Bika PT Schemes
Bika Feeds PTPT ProviderBika Lab Systems (Pty) LtdObjectivesBika Feeds PT aims to provide a cost effective tool based on internationally recognised standards to assist laboratories with monitoring and improving analytical performance and results integrity. It is a cooperative scheme which arranges the distribution of test samples and subsequent collation and analysis of the data provided by participants of the scheme. Bika Feeds PT is designed to operate in accordance with ISO/IEC 17043:2010 which provides guidance on general requirements for proficiency testing, and uses ISO 13528 statistical methods*. * ISO 13528 Statistical Methods for Inter laboratory Proficiency Testing, Robust Analysis Algorithm A is applied in Bika Interlab 2 ConfidentialityAll communication between Bika Feeds PT and participants is secure and in strict confidence. Sharing or distribution of results between participants shall be at the sole discretion and responsibility of participants. ResponsibilitiesThe Bika Feeds PT provider is responsible for all aspects of the PT scheme which includes maintaining the web based interlaboratory system and database, as well as data processing and reports generation. Collusion and Falsification of ResultsCorrupting PT results through unethical scientific conduct such as collusion by PT participants or co-ordinator, will nullify results until the suspicious data are removed, earlier statistics reported invalidated and recalculated and distributed. Painful and legally accountable. ParticipationParticipation in the Bika Feeds PT is open to all laboratories using either NIR prediction analysis or traditional wet chemistry methods. Participation LevelThe ideal number of participants is any number more than 15. Sample PreparationBika Feeds PT uses subcontractors for the preparation and distribution of PT samples. Subcontractor Commitments: Confidentiality and non-disclosure Analytical competency as demonstrated by participation in an accredited EPT Administrative competence and ability to communicate with and if necessary, educate participants Access to a suitable range of sample material Appropriate sample preparation facilities Ability to test sample homogeneity Creation of a Sample Inventory with refrigerated storage to conserve sample integrity Provision of packaging, labelling and sample distribution facilities Sample CriteriaPTS samples shall be similar to those routinely analysed by participating laboratories. The sample material shall be: Of sound quality Homogeneous in consistency Stable for at least 12months @ <10C Sample PreparationSample material, the preparation of PT samples, and the results homogeneity tests are documented and published to participants on-line. The material is milled using a cross beater hammer mill with 1mmØ sieve. The milled material is then transferred to a large round bottom plastic mixing bowl and blended with an electric mixer set at medium speed for 5mins. The blended sample is allowed to equilibrate in the bowl at room temperature for 2hrs and the blending process repeated. A clean spoon is then used to sub-sample ±10g milled material from the surface, middle and bottom of the bowl and each sub-sample transferred to individual sample containers for replicate analysis of crude protein, ash and soluble chlorides. Homogeneity is confirmed when the individual test results fall within 1.5sd and the replicate mean within 1sd of the method used. Failure to achieve this performance criteria requires each of the sub-samples to be returned to the bulk sample and the blending and testing process repeated. Approximately 200g prepared material that has met the requirements is spooned into 70 micron thickness plastic vacuum bags and sealed with a heat sealer. Each vacuum sealed bag of prepared PT sample material is labelled with: Product (type of sample) PT Round number Unique Sequential ID Date packaged
|
Control of Sample MaterialSample Inventory records are kept on-line for the following information: Product (Sample type), quantity and storage location All relevant information of prepared PT samples linked to them Dates samples are checked out of storage Samples damaged or lost and replaced Dispatch dates per sample distributed Courier tracking information are kept on-line for all dispatch samples, linked to storage positions for hard copies where applicable After each PT Round, its method means are compared with the homogeneity means determined earlier, for protein, ash and chlorides Sample Distribution and Reporting DeadlinePT Round schedules are published on for Bika Feeds PT pages on-line and closing dates included in the emails sent to participants before Rounds open. The email notifications also include: PT Round title and ID Sample dispatch Date Participant’s address If a courier was used, a tracking number (way bill) and link to online tracking Round open and closing date time Any changes to the originally published schedule An undertaking of free replacement of lost or damaged samples, participants pay courier costs Selection of Analyses (Analytes, ISO Properties)Participating laboratories selects which analysis results to return based on those they routinely perform. The following Analytes, ISO Properties, are currently included but can be expanded on request: Ash Results CapturingInstructions for use of the web based data capturing is available in the on-line manual. Results capturing for a Round can only be done between its start and end date times. Authorised participants do so in strict confidentiality. Results cannot be corrected or withdrawn after the Round has closed. For reproducibility assessment, participants enter results for each analyte in duplicate. This information assesses both method imprecision and sample homogeneity. The system restricts the number of significant digits that can be captured for each analyte. Participants may also capture additional comments for the PT coordinator's review. Participant Performance & Statistical AnalysisRobust Analysis Algorithm A of ISO 13528, Statistical Methods for Inter laboratory Proficiency Testing is used to calculate participants’ performance parameters. Please see ISO 13528 Robust Analysis Algorithm A in the online manual for more information. An abridged outline: Ranking participant performance by "Z Score" represents the distance between the participant score and the population mean. The Z Score is negative when the participant is below the mean and positive when above. A Z Score of ± 2 Z or less is designated a pass and a score of ± 3 Z invokes a warning and anything larger is reported as a fail. As Bika PT is a consensus-based program, the analyte's assigned value is the Robust mean of participant results after obvious errors have been removed in the statistical calculations. The Standard Deviation of proficiency is established from the Robust Inter-Laboratory Standard Deviation specific to the actual analyte and is adjusted for outliers and statistical distribution of the test data. Graphical presentations of results and Z Scores assist with visual interpretation. BibliographyISO 17043 · Conformity assessment - General requirements for proficiency testing ISO 13528 · Statistical Methods for Inter laboratory Proficiency Testing 2006 IUPAC, Pure and Applied Chemistry 78, 145–196. |