Characterization of Perfluorooctane Sulfonate by Gas Chromatography/ Mass Spectrometry

Joumal of Donghua Uhiversity(Eng Ed )Vo. 27, No 6(2010)819Characterization of Perfluorooctane Sulfonate by Gas Chromatography/Mass SpectrometryMENG Li-juan(孟厕娟)2, YANG Yong(杨勇)2, LIN Miao(林苗)aborutory of Science Techmology of Eco-Tertile, Ministry of Education, Donghua University, Shanghai 201620,ection Center of Induatrial Product& Raw Materials, Shanghai Entry-Exit Inpection Quarantine Bureaw, Shanghai 200135,Abstract: With quantitative conversion toperfluorooctanoate(PFOA), perfhuorohexane sulfonate(PFHS), and FOSA are detected only occasionally and at(PFOS)that is difficult to analyze can be separated by lower concentrations.conventional techniques and then be characterized. In thisPFOS is an eight-sulfonate group at one end(CF;(CF2 ) SO, H), PFOS andsulfonic acids were converted to corresponding sulfoneits derivatives(C Fir SO X, x metal salt (O Mby reaction with triethylorthoacetate(TEOA) in the presence halide, amide, and other derivatives including polymersof solvent were described, and then PFOS was analyzed as see Fig. 1)have been widely used as a coating material onethyl ester derivatives. Mass spectra(Ms)werepaper, photographs, packaging, and textile products asusing electron ionization(EI)mode. And the EI spectra of they repel both water and oir a. The surface activity ofthe volatile derivatives show ions characteristic of both the these compounds and their stability even at highfluorinated hydrocarbon and the sulfonic ester portion of the temperature also allow them to be used in fire-fightingmoleculesfoam, hydraulic fluids, and metal plating solKey words: perfluorooctane sulfonate (PFOS), GC/EI- addition, PFOS and its derivatives play an important role inMS: characterization derivationthe semiconductor industry because of their unique opticalaLC nember: TS107Document code:A characteristics and acid-generating efficiency. ThArtice II1672-5220(2010)06-0819-06semiconductor industry in the European Union(EU) aloneestimated 470 kg annually!IntroductionThe unique chemical/physical properties of fluorinemake fluorinated organic compounds uscful for manyX=OH, metal salt(O"M),halide, amidecommercial applications, and industrial production of theseand other derivatives including polymersgnificantly since the carFig. 1 Molecular structures of perfluorooctane sulfonate1980s. Fluorinated organics are used as refrigerants, sur-These widespread observations quickly led tofactants, and polymers and as components of voluntary manufacturing phase-out by the main producer ofpharmaceuticals, fire retardants, lubricants, andPFOS, I53 and garnered the attention of national andinsecticides[l nhe strong carbon-fluorine international environmental protection agencies. As a(C-F) bond associated with fluorinated alkyl substances result, PFOS and related substances have been on theFASs), fluorinated organics are environmentally agenda of the Organization for Economic Co-operation andistent substances that have been detected worldwide in Development(OECD)since the year 20003. And the EUan blood, water, soils, sediments, air, and biota has proposed legislation tothe use of PFoS ansamples. So the pervasive contamination of wildlife m) and Member States have applied these measures from 27 Junethe general human population o, m with perfluorinated 2008 7. Despite its manufacturing phase-out ) such aacids and heptadecafluorooctane sulfonamide(POSA) have source may serve as a continuing source of PFOS to thebeen described in many recent publicationsenvironment, therefore highlighting the importance ofPerfluorooctane sulfonate PFOS) is中国煤化 Tuse of its exceptionalReceived date: 2009-09-28CNMHGFoundation item Shanghai Municipal Bureau of Quality and Technical Supervision, china (No. o91B10n)Correspondence should be addrcwad to LIN Mimo, professor, E-mail: linmiaogdhu educn820Joumal of Donghua Uhiversity(Eng. Ed. )Vol 27, No 6(2010)selectivity, has been used for the analysis of a wide range in this experiment were also precleaned in the same wayof volatile materials containing close-boiling homologs and 1. 