The Australasian Soil and Plant Analysis Council Inc (ASPAC) is an organisation that supports continuing improvement in laboratory performance, and also believes consumers need to be aware that laboratories do not all perform to the same, impeccable standard. When a farmer, extension officer or researcher sends soil and plant samples to a laboratory, how can they be sure the results are reliable? Analytical testing is like any other product - the quality can range from very good to the opposite extreme.

The following few simple questions can help ensure a wise and rewarding investment. These questions assume the client (eg. farmer, extension officer, researcher) is certain of the method or methods to be used.

The Australasian Soil and Plant Analysis Council Inc (ASPAC) is an organisation that supports continuing improvement in laboratory performance, and also believes consumers need to be aware that laboratories do not all perform to the same, impeccable standard. When a farmer, extension officer or researcher sends soil and plant samples to a laboratory, how can they be sure the results are reliable? Analytical testing is like any other product - the quality can range from very good to the opposite extreme.

The following few simple questions can help ensure a wise and rewarding investment. These questions assume the client (eg. farmer, extension officer, researcher) is certain of the method or methods to be used.

Are you an ISO accredited lab?

There is a special standard (ISO 17025) against which testing laboratories are audited. Independent assessors review the laboratory's Quality Assurance protocols and procedures, regularly inspect the laboratory, and ensure high standards are in place before awarding this accreditation. This does not guarantee nothing will ever go wrong (mistakes can always happen); it does provide proof the lab has good systems, appropriate staff and high standards.

Do you compare well against other labs?

Ask if they participate in Laboratory Proficiency programmes. These are also known as inter-laboratory comparisons, or round robins. They involve a central co-ordinator preparing well-mixed samples, dividing these into homogenous sub-samples and sending these periodically to participating laboratories for analysis. The proficiency program co-ordinator processes the reported values after a specified time to identify laboratories with acceptable and outlier results.

ASPAC runs such programmes for soils and plants. It also issues Certificates of Proficiency for each program on a method-by-method basis.

Ask the laboratory if they have an ASPAC Certificate of Proficiency for the test or tests of interest. Have confidence in the laboratory if the method is listed on the Certificate issued following the most recent ASPAC Program. Be cautious if the laboratory cannot or will not produce the ASPAC Certificate or if that Certificate does not list one or more of the tests of most interest to you.

What do you do to be sure your results are right?

This question is like doing a quick quality audit yourself, and obviously cannot be as comprehensive as a full ISO audit. But the labs answers may either re-assure you, or ring warning bells. They should be running check samples in every batch of analyses, and should be participating in some type of proficiency programme. If they are not doing these basics, be afraid; be very afraid.