Document 3LKJkaLVGLe8OaYwam9BXO4D

p. 1 j4/\ o2.-,)-6 300 9 Du Pont de Nemours (Nederland) BV Dordrecht Works To : C .L . Gueris - Geneva cc . T .J .B. Schroots From :R .A . Brandenburg - Dordrecht F . Marcoz M v d . Noort C . de Heer H . Berrjamins Dordrecht, 30 Janua ry 1997 RESULTS OF DU PONTS ANALYSES OF C-8 IN HOSTAFLON TUBES Ref : My summary of 6-dec-96 meeting in Geneva about c-8 in PTFE for food contact applications Dear Chris , Here are the results of our C-8 analyses on HostdOon tubes The conclusion is that it we agree extraction depth is less than 3 mm, only minor toxicity testing is required . I am looking forward to the results of Hoechst and IC! . Samples provided by Dr . Mitterberger of Dyneon : A 1 kg of Hoslaflon TF 2025 tubes 12 mm diam, t mm thickness B 1 kg of same tubes, shredded by Dyneon, ca 5X5X1 mm C samples A, cut in ri ngs ( 1-2 mm) and further shredded by DuPont laboratory, ca 1 mm3 . Extractions EID751385 p. 2 1 . In chlorotornVwater B2-1 50 grams of B refluxed lor 2 his in a mixture of 40 ml CHC13 and 25 ml. H20 C2-1 50 grams of C refluxed for 2 his in a mixture of 40 ml CHCI3 and 25 ml H2 0 2 . In ethanol 99 .8 % B2-2 200 grams of B refluxed for 2 his in 250 ml ethanol, pH > 10 (by adding NaOH ) C2-2 192 grams of C refluxed for 2 his in 250 ml ethanol, pH > 10 B2-8 as B2-2, refluxed for 8 hrs in 250 ml ethanol, pH > 1 0 C2-B as C2-2, refluxed for 8 hrs in 250 ml ethanol, pH > 10 E1D751386 p. 3 Analyse s 1_ Methylene Blue method short description To the 25 ml water layer was added : -5 ml rnethylene blue -1 ml 2 N H2SO4 This was extracted 3 times in 15 mt CHCI3 . The 45 ml extract was completed to 50 ml with CHCI3, and extinction at 640 nm was measured on a UV-Vis spectrophotometer, and compared with a calibration 1ine . 2 . GC method shod description (Du Pont ref . WW-3690) The 250 ml ethanol was evaporated on a steam plate- This took appr . 48 hours . The residue was esterified with 10 ml . methanol containing 1 .5 mol H2SO4 per Gter methanol at appr. 54 C during 2 hours _ To this mixture was added 10 ml hexane and 20 mt of a stock solution of 180 gA NaCI solution in water . After shaking and phase separation 5 microliter of the hexane layer was injected on a GC capillary column with ECD detector . (50 m . 0 .53 mm CP S7 5CB fused silica)_ Peak area was calculated into concentration by comparison to the peak area of 1 ppm of an esterified standard solution of C-8 . We used a 1 ppm C-9 solution as an internal standard to correct for variations in injection volume. Results B2-1 120 ppm wt CHCI3 Dyneon shred, Me-blue C2-1 .410 ppm wt CHC 1 3 DuPont shred, Me-blue B2-2 .068 ppm wt EthOH Dyneon shred, GC C2-2 .097 ppm wt EthOH DuPont shred, GC 62-8 .065 ppm wt EthOH Dyneon shred, GC C2-8 106 ppm wt EthOH DuPont shred, GC EZD751387 p. 4 Discussion 1 . As we discussed before, the higher numbers found with the methylene blue method are less reliable . due to: - extinction values 0 .033 and 0.066 were too low lor reliable result - there may have been other anionic surfaclanls in the laboratory glassware, which significantly contribute to the blue color i n this low concentration range . 2 . We found little difference between 2 hours and 8 hours extraction . This suggests that 2 hours of extraction should be sufficien t 3 . The finer shred made at the DuPont laboratory gave results that are roughly 50 % higher than Dyneon shred. EID751388 p. 5 4 . In the food extraction tests, 6 dm2 of PTFE surface is exposed to 1 kg of the extraction medium. If we assume the effective extraction depth is d mm, this corresponds with 0 . 06 'd dm3 = 0 .1296 ' d kg of PTFE exposed to f kg of the extrac tion medium . We hope to rind less than 50 mic rogram of C-8 per kg of extraction medium, so that onty minor toxicity tes ting would be required . So the 0 .1296' d kg of PT FE should contain less than 50 microgram of C-8. In other words the C-8 concentration in the PTFE should be less than 3861d microgram per kg . If we take d = 1 mm, the concentra tion should not exceed 386 ppb . We find appr. 100 ppb . As you can see, d is rather importanl . If we decide that effective extraction depth is 4 mm, the concentration should not exceed 96 ppb . compared to actual 100 ppb. EstKna tion of extraction depth There is some indication that extraction depth is less than 1 rnm . The Dyneon shredded tube pieces were flat pieces of I rnm thickness (= tube wall thickness), and appr. 5 x 5 mm size . Apparently even though the smallest size is 1 mm, and both flat sides of the flat pieces are exposed to the extraction medium, this is not enough to take out all C-8, as evidenced by the lact that cutting into smaller pieces gav e 50 % higher numbers . Although what follows is speculati ve, here is a calculation of the effect of cutting : Suppose all large pieces are exactly 5 x 5 x 1 mm, and the small ones are 1 x 1 x 1 mm . Th en each large piece can be cut into 25 small ones . Each small piece has a surface area of 6 mm2, so 25 of them have a surface area of 150 rnm2 . This should be compared with the surf-ace area of the large piece from wtiich they were cut : 2 x 25 mrn2 + 4 x 5 mrn2 = 70 mrn2. So cutting into small pieces raises the surface EID751389 p. 6 area by a (actor 2, and the analytical result by a factor 1 . 5 If the extraction depth is d mm, you can show that for 25 1 mm3 cubes, the extracted volume = 25*(6d - 12d"2 + Sd"3) mm 3 = 150d-300d"2+200d" 3 For a 1 x 5 x 5 piece the extracted volume is 70d - 44 d"2 + 3d^:i . Let us assume that the factor 1 .5 increase in C-8 result is fully caused by the increased extracted volume . Than we can say that .150 d-300d^2+ 200d"3= 1 .5x170d-44d"2+8d^3j. d can be solved by algebra, and we find d= 0 .2387 mm . Al this extraction depth the increase in extracted volume of I mm3 pieces is exactly 1 .5 times as high as the extracted volume of the same weight of 5 x 5 x 1 mm3 pieces . EID751390