Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Sodium Sulfate, Anhydrous 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
ABSTRACT This monograph for Sodium Sulfate, Anhydrous provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), 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, pH of a 5% Solution at 25.0 °C, Insoluble Matter, Loss on Ignition, Chloride, Nitrogen Compounds, Phosphate, Heavy Metals, Iron, Calcium, Magnesium, Potassium, and Extraction−Concentration Suitability.
Na2SO4
Formula Wt 142.04
CAS No. 7757-82-6
Suitable for general use or in extraction–concentration analysis. Product labeling shall designate the uses for which suitability is represented on the basis of meeting the relevant specifications and tests. The extraction–concentration suitability specifications include all of the specifications for general use.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . .
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white solid Kjeldahl nitrogen determination; drying agent melting point, 884 °C 20 g in 100 mL at 20 °C
SPECIFICATIONS General Use Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% Na2SO4 pH of a 5% solution at 25.0 °C . . . . . . . . . . . 5.2–9.2 Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . 0.01% Loss on ignition. . . . . . . . . . . . . . . . . . . . . 0.5% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . 0.001% Nitrogen compounds (as N) . . . . . . . . . . . . . 5 ppm
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4368 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Phosphate (PO4) . . . . . . . Heavy metals (by ICP–OES) Iron (Fe) . . . . . . . . . . . . Calcium (Ca) . . . . . . . . . Magnesium (Mg) . . . . . . . Potassium (K) . . . . . . . . .
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. 0.001% . 5 ppm . 0.001% . 0.01% . 0.005% . 0.01%
Specific Use Extraction–concentration suitability. . . . . . . . Passes test
TESTS Assay (By indirect acid–base titrimetry after ion exchange, [Part 2: Titrimetric Methods; Ion-Exchange Column Assays; Method for Ion-Exchange Column Assays]). Weigh accurately about 0.3 g of sample, and dissolve in about 50 mL of water. Pass the sample solution through the column at a rate of about 5 mL/min, collecting the eluate in a 500 mL titration flask. Wash the column with water at a rate of about 10 mL/min, collecting the washings in the same flask. Add 0.15 mL of phenolphthalein indicator solution, and titrate the eluate with 0.1 N sodium hydroxide. Continue to wash the column and to titrate the eluate until the passage of 50 mL of water requires no further titrant. One milliliter of 0.1 N sodium hydroxide corresponds to 0.007102 g of Na2SO4.
Note: All water used in the assay must be free of carbon dioxide and ammonia.
pH of a 5% Solution at 25.0 °C [Part 2: Direct Electrometric Methods; pH Potentiometry; pH Range; Procedure for pH of a 5% Solution at 25.0 °C].
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use 10.0 g dissolved in 100 mL of water.
Loss on Ignition Weigh accurately about 2 g in a tared, preconditioned dish or crucible, and ignite at 800 ± 25 °C for 15 min.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 1.0 g.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4368 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Nitrogen Compounds [Part 2: Colorimetry and Turbidimetry; Nitrogen Compounds: Test for Ammonia, Amines, and Nitrogen Compounds Reduced by Aluminum]. Use 2.0 g. For the standard, use 0.01 mg of nitrogen ion (N).
Phosphate [Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 1 (Direct Molybdenum Blue)]. Dissolve 2.0 g in 20 mL of 0.5 N sulfuric acid. For the standard, dilute 0.02 mg of phosphate ion (PO4) to 20 mL with 0.5 N sulfuric acid.
Heavy Metals ([Part 2: Trace and Ultratrace Elemental Analysis; Inductively Coupled Plasma−Optical Emission Spectroscopy (ICP–OES); Calculation of Heavy Metals (by ICP–OES) Results], by ICP–OES). Use 2.0 g sample.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 1.0 g of sample.
Calcium, Magnesium, and Potassium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium, Magnesium, and Potassium
S a m p l e S t o c k S o l u t i o n . Dissolve 4.0 g in 50 mL of water, and transfer to a 100 mL volumetric flask. Dilute to the mark with water (1 mL = 0.04 g).
For the Determination of Calcium, Magnesium, and Potassium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.40
0.02; 0.04
N/A
No
Mg
285.2
0.40
0.01; 0.02
A/A
Yes
K
766.5
0.10
0.01; 0.02
A/A
No
*A/A is air/acetylene; N/A is nitrous oxide/acetylene.
Extraction−Concentration Suitability [Part 2: Chromatography; Recommended Procedures; Extraction−Concentration; Solvent Suitability for Extraction−Concentration]. Prepare a method blank to check the glassware and dichloromethane before beginning the sample analysis; follow the sample procedure below, except omit the sample. Dry about 55 g of sample in a shallow tray at 400 °C for 1 h, and allow to cool in a desiccator. Transfer 50 ± 0.1 g of the dried sample, accurately weighed, to a 250 mL conical flask, add 60 mL of extraction–concentration grade dichloromethane, and allow to stand for 2–3 min. Swirl every 15 s to mix. Allow to stand until any fines that may be present have settled, and then decant the dichloromethane into a Kuderna–Danish flask equipped with a 3-ball Snyder column and a 10 mL concentrator tip. Extract the sample with two additional 60 mL portions of dichloromethane, as described above, combine the extracts, and concentrate the contents of the flasks to 1 mL. Perform solvent exchange using 15 mL of extraction–concentration
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4368 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
grade hexanes in the Kuderna–Danish flask, and concentrate to 1 mL. Place a micro Snyder column on the 10 mL tip, perform two additional solvent exchanges, using 5 mL of hexanes each time, and concentrate to 1.0 mL. Inject 5.0 µL of the concentrate from the method blank into a gas chromatograph equipped with an electron capture detector (ECD) and a flame ionization detector (FID), as described in [Part 2: Chromatography; Recommended Procedures; Extraction−Concentration; Procedure for ECD and FID Suitability]. Dilute each standard specified in the ECD and FID suitability tests with an equal volume of hexanes, giving concentrations of 0.5 µg/L heptachlor epoxide and 0.5 mg/L of 2-octanol, respectively, and inject 1.0 µL of each into the chromatograph. Finally, inject 5.0 µL of the 180:1 concentrate from the sample into the chromatograph. Calculate the concentration of contaminants in the sample by comparing the sample peak heights with the height of the heptachlor epoxide and 2-octanol peaks from the injection of the standards, correcting for any contribution of the solvents as determined by the method blank. No peak in the extract of the sample shall exceed the height of the standard when measured as described in [Part 2: Chromatography; Recommended Procedures; LC Suitability; Procedure for Absorbance].
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DOI:10.1021/acsreagents.4368 ACS Reagent Chemicals, Part 4
