In response to complaints from some ISO-CHEK® certified laboratories, we are initiating some changes to the ISO-CHEK® sampling cassettes.
 

The existing ISO-CHEK® configuration is:
 

Reasons for the Change

The old configuration put the PTFE filter and the fiber glass filter into intimate contact. This intimate contact allowed the MAMA reagent to transfer to the PTFE filter. The MAMA on the PTFE filter elutes at a point that causes interference with the desired peaks. To eliminate this interference, we are separating the PTFE filter by placing it in the half inch spacer with a "washer" type support pad.

This new configuration has been tested by pulling 3 liters per minute air flow without compromising the PTFE filter's seal. Chromatograms of blanks of the PTFE filters showed complete elimination of the MAMA peaks.

Additionally, users in the field would sometimes inadvertently pick off both the PTFE filter and the fiber glass filter and place them in the derivatizing solution, effectively destroying the sample. The new configuration should make this mistake a rarity.

Acknowledgments

Omega Specialty wishes to thank Glenn Fletcher of McMaster Occupational Health Laboratories and Andean Tan of Galson Laboratories, both participants of the ISO-CHEK® proficiency program, for bringing this short coming to our attention, and for suggesting the corrective actions.

We would also like to thank Lucile Richard of the IRSST for doing the analysis on the blank PTFE filters.

Omega Specialty Instrument Co. will initiate appropriate action as necessary to change the two ASTM standard methods to incorporate the above changes as they come up for review.

Please Note

Please make sure your customer service people and all instructions given to your clients change the instructions pertaining to sampling.