Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Trichloroacetic Acid 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 Trichloroacetic Acid provides, in addition to common physical constants, a general description including typical appearance, applications, change in state (approximate), aqueous solubility, and pKa. The monograph also details the following specifications and corresponding tests for verifying that a substance meets ACS Reagent Grade specifications including: Assay, Clarity of Solution, Insoluble Matter, Residue after Ignition, Chloride, Nitrate, Phosphate, Sulfate, Heavy Metals, Iron, and Substances Darkened by Sulfuric Acid.
CCl3COOH
Formula Wt 163.38
CAS No. 76-03-9
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . . pKa . . . . . . . . . . . . . . . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
colorless to white solid detection of albumin melting point, 57–58 °C; boiling point, 197–198 °C very soluble 0.7
SPECIFICATIONS Assay . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≥99.0% CCl3COOH Clarity of solution . . . . . . . . . . . . . . . . . . . . Passes test Maximum Allowable Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.01% Residue after ignition. . . . . . . . . . . . . . . . . . 0.03% Chloride (Cl) . . . . . . . . . . . . . . . . . . . . . . . 0.002% Nitrate (NO3) . . . . . . . . . . . . . . . . . . . . . . . 0.002%
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4411 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Phosphate (PO4) . . . . . . . . . . . . . . Sulfate (SO4) . . . . . . . . . . . . . . . . Heavy metals (as Pb) . . . . . . . . . . . Iron (Fe) . . . . . . . . . . . . . . . . . . . Substances darkened by sulfuric acid .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
5 ppm 0.02% 0.002% 0.001% Passes test
TESTS Assay (By acid–base titrimetry). Weigh accurately about 5.0 g, previously dried for 24 h over an efficient desiccant, and dissolve in 20 mL of water in a 500 mL reflux flask. Add 0.15 mL of methyl red indicator solution, and titrate with 1 N sodium hydroxide volumetric solution to a distinct yellow color, then add 50.0 mL of 1 N sulfuric acid volumetric solution. Add sufficient dioxane to make the final solution at least 55% dioxane. Add silicon carbide boiling chips, and boil gently under complete reflux for 1 h. Cool, add 0.15 mL of methyl red indicator solution, and titrate the excess of sulfuric acid with 1 N sodium hydroxide, the end point being the distinct transition from a light orange color to a definite yellow color. Correct for the acid present in the dioxane by running a concomitant blank, containing 2.5 mL of chloroform. One milliliter of 1 N sodium hydroxide corresponds to 0.1634 g of CCl3COOH.
Clarity of Solution Dissolve 10.0 g in 100 mL of water in a 250 mL conical flask. The solution should be clear and colorless and contain no significant amount of insoluble matter, such as minute fibers and/or other particles causing haze or reduced transparency. Reserve the solution for the test for insoluble matter.
Insoluble Matter [Part 2: Gravimetric Methods; Insoluble Matter]. Use the solution reserved from the clarity of solution test.
Residue after Ignition [Part 2: Gravimetric Methods; Residue after Ignition]. Ignite 5.0 g.
Chloride [Part 2: Colorimetry and Turbidimetry; Chloride]. Use 0.5 g.
Nitrate [Part 2: Colorimetry and Turbidimetry; Nitrate; Procedure for Nitrate, Method 1 (Brucine Sulfate)]. For sample solution A, use 0.25 g. For control solution B, use 0.25 g with 0.5 mL of nitrate ion (NO3) standard solution. †
For the Determination of Phosphate, Sulfate, Heavy Metals, and Iron
S a m p l e S o l u t i o n A . Evaporate 5.0 g to dryness in a beaker on a hot plate (~100 °C). Dissolve in about 10 mL of water, filter if necessary, and dilute with water to 100 mL (1 mL = 0.05 g).
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4411 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
†
Phosphate
[Part 2: Colorimetry and Turbidimetry; Phosphate; Procedure for Phosphate, Method 2 (Extracted Molybdenum Blue)]. Dilute 40 mL of sample solution A (2.0 g sample) with water to about 80 mL. Add 0.5 g of ammonium molybdate, and adjust the pH to 1.8 (using a pH meter) with dilute hydrochloric acid (1:9). Heat to boiling, cool to room temperature, dilute with water to 90 mL, and add 10 mL of hydrochloric acid. Continue as described, and carry along a standard containing 0.01 mg of phosphate ion (PO4) treated in the same manner as the 40 mL of sample solution A.
Sulfate† [Part 2: Colorimetry and Turbidimetry; Sulfate; Procedure for Sulfate, Method 1]. Use 5.0 mL of sample solution A (0.25 g sample).
Heavy Metals† [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Use 20 mL of sample solution A (1 g sample) with water to 25 mL.
Iron† [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use 20 mL of sample solution A (1 g sample).
Substances Darkened by Sulfuric Acid Dissolve 1.0 g in 10 mL of sulfuric acid, and digest in a covered beaker on a hot plate (~100 °C) for 15 min. Any color should not exceed that produced when 10 mL of sulfuric acid is added to 1 mL of water containing 0.1 mg of sucrose and heated in the same way as the sample.
© 2017 American Chemical Society
C
DOI:10.1021/acsreagents.4411 ACS Reagent Chemicals, Part 4
