Quality control Subject

Part I presents aspects of antimicrobial product evaluations from three important perspectives. First, a chapter on developing effective antimicrobial products provides a broad view approach in developing topical antimicrobials. These views include marketing, science, and quality assurance. They include objective aspects, including antimicrobial effectiveness, label claims, and quality control subjective aspects, such as perceived ease of use, feel, fragrance and shared professional beliefs, such as value of an iodophor, a chlorhexidine gluconate, or triclosan products. 

During take-off and landing, the wheels of modem aircraft are subject to great stress. New high-performance brake systems and aggressive environmental influences push the wheels closer and closer to their limit. These conditions as well as increased requirements for safety and quality control now necessitate that wheels are tested much more comprehensively than in the past. 

Quality Control. Reproducible production of perfumes requires careful quality control of all materials used as well as the compounding process itself. The use of analytical tools has iacreased over the years with their availability, but there can be no substitute for organoleptic evaluation. The human nose is far more sensitive than any analytical instmment for certain materials, yet it is also quite limited as a quantitative tool and is subject to fatigue. There are also weU-documented examples of specific anosmias ia iadividuals, ie, iaability to smell certain odor types, which is somewhat analogous to color-blindness. 

It should also not be assumed that these requirements are only intended for implementation by a department with the title Inspection or Test. Whenever a product is supplied, produced, or repaired, rebuilt, modified, or otherwise changed, it should be subject to verification that it conforms with the prescribed requirements and any deficiencies corrected before being released for use. That is what control means. Control is not just the inspection part of the process and hence quality control , which for years was the name given to inspection departments, was misunderstood. Inspection and test don t control quality. Inspection and test merely measure the quality achieved and pass the results to the producer for remedial action. 

Quality control tests are intended to detect produced materials which deviate from manufacturing specifications, and thus may result in questionable performance. The materials are usually subjected to spectrographic analysis which is the primary quality control check. The exposure tests are necessarily of short duration (hours or days), in which the test conditions attempt to reflect the environment of operation, for example using artificial seawater for a marine application. Since a property that is reproducible and indicative of a consistent quality anode is all that is required, there is no attempt to mirror, except in the crudest fashion, current density profiles. 

Product quality control relates to appearance and methods of assessing it either by subjective visual inspection or by objective tests such as reflectivity or surface roughness. 

In a modern industrialised society the analytical chemist has a very important role to play. Thus most manufacturing industries rely upon both qualitative and quantitative chemical analysis to ensure that the raw materials used meet certain specifications, and also to check the quality of the final product. The examination of raw materials is carried out to ensure that there are no unusual substances present which might be deleterious to the manufacturing process or appear as a harmful impurity in the final product. Further, since the value of the raw material may be governed by the amount of the required ingredient which it contains, a quantitative analysis is performed to establish the proportion of the essential component this procedure is often referred to as assaying. The final manufactured product is subject to quality control to ensure that its essential components are present within a pre-determined range of composition, whilst impurities do not exceed certain specified limits. The semiconductor industry is an example of an industry whose very existence is dependent upon very accurate determination of substances present in extremely minute quantities. 

The successful and profitable conduct of a frozen food quality program requires suitable and workable standards of product quality and condition, and suitable methods for determining the degree of product conformance with the standards. The methods used may be either subjective or objective in character, or a combination of both the most consistent and reproducible results will be obtained with objective methods. Present-day frozen food standards are, for the most part, based upon subjective methods of quality determination. These are certainly better than none at all but they are subject to considerable misinterpretation and human error, and for this reason leave much to be desired in providing a sound basis for quality control. 

Disorders caused by misfolded mutant proteins that fail to pass the quality control system of the ER (e.g., mutations of the cystic fibrosis transmembrane regulator protein (CFTR) causing cystic fibrosis). The mutant proteins are retrotranslocated into the cytosol and finally subjected to proteolysis. In some... 

The Production Department was not amused, because lower values had been expected. Quality Control was blamed for using an insensitive, unse-lective, and imprecise test, and thereby unnecessarily frightening top management. This outcome had been anticipated, and a better method, namely polarography, was already being set up. The same samples were run, this time in duplicate, with much the same results. A relative confidence interval of 25% was assumed. Because of increased specificity, there were now less doubts as to the amounts of this particular heavy metal that were actually present. To rule out artifacts, the four samples were sent to outside laboratories to do repeat tests with different methods X-ray fluorescence (XRFi °) and inductively coupled plasma spectrometry (ICP). The confidence limits were determined to be 10% resp. 3%. Figure 4.23 summarizes the results. Because each method has its own specificity pattern, and is subject to intrinsic artifacts, a direct statistical comparison cannot be performed without first correcting the apparent concentrations in order to obtain presumably true... 

The subject of quality control and surveillance is discussed in a chapter on sterilization control and sterihty testing, whieh deals with aspects Of in-process and post-process control. 

If the product is to be used for pharmaceuticals the GMP rules must be obeyed during plant operation. All chemicals to be tested in clinical studies with humans must be prepared according to GMP. This leads to very detailed documentation since if you haven t documented it, you haven t done it . All procedures for manufacturing and changes in procedures are subject to approval by quality control departments. This decreases the flexibility in process development. Products that are contaminated too much must be reprocessed according to the GMP guidelines. All equipment to be used in the pilot plant must be validated before use. 