2 Instrumentationisomers. However, the polarity and nonvolatility ofStandards were analyzed by gC-EI-MS using ansulfonate moiety requires derivatization prior to Gc Agilcnt 5973N mass spectrometer coupled to a 6890 GCanalysis. So attempts to develop instrumental methods fo(Palo Alto, CA, USA). The gC was fitted with a Dbanalysis of perfluorooctane sulfonic substances are hindered 5ms(30 m X 0. 25 mm I. D.,0. 250 Fm film thicknessby their polarity and nonvolatility. As a result, the Agilent)column. Samples were injected(1.0 FL) by anhnique most widely used to analyze these compounds has Agilent 7683 Automatic Liquid Sampler using splitlessbeen liquid chromatography ( LC) coupled to mass injection, and the temperature program for the DB-5spectrometry(MS)or tandem mass spectrometry(Mscolumn had an initial temperature of 45 t for 2 minMS)ofs℃· min"to90℃ and held at9℃Now, nonvolatile or low volatility compounds have for 2 min, 15C min"to 190 C and held at 190 C for 2also been analyzed, following conversion to more volatilemin, and subscqucntly 25C. min"to 280 C, followed byderivatives). For example, gas chromatography-mass a 5-min hold, and mass spectrometer source temperaturespectrometry(GC-MS), with prior derivatization, has 240 C. Splitless injection was used for all analyses. Typicalbecn used to measure fluorinated carboxylatesoperating conditions for electron impact ionization werethe attractive aspects is the possibility to identify sulfonates with 70 eV ionizing energy and a filament emission currentby Ms detection. Therefore, several new methods are of 300 HA. The injector port temperature program trackedherein proposed for analyzing complex mixtures of the GC oven temperature program plus 3 C. Heliumnonvolatile perfluorooctane sulfonic acids and salts by Gc (99. 999%; constant flow 1 mL. min)was used as theof volatile derivatives. The suggested techniques are faster, carrier. The mass spectrometer was calibrated and tuned tomore convenient, and more precise than liquid and paper optimize each mode of operation accordingtography approaches, and have the advantages of manufacturer's recommendations. Mass ranges andselectivity and accuracy over infrared spectrophotometric for product ion analyses were selected as needd. Spectrawere recorded every secondMore recently.gas chromatography1.3 Treatment of samplesionization-mass spectromctry(GC-El-MS) has been usedTextile samples were collected from one treadingfor the analysis of some fluorinated neutral compounds, company. Firstly, the typical fabric samples wereand its application in ambient atmospheric monitoring has selected for analysis, and then we cut them into smallalso becn describedinpieces, mixed well, and weighed 1. 000 0 g(accurate toThe objective ofstudto develop a 0.00001 gmprehensive and sensitive GC-EI-MS analyticalSamples were extracted with the solvent CH,method for characterizing PFOS(CF:(CF, )1 sO, Ho=l 1( volume ratio), pHs by the ultrasonic-Following quantitative conversion to volatile derivatives microwave-assisted-extractor. The volume of the extractingwith triethylorthoacctatc(TEOA), PFOS is analyzed as solvent used in all assays was 100 mL, Extract liquid wasethyl ester derivative by GC/MSevaporated on a rotary evaporator until dry. And 2.0 mLof solution comprised of 1: 1 corresponding solvent and1 Experimentalpure water was added into the bottle to dissolve the mattersof interest and water phasremoved. After1. 1 Chemicals and standardspurification, the extracts were derivatizedPerfluorooctane sulfonic acid (98%)was purchased 1. 