Document ZJOvX57GBwVGo0eXbxZDkLGw8

AR226-3336 DuPont Fluoroproducts Washington Works Melts Technology Report Contribution Name: Stephen R. Peck Date: 5/2/03 s^^^^^^^^^^^^^^^Hs TECH1NROOLLOOGY RE PORT TABLE OF CONTENTS (ABSTRACT SECTION) I. SAFETY, HEALTH AND ENVIRONMENTAL A. ANALYTICAL DEVELOPMENTS FOR DETERMINATION Pag OF AMMONIUM PERFLUOROOCTANOATE . KW1C: [AMMONIUM PERFLUOROOCTANOATE, APFO, C-8, GC, HPLC, Triton X-100] Changes to three chromatographic methods for the determination of APFO are described. Included are revisions of gas chromatographic methods for dry resin and air samples and a rapid method for determination of APPO and TritonX-100 in aqueous samples by liquid chromatography. (STEPHEN R. PECK) Company Sanitized. Does nol contain TSCA CBI TEFLON TECHNOLOGY REPORT , .. I. > <. f<?- SAFETY, HEALTH AND ENVIRONMENTAL B. ANALYTICAL DEVELOPMENTS FOR DETERMINATION OF AMMONIUM PERFLUOROOCTANOATE ^ i .. STEPHEN R. PECK, S. Hopkins, M. Jacobs, S. Mayle, M. A. Parsons, M. E. Reeder, D. Riggs Summary Changes to three chromatographic methods for the determination of APFO are described. Included are revisions of gas chromatographic methods for dry resin and air samples and a rapid method for determination of APFO and TritonX-100 in aqueous samples by liquid chromatography. This report describes recent analytical method developments intended to enhance me effectiveness of the determination of APFO content of various sample types. Changes to three procedures will be discussed separately. A reference to this report will be included in the method procedures to document the technical basis for the changes. Part I: Determination of APFO in dry resin by gas chromatography: This method is performed in thfBcontrol lab as WW-3690. In this procedure, the dry sample is treated with acidic mefnanoHo convert the APFO to its methvl ester. The ester is extracted into hexane and analyzed by GC-ECD. An internal standard is included, and the response of its ester is used to normalize the peak. for the methyl-PFO. : Originally, WW-3690 was used almost exclusively for PTFE fine powder resins J->ut the application of the procedure has been broadened to dry FEP and PFA fluffJ fluoroadditive, process filters, and other dry material. Company Sanitized. Does notcon(a?n TSCACBI WW-3690 requires ^significant amount of sample preparation and handling compared to other GC methods irfkLab. One complication was the use of a spinning riffler to yield a "representative" sample of resin. In order to obtain a single analytical result, 4 tests had to be performed: 1. Sample blank 2. APFO external calibration sample 3. Polymer "control" (standard) sample 4. Process sample The original method specified use of 1.000 .001 grams of C-8 solution - extremely difficult to achieve for a methanol solution. Nonadecafluorodecanoic acid (C-10) was used as an internal standard. A "blank" (containing C-10) was tested to account for residual APFO in the C-10 solution. Adjusting the APFO response for each sample to compensate for this impurity led to a complex series of calculations. The internal standard was originally used to account for differences in injection volume. With the acquisition of auto-injectors, variation in injection volume is small; however, an internal standard is still needed for this test. It is observed that the internal standard peaks are depressed in the presence of polymer. This is possibly due to interaction of the fluorinated (C-x) esters with the polymer surface, and a portion of the ester is not available for injection on the GC. The internal standard is used to adjust the sample response for incomplete recovery of the esters. The APFO peak is divided by the internal standard peak to yield a normalized response factor. The following components of the method were examined for possible simplification of the procedure as a way to improve cycle time and avoid introduction of error due to unnecessary steps: 1. Discontinuing use of spuming riffler. 