Quality control tests or improvement of existing processes. Raw materials from various sources can be used in the manufacture of fine chemicals and pharmaceuticals. The raw materials can contain different impurities at various concentrations. Therefore, before the raw material is purchased and used in a full-scale batch its quality should be tested in a small-scale reactor. Existing full-scale procedures are subject to continuous modifications for troubleshooting and for improving process performance. Laboratory reactors used for tests of these two kinds are usually down-scaled reactors or reactors being a part of the full scale-reactor. 

The determination and analysis of sensory properties plays an important role in the development of new consumer products. Particularly in the food industry sensory analysis has become an indispensable tool in research, development, marketing and quality control. The discipline of sensory analysis covers a wide spectrum of subjects physiology of sensory perception, psychology of human behaviour, flavour chemistry, physics of emulsion break-up and flavour release, testing methodology, consumer research, statistical data analysis. Not all of these aspects are of direct interest for the chemometrician. In this chapter we will cover a few topics in the analysis of sensory data. General introductory books are e.g. Refs. [1-3]. 

ISO Guide 33 (1998) deals with other uses of RMs. It elaborates on various uses of RMs, excluding calibration, which is the subject of ISO Guide 32. In most cases, RMs are used as a quality control measure, i.e. to assess the performance of a measurement method. Most matrix RMs are produced with this purpose in mind. Other purposes of RMs are the maintenance of conventional scales, such as the octane number and the pH scale. ISO Guide 33 provides guidance on the proper use of RMs, and therefore it is together with ISO Guide 32 the most important document for users of CRMs. 

Some of the intended categories of use of radioisotopic reference material have been reviewed recently by Fajgelj et al. (1999). They include assignment of property values, establishing the traceability of a measurement result, determining the uncertainty of a measurement result, calibration of an apparatus, assessment of a measurement method, use for recovery studies and use for quality control purposes. It should be noted however that, in general, natural matrix reference materials are not recommended for calibration purposes. This should preferably be done with pure chemical forms of the element labelled with the isotope of interest. Calibrated isotopic sources of this kind are available from a number of commercial suppliers and are not the subject of this review. 

The surface of concrete may be subjected to cycles of wetting and drying during normal service life. This process is a durability concern as harmful ions such as chlorides or sulfates can easily penetrate with the adsorbed water and there is the potential for saturation prior to freezing. Measuring the rate of water penetration into a dry concrete surface is thus important to the quality control of concrete mixes - hopefully yielding a durable product. 

The major drawback to using the Florida study to support the correlation between indoor and soil measurements was that the indoor measurements were obtained from 3-day closed-house charcoal measurements, and soil radon was obtained from 1-month alpha track measurements buried 1 ft beneath the soil surface. Comparisons of charcoal and alpha track data are generally not recommended since they are quite different measurement techniques, and represent radon levels over different time periods. However, the study was subjected to numerous quality control checks including deployment of alpha track detectors in 10% of the houses to obtain a check on indoor air measurements made by charcoal canisters. In spite of the measurement drawbacks, the study indicates that soil radon measurements taken alone are not a dependable predictor of potential indoor radon concentration. 

Data from attrition tests are usually presented as simple numbers called friability or attrition indices. Most of these indices are used as measures in quality control by subjecting the materials to a standard procedure. By comparing the test results with those of known materials, it is possible to give a relative characterization of the tested materials. Examples are given in Sec. 4.3. 

Friability tests can be used for various purposes. They are widely used in quality control. Here, samples of produced material are subjected to a more or less arbitrary but well defined stress. The attrition extent is assessed by comparison with a standard value and a decision is reached whether the material meets the standard. Moreover, friability tests are often used for comparison of different materials to select the most attrition-resistant one. This is a usual procedure in the case of catalyst development. For example, Contractor et al. (1989) tested anew developed fluidized bed VPO-catalyst in a submerged-jet attrition test (described below). Furthermore, the specific attrition rate of a material in a certain process can be roughly estimated by friability tests. In this case the stress must be similar to that occurring in the process and the obtained degradation extent must be compared with those of other materials from which the process attrition rate is known. 

Quality control of sampling. While it is recognised that the quality of the analytical result can be no better than that of the sample, quality control of sampling is a separate subject and in many areas not yet fully developed. Moreover, in many instances analytical laboratories have no control over sampling practice and quality. 

The guidelines stress, however, that internal quality control is not foolproof even when properly executed. Obviously it is subject to errors of both kinds , i.e. runs that are in control will occasionally be rejected and runs that are out of control occasionally accepted. Of more importance, IQC cannot usually identify sporadic gross errors or short-term disturbances in the analytical system that affect the results for individual test materials. Moreover, inferences based on IQC results are applicable only to test materials that fall within the scope of the analytical method validation. Despite these limitations, which professional experience and diligence can alleviate to a degree, internal quality control is the principal recourse available for ensuring that only data of appropriate quality are released from a laboratory. When properly executed it is very successful. 

Reference and research methods. These are generally more sophisticated procedures that are used by central quality control laboratories or by government agencies with qualified personnel. These methods are often used to verify results obtained by the rapid methods described below or to calibrate the instruments. They may also be used to verify additives declared on the label of a food product or to check for the use of non-permitted additives. This aspect is of increasing importance since legislation may vaiy between different countries, and food products are frequently subject to inter-market exports . The most important characteristics of these analytical procedures are ... 

Thus prototype evaluation was performed using a variety of standardized tests, including various objective and subjective measures. Many of these laboratory tests were already being used to assess attributes of other products, either as quality control tests for ordinary soap bars or else in the development of detergent-based household products like laundry detergents or hard-surface cleansers. 

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