EnviroMail™ 94 - PFOS PFOA and Why Do My Laboratory Results not Agree

In June 2009, ALS became the first NATA accredited laboratory for PFOS/PFOA analysis in Australia. Six years down the track and there are now several laboratories accredited to perform PFOS/PFOA and PFC analysis. Over the years there have been a number of differences between laboratory results and a recent proficiency trial confirmed differences still exist. One issue is that industry practitioners are unsure which results are correct. This EnviroMail intends to provide good science and logic to explain why results may be different such that industry can make decisions and understand which numbers are most likely to be accurate for your needs.

 

WHAT DO PROFICIENCY TRIALS SHOW?

 

ALS has participated in a number of proficiency trials on PFOS/PFOA The first finding of ALS investigations following the most recent trial is the difference in the ways laboratories appear to calculate results.

 

• Some Laboratories quantify using standards that contain both linear and branched PFOS

• Some Laboratories quantify using standards that contain only linear PFOS

• Some correct for recoveries

• Some labs do not correct for recoveries (as per NEPM)
 

This EnviroMail provides further insights into which results might be correct however the big question is ‘were proficiency samples spiked with the typical PFOS profile seen in the environment or were they spiked with Linear PFOS’. In the proficiency trial provided in this Enviromail, the answer is linear PFOS and of course the labs that calibrate using linear PFOS (only) will therefore appear to have better proficiency accuracy.

 

The question to the expert is ‘do samples in the Environment only contain linear PFOS?’ There are lots of views. ALS has analysed many thousands of samples over the last six years. Data follows overleaf from select major projects.

 

To read the full article please click on the link below.