American Chemical Society Publications:

About the Committee on Analytical Reagents

The ACS Committee on Analytical Reagents evolved from a Committee on the Purity of Chemical Reagents that was established in 1903. Analysts then were disturbed by the quality of reagents available and the discrepancies between labels and the actual purity of the materials. The Committee’s role in resolving these issues expanded rapidly after its 1921 publication of specifications for ammonium hydroxide and for hydrochloric, nitric, and sulfuric acids. Specifications appeared initially in Industrial and Engineering Chemistry and later in its Analytical Edition. In 1941, the existing specifications were reprinted in a single pamphlet. Revisions and new specifications were later gathered into a book, the 1950 edition of Reagent Chemicals. Two editions per decade followed except during the 1970s, when only one edition was published.

The commonplace introduction of instrumentation into analytical laboratories, beginning in the late 1950s, resulted in dramatic improvements in the sensitivity and accuracy of analytical measurements. In line with these improved instruments, the requirements for reagent chemicals and the tests used to measure their purity needed to be improved. Under the capable leadership of Stanley Clabaugh and later Vernon A. Stenger, Samuel M. Tuthill, and Wallace Rohrbough, these improvements were made during the 1960s and 1970s. The first instrumental technique, flame emission spectroscopy, was introduced into the book in 1961. It was followed by other appropriate techniques in an effort to develop test methods that would be as accurate and cost-effective as possible.

The Eighth Edition, which became official in 1993, substantially changed and updated the general procedures and attempted to make the book easier to read. Format changes included a new requirement layout and a continuation of the trend toward detailed general methods in the front of the book, with only reagent-specific test conditions under each individual chemical. Updated methods included gas chromatography (in which capillary columns were first used) water determination (in which coulometric methods were added) and the replacement of flame emission techniques by atomic absorption for metal determinations. Sections on determining method detection limits and the preparation and standardization of volumetric solutions were also added. In addition, the Eighth Edition saw the elimination of boiling point and density requirements and the replacement of the test for substances not precipitated by ammonium sulfide by specific metals determination using atomic absorption.

The Ninth Edition continued the trend of eliminating or simplifying some of the tedious classical procedures for trace analysis, and adding instrumental methods where possible. Classical procedures such as gravimetry and titrimetry, however, continued to be the corner stone of the assay procedures for inorganic reagents because of their inherent higher precision and accuracy for the determination of major components. New analytical techniques introduced included mass, infrared and, plasma emission spectroscopy, and ion and thin layer chromatography. For the first time reagents suitable for use in ultra trace analysis, such as sub-boiled acids packaged in Teflon containers, were specified. This required that "clean room" analytical practices be covered, and accounts for the inclusion of more sophisticated analytical techniques such as plasma emission spectroscopy. The most significant change in this edition was the addition of standard grade reference materials. This was done at the request of the Chemical Reference Materials Manufacturers Association (CRMMA) with the support and encouragement of the National Institute of Standards and Technology (NIST) and the U.S. Environmental Protection Agency (EPA). Approximately four hundred standards were specified in a separate section following the traditional reagent chemicals.

Early in the planning stages for the Tenth Edition of Reagent Chemicals, Committee members voiced a desire for one book that met all of their needs for information on analytical reagents. They acknowledged that Reagent Chemicals is used in conjunction with other texts for information on the physical properties and the uses of analytical reagents. This resulted in a new direction for Reagent Chemicals, the inclusion of general physical properties and analytical uses for each reagent.

The Tenth Edition continues the initiative to simplify the classical chemical methods and substitute instrumental analysis where appropriate. This edition introduces a new instrumental method, inductively coupled plasma mass spectrometry (ICP–MS) for trace metal analysis. It also revises and updates procedures for polarography. Tests have been modified to take into account current laboratory practices and technology, as well as to eliminate the use of environmentally harmful chemicals.

Since the Ninth Edition, the Committee on Analytical Reagents has required validation
protocols as part of the approval process for adding new reagents. In the Tenth Edition,
32 new reagents and three new classes of standard-grade reference materials are introduced, all of which have validation protocols.

Other improvements in the Tenth Edition are intended to make the book easier to use. Some of these improvements include a CAS number index, a separate index for the standard-grade reference materials, complete assay calculations with titer values, an updated table of atomic weights, frequently used mathematical equations, a quick reference page on how to read a monograph, division of the book into parts, and a detailed table of contents for each part.

Finally, a subtitle has been added to the Tenth Edition. This represents a slight shift in thinking and internal nomenclature. Traditionally, the Committee has referred to the individual entry for each reagent chemical as a specification, and each specification had two components: the requirements and the tests. However, these terms led to some confusion and, beginning with the Tenth Edition, the Committee has adopted the term monograph for the complete package of information for each reagent chemical—the general description, specifications, requirements, and tests. The specification refers to the purity requirements of the reagent, and the requirement is the level of purity required for the reagent to be considered “ACS Reagent Grade”.