In addition to availability of state of art test facilities and skilled manpower it is important for all laboratories to have sound quality management systems in place.
However, if due care and control is not exercised over critical laboratory samples and facilities the benefits of quality management systems will get minimized.
To make a start it is desirable to list out some of the critical supplies and samples before adopting the desired practices for their evaluation and handling.
- Reference materials and Working standards
- Samples received for proficiency testing.
- Calibration tools
- Volumetric glassware
Reference Materials and Working Standards
Reference materials and working standards constitute the foundation blocks of all analysis. These materials have to meet the required standards of purity as well as bear traceability to their origin.
Certified reference materials play an important role in the laboratory. The results of any analysis are authentic only when they are related to certified reference materials. Ideally a certified reference material should be used every time an analysis is performed but this is not feasible as the cost of reference materials is very high. The available alternative is to make use of working standards.
A working standard is prepared from highest purity grade material whose composition is compared with the certified reference material through analysis. However, even under stipulated storage conditions the composition can change over a period of time so it becomes necessary to revalidate or prepare it afresh on expiry of the validity period. A working standard should never be used post its expiry date.
The standard should be purchased from a supplier approved by the quality manager. Its purchase record along with payment details should be preserved for future reference and audit purpose. On purchase its quality should be checked so that it conforms to specifications. The analysis result should be recorded and an expiry date label pasted on the container. It is important to store the standard under prescribed conditions of temperature, humidity and exposure to light.
The standard should be consumed within 3 months of opening of the vial. Outdated standards should be replaced by new ones and the list of valid working standards should be updated whenever a replacement is made.
Samples received for proficiency testing
Proficiency testing is a regulatory requirement of accredited laboratories. Each accredited laboratory participates in such programs to validate its testing proficiency.
The samples received for proficiency testing do not require any special treatment. However, in order to ascertain the product received the laboratory needs to adhere to the conditions and requirements of the test. It is equally important to ascertain the condition and labeling of the sample.
- Examine the correctness of information provided with the sample and ensure the sealing is intact.
- Record the physical appearance of the sample on receipt
- Take note of storage conditions and preserve sample prior to analysis under the required conditions.
- Analyze the sample on high priority. Ensure that only calibrated instruments,and volumetric apparatus are used for analysis.
- Maintain and record the environmental conditions during the analysis.
- Make use of highest purity grade reagents for analysis.
The quality of results of analysis depends on the calibration status of the instrument, sensing devices and temperature recording devices. Even the weighing balance is required to be calibrated using a set of calibrated weights bearing certification from national meteorology laboratories. The weights should be handled carefully using a pair of forceps. And the weight box should be kept under controlled humidity conditions. All such measurement instruments and devices need to be used under controlled environmental conditions
Like weighing balance and weights volumetric glassware such as volumetric flasks, burettes, pipettes, micropipettes need to be calibrated before putting to regular use. However, unlike instruments volumetric apparatus may be calibrated only once at time of introduction. Care must be exercised so as not to expose volumetric glassware to extremes of temperature.
The article highlights the need for maintaining high standards of testing in laboratories. Apart from a regular training schedule it is necessary to conduct recommended evaluation and handling schedule of all critical laboratory samples and supplies.