4 Analysis of perfluorooctane sulfonic acid asfrom Accu Standard, Inc. (USA). Triethyl orthoacetateethyl ester derivatives(97%)was obtained from Accu Standard, Inc. (USA. l,Methylation of various sulfonates and disulfonates was2-Dichoroethane and methanol(AR)was purchased from reported by Heywood et al. ta for the Ms analysis ofSinoparm Chemical Reagent Co, Ltd.compounds with direct inlet. They employed diazomethaneThe solution (1 000 mg/L)of perfluorooctaror tetramethylammonium cation as methylating agentssulfonic acid was prepared in 1, 2-dichoroethane, in And diazomethane was also reported to be a convenientpolypropylene (PP)volumetric tubes, and then diluted reagent for the esterification in other reports, but thatwith 1, 2-dichoroethane to prepare the standards needed.中国煤化工earTo minimize possible contaron, the standardswere stored in 1-L PP bottles, precleaned by thoroughCNMH Remains ambigousing with l, 2-dichoroethane and all ents needed Timcthylsilylesters of sulfonates were not etected by flameJoumal of Donghua Uhiversity(Eng. Ed. )Vol 27, No 6(2010) 821ionization detector( FID)[a. However, the reaction with we found that 17. 25 min-peak only corresponded toTBDMsa(tert-butyldimethylsilyd chloride) is reported to be one compound by the"Peak Purity"functional key.suitable for sulfonate, hydroxyl, and amino groups, and Therefore we hypothesized that 17. 25 min-peak mayresult in stable and FiD- detectable products idMost of the above-mentioned methods were developedTo further verify the identity of the detected analytefor LAS (lincar alkyl benzene sulfonates) analysis and were the quantity of PFos was doubled and other substance 'sapplicable to other monosulfonated aromates". 5. M)quantity were not changed, followed by derivation andPerfluorooctanesulfonic acids are converted to analysis as described above. Additionally, when 1,2corresponding ethyl ester by reaction with triethylorthacetato dichloroethane substituted methanol as the solvent in this(TEOA) in the presence of 1, 2-dichloroctane as solvent"experiment, the 17. 25-min peak moved to 17. 73 min.The reaction with triethylorthacetate is as follows:Figure 3 shows that the abundance of 17. 73-min peak2CHI, SOH+ CH, C(CHs O)-increases while other peaks hardly change the2CH7 SO C Hs CH, COCH,concentration of 2 was twice as more as 1). That's to say,he solution of perfluorooctane sulfonic acids in 1, 2- these analysis also suggested that the 17.73dichoroethane was mixed with some volume of triethylbe the derivatized PFOSorthoacetate. The mixture was heated in water bath at 2, 2 Identification of target analyte60c for 90 min and then allowed to cool. In order to achieveMass spectrum analysis, which can give full productcomplete esterification of PFOS, large excess of TEOA was ions spectra, was used for verification of analyte identityThats to say, derivatized PFOS has a characteristic MSfragmentation pattern which can be used to identify the2 Results and DiscussionPFOS in complex environmental matrices2. 1 Characterization of the retention timeelectron impact(ED)ionization. During 70 cV ionizationBlank solution (a parallel experiment for which derivatized PFOS was unstable and readily fragmented byPFOS was not added)and the standards were prepared rupture of the C- bond, so that their molecular ionat the same time with the same volume. then, gc(M', m/z 528)was not detected. When the chargeMS, with prior derivatization, was used to analyze remained with P-C portion of these molecules, two seriesthem as above. Standard injcctions were initiallyof ions commonly observed in the EI spectra of derivatizedacquired in full-scan mode to determine the retentionperfluorooctane sulfonic acids were present. And thetime and fragmentation pattern of each analyte. Thenfragmentation pathway was thought to involve a cyclicthey were acquired in selected ion monitoring SIM) intermediate ion(,, m/z 50). One series started atmode in EI mode. A GC-MS chromatogram is m/z 69 [CF,]"and the other at m/z 131 [CF,]",andpresented in Fig. 2. It was observed that they had good each increased by 50, i. e, m/z69,119,169,219,andresolution and peak shape. Figure 2 also shows that them/z 131, 181, 231, and 281, respectively. The proposedtwo chromatograms are almost the same, exceptEI and product ion fragmentation pathways are shown inretention time of 17. 