Purity management

In the past, specifications for metal ion content and particles have been arbitrarily reduced for each new generation (smaller geometry) of devices. Recently, research has been conducted on the correlation of device performance with various impurities. While impurity specifications will continually drop, only troublesome impurities will be reduced. This change in strategy of purity management will reduce the burden on chemical suppliers, especially as specifications move toward 1 part per trillion (ppt) for metals and to the theoretical limits of particle size detection of optical counters. Semiconductor Equipment and Materials International (SEMI) has recently initiated an effort to reduce the number of specified metals down to 17 (Table 15.4) from over 30. 

Some 14,700 gal of MTBE are produeed eaeh day. The MTBE produetion faeility relies on an Olefiex design system that eonverts isobutane to isobutylene, the basie ingredient in MTBE. The Olefiex unit manages to reeyele isobutane so that ultimately 100% is eonverted to isobutylene, and byproduet hydrogen used in the proeess is reeyeled and proeessed to 99.9% purity. 

The scope of my comments will cover not the development of analytical methods but rather the process of choosing methods which give useful answers to the questions posed by the research chemist, the process engineer or the product marketing manager. The analytical chemist is always faced with the paranoia causing problem of not being able to be confident in a purity measurement until it can be shown that impurities do not interfere. 

In chromatography techniques, selectivity can be proved by the existence of good separation between the analyte and the other components (such as the matrix, impurities, degradation product(s), and metabolites). A consequence of this requirement is that the resolution of the analyte from the other components should be more than 1.5-2.0. In order to detect the possibility of coelution of other substance(s), the purity of the analyte peak should also be determined. For instance, the UV-Vis spectrum of the analyte peak/spot can be used to determine 4the purity of the analyte peak/spot, in this case the correlation coefficient V (this term is used by the software of DAD System Manager Hitachi, and CATS from Camag). With the same meaning and mathematical equation, other terms are used, such as Match... 

Developing a management system is not a one-time project. It must be able to manage even subtle material, equipment or personnel changes that may have a significant effect on the safety of the operation. These may include a minor change in raw material purity, a modification to the shape of a vessel where heat transfer is important, or a change in how an operation is supervised. 

In this chapter, the purity and management of pharmaceutical chemicals, would be discussed briefly so as to take adequate cognizance of the importance of standardization of these substances, in addition to their management by Official Methods. 

These two errors have been duly discussed under the chapter on Pharmaceutical Chemicals Purity and Management (Section 1.3.2.2). 

Part—I has three chapters that exclusively deal with General Aspects of pharmaceutical analysis. Chapter 1 focuses on the pharmaceutical chemicals and their respective purity and management. Critical information with regard to description of the finished product, sampling procedures, bioavailability, identification tests, physical constants and miscellaneous characteristics, such as ash values, loss on drying, clarity and color of solution, specific tests, limit tests of metallic and non-metallic impurities, limits of moisture content, volatile and non-volatile matter and lastly residue on ignition have also been dealt with. Each section provides adequate procedural details supported by ample typical examples from the Official Compendia. Chapter 2 embraces the theory and technique of quantitative analysis with specific emphasis on volumetric analysis, volumetric apparatus, their specifications, standardization and utility. It also includes biomedical analytical chemistry, colorimetric assays, theory and assay of biochemicals, such as urea, bilirubin, cholesterol and enzymatic assays, such as alkaline phosphatase, lactate dehydrogenase, salient features of radioimmunoassay and automated methods of chemical analysis. Chapter 3 provides special emphasis on errors in pharmaceutical analysis and their statistical validation. The first aspect is related to errors in pharmaceutical analysis and embodies classification of errors, accuracy, precision and makes... 

They produce a manageable number of compounds that can all be analyzed for identity and purity. 

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