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HomeMy WebLinkAbout2019.03.01_CCO.p11_Table3PlusMethodConsentOrder Determination of Table 3 Plus Compounds by LC/MS/MS Chemours Fluoroproducts Analytical Method Revision date 1/10/2019 Instrument Setup (Note: Trapping column installed on Line A. Delay column installed between mixer and multisampler.) Instrument: Agilent 1290 Infinity II LC with 6470 Triple Quad MS Analytical Column: Agilent InfinityLab Poroshell 120 EC-C18 (2.1 x 50 mm, 2.7 µm); P/N: 699775-902 Guard Column: Agilent InfinityLab Poroshell 120 EC-C18 (2.1 x 5 mm, 2.7 µm); P/N: 821725-911 Trapping Column: Restek Ultra Aqueous C18 (4.6 x 50 mm, 5 µm); P/N: 9178555 Delay Column: Agilent Zorbax Eclipse Plus C18 (4.6 x 50 mm, 3.5 µm); P/N: 959943-902 Consumables (Note: Avoid using glass. All standards, samples, and stock solutions should be prepped and stored in HDPE or PP containers. Part numbers are provided below, but substitutions of similar products can be made.) LC vials: Microsolv, Cat. No. 9502S-PP-Clear LC caps: VWR, P/N: 82028-424 Scintillation vials: VWR, P/N: 66021-692 (used for sample and standard dilutions) HDPE bottles: Thermo Scientific, P/N: 2104-0004 (used for calibration stocks) Luer-Lock syringes: Microsolv, P/N: 58903-S-K 0.2 um GHP filters: Pall Acrodisc, P/N: 4554 (or substitute with same dimensions and filter material) Sample Preparation All standards and stocks are prepared with a 50:50 methanol:water diluent. A 10-point calibration curve is made from a 100 ppb mixed stock standard (containing the twenty-four Table 3 Plus analytes) at the following dilutions: 0.01 ppb, 0.05 ppb, 0.1 ppb, 0.25 ppb, 0.5 ppb, 1 ppb, 5 ppb, 10 ppb, 25 ppb, and 50 ppb. Prepped standards should be filtered in the same way as the samples. Note: The 100 ppb mixed stock standard is prepared in ultrapure water. The stock standard should be stored in a refrigerator when not in use. After allowing the stock to warm to room temperature, an aliquot is diluted 2x with methanol to produce a 50 ppb mixed standard in a 50:50 methanol:water matrix; this stock is then used for spiking and to prepare subsequent dilutions for the calibration curve. All samples are tested for pH when received to ensure that they are neutral (pH 6-8). If necessary, dilute solutions of KOH or H2SO4 are used to adjust pH accordingly. Samples are prepared in duplicate with duplicate spikes at different dilutions depending on the expected concentration of the analytes. Each sample prep starts with a 2x dilution in methanol to produce a 50:50 methanol:water matrix. Subsequent dilutions are made with a 50:50 methanol:water mix. A 2x dilution will be appropriate for most groundwater analyses (trace levels expected). If expected concentration is unknown, err on side of caution and use large dilution factor initially. If not detected, reprep with smaller dilution factor. Example preparations are listed below. 2x dilution and spike: 2.5 mL of sample is diluted with 2.5 mL of LC/MS grade methanol in a scintillation vial, then vortexed and filtered with a 0.2 um GHP syringe filter. To prepare spikes, 2.5 mL of sample is diluted with 2.4 mL of LC/MS grade methanol and 100 µL of 100 ppb spike solution in a scintillation vial, then vortexed and filtered with a 0.2 um GHP filter. Final expected concentration of spike in vial is 2.0 ppb. 100x dilution and spike: 2.5 mL of sample is diluted with 2.5 mL of LC/MS grade methanol in a scintillation