QSOP – 202E: TEST PROCEDURE FOR MEASURING PFOA IN PTFE MICROPOWDER

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PREPARED BY: Bin Chen August 15, 2018

SCOPE:
This internal method is developed for the determination of the PFOA concentration in PTFE powder products by using LC-MS. The method is applicable to a concentration range of 0.1 to100 ug/kg (ppb) for PFOA. Higher concentration samples should be diluted to the range for the test. Results lower than 0.1 ug/kg (ppb) will be reported as < 0.1 ug/kg (ppb).

APPARATUS and Reagents:
LC-MS
Vials for auto-sampler (Waters or equivalent)
Centrifuge Tube (Polypropylene) (15 mL)
Methanol (LC-MS grade)
Perfluorooctanoic Acid (PFOA, > 95%)
PFOA standard solutions (0.1 ug/L to 100 ug/L in methanol) prepared accordingly

PROCEDURE:
Sample Preparation:
PTFE powder sample is added into a 15 mL centrifuge tube (Polypropylene) followed by the addition of Methanol (LC-MS grade). The centrifuge tube is then tightly closed by screw cap and put into a ventilated oven. After 24 hours, the mixture is stirred and centrifuged for 10 minutes. The supernatant solution is transferred into a sample vial for LC-MS test.

LC- MS Test:
(1) The operating condition of the LC-MS is optimized in the electrospray ionization (ESI) negative mode in accordance with the manufacture’s instruction. The appropriate HPLC gradient program for the mobile phase is determined experimentally during method development and validation.
(2) The standard PFOA solutions are tested with LC-MS to develop a calibration curve which is used to determine the PFOA concentration in each tested methanol solution sample.
(3) The sample vial is put into auto-sampler in the LC-MS instrument and is analyzed by choosing suitable developed methods. The test report will be created accordingly.
(4) If the PFOA concentrations of samples lie outside the upper range of the calibration curve, the sample solutions should be diluted by the appropriate factor.
(5) If the PFOA concentrations of samples are less than 25 ppb, the products are considered as REACH compliant