Total solids and fat determination in milk; Interlaboratory testing

In the framework of quality management systems, proficiency tests become an important and useful tool for comparing results and so verifying technical competence of laboratories objectively. Additionally, in the accreditation requirements of ISO/IEC 17025 laboratories are asked to participate in proficiency tests regardless of other quality assurance activities for checking validity of tests results. Under the frame of IPA 2008 Project “Regional Quality Infrastructure in the Western Balkans and Turkey”, the Dairy Laboratory, part of Food Quality Department, in the Institute of Food Safety and Veterinary in Tirana, took part in a Proficiency Testing for comparison on fat, proteins and total solids in heat-treated milk (UHT) as part of the Proficiency Testing Protocol 5 (PT5) organized by the Dairy Laboratory, Biotechnical Faculty- Podgorica, Montenegro. There were 8 laboratories that participated in PT. 7 samples were sent to each participant laboratories and after getting back the results, the statistical calculations were done by the organizing body. This PT was the first one our laboratory took part in. Our results achieved encouraged us to present the work done and to analyze the factors we think have influenced. In this paper we have presented our work for total solids and fat content determination in seven milk samples analyzed according to the respective method presented in following. The results for total solids and fat content for each sample analyzed are showed in the respective tables as well as the results for accuracy assessment, i.e, comparability with the reference results and repeatability achieved by each laboratory.