Participation in Proficiency Testing (PT) and Inter-Laboratory Comparison studies is an essential part of Chemex QA program

At Chemex we believe that participating in PT schemes run by industry bodies is essential.  Firstly, it makes things easier for you, our customers, because the accreditations we have mean that our work is accepted pretty much anywhere in the world.   Secondly, we believe that voluntarily submitting to external, independently-conceived, interlaboratory data assessments is one of the best ways to prove our worth and give our customers peace of mind.  By submitting our data to an external data reviewer and passing required quality control targets we are gathering proof of our high performance levels so you can be confident of the results we will provide.  In the following paragraphs our participation in proficiency testing schemes are fully explained along with the criteria required to win them.

Chemex PT scheme participation includes:

-AQUACHECK scheme, organised by LGC Proficiency Testing Group, UK.  The scheme is applicable to Chemex inorganics, metals, PCBs and pesticides analytical methods for water and effluent matrices.
-CONTEST, contaminated land proficiency testing scheme, organised by LGC Proficiency Testing Group, UK. Chemex participates in Metals and Organics in soil groups.
-RT Corporation Ltd PT scheme is used to supplement the two above to cover organics waste water parameters and PCBs (Aroclors) in soil.
-New Jersey PT scheme, currently organised by Environmental Resource Associates (ERA), USA. Chemex regular participation in VOCs and SVOCs contaminated soil and water sample analysis ensures compliance to the US EPA laboratory certification requirements.

All data obtained from the PT studies is evaluated by Chemex QA Unit and laboratory managers.  Results are assessed for their accuracy, precision and comparability with other participating laboratories.  Z-scores are used as a PT scheme performance index. The magnitude of the Z-score can be interpreted as follows:
Z≤ 2 Satisfactory, 2 < Z > 3 Questionable Performance, 3 ≤ Z Unsatisfactory.
 
Any Z-scores >2 are immediately investigated and corrective action assigned to eliminate the poor analysis results.

Chemex is an active participant of various Inter-Laboratory studies organised for the purpose of a new method or a new reference material validation. In 2007 Chemex took part in LGC soil and drinking water reference material studies.