Special considerations in analysis of critical laboratory samples

Referal laboratories play a significant role in all countries as they are considered to be authoritative and results communicated by them are accepted without questioning. Such laboratories analyze hundreds of samples daily. Analysis of each and every sample is important but at times critical samples are required to be analyzed. Such samples are often received from regulatory bodies under proficiency testing programmes, environment control boards, litigation samples, standard reference materials and samples whose results are under dispute. Analysis of such samples require additional attention as the reputation or even ranking of laboratories both by national and international bodies is under stake.

A Modern Analytical Laboratory

Chemicals and Reagents

The quality of analysis results depends to a great extent on the purity of chemicals and reagents used in testing.

• It is advisable to use highest purity grade chemicals available.
• Procure material only from approved vendors.
• Always use clean spatulas or pipettes for withdrawing materials form bottles. Do not leave bottles uncapped after use
• Store chemicals under prescribed storage conditions.
• Do not use any material after its date of expiry.
• Prepare reagents and buffer solutions required for analysis fresh before analysis and do not store for subsequent use.

Analysis method

Use only approved methods of analysis. If a new method is developed for any particular application always validate before adoption for routine use. No changes should be made at one’s discretion and if any such changes are desired further revalidation should be carried out.

Volumetric Glassware

Like chemicals and reagents, glassware should also be procured from approved and reputed suppliers.

• Glassware used for critical sample analysis should be Grade A and accompanied with a certificate of calibration.
• All volumetric measurements should be made under a standard temperature of 25⁰C
• Ensure cleanliness of glassware  used for such analysis

Sample Receipt and Storage

Sample handling is important for reliability of results. On receipt following should be ensured

• Packet or container should be intact and there are no leaks or cracks
• Record the physical state and description of the sample upon receipt
• The label is properly affixed and contains all relevant information on the sample
• A sample is accompanied with a letter containing the parameters for testing
• The sample reaches the laboratory under required storage conditions and is retained under the same conditions till the time of analysis
• Retain a portion of the sample for verification of results.
• Accord highest priority to testing of critical samples

Sample Analysis

• The sample should be divided and given to at least three different validated analysts
• After compilation average value should be reported. If fluctuations are significant revalidation through repeat analysis should be carried out.
• All instrument facilities used should be calibrated in advance and calibration records should be available for verification.

Record Keeping

Record keeping is the last stage that completes the analysis. Records are essential for repeat testing, validation of conditions used for analysis, laboratory approvals, sharing of results with regulatory agencies, courts, presentation during audits and even sharing with the public in the interest of social welfare.

The responsibility and confidence placed by all on reference laboratories should never be underestimated so before analysis results are released referral laboratories should ensure that all precautionary measures were complied with. This will help retain the supremacy of reference laboratories over other laboratories.