Working Procedure for Incoming Samples received by a laboratory may be for compliance testing or for investigative testing. Samples for compliance testing include routine samples for control, samples suspected of not complying with the specifications or samples submitted in connection with a marketing authorization process. Close collaboration with the providers of the samples is important. In particular it is important that the sample is large enough to enable, if required, a number of replicate tests to be carried out (see Part three, section 14.3) and for part of the sample to be retained (see Part three, section 20).
Samples for investigative testing may be submitted by various sources including customs, police and medicines inspectors. These samples comprise suspicious, illegal or counterfeit substances or products. Usually, the primary objective of investigative testing is to identify the substance or the ingredient in the product and, if sufficient substance or product is available, to estimate the purity or content. Well-documented screening procedures should be in place as well as confirmatory analytical procedures to positively identify the substance or the ingredient(s). If an estimation of the content of an identified ingredient is required then an appropriate quantitative analytical procedure should be applied. The value obtained should be reported with an indication of the uncertainty of measurement if required (see Part three, section 18.10).
It is common for a sample to be taken and divided into three approximately equal portions for submission to the laboratory:
— one for immediate testing;
— the second for confirmation of testing if required; and — the third for retention in case of dispute.
If the laboratory is responsible for sampling of substances, materials or products for subsequent testing then it should have a sampling plan and an internal procedure for sampling available to all analysts and technicians working in the laboratory. Samples should be representative of the batches of material from which they are taken and sampling should be carried out so as to avoid contamination and other adverse effects on quality, or mix-up of or by the material being sampled. All the relevant data related to sampling should be recorded.
Note:Guidelines for sampling of pharmaceutical products and related materials were adopted by the WHO Expert Committee on Specifications for Pharmaceutical Preparations at its thirty-ninth meeting(22).
A standard test request form should be filled out and should accompany each sample submitted to the laboratory. In the case of a pharmaceutical manufacturer’s laboratory the requirements may be given in the master production instructions.
The test request form should provide or leave space for the following information:
(a) the name of the institution or inspector that supplied the sample; (b) the source of the material;
- a full description of the medicine, including its composition, international non proprietary name (INN) (if available) and brand name(s);
- dosage form and concentration or strength, the manufacturer, the batch number (if available) and the marketing authorization number;
- the size of the sample;
- the reason for requesting the analysis;
- the date on which the sample was collected;
- the size of the consignment from which it was taken, when appropriate;
- the expiry date (for pharmaceutical products) or retest date (for
APIs and pharmaceutical excipients);
- the specification to be used for testing;
- a record of any further comments (e.g. discrepancies found or associated hazard); and
- the required storage conditions.
The laboratory should review the test request to ensure that:
- the requirements are adequately defined and the laboratory has the capability and resources to meet them; and
- the appropriate tests and/or methods are selected and are capable of meeting customers’ requirements.
Any issue should be resolved with the originator of the request for analysis before testing starts and a record of the review should be kept.
Registration and labelling
All newly delivered samples and accompanying documents (e.g. the test request) should be assigned a registration number. Separate registration numbers should be assigned to requests referring to two or more medicines, different dosage forms, or different batches of the same medicine or different sources of the same batch. If applicable, a unique registration number should also be assigned to any incoming retained sample (see Part three, section 20).
A label bearing the registration number should be affixed to each container of the sample. Care should be taken to avoid obscuring any other markings or inscriptions.
A register should be kept, which may be a record book, a card file or data-processing equipment, in which the following information is recorded:
- the registration number of the sample;
- the date of receipt; and
- the specific unit to which the sample was forwarded.
Visual inspection of the submitted sample
The sample received should be visually inspected by laboratory staff to ensure that the labeling conforms with the information contained in the test request. The findings should be recorded, dated and signed. If discrepancies are found, or if the sample is obviously damaged, this fact should be recorded without delay on the test request form. Any queries should be immediately referred back to the provider of the sample.
The sample prior to testing, the retained sample (see Part three, section 20) and any portions of the sample remaining after performance of all the required tests should be stored safely, taking into account the storage conditions (22, 23) specified for the sample.
Forwarding to testing
The specific unit to which the sample is sent for testing is determined by the person responsible.
The examination of a sample should not be started before the relevant test request has been received.
The sample should be properly stored until all relevant documentation has been received.
A request for analysis may be accepted verbally only in emergencies. All details should immediately be placed on record pending the receipt of written confirmation.
Unless a computerized system is used, copies or duplicates of all documentation should accompany each numbered sample when sent to the specific unit.
Testing should be performed as described under Part three, section 17.