Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Methanol (Methyl Alcohol)
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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 Methanol provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), aqueous solubility, and density. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Substances Darkened by Sulfuric Acid, Substances Reducing Permanganate, Solubility in Water, Color (APHA), Water, Residue after Evaporation, Carbonyl Compounds, Titrable Acid, Titrable Base, Ultraviolet Spectrophotometry, Liquid Chromatography Suitability, and Extraction–Concentration Suitability.
CH3OH
Formula Wt 32.04
CAS No. 67-56-1
Suitable for general use or in high-performance liquid chromatography, extraction–concentration analysis, or ultraviolet spectrophotometry. Product labeling shall designate the uses for which suitability is represented based on meeting the relevant specifications and tests. The ultraviolet spectrophotometry and liquid chromatography suitability specifications include all of the specifications for general use. The extraction–concentration suitability specifications include only the general use specification for color.
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . . Density . . . . . . . . . . . . . . . .
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clear, colorless liquid organic solvent boiling point, 65 °C miscible 0.79
SPECIFICATIONS General Use Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.8% CH3OH Substances darkened by sulfuric acid . . . . . . . Passes test
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4222 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Substances reducing permanganate . . . . . . . . Passes test Solubility in water . . . . . . . . . . . . . . . . . . . Passes test
Color (APHA) . . . . . . . . . Water (H2O) . . . . . . . . . . Residue after evaporation . Carbonyl compounds . . . . Titrable acid . . . . . . . . . Titrable base . . . . . . . . .
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Maximum Allowable . 10 . 0.1% . 0.001% . 0.001% each of acetone, formaldehyde and acetaldehyde . 0.0003 meq/g . 0.0002 meq/g
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Absorbance (AU) . 0.01 . 0.04 . 0.10 . 0.20 . 0.40 . 0.80 . 1.00
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Specific Use Ultraviolet Spectrophotometry Wavelength (nm) 280–400 . . . . . . . . . . . . . . . . 260 . . . . . . . . . . . . . . . . . . . 240 . . . . . . . . . . . . . . . . . . . 230 . . . . . . . . . . . . . . . . . . . 220 . . . . . . . . . . . . . . . . . . . 210 . . . . . . . . . . . . . . . . . . . 205 . . . . . . . . . . . . . . . . . . .
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Liquid Chromatography Suitability Absorbance . . . . . . . . . . . . . . . . . . . . . . . Passes test Gradient elution . . . . . . . . . . . . . . . . . . . . Passes test Extraction–Concentration Suitability Absorbance . . . . . . . . . . . . . . . . . . . . . . . Passes test GC–FID . . . . . . . . . . . . . . . . . . . . . . . . . . Passes test GC–ECD . . . . . . . . . . . . . . . . . . . . . . . . . . Passes test
TESTS Assay Analyze the sample by gas chromatography using the general parameters cited in [Part 2: Chromatography; Recommended Procedures; Gas Chromatography]. The following specific conditions are also required. Column . . . . . . . . . . . . . . . . . . . . . . . . . . Type I, methyl silicone Measure the area under all peaks, and calculate the methanol content in area percent. Correct for water content.
Substances Darkened by Sulfuric Acid Cool 10 mL of sulfuric acid contained in a small conical flask to 10 °C, and add dropwise with constant agitation 10 mL of the sample, keeping the temperature of the mixture below 20 °C. The mixture should have no more color than the acid or methanol before mixing.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4222 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Substances Reducing Permanganate Cool 20 mL to 15 °C, add 0.10 mL of 0.1 N potassium permanganate volumetric solution, and allow to stand at 15 °C for 15 min. The pink color should not be entirely discharged.
Solubility in Water Dilute 15 mL with 45 mL of water, mix, and allow to stand for 1 h. The solution should be as clear as an equal volume of water.
Color (APHA) [Part 2: Measurement of Physical Properties; Color (APHA); Procedure for Color (APHA)].
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Water [Part 2: Titrimetric Methods; Water by the Karl Fischer Method; Volumetric Procedure; Volumetric Procedure for Samples Using Karl Fischer Reagent, Method 1]. Use 25 mL (19.8 g) of the sample.
Residue after Evaporation [Part 2: Gravimetric Methods; Residue after Evaporation]. Evaporate 100 g (125 mL) in a tared, preconditioned dish on a hot plate (~100 °C), and dry the residue at 105 °C for 30 min.
Carbonyl Compounds Test solution preparation: Add 2.0 µL formaldehyde solution (37%), 1.0 µL acetaldehyde, and 1.0 µL acetone to 100.0 ml of the sample. Analyze the sample and the test solution by GC–MS according to the procedure in [Part 2: Chromatography; Gas Chromatography–Mass Spectrometry]. For the column in [Part 2: Chromatography; Gas Chromatography–Mass Spectrometry], set inlet temperature and pressure to 120 °C and 154 kPa. Inject 5 µL of sample with a 5:1 split ratio. Oven temperature profile: isothermal at 40 °C for 10 min, 5 °C/min to 100 °C. The area of each of the carbonyl peaks in the sample should be no greater than half that of the corresponding peak in the test solution.
Titrable Acid To 25 mL of water and 10 mL of ethyl alcohol in a glass-stoppered flask, add 0.50 mL of phenolphthalein indicator solution and 0.01 N sodium hydroxide until a slight pink color persists after shaking for 30 s. Add 15 g (19 mL) of sample, mix well, and titrate with 0.01 N sodium hydroxide until the pink color is restored. Not more than 0.50 mL should be required. Note: Special care should be taken during the addition of the sample and titration to avoid contamination from carbon dioxide.
Titrable Base Dilute 22.6 g (28.6 mL) with 25 mL of water and add 0.15 mL of methyl red indicator solution. Not more than 0.40 mL of 0.01 N hydrochloric acid should be required to produce a pink color.
Ultraviolet Spectrophotometry Use the procedure in [Part 2: Chromatography; Recommended Procedures; LC Suitability; Procedure for Absorbance] to determine the absorbance.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4222 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Liquid Chromatography Suitability Analyze the sample, using the gradient elution procedure cited in [Part 2: Chromatography; Recommended Procedures; Liquid Chromatography; Solvent Suitability for Liquid Chromatography; Procedure for Liquid Chromatography]. Use the procedure in [Part 2: Chromatography; Recommended Procedures; LC Suitability; Procedure for Absorbance] to determine the absorbance.
Extraction–Concentration Suitability
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Analyze the sample using the general procedure cited in [Part 2: Chromatography; Recommended Procedures; Extraction−Concentration; Solvent Suitability for Extraction−Concentration]. Use the procedure in [Part 2: Chromatography; Recommended Procedures; LC Suitability; Procedure for Absorbance] to determine the absorbance.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.4222 ACS Reagent Chemicals, Part 4
