Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Potassium Bitartrate (Potassium Hydrogen Tartrate) 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 Potassium Bitartrate 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 in Ammonium Hydroxide, Chloride, Ammonium, Sulfate, Calcium, Sodium, Heavy Metals, and Iron.
KOCO(CHOH)2COOH
Formula Wt 188.18
CAS No. 868-14-4
GENERAL DESCRIPTION Typical appearance . . . . . . . . . . . . . . . . . . . white solid Applications . . . . . . . . . . . . . . . . . . . . . . . . buffering agent Aqueous solubility . . . . . . . . . . . . . . . . . . . . 1 g in 162 mL
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99.0–101.0% C4H5O6K Maximum Allowable Insoluble matter in ammonium hydroxide . . . . . 0.005% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.005% Ammonium (NH4) . . . . . . . . . . . . . . . . . . . . 0.01% Sulfate (SO4) . . . . . . . . . . . . . . . . . . . . . . . 0.01% Calcium (Ca) . . . . . . . . . . . . . . . . . . . . . . . 0.05% Sodium (Na) . . . . . . . . . . . . . . . . . . . . . . . . 0.05% Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 0.001% Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 0.002%
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4277 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
TESTS Assay (By acid–base titrimetry). Weigh accurately about 0.7 g, and dissolve in 200 mL of water. Add 0.15 mL of phenolphthalein indicator solution, and titrate with 0.1 N sodium hydroxide to a pink end point. One milliliter of 0.1 N sodium hydroxide corresponds to 0.01882 g of C4H5O6K.
Insoluble Matter in Ammonium Hydroxide [Part 2: Gravimetric Methods; Insoluble Matter]. Use 20 g dissolved in a mixture of 100 mL of water and 30 mL of ammonium hydroxide.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 0.20 g.
Ammonium Dissolve 1.0 g in 200 mL of ammonia-free water in a 250 mL volumetric flask, and dilute to the mark with water. To 50.0 mL (0.2 g sample) of this solution, add 2 mL of freshly boiled 10% sodium hydroxide reagent solution, and mix. Add 2 mL of Nessler reagent, and mix again. Any color should not exceed that produced by 0.02 mg of ammonium ion (NH4) in an equal volume of solution containing the quantities of reagents used in the test.
Sulfate [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 3]. Ignite 0.50 g, protected from sulfur and preferably in an electric muffle furnace, until nearly free of carbon. Boil the residue with 20 mL of water and 2 mL of hydrogen peroxide for 5 min. Add 10 mg of sodium carbonate and 5 mL of hydrochloric acid, and evaporate to dryness on a hot plate (~100 °C). Prepare a standard by evaporating 10 mg of sodium carbonate, 2 mL of hydrogen peroxide, 0.05 mg of sulfate ion (SO4) standard solution, and 5 mL of hydrochloric acid to dryness on a hot plate (~100 °C). Dissolve the residue from each in a minimum amount of water and proceed as directed in the test beginning with “Add 1mL of dilute hydrochloric acid (1:19)…”.
Calcium and Sodium (By flame AAS, [Part 2: Trace and Ultratrace Elemental Analysis; Atomic Absorption Spectroscopy; Analysis; Procedure for Flame AAS]).
For the Determination of Calcium and Sodium
S a m p l e S t o c k S o l u t i o n . Dissolve 1.0 g of sample in 80 mL of (1:7) hydrochloric acid, and digest on a hot plate (~100 °C) for 20 min. Cool, transfer to a 100 mL volumetric flask, and dilute to the mark with water (1 mL = 0.01 g).
To each of four flasks, add 5 mL of 5% potassium chloride solution to suppress ionization interferences, dilute to the mark with water, mix well, and continue with the procedure.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4277 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
For the Determination of Calcium and Sodium
Element
Wavelength (nm)
Sample Wt (g)
Standard Added (mg)
Flame Type*
Background Correction
Ca
422.7
0.10
0.025; 0.05
N/A
No
Na
589.0
0.10
0.025; 0.05
A/A
No
*A/A is air/acetylene, N/A is nitrous oxide/acetylene.
Heavy Metals Ignite 5.0 g in a platinum dish at 500–600 °C. Dissolve the residue in 30 mL of water and 2 mL of hydrochloric acid, filter, dilute to 50 mL, and mix. For the sample, transfer 30 mL of the filtrate to a suitable Nessler tube. For the standard, add 0.02 mg of lead ion (Pb) to a 10 mL portion of the filtrate, also in a Nessler tube, dilute to 30 mL, and mix. Adjust the pH of the sample and standard solutions to between 3 and 4 (using a pH meter) with 1 N acetic acid or 10% ammonium hydroxide reagent solution. Dilute each solution to 40 mL, mix, add 10 mL of freshly prepared hydrogen sulfide water to each, and mix. Any brown color in the sample solution must not exceed that in the standard.
Iron To 0.5 g, add 25 mL of water, 3 mL of hydrochloric acid, and 3 drops of nitric acid. Boil for 1 min. Cool, dilute to 50 mL, and add 3 mL of 30% ammoniumthiocyanate reagent solution. Compare to an iron ion (Fe) standard solution treated exactly as the sample.
© 2017 American Chemical Society
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DOI:10.1021/acsreagents.4277 ACS Reagent Chemicals, Part 4