vial, then vortexed to make a 2x prep. 100 µL of the 2x prep is diluted to 5.0 mL using 50:50 methanol:water, then vortexed and filtered with a 0.2 um GHP syringe filter. To prepare spikes, 100 µL of the 2x prep is diluted with 4.8 mL of 50:50 methanol:water and 100 µL of 100 ppb spike solution in a scintillation vial, then vortexed and filtered with a 0.2 um GHP filter. Final expected concentration of spike in vial is 2.0 ppb. QC sample: A 5 ppb QC sample is prepared from a stock standard solution separate from the one used for calibration following the same dilution and filtering protocol as for samples. Analytical Method LC Operating Conditions: Mobile phase A: 2 mM Ammonium Acetate in 5:95 Acetonitrile:Water Mobile phase B: Acetonitrile Needle/seat wash: 50:50 Acetonitrile:Water, Multi-wash option using 2 cycles of seat back flush and needle wash (10 seconds each) Seal wash: 10:90 Isopropanol:Water Injection volume: 5.00 µL Flow rate: 0.500 mL/min Maximum pressure: 600.00 bar Solvent gradient: End time: 9.50 mins Column temp: 50.0°C MS Operating Conditions: Ion mode: ESI negative Scan type: MRM Gas temp: 150°C Gas flow: 8 L/min Nebulizer: 45 psi Sheath gas heater: 200°C Sheath gas flow: 8 L/min Capillary: 3500 V Nozzle voltage: 0 V Time A B Initial 0.00 min 85% 15% 1 1.00 min 85% 15% 2 5.00 min 10% 90% 3 6.40 min 10% 90% 4 6.50 min 85% 15% QQQ Acquisition Parameters: Compound Name MRM Transition RT (mins) Dwell (msec) Frag (V) CE (V) Cell Accelerator (V) DFSA 175.0 -> 131.0 0.268 50 72 12 2 MMF 139.0 -> 95.0 0.271 50 93 8 1 MTP 175.0 -> 97.0 0.370 50 78 12 1 PPF acid 163.0 -> 118.9 0.394 50 58 8 5 PFMOAA 179.0 -> 84.9 0.437 50 54 12 1 R-EVE 405.0 -> 217.0 0.420 50 100 16 4 Byproduct 4 440.9 -> 241.0 0.509 50 114 28 1 Byproduct 5 439.0 -> 343.0 0.510 50 126 30 1 PMPA 229.0 -> 184.9 0.662 50 55 4 5 PFO2HxA 245.0 -> 85.0 1.046 50 60 8 1 NVHOS 297.0 -> 135.0 1.655 50 123 28 1 PEPA 279.0 -> 234.9 1.702 50 58 4 4 PFECA B 295.0 -> 201.0 3.027 50 55 8 3 PFO3OA 310.9 -> 85.0 3.298 50 54 12 3 PES 314.9 -> 135.0 3.388 50 109 20 5 HFPO-DA 329.0 -> 284.9 3.386 50 75 0 4 HFPO-DA_qualifier 329.0 -> 169.0 3.386 50 75 12 1 PFECA_G 378.9 -> 184.9 3.702 50 87 16 4 PFO4DA 376.9 -> 85.0 3.794 50 66 20 3 Hydro-EVE Acid 427.0 -> 282.9 3.825 50 90 12 3 EVE Acid 407.0 -> 262.9 3.825 50 78 8 2 Byproduct 6 397.0 -> 217.0 3.951 50 122 27 1 Byproduct 2 463.0 -> 262.9 4.072 50 160 32 1 Byproduct 1 443.0 -> 146.9 4.084 50 143 30 1 PFO5DoA 442.9 -> 85.0 4.085 50 66 8 1 Data Processing Calibration: The full set of 10 calibration standards should be run at the beginning and end of a sequence of samples. All 20 standard injections are used in constructing the calibration curve for quantitation of unknowns. Continuing calibration checks should be performed after every 10 sample injections in the sequence using a mid-level standard; these are not included as points in the calibration curve. The curve should be linear, not forced through the origin, and weighted 1/x. The acceptable accuracy range is 70%-130%. Blanks: Three blanks should be run at the beginning of each sequence—a methanol blank taken from the vessel used to perform 2x dilutions of aqueous stock standard and samples; a 50:50 methanol:water blank from the vessel used to perform subsequent dilutions; and an environmental blank consisting of ultrapure water taken from the same type of container used for sampling. Target analyte concentrations in all blanks must be less than one-half