2. Discontinue the "blank" sample. 3. Replace C-l 0 with less toxic perfluoroheptanoic acid (C-7). 4. Revise calculations to incorporate actual mass of APFO used as an external standard. 5. Replace the polymer control sample with statistical monitoring of the response of the APFO external calibration, solution. ofyUBwas To compare the impact of these changes, a sample procedure (Procedure 1) arid the revised procedure (Procedure 2). tested by the method Four replicates were tested. Results are in Table SKP-1: ; . Company Sanitized. Does not contain TSCA CBI Table SRP-1: APFO content (ppm) average Procedure 1 0.9 0.6 0.9 1.1 0.9 Procedure 2 1.9 1.1 1.5 1.1 1.4 Procedure 2 shows slightly higher results; however, this difference is considered acceptable for two reasons. First, the specification limit for residual APPO inJ----B^s 15 ppm. Second, all of these results approach the quoted sensitivity of 1 ppm for the method. Due to advantages of faster cycle time, less toxic internal standard, and streamlined calculations, the changes have been incorporated into WW-3690. To replace the polymer control sample, a response factor for the external calibration solution as follows: Factor = [(C8 peak/C7 peak)/mass used]. Part n: Determination of APFO in air samples: This procedure (WW-3627) has been used for several years for industrial hygiene monitoring of personnel exposure. A portable pump is used to draw a known volume of air through a specially-treated Tenax trap. The Tenax is then flushed into a vial, and the eluted APFO is determined by GC-ECD. Historically, C-10 has been used^s an internal standard, and the tubes were individually treated with a mixture of reagents iifBHMd One objective of this study was to evaluate eliminating the use of the internal standard. Since all samples are tested as clear solutions, there are no surface interactions to affect recovery of the C-8 ester (see above). Since an auto-injector is used, and a series of external standards are run with each series of air samples, use of an internal standard is redundant. A second objective of this test was to compare a batch of tubes that were commercially treated by SKC to those prepared in B-3. The treated Tenax tubes were "spiked" with weighed amounts of a standard APFO solution (1.0 microgram/mL). 'A series of external standards were used as outlined in WW-3627. The GC response of each tube was then used to calculate an observed APFO loading. This was divided by the calculated loading to calculate the recovery efficiency for each tube. Results are in Tables SRP-2 through 5. The average recovery for each set exceeds 100%. CompanySanitized. Does not contain TSCA CBI One factor is possibly fhe accuracy of the digital pipet used to deliver aliquots of standard APFO solutions for the calibration plots. Calibration plots prepared with C-10 internal standard (old procedure) and with no internal standard are shown in Figures SRP-1 and 2, respectively. Linearity is comparable and slightly better w/o C-10. Recoveries averaged 113% for the C-10 method vs. 111% with no internal standard. The results indicate that the internal standard is not needed. Comparable results were also noted between Tenax traps which had been prepared in B-3 vs. using traps that were pretreated by SKC. For the B-3 traps, average recovery was 113%. The SKC traps showed an average recovery of 110%. Based on these results, it is recommended that me use of the internal standard be discontinued and that the pre-treated Tenax traps may be used for WW-3627. Table SRP-2: APFO Recovery (%); C-10 Internal Standard tube tig added ug found %recoveiy 10-6 0.2469 0.2751 111 10-9 0.2021 0.2293 113 10-12 '0.1790 0.2034- 114 10-21 0.2829 0.3194 113 10-24 0.1863 0.2025 109 10-27 0.1563 0.1841 118 10-30 0.1209 0.1371 113 average % 113 recovery: Table SRP-3: APFO Recovery (%): No Internal Standard --tube- - -ug-added tig-found %recovery 0-4 0.3016 0.34010 113 0-7 - 0.3527 0.38485 109 0-10 0.4630 0.43338 94 0-13 0.1583 0.19637 124 0-15 0.1405 0.17720 126 0-19 0.2913 0.2979 102 0-22 0.2053 0.2063 100 0-25 0.1440 0.1601 111 : 0-28 0:0930 0.1075 116 average % 111 recovery: Company Sanitized. Does no! conlain TSCA CBI Figure SRP-1: Calibration Plot (C-10 Internal Standard) 30000 25000 . i 20000 . 