine chemicals with quality you can count on including those with CAS number 149-44-0, Whether you call it Sodium Formaldehyde Sulfoxylate or Hydroxymethanesulfinic Acid Sodium Salt you can be assured the products offered by Spectrum, meet or exceed the grade requirements or specifications for each individual product.
CH3NaO3S 118.09
CH3NaO3S · 2H2O 154.11
Methanesulfinic acid, hydroxy-, monosodium salt;
Monosodium hydroxymethanesulfinate
[149-44-0] Dihydrate [6035-47-8]
DEFINITION
Sodium Formaldehyde Sulfoxylate contains an amount of sodium formaldehyde sulfoxylate (CH3NaO3S) equivalent to NLT 45.5% and NMT 54.5% of SO2, calculated on the dried basis.
Sodium hydroxymethylsulfinate may contain a suitable stabilizer, such as sodium carbonate.
Entry :D05861
Name
Sodium formaldehyde sulfoxylate (NF);
Sodium formaldehyde sulfoxylate anhydorous
Formula : CH3SO3. Na
Exact mass : 117.9701
Mol weight : 118.0875
Efficacy : Pharmaceutic aid (preservative)
Other DBs
CAS: 149-44-0
PubChem: 47207522
LigandBox: D05861
NIKKAJI: J78.385D
Our water soluble reducing agents are supplied globally to improve emulsion polymers. New regulatory demands for VOC/Formaldehyde reduction in coatings and adhesives are achievable with our advanced reducing agents, enabling waterborne polymers to replace solvent based materials in many areas.
Other typical industrial uses include textile, paper, and mineral bleaching.
Advanced Formaldehyde Free Reducing Agents
Formaldehyde free reducing agents from Brüggemann enable solutions for the latest technical challenges of environmental awareness, rising quality demands, and improved application performance.
Our products and techniques enable emulsion polymer producers to improve efficiency with more sustainable raw materials.
All offer the following attributes:
Formaldehyde and VOC free
Increased reactivity – better performance at lower dosage and time
Low to zero residual free monomer level
Non yellowing
FDA Direct Food Contact approval
Dust free micro granules
Royce SFS is a concentrated reducing agent used as a redox catalyst in emulsion polymerization of many types of synthetic rubber.
Royce SFS is also widely used in the reductive clearing of disperse dyed synthetic fiber.
Abstract
The invention discloses a production method of sodium formaldehyde sulfoxylate.
Sodium hydroxymethylsulfinate In the production method, anhydrous sodium sulfite is firstly added in the concentration process of a prepared sodium formaldehyde sulfoxylate solution; and a sodium hydroxide solution or a soda ash solution is added before the prepared sodium formaldehyde sulfoxylate solution is concentrated.
Sodium hydroxymethylsulfinate advantage is to provide a production method of odorless anhydrous sodium sulfite, thus the odor of free formaldehyde in products is eliminated, the odor generated because products are affected with damp and decomposed is eliminated, and moisture absorption, caking and decomposition of products are prevented, so that the storage stationary phase of the products is long and can be stored for a year under a closed state but not caked and stunk, and the product quality is improved; 35% of aqueous solution is transparent after the product is dissolved; and the production method is environment-friendly and clean, and is suitable for production of platy, blocky, powdered, granular and crushed sodium formaldehyde sulfoxylate products.
Sodium formaldehyde sulphoxylate is shown to be an inexpensive, efficient reagent for the dehalogenation of phenacyl halides and other α-haloketones. Some possible mechanisms for the reduction are discussed.
In 1934 Rosenthal1 recommended sodium formaldehyde sulfoxylate as an antidote in acute mercury poisoning and at the same time reported ten cases in which it had been used without a fatality.
Later in the same year we2 reported seven cases in which this new antidote had been used, with, however, three deaths.
Since that date we have observed the use of sodium formaldehyde sulfoxylate in an additional thirty-three cases of mercury bichloride ingestion, and the combined forty cases form the basis of this report.
We make this contribution solely for the purpose of adding to the literature a representative number of cases in which this method of treatment has been used, for only by such reports can the proper place of this antidote in the treatment of acute mercury poisoning be determined.
A novel method was developed to determine sodium formaldehyde sulfoxylate residues in wheat flour and starch noodles without degradation.
