Document dep7Q0mMYd1QKx0qoE8KOY9Q

I CEN TRAAL 1N ST1T U U T V O O R V O ED IN G SO N D ER Z O EK U trech tsew eg 48 Z e ist CENTRAL INSTITUTE FOR NUTRITION AND FOOD RESEARCH AR226-3331 REPORT NO . B78-1484 DETERMINATION OF POSSIBLE RESIDUES OF MONOMERS AND C8-EMULSIFIER IN VARIOUS PERFLDOROCARBON POLYMERS Authors At the request of Approved by ' Analysis No Dat Number of copies Drs. D. van Battum, M.A.H. Rijk, A. Schouten and A. Tas : Du Pont de Nemours International SA, Geneva, Switzerland Hoechst AG, Gendorf, Germany ICI Ltd, Welwyn Garden City, England : Prof.Ir. B. Krol : B78-I484 : July 1979 : 10 Gehele o f iedeeltelllk publlkatle van dit raooort Is zander scbrlftelltkn toestemmlna verboden. B78-I48|4 -2 INDEX SUMMARY pag 3 PURPOSE OF THE INVESTIGATION 4 < Mn Ui Ui ^ ^ 2. PROCEDURE 2.1 Determination of monomers 2.1.1 Extraction 2.1.2 Analysis of the extracts 2.2 Determination of C8-emulsifier 2.2.1 Extraction 2.2.2 Analysis of the extracts 2.3 Determination of the specific migration of C8-emulsifier 4 3. RESULTS 3.1 Monomer content 3.2 C8-emulsifier content 3.3 Specific migrationof C8-emulsifier 6 6 7 7 FIGURE 1 : GAS CHROMATOGRAM OF A STANDARD SOLUTION OF TETRAFLUOROETHYLENE IN HEXANE CONTAINING 3.2 ng/ml FIGURE 2 : CALIBRATION GRAPH FOR THE DETERMINATION OF HEXAFLUOROPROPYLENE IN HEXANE FIGURE 3 : GAS CHROMATOGRAM OF A STANDARD SOLUTION OF HEXAFLUOROPROPYLENE IN HEXANE CONTAINING 26 ng/ml FIGURE 4 CALIBRATION GRAPH FOR THE DETERMINATION OF C8- EMULSIFIER . I B78-1484 -3- SUMMARY Samples of various perfluorocarbon polymers were examined for the possible presence of.residues of monomers (tetrafluoroethylene and hexafluoropropylene) and the emulsifier (ammonium perfluorooctanoate) used in the manufac turing process. . In addition, the specific migration of the C8-emulsifier from skived tape and tubing into distilled water (10 d - 40 C) was determined. The residual tetrafluoroethylene content of all samples, as determined by gas chromatography - mass spectrometry, was found to be less than 0.01 mg per kg polymer. The TEFLON 100 FEP resin - the only one for which hexafluoropropylene was used in the manufacturing process - was found to contain 0.08 mg HFP per kg polymer. The C8-emulsifier content of the various polymer samples varied from 0.2 to 94 mg/kg. The specific migration of the C8-emulsifier was found to vary from 0.007 mg/dm^ to less than 0.005 mg/dm2. ./ 4 B78-1484 - 4- DETERMINATION OF POSSIBLE RESIDUES OF MONOMERS AMD C8-EMULSIFIER IN VARIOUS PERFLUOROCARBON POLYMERS 1. PURPOSE OF THE INVESTIGATION It was requested by Du Pont de Nemours SA, Hoechst AG and ICI Ltd. to determine the possible residues of monomers (tetrafluoroethylene and hexafluoropropylene) and C8-emulsifier (ammonium perfluorooctanoate) in various perfluorocarbon polymers, viz.: - TEFLON 701-N PTFE granular resin (unsintered) - Skived tape made from billet moulded out of TEFLON 701-N (sintered) - Unsintered tape made from TEFLON 669-N PTFE fine powder - TEFLON 100 FEP resin (extruded during manufacture in the range of 300 - 350 C) - HOSTAFLON TF 1620 granular resin - Skived tape made from HOSTAFLON TF 1620 - HOSTAFLON TF 2026 480 906 granular resin - Tubing made from HOSTAFLON TF 2026 480 906 - FLUON G 163 granular resin (unsintered) - Skived tape made from FLUON G 163 - Unsintered tape made from FLUON CD 1 coagulated dispersion powder 2. PROCEDURE 2.1 Determination of monomers 2.1.1 Extraction One g samples of the various polymers were extracted for 24 h at room temperature in 6 ml vials with 5 ml portions of hexane. 