Document Eq5oEdrb8Rv28mRY4K17Xq98x

Determination of PFOA in the aqueous polymeric dispersion Sample Aqueous polymeric dispersion: ASAHIGUARD AG-955 1. Test and control substances The test substance, perfluorooctanoic acid (PFOA, 98.9 %, lot. C17001401), and the surrogate standard, 9-hydrohexadecafluorononanoic acid (9H-PFNA, 97.8%, lot. C58002501), were purchased from Daikin Fine Chemical (Osaka, Japan). Distilled water was produced in-house and checked for contaminants by LC/MS before use. Distilled water was filtered through a pre-column, Preclean-ORG (GL Sciences Inc. (Tokyo, Japan)) placed between HPLC pump and auto-sampler. HPLC grade methanol (MeOH), reagent grade ethanol (EtOH) and isopropanol (IPA), and reagent grade ammonium acetate were purchased from Kanto Chemical Co., Inc. In order to avoid contamination, disposable lab ware (tubes, pipettes, etc) was used. 2 mmol/L ammonium acetate solution was prepared by weighing 154 mg of ammonium acetate and dissolving in 1 L of distilled water. 2. Preparation of fortification standards 50 g/ml and 100 g/ml PFOA solution was prepared using a solvent (2 / 8 (wt) mixture of distilled water / ethanol). 10 mg/ml 8-2 alcohol solution was prepared using isopropanol (IPA) for solvent for the use of latter section (2-3). 3. Preparation of a surrogate standard 100 ng/ml 9H-PFNA solution was prepared using a solvent (1 / 1 (wt) mixture of distilled water / ethanol). 4. Preparation of calibration standards 0, 0.1, 0.2, 0.4 ml of the 100 g/ml PFOA solution was diluted by IPA up to 5 ml. 100 l of the each solution and 9ml of 100 ng/ml 9H-PFNA solution was mixed in a vial. About 1 ml of each solution was filtered through a 0.2 m filter, Millex-LG (MILLIPORE, U.S.A), into an auto-sampler vial and injected twice into LC/MS conditioned as follows. 5. Extraction of PFOA from the aqueous polymeric dispersion Before the sampling of the aqueous polymeric dispersion they were shaken well without generating bubbles to homogenize the aqueous polymeric dispersion. 1 ml of the aqueous polymeric dispersion was put in each of four centrifugation vials. Fortification of PFOA and 8-2 alcohol were conducted as listed in Table 1. Fortification of 8-2 alcohol was conducted for the use of latter section (2-3). IPA was added into all vials until total amount with fortification solution was 5 ml. After putting a lid, each of five vials (with the blank) was shaken vigorously and the precipitation was separated by centrifugation at 6000 rpm for 10 minutes. 100 l of the each supernatant and 9ml of 100 ng/ml 9H-PFNA solution was mixed in a vial. About 1 ml of each solution was filtered through the 0.2 m filter into an auto-sampler vial and injected into LC/MS conditioned as follows. These procedures were repeated once again for the verification of the reproducibility. Table 1 Fortification of C8 precursors and PFOA Sample Fortification 10 mg/ml 8-2 alcohol PFOA A 0 l 0 l B 50 l 100 l X 50 g/ml C 100 l 100 l X 100 g/ml D 200 l 200 l X 100 g/ml 6. LC/MS analysis LC/MS analysis was conducted with the conditions listed below. <Instruments> (1) LC/MS HPLC Mass spectrometer (2) LC column (3) PC (4) Software (5) LC/MS vial Tomsic Agilent Technologies, Model 1100 Agilent Technologies, Model 1100MSD (SL) Imtakt (Tokyo, Japan), cadenza CD-C18 2 mm (diameter) X 100 mm Hewlett Packard Kayak PC Workstation OS: MS-Windows NT 4.0 LC/MSD ChemStation, Rev. A. 08. 03 2ml vial for auto-sampler, Chromatography-Convenience 400-C80, (Tokyo, Japan) <Analytical conditions> (1) Column temp. (2) Mobile phase (3) Gradient condition 35 C A: 2 mmol/L ammonium acetate B: Methanol time/min 0 2 5 15 15.01 25 (4) Flow rate (5) Injection volume (6) Retention time B/ 57 57 100 100 57 57 0.3 mL/min 5 L PFOA (4.3 min), 9H-PFNA (2.5 min) <MS operating parameters> (1) Ionization mode Electrospray (ESI) (negative ion mode) (2) Fragmentor voltage 100 V (3) Ion monitored m/z = 413 (C7F15COO-), 445 (CF2H(CF2)7COO-) (4) Desolvation temperature 350 C (5) Nebulizer gas N2 (6) Desolvation N2 12 L/min 7. Results Two calibration curves for standard addition method are plotted and shown in Fig. 1 for the ratio of (peak area of m/z = 413) / (peak area of m/z = 445) as a vertical axis against the amount of PFOA fortification (g) as a horizontal axis. The coefficients of correlation are more than 0.9990 for both curves, and the amounts of PFOA determined in the aqueous polymeric dispersion are 7.2 ppm and 7.0 ppm (average 7.1 ppm). 7.1 ppm is equivalent to 1.7 x 10-5 mol/kg (specific gravity of AG955 is 1.090). Two calibration curves for PFOA calibration standards are shown in Fig. 2 for the same axis with Fig. 1. PFOA is not detected (zero count) for 0 g standard (blank). The coefficients of correlation are more than 0.9995, and the recovery defined as (the slope for the standard addition) / (the slope for the calibration standards) was 95%. 0.4 0.3 0.2 0.1 0 0 y = 0.0132 x + 0.1038 R2 = 0.9990 y = 0.0135x + 0.1019 R2 = 0.9993 5 10 15 20 PFOA fortification (g) 0.6 0.5 0.4 0.3 0.2 0.1 0 0 y = 0.0139x + 0.0019 R2 = 0.9995 y = 0.0141x - 0.0044 R2 = 0.9996 10 20 30 40 50 PFOA amount in 5 ml standard (g) Fig. 1 Calibration curves for AG-955 Fig. 2 Calibration curves for PFOA count (m/z = 413) / (m/z = 445) count (m/z = 413) / (m/z = 445) by standard addition method calibration standards