The samples were extracted ultrasonically with water and the extracted analytes were separated by capillary electrophoresis (CE) in combination with capacitively coupled contactless conductivity detection (CE-C4D).
Under optimal conditions, the linear range was 1.00–200 μg/mL (r2 = 0.999 8), and the limit of detection for both food matrices was 10 mg/kg.
Recoveries varying from 84.0% to 94.7% with a relative standard deviation (RSD) smaller than 5% were achieved for the analyte spiked between 20 and 100 mg/kg.
Sodium hydroxymethylsulfinate proposed method was simple and rapid.
Sodium hydroxymethylsulfinate has beensuccessfully applied for analysis of sodium formaldehyde sulfoxylate in wheat flour and bean starch noodles.
CH3NaO3S 118.09
Methanesulfinic acid,hydroxy-,monosodium salt.
Monosodium hydroxymethanesulfinate [149-44-0].
Dihydrate 154.11 [6035-47-8].
»Sodium Formaldehyde Sulfoxylate contains an amount of CH3NaO3Sequivalent to not less than 45.5percent and not more than 54.5percent of SO2,calculated on the dried basis.
Sodium hydroxymethylsulfinate may contain a suitable stabilizer,such as sodium carbonate.
Packaging and storage— Preserve in well-closed,light-resistant containers,and store at controlled room temperature.
Clarity and color of solution— Dissolve 1g in 20mLof water,and transfer 10mLto a 20-×150-mm test tube.Compare with water in a similar test tube:the liquids are equally clear and,when viewed transversely by transmitted light,exhibit no apparent difference in color.
Identification—
A: Dissolve about 4g in 10mLof water in a test tube,and add 1mLof silver-ammonia-nitrate TS:metallic silver is produced,either as a finely divided,gray precipitate or as a bright metallic mirror on the inner surface of the tube.
B: Dissolve about 40mg of salicylic acid in 5mLof sulfuric acid,add about 50mg of Sodium Formaldehyde Sulfoxylate,and warm very gently:a permanent,deep red color appears.
Alkalinity— Dissolve 1.0g in 50mLof water,add phenolphthalein TS,and titrate with 0.10Nsulfuric acid:not more than 3.5mLis required for neutralization.
pHá791ñ: between 9.5and 10.5,in a solution (1in 50).
Loss on drying á731ñ— Dry it at 105for 3hours:it loses not more than 27.0%of its weight.
Sulfide— Dissolve 6g in 14mLof water in a test tube,and wet a strip of lead acetate test paper with the clear solution:no discoloration is evident within 5minutes.
Iron— Transfer 1.0g to a suitable crucible,and carefully ignite,initially at a low temperature until thoroughly charred,and finally,preferably in a muffle furnace,at 500to 600until the carbon is all burned off.
Cool,dissolve the residue in 2mLof hydrochloric acid,and dilute with water to 50mL.Add about 50mg of ammonium persulfate and 5mLof ammonium thiocyanate TS,mix,and transfer to a color-comparison tube.
Treat in the same manner 5.0mLof a solution of ferric ammonium sulfate,prepared by dissolving 43.2mg of ferric ammonium sulfate in 10mLof 2Nsulfuric acid and adding water to make 1000mL,each mLrepresenting 5µg of Fe.
The color of the test solution is not deeper than that of the solution containing the standard iron solution (0.0025%).
Sodium sulfite— Transfer 4.0mLof the solution prepared for the Assayto a conical flask containing 100mLof water.
Add 2mLof formaldehyde TS,and titrate with the same 0.1Niodine VSthat is used for the Assay,adding 3mLof starch TSas the endpoint is approached.
Calculate the percentage of Na2SO3in the Sodium Formaldehyde Sulfoxylate taken by the formula:
(1.25)(63.02)(V2-V1)(N/W),
in which 63.02is the equivalent weight of sodium sulfite;V1and V2are the volumes,in mL,of 0.1Niodine VSconsumed in this titration and in the titration performed in the Assay,respectively;Nis the exact normality of the iodine solution;and Wis the weight,in g,of Sodium Formaldehyde Sulfoxylate taken for the Assay:not more than 5.0%of Na2SO3,calculated on the dried basis,is found.
