Quality control among laboratories

The quality control unit in a cosmetics company supervised the processing of the weekly batch of shampoo by determining, among other parameters, the viscosity and the dry residue. Control charts showed nothing spectacular. (See Fig. 4.10, top.) The cusum charts were just as uneventful, except for that displaying the dry residue (Fig. 4.10, middle and bottom) The change in trend in the middle of the chart was unmistakable. Since the analytical method was very simple and well-proven, no change in laboratory personnel had taken place in the period, and the calibration of the balances was done on a weekly basis, suspicions turned elsewhere. A first hypothesis,... 

All aspects of the laboratory s work which might affect the validity of the final result should be inspected. This will include, for example, documentation, equipment, calibrations, methods, materials, record keeping, sample recording, labelling, quality control checks and log of daily checks, among many others. Some aspects, however, are outside the scope of such an audit, such as safety and security matters, which usually have separate arrangements for auditing. 

The secondary DQIs are not immediately obvious to the data user not all of them are applied for data quality evaluation. Nevertheless, they are among the fundamental concepts of analytical chemistry, have a great effect on results of qualitative and quantitative analysis, and affect the outcome of the primary DQIs. The meaning and importance of the secondary DQIs are discussed in Chapter 4, which details laboratory analysis and quality control. The secondary DQIs, which include sensitivity, recovery, memory effects, method detection limit, limit of quantitation, repeatability, and reproducibility, are defined as follows ... 

In spite of the several advantages over HPLC, CLC has not yet achieved its maturity as a separation technique to be used worldwide, particularly as a routine technique for quality control laboratories. Among the limitations still hindering the further development of CLC, one of the most critical ones is the very limited availability of commercial equipment dedicated to this... 

Analytical pyrolysis is used frequently in practice for qualitative identification and for obtaining quantitative or semiquantitative information on samples containing polymers, either synthetic or natural. However, most of this work remains unreported in peer reviewed literature but is rather common in industrial laboratories. Since the objects made from plastic or elastomers are typically insoluble or not easily analyzed by other techniques, analytical pyrolysis is very successful in this type of analysis [11]. The very small amount of material necessary for pyrolysis also allows in many cases performance of the analysis without the destruction of the object to be investigated. Qualitative and quantitative work includes applications for the identification of unknown samples and also for quality control purposes, evaluation of starting materials, evaluation of finished products, reverse engineering and competitor s product analysis, etc. [1]. Among other applications, Py-GC/MS can be used to quantitatively differentiate between natural and synthetic organic materials [12]. 

Often the analysis of a compound is best left to specialists. Analytical chemists may be very helpful in developing an in-process assay for the laboratory or pilot plant and in purifying an impurity. Quality control (QC) chemists may be key in recognizing a new impurity in a manufacturing batch. Spectroscopists know how to get the best performance from their instruments. Good teamwork among the analysts and other chemists is essential to the efficient development of a process. 

Whitehead (W6) described an IBM-870 system for the recording of laboratory data on punch cards based on an earlier description by Peacock et al. (PI). The primary purpose of this system was to improve the presentation of individual laboratory reports, but the cards were subsequently sorted and the data on them subjected to statistical analysis, some of which revealed hitherto unsuspected sources of error as a result of variation in the technical performance of individual members of staff. Whitehead was among the first to apply cusum techniques to clinical chemistry laboratory data for control purposes, but his off-line system was not able to provide quality control information of immediate value to the laboratory. 

Common supports such as AI O, and SiOp are made by catalyst manufacturers using modifications of these procedures. Excellent product quality control is achieved with a wide range of properties. In preparing catalysts, the laboratory chemist is advised to select suitable supports from among those available, unless changes in procedure are essential. Much labor, time, and frustration is saved. Suppliers of supports are listed in... 

Hardly any information is available on the knowledge of iodine nutrition among wholesalers and retailers. As a group they are probably the least informed about iodine nutrition and the consequences of iodine deficiency or excess (Ling, 2004). Only in circumstances where repackaging occurs, and in wholesaler or large retailer companies with in-house quality control laboratories, may one find some awareness of iodine nutrition and an awareness of legal requirements and consumers iodine health. 

Virtually all analytical test methods require some form of calibration or verification before actual samples are analyzed. Different test methods require different calibration intervals. Thus, a decision about appropriate calibration fiequency must be made on a case by case basis. There is a tendency among many laboratories to do the bare minimum calibrations similar to their approach toward quality control requirements. This is not the way to achieve superior performance. Moreover, if an instrument is out-of-calibration, under no circumstances can data fiom that instrument be reported to the customers. 

In spite of the several advantages over HPLC, CLC has not yet achieved its maturity as a separation technique to be used worldwide, particularly as a routine technique for quality control laboratories. Among the limitations still hindering the further development of CLC, one of the most critical ones is the very limited availability of commercial equipment dedicated to this technique. Even so, most systems are simple adaptations of parts already used for HPLC, by just decreasing their sizes and volumes without specifically having CLC in consideration. Therefore, in order to become a routine technique as its counterpart in GC, capillary LC still has to have a broader interest for the instrument manufacmring companies in the technique before it will spread out beyond the academic environment. Those who have worked with packed columns in GC in the 1960s have already seen this same history. 

---