Guidelines for the preservation of official
samples for analysis

Minimise the effects of handling and storage on food samples taken for chemical and compositional analysis to help assure reliable and verifiable results.

The composition of food samples and the levels of analytes within them can be markedly affected by the conditions under which the samples are stored. Identifying and using the most appropriate storage conditions for particular samples prior to analysis is, therefore, often critical to the final analytical result. This is particularly important for official samples, where the test results could be used in legal proceedings.

This guide provides information, beyond that already available, on transport and storage of official food samples intended for chemical and compositional analysis. It is aimed at food analysts and those who need to take and retain official food samples for analysis ­ including enforcement authorities and food companies taking samples for due diligence purposes. Produced in collaboration with Hampshire County Scientific Services as part of a project commissioned by the UK Government, it provides guidance on:

• how samples should be divided at the time of sampling
• the types of containers that should be used for the sub-samples
• transport and storage of samples for analysis
• practical tips on samples which present particular difficulties
• advice to food sellers on retaining samples for independent assessment
• factors affecting sample deterioration

Note that the guide does not cover samples intended for microbiological examination.

Contents

• Introduction
• Division of samples for analysis
• Containers for samples
  - Types of container
  - Factors governing container choice
  - Security and labelling
• Transport and storage of samples
  - Definitions
  - Liaison with the laboratory
  - Transport
  - Storage conditions - food types
  - Storage conditions ­ analytes
  - Monitoring storage
  - Complaint samples
  - Sample receipt and movement
• When 3-part sampling is difficult
• Advice to food owners / sellers
• Additional information for food specialists
  - Factors affecting sample deterioration
  - Best practice for ambient, chilled and frozen storage
  - Supporting data
• References and appendices