Quality Control in the Laboratory

While these are two separate and distinct activities, each must complement the other to ensure a quality program. Day to day quality control in the laboratory is the obligation of the chemist. The chemist develops the methods, calibrates the instruments, and with management approval develops the standard operating procedures for the laboratory. Quality control is running duplicate samples, reagent blanks, fortification samples, linearity checks and confirmatory analyses. 

Recently, the effectiveness of a three-phase fiber for aroma compounds analysis has been proved. In particular, the CAR-PDMS-DVB phase (50/30 pan x 1cm) appears to be effective in overcoming the lack of selectivity towards some compounds of one-phase or two-phase fiber. Furthermore, the use of an autosampling system permits an easier development of methods and a larger applicability for quality control in the laboratory (Fedrizzi and Versini, unpublished data). In this case, 1 g of NaCl in a 20 mL vial was added to 5 mL of wine and 5 xL methyl heptanoate (200 ppm in a methanolic solution) as internal standard. The sampling was performed during stirring at 40 °C for 20 min. 

What happens quantitatively on a larger scale is answered in experiments which tend to produce solutions for the physical problems. Usually they involve the trial of one catalyst recipe and a few reactor types giving the optimum space-time yields of desired product together with auxiliary heat transfer and pressure-drop data. The catalyst abrogate is preferably of the probable plant size, produced under conditions of quality control in the laboratory or the plant. 

Quality control (QC) refers to the operational techniques and activities that are used to fulfill requirements for quality. Internal quality control comprises the routine practical procedures that enable the analytical chemist to make a decision on whether to accept a result or a group of results as fit for purpose, or reject them and repeat the analysis. Tools for quality control include the use of reference standards and certified reference materials, the use of positive (spiked or incurred) and negative control samples and control charts, replicate analyses, and proficiency tests. Quality control in the laboratory is discussed in more detail in Section 10.5 of this chapter. 

A common laboratory technique for determining the concentration of a solute is titration (Fig. L.2). Titrations are usually either acid-base titrations, in which an acid reacts with a base, or redox titrations, in which the reaction is between a reducing agent and an oxidizing agent. Titrations are widely used to monitor water purity and blood composition and for quality control in the food industry. 

There are a number of prerequisites for properly using CRMs in these tasks, including established quality control of the laboratory s analytical measurement operations and proven statistical control of the analytical measurement process. Publications describing the use of RMs and CRMs are not as plentiful as those on how CRMs are made but, in addition to the ISO/REMCO Guides 30-35, the ISO/REMCO publication The role of reference materials in achieving quality in analytical chemis-try"(ISO 9000 1987), the NIST Handbook for SRM users (Taylor 1995), and the various LGC-VAM publications listed under Further Reading should all be consulted. 

Gillis, J. and Callio, S., Quality Assurance/Quality Control in the Analytical Testing Laboratory, ACS Short Course Manual, American Chemical Society, Washington, D.C., 1997. 

While the provision of suitably validated analytical methods is a necessary requirement for ensuring compliance with MRLs, the method alone is not sufficient to ensure creditable analytical measurements. In addition to selecting suitable methods, the analyst must demonstrate that the method is operating under statistical control in the laboratory and is performed to meet performance specifications as required by the analytical problem. This means that all methods should be applied in an environment with appropriate quality assurance procedures and performance evaluation checks. 

Quality Assurance and Quality Control in the Analytical Chemical Laboratory ... 

In the authors laboratory, the IS response of a sample is compared to the mean IS response of the accepted calibration standards and quality controls in the same run, i.e., those that meet the acceptance criterion of accuracy and do not show other abnormality (e.g., poor chromatography). When the IS response of a sample is outside 50 % of the mean IS signal of calibration standards and quality controls, the sample will be repeated. Moreover, an investigation may be initiated for repeated abnormal IS signal and when there is a pattern or trend. This acceptance criterion was also recommended by others (e.g., [13]). Alternatively, though not reported, some compare the IS response of a sample to those of adjacent samples or to the mean IS response of all the samples in a batch. No matter what approach is used, it is important to be able to single out abnormal samples and to perform corrective actions to ensure that their reported concentrations are accurate. 

Reversed-phase HPLC will find increased application in the analysis of purine antimetabolites and nucleoside antibiotics, both in the chemical laboratory for monitoring serum levels in chemotherapeutic treatment and in quality control in the pharmaceutical industry. In addition, RPLC will be used as a clinical diagnostic tool and aid the clinician in the detection of disease, in confirming a diagnosis, and in monitoring the causes of disease or effectiveness of therapy. 

Konieczka, P., Namiemik, J. Quality Assurance and Quality Control in the Chemical Analytical Laboratory A Practical Approach. CRC PressATaylor and Francis, Boca Raton, FL (2009)... 

CRMs are an important tool for quality assurance and quality control in analytical laboratories. They are used for verification of accuracy and precision (i.e., reliability of the results of analysis, validation of analytical procedures, establishing measurement traceability, and calibration of measurement equipment). Use of CRMs is recommended by the ISO/IEC 17025 standard and therefore it is obligatory for those who wish to obtain and maintain accreditation of the laboratory. 

At-line At-line is the fully automated analysis in a laboratory. The sample is still taken manually or by stand-alone devices. The sample is transported to the laboratory, e.g., by pneumatic delivery. Several hundred samples can be measured per day, allowing for precise quality control of slow processes. At-line laser diffraction is widely used for quality control in the cement industry. See Fig. 21-22. 

W. Funk, V. Dammann, G. Donnevert and S. lanelli, Quality Assurance in Analytical Chemistry, Wiley-VCH, Weinheim, 2nd edn, 2007 E. Prichard and V. Barwick, Quality Assurance in Analytical Chemistry, John Wiley Sons, Ltd, Chichester, 2007 P. Konieczka and J. Namiesnik, Quality Assurance and Quality Control in the Analytical Chemical Laboratory, CRC Press, Boca Raton, 2009 l.N. Papadoyannis and V.F. Samaridou, J. Liq. Chromatogr. Rel. Tech., 27, 753 (2004). 

B. Quality control laboratory In production premises a special and separate laboratory should be maintained for quality control department The laboratory should ... 

Aitio, A (1981). Quality control in the occupational toxicology laboratory. WHO Regional Office for Europe, Copenhagen, 1-49. 

In the last decade, there has been a marked increase in the toxicological and clinical demand for trace element analysis which has been reviewed by a number of authors (Delves, 1987 Kruse-Jarres. 1987 Versieck and Cornells, 1989). This places big demands on the reliability of such analyses and highlights the importance of quality control in the determination of trace elements (Boyd. 1983 Brown. 1982 Inhat et al., 1986a,b Delves. 1987 Ihnat, 1988 McKenzie and Smythe, 1988 Versieck and Cornells, 1989 Brown, 1991). Early interlaboratory comparison studies revealed that there were serious difficulties in achieving precise and unbiased quantitative measurements of trace metals in biological materials. Moreover, reported normal concentrations of some trace metals varied by several orders of magnitude when results from so-called specialised laboratories were compared (Versieck, 1984 Ihnat, 1988 Versieck and Cornells, 1989). In the last... 

Control charts should be used as soon as the method is under control in the laboratory using reference materials of good quality (i.e. stable, homogeneous and relevant with respect to matrix and interferences). 

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