Analytical Measurements Should be Made to Satisfy an Agreed Requirement - Essay Example

Analytical Measurements Should be Made to Satisfy an Agreed Requirement Introduction a. The objective of making a measurement is to either resolve an issue or to answer a query. The results obtained from measurements are used to resolve and answer the issue or query in question. The objectives behind making measurements span over a wide range. The nature of issues to be resolved might be of significance to various fields like legal, forensic, regulatory, health, research, classroom demonstrations, etc. Thus, the results obtained from various measurements are utilized in formulating a decisive conclusion to the issue in question. (4, 10) b. Prior to making a final judgement the results thus obtained from measurements should be compared to the existing standards already laid down to interpret the lower and upper limits. For example, in determining the level of alcohol in the blood of a driver charged with driving while drunk, there should be an existing standard level of alcohol in blood considered safe for driving and a limit above which it is unsafe to drive. The result obtained from the blood sample of this driver is then compared to the standard limit. (4, 10) c. A valid measurement is the one which does not result in misleading an observer, or the customer of a laboratory making the measurement. That is to say, that if the customer makes a decision relying on the information obtained by a valid measurement then the decision is correct. (4, 10) d. A valid measurement in itself may not be particularly accurate or precise, but if a conclusion is to be reached as to how the result differs from a standard then the measurement will have sufficient accuracy and precision to satisfy customer's requirement. The correctness of a decision reached by relying on the information obtained through analytical measurement indicates the validity of measurement. (1, 4, 10) e. The aim of the agency making Valid Measurement, normally a laboratory, is to provide their customers with results that are not ambiguous and confusing and meet customer requirements. That is why Analytical Measurement should be made to satisfy an agreed requirement. (10) Importance f. In analytical measurements the quality of data extracted is all that matters and good information thus gained is an outcome of good measuring techniques applied. For data to be of good quality the technique employed should be validated by being precise, repeatable, reproducible and stable. (8,9) g. A precise technique does not have deviations in the result of same measurement. There should be no change in methodology of measurement and neither should there be a change in what is being measured. The repeatable technique should render the same result when the same object is measured over a number of times. A reproducible technique is the one which when repeated produces the same result. A stable technique does not change over a period of time and if repeated, in times to come, it should be able to give same results as in the past. (2, 5) h. Laboratory of the Government Chemist (LGC) and National Physical Laboratory (NPL) have jointly developed Valid Analytical Measurement (VAM) principles, as part of their VAM programme to sketch a design for laboratories involved in making analytical measurements. Out of the six principles as laid down "Analytical measurements should be made to satisfy an agreed requirement" (4) is the first. (4) i. To realize the importance of agreed requirements consider that there a number of tests which can be performed to carry out a measurement. An analyst, being an expert, must enter into a dialogue with the customer to discuss the quality of results, time and cost of these tests. The analyst must have the knowledge to identify customer's requirements. Moreover, it is important to gain an insight into the criticality of the measurement by virtue of discussion with the customer. As such, it becomes necessary to know for what purpose the result will be used. (4, 5, 6) j. All critical and non-critical issues must be explained to the customer prior to making a final plan. It is vital that issues like delivery, composition and history of samples are resolved beforehand. This makes the analyst feel confidant and he or she then has a clear scope of work that lies ahead. To summarize, the following list includes the factors which should generally be agreed upon. i. Sample 1. Delivery 2. History and nature 3. Does the sample require to be identified or the constituents are already known ii. Criticality of the results; the uncertainty range iii. Financial aspects iv. Time factor v. Quality control and assurance (QC/QA) requirement vi. Acceptance of results by another party vii. Legal aspects covering regulatory constraints (2, 7, 8, 9) Example k. Striking a balance between time, cost and quality depends on the criticality of measurement and perhaps can be best understood by an example. A customer in interested in knowing if a sample contains more than 1 mg/kg of certain material. There are two options to select from. One is quick and economical but with an uncertainty range of 25%. The other is comparatively more time consuming, expensive and has an uncertainty range of 5%. The option required of the two available should depend on the nature of the sample. If