of the method LOQ. Method and/or solvent blanks are also used to monitor for carryover between samples, particularly those with analyte levels detected at high concentrations. A typical sequence consists of duplicate preps followed by their respective spikes, then a 50:50 methanol:water blank, and repeating with subsequent sample prep/spike segments. Blanks in between sample segments should be analyzed to quickly identify carryover contamination and are subject to the same concentration criteria as described in the paragraph above. Duplicates: Duplicate preps of the same sample must have a %RPD of ≤25% at mid- and high- range concentrations and ≤50% at the minimum reporting limit (see equation below). %RPD = (sample result - duplicate result) * 100 (sample result + duplicate result)/2 Results outside this range require a duplicate reprep. Both results should be reported, along with the average. Spikes: Acceptable spike recovery is in the range of 70%-130%. Spike recovery outside this range does not necessitate reprep, but results should be flagged for further investigation due to possible matrix effects. QC Sample: A QC sample of known concentration should be prepped from a standard stock solution separate from the one used for the calibration. Results must be within 70%-130% of the true value. Appendix A: Compound Details Compound Name Molecular Formula Structure CASRN DFSA C2H2F2O5S 422-67-3 MMF C3H2F2O4 1514-85-8 MTP C4H4F4O3 93449-21-9 PPF Acid C3HF5O2 422-64-0 PFMOAA C3HF5O3 674-13-5 R-EVE C8H2F12O5 N/A Byproduct 4 C7H2F12O6S N/A Byproduct 5 C7H3F11O7S N/A PMPA C4HF7O3 13140-29-9 PFO2HxA C4HF7O4 39492-88-1 NVHOS C4H2F8O4S 1132933-86-8 PEPA C5HF9O3 267239-61-2 PFECA B C5HF9O4 151772-58-6 PFO3OA C5HF9O5 39492-89-2 PES C4HF9O4S 113507-82-7 HFPO-DA C6HF11O3 13252-13-6 PFECA G C7HF13O3 801212-59-9 PFO4DA C6HF11O6 39492-90-5 Hydro-EVE Acid C8H2F14O4 773804-62-9 EVE Acid C8HF13O4 69087-46-3 Byproduct 6 C6H2F12O4S N/A Byproduct 1 C7HF13O5S 29311-67-9 Byproduct 2 C7H2F14O5S 749836-20-2 PFO5DoA C7HF13O7 39492-91-6 Appendix B: Recommendations for Instrument Maintenance Before starting a sequence, run an isopropanol blank and 3 method blanks (50:50 methanol:water) to flush the system and establish a “clean” baseline. At the end of a sequence, run a “steam clean” line and end with an “idle” line (see screenshot below). Both of these methods should be set up to utilize lines A2 and B2, which are 95:5 water:methanol and 100% methanol, respectively. This will help to flush out any salts or other buildup that has accumulated in the system. It is recommended to run the idle method while the system is not actively being used. After the idle method has completed and while the source temperatures are still low, open the spray chamber and wipe down all surfaces – especially the spray shield and surrounding area – with a 50:50 mixture of isopropanol and ultrapure water on a Kimwipe. This should be done daily to prevent buildup. A 50:50 acetonitrile:water mixture works well as a needle/seat rinse to minimize carryover. A solution of 90:10 water:isopropanol should be used as the seal wash solvent, which should be primed if bubbles are observed in the clear tubing between pump heads. Solvent reservoirs should be periodically rinsed with isopropanol before rinsing and refilling with the intended solvent. If possible, store solvents in amber bottles to inhibit microbial growth, and prepare fresh solvents if not used within 1-2 weeks.