2.1.2 Analysis of the extracts The extracts were analysed by capillary gas chromatography - mass spec trometry. One pi of each extract was injected and the tetrafluoroethylene (TFE) or hexafluoropropylene (HFF) content of the extracts was estimated by means of injecting known quantities of standard TFE and HFP solutions. - standard solutions Stock solutions of TFE and HFP were obtained by courtesy of Du Pont de Nemours (Nederland) B.V. t Dordrecht, the Netherlands. The TFE standard was reported to contain 3.18 mg TFE per ml, the HFP standard 2.68 mg HFP per ml. From these stock solutions diluted standard solutions were prepared, containing 3.2 ng/ml (TFE) and 268, 134, 54 and 26 ng/ml (HFP) respect ively. , ' /5 B78-1484) -5- -- gas chromatography The column was a glass capillary, length 80 m, internal dia 0.5 mm, stationary phase SE 30, carrier gas helium 4 ml/min column tempera ture 25 C. , The column was coupled to a Varian MAT 112 S mass spectrometer, which was run with 0.7 mA emission at 70 eV ionizing energy. Quantitative analysis was accomplished by.selected ion monitoring, using the peaks at m/e 81 and 100 for TFE and at m/e 131 and 150 for HFP. Integration time was 0.01 sec for the reference channel and 0.03 sec for the other channels. The amplification of the channels was 0.03 V. - detection limits Figure 1 shows the gas chromatogram of 1 pi of a diluted standard sol ution of TFE, containing 3.2 ng/ml TFE. It can be deduced therefore that 2 ng TFE per ml, corresponding to 0.01 mg TFE per kg polymer (0.01 ppm), can still be detected. _ From the calibration graph for the determination of HFP, obtained by injecting one pi quantities of the afore--mentioned HFP standard sol utions (see fig. 2 and 3) it can be deduced that 3 ng HFP per ml, corresponding to 0.015 mg HFP per kg polymer (0.015 ppm), can still be detected. 2.2 Determination of C8-emlsifier The procedure followed was derived from instruction code No. T 200.185, obtained from Du Pont de Nemours SA. 2.2.1 Extraction Ten gram portions of the granular resin samples were for 8 h extracted under reflux with methanol. Samples of the tapes and tubing, having a total surface area of 2 dm2, were cut in strips of 2.5 x 10 cm and also extracted under reflux with methanol. 2.2.2 Analysis of the extracts The extracts were filtered over a glass filter and the filtrates were evaporated till dry by means of a rotating evaporator. Subsequently, 100- ml distilled water was added to the residue of each extract and the solution was acidified to pH 1.6 -- 3.0 with 0.1 N sulphuric acid. Then one ml of an Azure A solution* (40 mg in 5 ml 0.1 N sulphuric acid, subsequently diluted with water to 100 ml) was added. The resulting sol ution was shaken for 2 min with 10 ml chloroform. After separation of the layers the chloroform layer was transferred to a test tube containing approximately I g anhydrous sodium sulphate. After the mixture was * Azure A (7-dimethylamino-3-imino-3-HTfenothiazinehydrochloride) was taken as the complexing agent instead of Methylene Blue as prescribed m the afore--mentioned