Standards of Purity

Meets standards of purity (and impurity) set by the American Chemical Society. 

Fine chemicals are generally considered chemicals that are manufactured to high and weU-defined standards of purity, as opposed to heavy chemicals made in large amounts to technical levels of purity. Fine chemicals usually are thought of as being produced on a small scale and the production of some fine chemicals is in tens or hundreds of kilograms per year. The production of others, especially fine chemicals used as dmgs or food additives (qv), is, however, in thousands of metric tons (see Pharmaceuticals). For example, the 1990 U.S. production of aspirin [50-78-2] and acetaminophen [103-90-2] was on the order of 20,500 t and 15,000 t, respectively. 

Monobasic aluminum acetate is dispensed as a 7% aqueous solution for the topical treatment of certain dermatological conditions, where a combination of detergent, antiseptic, astringent, and heat-dispersant effects are needed (12). The solution, diluted with 20—40 parts water, is appHed topically to the skin and mucous membranes as a wet dressing (13). Burrow s solution, prepared from aluminum subacetate solution by the addition of a specific amount of acetic acid, is also used as a topical wet dressing. Standards of purity and concentration have been estabHshed for both pharmaceutical aluminum acetate solutions (13). Each 100 mL of aluminum subacetate solution yields 2.30—2.60 g of aluminum oxide and 5.43—6.13 g of acetic acid upon hydrolysis. For the Burow s solution, each 100 mL yields 1.20—1.45 g of aluminum oxide and 4.25—5.12 g of acetic acid. Both solutions may be stabilized to hydrolysis by the addition of boric acid in amounts not to exceed 0.9% and 0.6% for the subacetate and Burow s solutions, respectively (13). 

The Safe Drinking Water Act protects the quality of drinking water in the IJ.S. This law focu.ses on all waters actually or potentially designated for drinking use, whether above or below ground. The Act authorized EPA to establish safe standards of purity and required all owners or operators of public water systems to comply with primary (health-related) standards. State governments, that assume this power from EPA, also encourage attainment of secondary standards (nuisance-related). 

Certified reagent A reagent that meets the standards of purity established by the manufacturer. The certificate of analysis is on the label. 

Hesse used the results reported in these certificates to begin to formulate the standards of purity which he would expect from a certifiable dye. If one certificate reported a particularly good result for, say, salt in a given dye, that would become the temporary minimum. He strove to secure for the country not some elusive threoretically pure dyes, but simply the best that industry could do if pushed, pushed as he had become convinced it had never been pushed before (33). 

It is, however, pertinent to mention here that pharmaceutical chemicals must maintain a very high degree of chemical purity. It is quite obvious that a state of absolute purity may not be achievable, but a sincere effort must be exercised to obtain the maximum freedom from foreign substances. Bearing in mind the exorbitant operational costs to attain the highest standards of purity, perhaps some of these processes are not economically viable. Therefore, a compromise has got to be made to strike a balance between the purity of a substance at a reasonably viable cost and at the same time its purity e.g.. being fully acceptable for all pharmaceutical usages. 

Keeping in view the various methods of manufacture of a pharmaceutical substance vis-a-vis its standards of purity, types of impurity and changing pattern of stability, a broad-based highest attainable standard is always fixed. A few typical examples are stated below ... 

The net result of such regulation is that there are well-developed standards for the way in which quantitative and, increasingly, qualitative measurements are carried out. There are also well-defined limits for various categories of impurity, all of which tends to emphasise the importance of measurements on the final API rather than on the process that produces it, for which the requirement is simply that the process remains under control . The importance of this summary is that at present, whatever the means of production, there is a requirement that the API will reach certain standards of purity as demonstrated by end-point measurement. Those standards effectively demand quantification of impurities down to about 0.05% for related organic impurities, in the region of ppb to low ppm for known toxins and low ppm levels for inorganics such as catal3Tic metals. 

Some of the dosage formulations available for protein pharmaceuticals are listed in Table 5.7. An examination of Table 5.7 reveals that no protein drug up until this time has been formulated for oral administration. Most protein drugs are administered by means of injection (parenteral administration). Parenteral administration includes intravenous, intra-arterial, intracardiac, intraspinal or intrathecal, intramuscular, intrasynovial, intracuta-neous or intradermal, subcutaneous injections, and injection directly into a dermal lesion (e.g., a wart). The parenteral route of administration requires a much higher standard of purity and sterility than oral administration. It also may require trained... 

Gold ornaments, articles and coins of very early and established antiquity are not abundant, and chemical analyses of them are not numerously recorded. Such analyses as have been made show wide variations in the purity of the gold, from a pure gold to gold with very high silver content, and the proportions of the two vary much between these limits, just as they do in the native gold from placers or mines, so that the analyses do not afford satisfactory evidence as to ancient standards of purity nor as to the results of their methods of separation. 

Seven years later, in a critical review on the synthesis of peptides, the following statement was made "Chemists in particular should respect the classical criteria of what constitutes synthesis of a natural product, i.e., that synthesis of a natural product has been achieved, when the physical, chemical and biological properties of the synthetic compound match those of the natural prototype. Unfortunately not a single one of the "synthetic proteins" satisfies these criteria. It is frequently argued that these criteria are not applicable to more complex situations, but lowering standards of purity is not likely to advance the field. Presently available analytical methods cannot adequately detect inhomogeneity in a high molecular peptide that is produced by stepwise synthesis. Consequently, the synthetic method must be chosen so that the product can be purified and critically evaluated by the available analytical techniques. F.M. Finn, 1976). 

Sterile products have several unique dosage form properties, such as freedom from micro-organisms, freedom from pyrogens, freedom from particulates, and extremely high standards of purity and quality however, the ultimate goal in the manufacture of a sterile product is absolute absence of microbial contamination. The emphasis of this chapter will be the validation of the sterilization processes responsible for achieving this goal. 

Pharmacopoeia An official compendium listing medicinal drugs, their properties, standards of purity, and other useful information. 

Examine the list of contents of most cosmetics and you will see a bewildering array of chemical names, but you can be sure that these have all been manufactured to agreed standards of purity and have been tested to ensure they are safe to use. By all means buy the cosmetics that appear to be nature resourced but don t imagine that this somehow confers an added benefit - it doesn t. And don t fool yourself into thinking that because it is free of chemicals that you are somehow protecting yourself - you aren t. 

---