easurement of trace hydrofluorocarbons, perfluoroent air. Details are provided for the hardware reed with a high performance gas chromatograph and

Transcription

1 ABSTRACT This paper reports on a method for the m carbons and chlorofluorocarbon in ambi quirements and performance accomplish mass spectrometer. To achieve measure required. However, ambient levels of w tions are presented on how to eliminate special operations are needed to fully re fluoromethane (Freon 14). Included in th

2 easurement of trace hydrofluorocarbons, perfluoroent air. Details are provided for the hardware reed with a high performance gas chromatograph and able concentration levels, a cryotrapping system is ater can interfere with the trapping process. Opmoisture during the measurement sequence. And coverable the very volatile species, especially tetrae discussion are chromatographic conditions, sam-

3 Measurement o

4 f Hydrofluorocarbons, by Gas Chrom

5 Perfluorocarbons and C atography and Mass Sp

6 hlorofluorocarbons in ectrometry

7 Ambient Air

8 Computed Detection Lim Area Counts t s 3.0 2

9 it for CF4,793

10 pling processes, especially for real time vided for linearity and detection limit stu

11 sampling, and data calculations. Results are prodies into the low pmol/mol (pptv) levels. E

12 xperimental Setup

13 by Edward Bramston-C Lotu Long B Comp

14 ook and Randy Bramsto s Consulting each, CA osite Chromatogram of variety of hydrofluorocarbo illustrating elution order; confirmed

15 -Cook ns, perfluorocarbons and chlorofluorocarbons, by NIST library searches

16

17 46,941 LOD m 4,746 52,196 44,381 52,131 49,466 48,329 49,742 where: m = ave t = t-fac s = stan

18 , nmol / mol rage tor for 99% confidence dard deviation

19 Efforts to Red

20 uce Greenhouse Gases

21 Alterations to TO-15 Primary trap - multi-bed hydrophobic absorbent materials Initial temperature: -48 o C during trapping Ramp to 202 o C for desorption Cryofocus trap - empty tubing Initial temperature: -195 o C during trapping Ramp to 202 o C for injection Nafion dryer installed to remove sample moisture; Carbon Dioxide passes thru trap to vent On-column injection at 16.4 minutes Sample loading: 500 ml

22

23 Tetrafluoride Hexafluoropropane ulfur Hexafluoride e oroethane

24 oromethane Dichlorodifluoromethane Chlorotrifluoromethane + Chlorodifluoromethane Tetrafluoroethane methane ne ane 1,2,2-tertrafluoroethane thane

25 Calibration Curve Report Curve Fit: Linear, Ignore, y = e+6x +1.5 ro-1,2,2-trifluoroethane 1.50 e (Mcounts)

26 1/X e+2 Tetrafluoromethane C

27 Resp. Factor RSD: 13% oeff. Det.(r2):0.9999

28 Montreal Protocol on Substances tha chlorofluorocarbons. Kyoto Protocol of binding red Doha Amendment in revised carbons and chlorofluorocarbons. September 2013 US/China agreeme ambient air Utility Regulator Group v EPA, 6/23/ lations for GHG

29 t Deplete Ozone Layer (1989) - banned most uction targets for all greenhouse gases list to include all hydrofluorocarbons, perfluoront - phase down GHG and regular monitoring of 4 - US Supreme Court ruling affirms EPA regu-

30 Chromatography Details Column - J&W GS-GASPRO, 60 m, 0.32 mm ID (Agilent, S Column flow: 1.5 ml/min Column temperature program Initial: +50 o C Ramp to -40 o C at -100 o C.min, hold for 10.8 minutes Ramp to +10 o C at +100 o C/min, hold 2.2 minutes Ramp to +110 o C at +10 o C/min, hold 5.5 minutes Ramp to +240 o C at +100 o C/min, hold 0.9 minutes

31 nta Clara, CA) Krypton 20

32 S Trifluoromethan Pentaflu 30 Retention Carbon Xenon

33 1,1,1,2- Butane Chloro Chloroethe 1,1-Difluoroeth Trichlorofluorome Time 40 Diflu Octafluoropropane 1,2-Dichloro-1, Chloroethane Dichloromethane

34 1,1,2-Trichlo Peak Si

35 Amount (nmol/mol)

36

37 Properties o Analyte ASHRAE Nu Tetrafluoromethane R-14 Hexafluoroethane R-116

38 f Some Halogenates ber Boiling Point ( o C) Global Concentration (nmol/mol)

39 Spectrometer Parameters Full scan only for initial peak locating Selected Ions Monitoring (SIM) for quantiation Scan range: 45 to 300 m/z Single quadrupole Electron ionization Filament current: 80 µa

40 Chroma

41 togram of Tetrafluoromethane in ambient air at Lo on December 11, 2013, using SIM at 60 m/z Tetrafluoromethane: 70 p Counts

42 s Alamitos, Ca. mol/mol 1. Cold initial trap 2. Nafion dryer re 3. Subambient ini 4. Detection limit ing

43 Summary temperatures mandated to fully snare tetrafluorom quired to remove water from sample loading tial column temperature needed to sharpen CF4 c well below ambient levels for most halocarbons w

44 ethane hromatography th Selected Ions Monitor- Conta

45 ct Information: Edward Bramston-Cook

46 Trifluoromethane R 23 Pentafuoroethane R-125 Difluoromethane R-32

47

48 Internal Standards not Used Mandate - Internal standard must not be present in sample Virtual all combinations of hydrogen, fluorine and chlorine are target

49 s analytes

50 Minutes

51 5. Linear range a 6. Many halocarb out by unique f

52 propriate for ambient measurements ons fully separated with chosen column and condi ragment patterns

53 tions or are easily picked

54 Technical Director Lotus Consulting 5781 Campo Walk Long Beach, CA /