25 min. It is indicated that nonecheme 1. Figure 4 shows that the ion at m/z 69 is theof the target analytes were detected in blanks solution, most intense ion in the spectrum. In other words, the ionwhile for the standards, the monitoring reveals a major at m/z 69 [CR J is the base ion of derivatizedpeak at a retention time of 17. 25 min. Furthermore,perfluorooctane sulfonic acids1725200163016401650l6.6016.7016.8016.90中国煤化工156RetentionCNMHGFig 2 GC-Ms chromatogram of mixture of PFOS as ethyl ester (mg/L), methanol as822Joumal of Donghua Uhiversity(Eng. Ed. Vol. 27, No 6(20107737000665543500322000550160016.5017.00175018.001850190019.50Time/minFig3 GC-MS chromatogram of mixture of PFOS as ethyl ester(mg.L-) 1, 2-dichloroethane as the solvent554150000100000297333300Fig 4 Mass spectrum of 17 73-minute pesI, however, the charge remained on the ethyl and interference from impurity in the solvent, becausesulphonate portion of the molecul after the C-S rupture, some large intensity fragment ions were assigned due toon thought to be [So, CH,]' at m/z 109 was formed. the loss of the capillary column. Therefore,someAnd additional losses from m/z 109 were not observed in ions in Fig. 4, which don' t result from the cleavagePig. 4, perhaps because m/z 109 was already a very small of the target analyte, are thought to be ions of thattypeThe third largest ion in the El spectrum was m/z 449Through analyzing mas spectrum, we finallyProduct ion analysis of m/z 528(M, molecular ion) confirmed that 17 73-minute peak was derivatized PFOSshowed a loss of 29 Da(-CHs) to m/z 499, and thenadditional loss of 50 Da[CHs] to m/z4493 ConclusionsMichael Rearrangement generates the ion at m/z 501(see Scheme 2). Sometimes, it wasn't present in the meWe have herein presented an indirect method forspectrum, perhaps because the intense of the ion at m/z中国煤化工 hod allows for501 was too smallDuring the characterization of GC-MS, special samCNMHobtain not onlyattention was paid to the loss of the capillary column exceptional selectivity, but abo molecular weight informationJoumal of Donghua Uhiversity(Eng. Ed. Vol 27, No 6(2010) 823-O-C,HF,C一S-0—cH-C Hm/z=528m/z=69m/z=1691/z=219m/z=26z=499m/z=130m/z=461m/z=449-CFC,FISO,"C, F.SO,C, FSOm/z=380m/z·3m/z=18Michal RearrangementFI C,-S--OH+H C=CH,m/z=528Scheme 2along with some diagnostic ions produced. Product ions[4] Kannan K, Corsolini S, Falandys J, et al419 are used to confirmPerfluorooctanesulfonate and Related Fluorinatedpresence of PFOS after analyzing. To avoid interferenceHydrocarbons in Marine Mammals, Fishes, and Birds fromand ensure complete selectivity, wemend thatCoasts of the Baltic and the Mediterranean Seas [J].derivatized PFos ion to be monitoredEnvironmental Scienoe& Technology, 2002, 36(15): 32103216reaction monitoring for quantitative determination ofPROS. This method has been proven of its utility in the [5] Kannan K. Franson J C, Bowerman ww, et al.Perfluorooctane Sulfonate in Fish-Eating Water Birdsacterion and quantization of PPOS, and furthercluding Bald Eagles and Albatrosses[J]. Envirormentaldevelopment of this method would allow the analysis ofScience& Technology, 2001, 35(15): 3065-3070.perfluorooctane sulfonic acids from difficult matrices[6] Kannan K, Hansen K J, Wade T L, et aL. PerfluorooctaneSulfonate in Oysters, Crassostrea Virginica, from