Quality control methods - Introduction

If a laboratory is to produce analytical results of a quality that is acceptable to its clients, and allow it to perform well in proficiency tests or collaborative trials (see below), it is obviously essential that the results obtained in that laboratory should show excellent consistency from day to day. Checking for such consistency is complicated by the occurrence of random errors, so several statistical techniques have been developed to show whether or not time-dependent trends are occurring in the results, alongside these inevitable random errors. These are referred to as quality control methods. 

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Among the neutron-deficient isotopes of Tc, " Tc seems to have suitable nuclear properties for application in positron emission tomography (PET) (Browne and Firestone 1986). Considering the relatively new lipophilic Tc-labeled flow tracers used in cardiac perfusion imaging (2-methoxyisobutyl isocyanide [MlBl], teboroxime, tetrofosmin) it would be reasonable to replace Tc with " Tc in order to carry out quantitative investigations of biodistribution and clearance with PET. With this replacement, the pharmacokinetics of useful Tc compounds could be studied in a number of cases, which would enhance the introduction of new Tc-labeled pharmaceuticals into clinical practice. The labeling and quality control methods are well known and partly subject of this book. Our task is to review the different methods for the production of Tc and also the separation technique from irradiated targets. 

Presently efforts of Ukrainian scientists in field of analysis of toxic organic substances directed on harmonization of the developed methods of analysis with the requirements of international standards and on wide introduction in practice of the quality control system in chromatographic researches. 

Spectral imaging is a complex and multidisciplinary field. The introduction of new FPAs is making it increasingly powerful and attractive. It has proven potential in qualitative pharmaceutical analysis and can be used when spatial information becomes relevant for an analytical application. Even if online applications and regulatory method validation require further study, the potential contribution of imaging to quality control and PAT needs no further demonstration. 

Three calibration blank standards should be analyzed to establish a representative blank level, after which the calibration standards are analyzed. After calibration, the quality control standard should be analyzed to verify the calibration. The sample introduction system is flushed with rinse blank, and the blank solution is analyzed to check for carry-over and the blank level. If the blank level is acceptable, the samples can be analyzed. If the blank values are too high, the flushing of the sample introduction system and analysis of the blank solution should be repeated until an acceptable blank level is reached. The calibration blank value, which is the same as the absolute value of the instrument response, must be lower than the method s detection limit. 

The identification of the fall off in plant output uses the same statistical process control methods as for product quality [D-4]. Usually, and certainly in the larger manufacturing units, these issues will be handled by the local plant support teams. However, sometimes output issues arise which are outside the more routine evolutionary techniques employed by the process control teams. A typical example is when the output from a process is constrained by a particular plant item. An improved piece of equipment needs to be identified and evaluated. The introduction of this equipment will usually necessitate process changes for maximum efficiency. This and similar packages of work are best done by an R D project team. 

Supercritical fluid chromatography (SFC) with open-tubular columns was first demonstrated in 1981 by Novotny and co-workers [1]. This technique, known as capillary SFC, was made available to the analytical community through the introduction of several commercial instruments in 1986. Initially difficult to use, improvements in instrumentation and hardware, coupled with a wider array of columns and restrictor options designed specifically for the technique, becoming available, have led to a general acceptance of the method in many laboratories. Not only useful as a research tool, capillary SFC is firmly established as an essential analytical method for production support and quality control in many industries. Some of these include chemical and petroleum manufacturing, pharmaceuticals, polymers, and environmental monitoring. 

There can be little doubt that the introduction of automatic systems of analysis into the clinical chemistry laboratory has had more far-reaching consequences than any other single recent development in the practice of this branch of scientific medicine. Automatic analysis is defined for the purposes of this review as the mechanization of manual methods of analysis, without the result of the analysis necessarily being used for control of the process (R5). It has influenced the quality control requirements of clinical laboratories in several ways some of these are connected with all forms of mechanization, though others are relevant only to mechanical systems that employ special principles of operation. 

The incidence of perceptible formaldehyde in homes, offices and schools has caused widespread uncertainty about the safety of living with formaldehyde. This uncertainty was enhanced by the large scale installation of urea formaldehyde foam insulation (UFFI) because a substantial part of this material was made from small scale resin batches prepared under questionable quality control conditions, and was installed by unskilled operators (10). The only reliable way to avoid such uncertainty is to know the emission rate of products and develop a design standard that allows prediction of indoor air levels. The first and most important step in this direction was achieved with the development and implementation of material emission standards. As indicated above, Japan led the field in 1974 with the introduction of the 24-hr desiccator test (6), FESYP followed with the formulation of the perforator test, the gas analysis method, and later with the introduction of air chambers (5). In the U.S. the FTM-1 (32) production test and the FTM-2 air chamber test (33) have made possible the implementation of a HUD standard for mobile homes (8) that is already implemented in some 90% of the UF wood production (35), regardless of product use. 

The book offers the reader in its first part a general and as detailed as necessary introduction into the basic principles and methods, starting with sampling, sample storage and sample treatment. These steps are of utmost importance for each analytical procedure. This is followed by the description of the potential of a number of modern trace analytical methods, i.e. atomic absorption and emission spectrometry, voltammetry, neutron activation and isotope dilution mass spectrometry. The latter method is an important reference method within a general concept for quality control and the generation of reference materials which are an absolute must in this context. 

The editors sincerely hope that this book will, with its introduction into the basic principles and limitations of the presently available trace analytical methodology and its detailed description of reliable procedures and quality control measures, serve as a valuable aid for all those who are involved in trace element analysis. It should be especially beneficial for analysts and researchers in clinical chemistry, toxicology, biochemical and environmental research first as a general overview and second to serve as a collection of elaborated methods for the reliable determination of the above-mentioned elements and some of their species in selected (human) biological specimens. 

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