Bika PT Schemes

Bika Feeds PT

PT Provider

Bika Lab Systems (Pty) Ltd

Objectives

Bika 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

Confidentiality

All 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.

Responsibilities

The 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 Results

Corrupting 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.

Participants are implored to practice frank honesty in capturing measurement results. Your data and action warning by the system are private. Where participants require they may contact Bika PT lab consultants to assist in corrective and preventative actions on-site.

Please contact theCo-ordinator for the round you are participating in.

Participation

Participation in the Bika Feeds PT is open to all laboratories using either NIR prediction analysis or traditional wet chemistry methods.

Participation Level

The ideal number of participants is any number more than 15.

Sample Preparation

Bika 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 Criteria

PTS 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 Preparation

Sample 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 Material

Sample 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 Deadline

PT 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
Calcium
Chlorides
Crude Protein
Crude Fat
Crude Fibre
NDF
ADF
Moisture
Phosphorus
Starch

Results Capturing

Instructions 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 Analysis

Robust 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.

Bibliography

ISO 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.