the results are expected to be very close to the limit, in this case 1 mg/kg, then the more expensive method should be used. On the other hand, if the results are expected to be well within limit like few Ng/Kg then the more cost effective method should be used. This is where an analyst should suggest what method is to be utilized and also bring the customer into an agreement. It is also important that analysts should have some background knowledge about the customer's nature of business so that he might be able to help in bringing the customer to an agreement. (4) Quality Control and Quality Assurance l. A great deal of time and hard work is put in by laboratories to maintain and improve their quality. To maintain quality means that a laboratory is fit to perform what it is meant to do. This amounts to be interpreted as; the laboratory will measure up to its task and will provide the customer with results and data of adequate accuracy so that this result and other related information can be used with all the satisfaction. Doing any better than the requirement would mean a higher cost factor for the customer which was actually not required by the customer in the first place. (2, 7, 8) m. Fulfillment of quality control and quality assurance requirements might be one of the many reasons why customers might be attracted to a particular laboratory. Moreover, for the purpose of basing decisions on the results of a laboratory it is imperative that the data may be known and documented properly. (3, 6) n. It is a requirement of result verification and validation that QC/QA procedures are followed and required documentation is completed. Such documentation along with result, data, permits to gauge the following indicators of data quality. Integrity and stability of sample Performance of test equipment during measurement Isolation of sample, contamination Identification and quantification of sample Precision and accuracy of analysis (9) o. To maintain the quality laboratories often comply with one or more international standards. Listed below are the three standards of international quality which laboratories tend to adhere with. (9) ISO/IEC 17025, 'General requirements for the competence of calibration and testing laboratories' ISO 9001, 'Quality management systems - Requirements' Good Laboratory Practice (GLP) p. Independent assessment of laboratory performance is also carried out through Proficiency Testing (PT) schemes. (4, 9) q. United Kingdom Accreditation Service (UKAS) measures up laboratory performances internationally and grants approvals relying on ISO/IEC 17025, which is an internationally accepted document of standards applying to laboratories performing tests or calibrations. (4, 9) r. ISO/IEC approval requires that a laboratory should have a quality management system which should level up to the requirements of ISO 9001; this being an international standard of Quality Management System. (4, 5, 9) s. GLP, however, is different from the two above. It is a set of legal requirements to control the design, conduct and monitoring, recording and reporting of work to be submitted for evaluation of chemicals, foods and pharmaceuticals for their use by humans, animals or environment. (4, 5, 7, 9) t. PT schemes facilitate a laboratory to compare its works with other laboratories carrying out similar work. It also helps the customers of laboratories if they wish to do the same. The main aim of PT schemes is to help the laboratories in laying out a schematic plan to monitor and improve the quality of their regular analytical measurement. (4) Bibliography 1. Downey, H. K., & Slocum, J. W. (1975). Uncertainty: Measures, Research, and Sources of Variation. The Academy of Management Journal , 18 (3), 562-578. 2. Eurachem & Co-Operation on International Traceability in Analytical Chemistry. (2000). Quantifying Uncertainty in Analytical Measurement (2nd Edition ed.). (S. L. Ellison, M. Rosslein, & A. Williams, Eds.) UK: Eurachem & CITAC. 3. Jenks, P. J. (2005). RM Column. Retrieved March 08, 2008, from Spectroscopy Europe: www.spectroscopyeurope.com/RM_17_4.pdf 4. National Measurement System. (n.d.). National Measurement System. (LGC Limited) Retrieved March 8, 2008, from Chemical and Biological Website: http://www.nmschembio.org.uk/GenericArticle.aspxm=99&amid=832 5. National Measurement System. (2002). VAM-Chemical Programme. Retrieved March 08, 2008, from Department of Business Enterprise and Regulatory Reform: http://www.berr.gov.uk/files/file32716.pdf 6. National Measurement System. (2002). VAM-Physical Programme. Retrieved March 08, 2008, from Department of Business Enterprise and Regulatory Reform: www.berr.gov.uk/files/file32719.pdf 7. National Physical Laboratory. (2006). Proposals for the 2006-2009 Valid Analytical Measurement - Physical Programme. Quality of Life. National Physical Laboratory. 8. Shaw, A., & Haar, G. t. (2006). Requirements for measurement standards in High Intensity Focused Ultrasound fields. Institute of Cancer Research, Quality of Life. National Physical Laboratory. 9. United States Environmental Protection Agency. (2001). Laboratory Documentation Required for Data Evaluation. USEPA Region 8, Quality Assurance. San Francisco: USEPA. 10. Valid Measurements [Online]// Valid Measurements.- Valid Measurements, 2008.- March 09, 2008.- http://www.vm-usa.com/valid.html. Read More