Definition pubs.acs.org/doi/book/10.1021/acsreagents
Other Considerations Part 1, Introduction and Definitions eISBN: 9780841230460 Tom Tyner Chair, ACS Committee on Analytical Reagents James Francis Secretary, ACS Committee on Analytical Reagents
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ABSTRACT The descriptions of the individual tests are intended to give all essential details without repetition of considerations that should be obvious to an experienced analyst. A few suggestions are given for precautions and procedures that are particularly applicable to the routine testing of reagent chemicals.
UNITS OF MEASURE Throughout this book, the International System of Units (SI, or Système International d'Unités) is used.
SAMPLING The main goal in sampling is to obtain and maintain (stabilize) samples that are representative. As a general rule, the analyst should recognize that the degree of error in the sampling portion of the analytical procedure is considerably higher than the degree of error in the methodology (adapted with permission from Schwedt, 1997). To eliminate accidental contamination or possible change in composition, samples for testing must be taken from freshly opened containers.
CONTAINERS The container is the device that holds the reagent or standard-grade reference material; it is, or may be, in direct contact with the reagent or standard. The closure is part of the container. The container in which a reagent or standard is sold and/or stored must be suitable for its intended purpose and should not interact physically or chemically with the contained reagent or standard so as to alter its quality (within a reasonable period of time or when mandated by an expiration date) beyond the requirements of the specification. Containers for solids normally have wide mouths to facilitate both the filling of the container and the removal of the contents. Containers for liquids normally have narrow mouths so the contents may be easily poured into other, frequently smaller, containers. Before being filled, the container should be free from extraneous particulate matter, otherwise clean and dry as necessary.
QUALITY OF REAGENTS Reagents and standard-grade reference materials used in testing materials included in this book should conform to ACS specifications. Reagents not covered by ACS specifications should be of the best grade obtainable and should be examined carefully for interfering impurities.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.1006 ACS Reagent Chemicals, Part 1
ACS Reagent Chemicals
Definition
pubs.acs.org/doi/book/10.1021/acsreagents
ADDED SUBSTANCES Unless otherwise specified for an individual reagent chemical, the reagents described in this volume may contain suitable preservatives or stabilizers, intentionally added to retard or inhibit the natural processes of deterioration. Such preservatives or stabilizers may be regarded as suitable only if the following conditions are met: They do not exceed the minimum quantity required to achieve the desired effect. They do not interfere with the tests and assays for the individual reagents unless specifically waived by this book. The presence of any added substance must be declared on the label of the individual package. Unless of a proprietary nature, the name and concentration of any added substance should be stated on the label.
Downloaded by CORNELL UNIV on June 15, 2017 | http://pubs.acs.org Publication Date (Web): February 28, 2017 | doi: 10.1021/acsreagents.1006
SUITABILITY FOR SPECIAL PURPOSES For some reagents, the Sixth and Seventh Editions of Reagent Chemicals had separate specifications defining them, such as “suitable for use in ultraviolet spectrophotometry”, “suitable for use in determining pesticide residues”, or “suitable for use in high-performance liquid chromatography”. Beginning with the Eighth Edition, these special-use reagent chemicals have been treated in a single integrated presentation. The seller shall designate in product labeling the suitability for one or more of these special uses on the basis of the relevant specifications and tests.
BLANK TESTS Many of the tests are for minute quantities of the impurities sought. Hence, complete blank tests must be made covering the water and other reagents used in each step of the tests, including, for example, filtration and ignition. Frequently, however, the directions stipulate a control, blank, or other device that corrects for possible impurities in the water and other reagents.
ELIMINATED TEST PROCEDURES Continuing a trend started with the Eighth Edition, tedious classical procedures are being eliminated and replaced with instrumental methods. The test, “Substances not precipitated by […]” is no longer used in the analysis of reagent chemicals.
© 2017 American Chemical Society
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ACS Reagent Chemicals ACS Reagent Chemicals; American Chemical Society: Washington, DC, 2017.
DOI:10.1021/acsreagents.1006 ACS Reagent Chemicals, Part 1