Du Pont procedure, because the results obtained with this reagent proved to be more reliable. /6 B78-148A -6- shaken, the absorbance spectrum of the clear supernatant was run between 700 and 600 nm with a reagent blank in the reference cell and the ab sorbance at 640 nm was determined. From the absorbance at 640 nm of sample and standard solutions the C8-emulsifier content of the extracts was calculated. - standard solutions A stock solution of C8-emulsifier in distilled water, containing 3 g ammonium perfluorooctanoate per 1, was prepared from which diluted standard solutions were made, containing 9, 15, 45, 60, 90 and 180 yg-C8-emulsifier per 100 ml respectively. The solutions thus obtained were further treated as described in section 2.2.2. - detection limits The calibration graph for the determination of C8-emulsiier is de picted in fig. 4. From this graph it can be deduced that 10 yg C8emulsifier per 100 ml water, corresponding to 1 mg/kg polymer (1 ppm) for the granular resin samples, can still be detected. 2.3 Determination of the specific migration of C8-emulsifier Samples of the skived tapes, unsintered tapes and tubing, having a total surface area of 2 dm^ were cut in strips of 2.5 x 10 cm. The strips were kept submerged in 100 ml distilled water for 10 d at 40 C. After the storage period the liquids were decanted, filtered over a coarse glass filter and further treated as described in section 2.2.2. The absorbance at 640 nm of the solutions was determined and then the C8-emulsifier content of the solutions was calculated by means of the calibration graph mentioned in section 2.2.2. From the results thus obtained the specific migration of ammonium perfluorooctanoate was calculated. 3. RESULTS The following results were obtained. 3.17-Monomer content sample TEFLON 701-N granular resin TEFLON 701-N skived tape TEFLON 669-N unsintered tape TEFLON 100 FEP granular resin H0STAFL0N TF 1620 granular resin H0STAFL0N TF 1620 skived tape H0STAFL0N TF 2026 granular resin HOSTAFLON TF 2026 tubing FLU0N G 163 granular resin FLU0N G 163 skived tape FLUON CD 1 unsintered tape monomer content (mg/kg) TFE HFP < 0.01 -- < 0.01 - < 0.01 - < 0.01 0.08 < 0.01 - < 0.01 - < 0.01 - < 0.01 - < 0.01 - < 0.01 ' - < 0.01 - B78-1484 - 7- 3.2 C8-emulsifier content sample TEFLON 701-N granular resin TEFLON 701-N skived tape TEFLON 669-N unsintered tape TEFLON 100 FEP granular resin HOSTAFLON TF 1620 granular resin H0STAFL0N TF 1620 skived tape HOSTAFLON TF 2026 granular resin HOSTAFLON TF 2026 tubing FLUON G 163 granular resin FLUON G 163 skived tape FLUON CD 1 unsintered tape C8-emulsifier content (mg/kg) 4 3.1 23.5 1.5 1.5 0.2 94 0.4 1.2 2.1 5.5 < . ^ '...w !1 . *' . 3.3 Specific migration of C8-emulsifier sample Specific migration of C8-emulsifier (mg/dm2) TEFLON 701-N skived tape TEFLON 669-N unsintered tape HOSTAFLON TF 1620 skived tape HOSTAFLON TF 2026 tubing FLUON G 163 skived tape FLUON CD 1 unsintered tape < 0.005 < 0.005 0.007 < 0.005 < 0.005 < 0.005 :r' CIVO-TNO IPs 79-07-23/YdV I .o r i l i K i Ii E I ! !I !! oI i CM s I : CN Pig Gas chromatogram of a standard solution of tetrafluoroethylene in hexane containing 3.2 ng/ml ,i  Fig. *2 Calibration graph for the determination of hexafluoropropylene in hexane 50 100 150 200 250 30( .20m-a-2120283 UhttSd&tfcKlfci* EULiifl.l