the GulfReferencesEnvironmental Contamination Toxicology, 2002, 42(3)[1] Key B D, Howell R D, Criddle CS. Fluorinated Organicsin the Biosphere [J]. Environmental Science& Technology, [7 J Kannan K, Koistinen J, Beckman K, ef al. Accumulation1997,31(9):2445-2454of Perfluorooctane Sulfonate in Marine Mammals [J][2] Guy W s, Taves D R, Brey w S, ef al. OrganicEnvirormental Science& Tachnology, 2001, 35(8): 1593Fluorocompounds in Human Pasma: Prevalence andCharacterization [M]//Filler B. Biochemistry Involving [8]KannanNewsted J, Halbrook R S, ef alCarbon-Fluorine Bonds. Washington Acs SympoRelated Fluorina1976;117-134中国煤化工ters from the united[ 3] Kannan K, Choi J W, Iseki N, et al. Concentrations ofCNMHGechnolos, 20Perfluorinated Acids in Livers of Birds from JapanKorea []. Chemosphere, 2002, 49(3): 225-231.[9] Giesy J P, Kannan K. Global Distribution of824Joumal of Donghua uhiversity(Eng. Ed. )Val 27, No 6(2010)Perfluorooctane Sulfonate in Wildlife []. EMirorumental [19] Hori H, Hayakawa E. Yamashita N, e al. HighScience& Technology, 2001, 35(7):1339-1Performance Liquid Chromatography with Conduct Metric[10] Hansen K J, Clemen L A, Ellefson M E, et al. CompoundDetection o Perfluorocarboxylic Acids andSpecific, Quantitative Characterization of OrganicPerfhuorosulonates [. Chemosphere, 2004, 57(4): 273Fluorochemical in Biological Matrices []. EvironmentalScience& Technology, 2001, 35(4)1766-770[20] Moody c A, Field J A. Determination of[11] Tavess DR, Evidence that There are Two Forms of fluoridePerfluorocarboxylates in Groundwater Impacted by Firein Human Serum LJ]. Nature, 1968, 217(5133): 1050Fighting Activity[J]. Enviromental Science Technology51.1999,3(16);2800-2806[12] Kissa E. Fluorinated Surfactants, Synthesis, Properties, [21] MartinJW, Muir DCG, Moody CA, et al. Collection ofand Applications[M]. New York: Mareel Dekker, 1994[13] Brooke D, Footitt A, Nwaogu T A. Environmental RiskChromatography/Chemical lonization Mass Spectrometryvaluation Report, Perfluorooctane Sulfonate ( PFOSJ]. Analytical Chemistry, 2002, 74(3)1 5841-590.[R]. Watford, Building Research Establishment Ltd, [22] Heywood A, Mathias A, williams A E. Identification ofby Mass Spectrometry [J].Agencys Science Group, 2004Analytical Chemistry,1970,4(11);1272-1273[14] U.S. CEPA. Perfluoroocty! Sulfonates: Proposed [23] Stokke O, Helland P. Analysis of Sulfonic Acids by GasSignificant New Use Rule, Federal Register [R].Kansas,U.S. Environmental Protection Agency, 2000, 65: 62319Derivatives [J]. Journal of Chromatograply. 1978, 1462333,[15] U.SCEPA. Perfhuorooctyl Sulfonates: Proposed [24] Lay K N, Hupe M. Gas Chromatographic Method for theSignificant New Use Rule, Federal Register [R].Kansas,assay of Aliphatic and Aromatic Sulfonates as Their TerI-U.S. Environmental Protection Agency, 2002, 67:11014butyldimethylxilyl Derivatives [J J. Journal of[16] Diderich B. Co-operation on Existing ChemicalHazard [25] Trehy M L, Gledhill W E, Orth R G. DelAsseasment of Perfluorooctane Sulfonate and Its Salts [R]Linear Alkylbenzenesulfonates and DialkyttctralinsulfonatesParis, Environment Directorate Joint Meeting of thein Water and Sediment by Gas Chromatography /MassChemicals Committee and OECD, 200Spectrometry []. Analytical Chemistry, 1990, 62(23)1[17] Footitt A, Nwaogu T A, crooke D, Perfluorooctane81-2586Risk Reduction Strategy and Analysis of [26] Kirkland JJ. Analysis of Sulfonic Acids and Salts by GasAdvantages and Drawbacks [R]. Norfolk, Risk and PolicyChromatography of Volatile Derivatives [J]. AnalyticalChemistry,1960,32(1);1388-1393.[18] Schultz MM. Barofsky D F, Field J A. Fluorinated Alkyl [27] Trujillo J 1, Gopalan A S. Facile Esterification o SulfonicSurfactants [n. Environmental EngineeringAcids and Carboxylic Acids with Triethylorthoacetate [J].20(5):487-501Tetrahedron Letter,1993,46(34):7355-7358.中国煤化工CNMHG