0 a 15000 10 - 0 0 10000 y=23853x+795.59 R2= 0.9951 .-* *.-"'" ..-"' .* ...."'' " 5000 n w - .-**" .*-"' ...' . T-----------~-----------I------------~----------I------------------------I----------------------~T----------------------------------------------------1 0 02 0.4 0.6 0.8 1 1.2 ugAPFO Figure SRP-2: Calibration Plot (No Internal Standard) 35000 -, 30000 - 25000 - y (A 20000- a . (A S, 15000- u .y) ,10000- y=31399x+818.14 R2 = 0.9978 :; " ^" .-'' ..--""" .*" . " ." . .' ' . . ' . : .. : ^^ - 5000- .-'' .*-'' ."'" 0 . .. ' ' . .'' . c 3 0.2 0.4 0.6 0.8 uGAPFO 1 1 2 Company Sanitized. Does not contain TSCA CBI Table SRP-4: APFO Recovery (%); Tenax Prepared in B-3 tube 10-6 10-9 10-12 0-4 0-7 0-10 0-13 0-15 ug added 0.2469 0.2021 0.1790 0.3016 0.3527 0.4630 0.1583 0.1405 ug found 0.2751 0.2293 0.2034 0.34010 0.38485 0.43338 0.19637 0.17720 %recovery 111 113 114 113 109 94 124 126 average % 113 recovery: Table SRP-5: APFO Recovery (%); Tenax Prepared by SKC tube 10-21 10-24 10-27 10-30 0-19 0-22 0-25 0-28 ug added 0.2829 0.1863 0.1563 0.1209 0.2913 0.2053 0.1440 0.0930 ug found 0.3194 0.2025 0.1841 0.1371 0.2979 0.2063 0.1601 0.1075 %pecovery 113 109 118 113 102 100 111 116 average % 110 recovery: Company^aniKzed, Does not contain TSCA CBI Part in: Determination ofAPFO and Triton X-100 in aqueous media: In 2002, the determination of APFO in aqueous media at Washington significantly improved by the acquisition of an Agilent HPLC (Reference 1). requires mi'mmql sample preparation and a 10-minute analysis time. Works was The method We have begun receiving supemate and other aqueous samples for the simultaneous determination of APFO and Triton X-100. Both compounds give a UV response and can be analyzed by HPLC; however, the retention time for Triton is nearly 1 hour on our standard method (see Figure SRP-3). Altering the composition of me mobile phase led to a significantly shorter analysis time (see Figure SRP-4). A detailed comparison of the two HPLC methods is given in Table SRP-6. A 2 micron filter is used to remove polymer solids from the samples prior to injection. Figure SRP-3: Table SRP-6: HPLC Method Comparison Perchloric Acid (0.6%) 10 10 Mobile Phase Composition (% of flow) Acetonitrile Water run time (min) -Retention Time (minutes) APFO Triton 40 50 90 6 : 53 50 40 20 3 12 Company Sanitized. Does not contain TSCA CBf Figure SRP-4: Company Sanitized. Does not contain T5CA CBt1 E 'Product t 1 1 I | i t 1 i, f i ! JEi Product .,, FEP Dispersion Lot# ^ 1 1 i 1 1 ! 1 1 h '. 4 ' J - Meas APFO ppm Wet Basis 982 1013 1020 1145 5351 5649 5942 5341 6201 6227 1762 1335 1733 1733 PFA Dispersion Lottf Meas APPO ppm Wet Basis 2302 3462 3350 3442 3466 1925 PTFE Dispersion Lotff Meas APFO ppm Wet Basis 565 575 625 448 492 1052 1126 928 1268 922 536 565 626 480 504 545 540 522 486 445 533 638 568 finished product APFO results-xis finished dispersion Company Sanlllze'd. Does not contain TSCA CBI 11/30/04 r ^\ RMS 137 Resin C8 (ppm) 0.4 - 3.0 0.5 EC 1.0 : ' 1.4 t 0.9 1.3 1.3 p: 1.0 1.1 1.2 1.2 1.0 1.0 r 1.0 1.0 1.0 \ t 1.0 \ ( 1.1 \ f 1.4 i 1.0 ~ 1.0 i 2.0 ! 1.0 ! 2.0 5.0 ^ I I 1.0 \ 1.0 f RMS 137 Resin -- WC8 (ppm) | 0.7 0.1 ; l 1.3 ( 1.1 1.0 1.5 ~ 1 1.0 L ' 1.9 ' 1.1 r t 1.0 b ~ r 2.0 1.0 G ' 2.5 CI [ 1.5 CI~ b } 1.4 1.4 p ? 1.0 ~ 0.9 1p fp~ u 0,8 ? 1.2 ; 0.8 nG 1.2 i" 4.7 H 1.1 i 2.0 L[ "f 0.7 1.7 1.0 j If 1 L ' I ^fl - --- 0.5 1.6 I 0.5 J ' 1.5 1 i 0.5 finished product APFO results.xis fine powder Company Sanitized. Does not contain TSCA CB1 11/30/04