SAMPLING FOR LABORATORY TESTING A presentation at the

SAMPLING FOR LABORATORY TESTING A presentation at the e-Learning Platform of Standards Organisation of Nigeria BY OJOMAH EMMAN AND ATTAHIRU STEPHEN Son training services April 2020

INTRODUCTION �Product Sampling is an integral part of the quality assurance and conformity assessment functions of SON � Testing as a conformity assessment activity is carried out by the SON Directorate of Laboratory Services �Sources of products(Samples ) for test in SON Laboratories include: q Inspectorate and Compliance q Ports & Border Samples q Product certification samples q Consumer Complaints Samples q SIM samples q State offices Samples q Walk -in customers Samples q Standard Project Samples

INTRODUCTION TO SAMPLING �Sampling: the selection of a subset of individuals from within a statistical population to estimate characteristics of the whole population �Population: This is the whole of the material whose properties we intend obtaining. �Sample: This is a fraction of the population which is usually selected for analysis. �Laboratory sample: This is the fraction of the sample which is finally used for laboratory analysis. �Production Batch: The quantity deriving from the same production

OBJECTIVES OF SAMPLING A sample is expected to mirror the population from which it comes, thus sampling is carried out to: 1. Obtain the maximum information about the characteristics of the population with the resources available in terms of time, money and manpower by studying the sample values only. 2. Obtain the best possible estimates of the population parameters. 3. For destructive testing, the very act of testing the desired characteristic of the product destroys it for the intended use. �

SAMPLING PROCESS-01 �Sampling requires two very important processes to be completed correctly. �The first is the sampling itself �the second is the paperwork associated with each sample �To give assurance of accurate results, samples must be Representative and Traceable

SAMPLING PROCESS-02 �All Sampling activities in Standards Organisation of Nigeria are carried out for the purpose of laboratory analysis to ascertain their conformance with relevant standards. �SON Laboratories do not carry out sampling except it is requested by the customer(Internal or External) �Thus Samplers(Factory Inspectors, SON staff, walk-in-customers) are to sample right. � Sampling during factory inspections involves collecting relatively small number of items from a lot or batch � Results from these samples are used to either accept or reject the entire lot or batch. �The acceptance or rejection criteria is the number of defective items found in a lot or batch.

SAMPLING PROCESS-03 Sampling Methods �Samplers are to use known sampling methods except where prevailing circumstance does not permit. �There are basically four sampling methods: q. Random q Systematic q. Stratified q Cluster �Whichever methods used should avoid bias reasonably.

SAMPLING PROCESS-04 Sampling Sizes �Sampling sizes for all products have been determined by SON Management and forwarded to the state offices for compliance and implementation. �Formulas, tables, and power function charts may be used for the determination of sample sizes where they are not provided �Some standards including Nigerian Industrial standards (NIS) have sampling plans which are expected to be implemented by the inspectors �For Food Fortification , general sampling plans (1 -3 methods) have been designed and forwarded to state offices and well known to inspectors.

SAMPLING PROCESS-05 Acceptance sampling �Acceptance sampling is a statistical measure which allows a company to determine the quality of a batch of products by selecting a specified number for testing �ISO 28598 -1: 2017 provides guidelines for acceptance sampling which also covers third-party inspection (certification of product, inspection and supervision) for observance of national and International Standard requirements �Samplers, especially factory inspectors, should endeavour to familiarize themselves with the ISO 28598 -1: 2017 guidelines.

MAINTAINING SAMPLE INTEGRITY-01 �Sample Integrity simply refers to the reliability or the quality of a sample being tested �Sample Integrity can be compromised by the following: qinadequate sample size qincorrect handling procedures q. Contamination qmislabelling

Maintaining sample integrity-02 �Collection, storage and transportation of samples should prevent sample deterioration and crosscontamination �Some properties of the analyte(s) of interest to be considered when handling samples include: q. Volatility q sensitivity to light q thermal stability qchemical reactivity

Maintaining sample integrity-03 �Sampling requirements for microbiology analysis: q Where food is in a packed form, the package should be sent to the laboratory unopened. q All containers and equipment for collection of scooped samples be sterilized. q The samples should be transported to the laboratory as soon as possible, and where possible within 36 hr of collection q Frozen food should be transported frozen, and others chilled at 0 to 5 o. C q Canned or dry non-perishable food may be stored at room temperature. q The laboratory should be given advanced notice of submission of perishable/short shelf life samples q Perishable/short shelf life Samples submitted after closing hours and on Fridays without prior arrangement may not be attended to by the laboratory

Maintaining sample integrity-04 �Samples are received in the lab when the following requirements are met: q The information submitted with the sample is complete. q The general physical condition of the sample is adequate q Adequacy of sample size q Sample within shelf life(where applicable) � Sample with integrity issues are rejected by the laboratory and relevant sources of samples communicated to with reason(s) for rejection.

Conclusion �The importance of sampling cannot be overemphasised as no matter how good the analytical method is nor how carefully the analysis is performed, if the quality of sampling is defective, so also is the result �the sampling stages should be carried out by, or under the direction of a skilled sampler with an understanding of the overall context of the analysis �All staff concerned with administration of the sample handling system should be properly trained

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