Monograph pubs.acs.org/doi/book/10.1021/acsreagents
Tris(hydroxymethyl)aminomethane (2-Amino-2-(hydroxymethyl)-1,3-propanediol; “Tris”) 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 Tris(hydroxymethyl)aminomethane 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, Absorbance, Water, Insoluble Matter, Heavy Metals, and Iron.
NH2C(CH2OH)3
Formula Wt 121.14
CAS No. 77-86-1
GENERAL DESCRIPTION Typical appearance . . . . . . . . Applications . . . . . . . . . . . . . Change in state (approximate) . Aqueous solubility . . . . . . . . . pKa . . . . . . . . . . . . . . . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
. . . . .
white solid buffering agent; acidimetric standard melting point, 171 °C 55 g in 100 mL at 25 °C 8.3
SPECIFICATIONS Assay (dry basis) . . . . . . . . . . . . . . . . . . . . . 99.8–100.1% C4H11NO3 Maximum Allowable Absorbance . . . . . . . . . . . . . . . . . . . . . . . . Passes test Water (H2O) . . . . . . . . . . . . . . . . . . . . . . . . 2% Insoluble matter . . . . . . . . . . . . . . . . . . . . . 0.005%
© 2017 American Chemical Society
A
DOI:10.1021/acsreagents.4416 ACS Reagent Chemicals, Part 4
ACS Reagent Chemicals
Monograph
pubs.acs.org/doi/book/10.1021/acsreagents
Heavy metals (as Pb) . . . . . . . . . . . . . . . . . . 5 ppm Iron (Fe) . . . . . . . . . . . . . . . . . . . . . . . . . . 5 ppm
TESTS Assay (By acid–base titrimetry). Weigh accurately about 0.5 g of sample previously dried at 105 °C for 3 h. Transfer to a 200 mL beaker, dissolve in 50 mL of carbon dioxide- and ammonia-free water, and titrate the solution with 0.1 N hydrochloric acid to a pH of 4.7, using a suitable pH meter. One milliliter of 0.1 N hydrochloric acid corresponds to 0.012114 g of C4H11NO3.
Absorbance Determine the absorbance of a 40% solution of the sample in water in a 1.00 cm cell at 290 nm against water in a similar matched cell set at zero absorbance as the reference liquid. The absorbance should not exceed 0.2 absorbance units.
Water [Part 2: Titrimetric Methods; Water by the Karl Fischer Method; Volumetric Procedure; Volumetric Procedure for Samples Using Karl Fischer Reagent, Method 1]. Use 1.0 g of the sample.
Insoluble Matter Dissolve 20.0 g in 200 mL of water. Filter through a tared, preconditioned filtering crucible, wash thoroughly, and dry at 105 °C.
Heavy Metals [Part 2: Colorimetry and Turbidimetry; Heavy Metals (as Lead); Procedure for Heavy Metals, Method 1]. Substitute glacial acetic acid for 1 N acetic acid to adjust pH in Method 1. Dissolve 6.0 g in about 20 mL of water, and dilute with water to 30 mL. Use 25 mL to prepare the sample solution, and use the remaining 5.0 mL to prepare the control solution.
Iron [Part 2: Colorimetry and Turbidimetry; Iron; Procedure for Iron, Method 1 (Ammonium Thiocyanate)]. Use a 2.0 g sample.
© 2017 American Chemical Society
B
DOI:10.1021/acsreagents.4416 ACS Reagent Chemicals, Part 4
