Monitoring and identification of hazardous air pollutants by fast capillar…

Monitoring and identification of hazardous air pollutants by fast capillary gas chromatography with PID/FID detection 1 J . N. DRISCOLL, & J.L. MACLACHLAN , PID A N A LY Z E R S , L L C , S A N D W I C H , M A & S TA N L E Y S T E A R N S , VA L C O INSTRUMENTS, INC., HOUSTON, TX H T T P : / / W W W. H N U. C O M A C S N AT I O N A L M E E T I N G , P H I L . , PA A U G . 2012PID Analyzers, LLC

What are Hazardous Air Pollutants (HAP’s)? 2 There are 187 hazardous air pollutants that range from gases such as ETO to semivolatiles like biphenyl that has a BP of 255.oC EPA has issued rules & regulations covering more than 80 categories of major industrial sources, such as chemical plants, oil refineries, aerospace manufacturers, and steel mills, as well as categories of smaller sources, such as dry cleaners, & commercial sterilizers Monitoring of these species will be necessary to comply with EPA regulationsPID Analyzers, LLC

Introduction 3 Much of the previous work on “fast GC” utilized short (5M) thin film capillary columns to elute solutes quickly and the result is rapid but inferior separations because of the short column. New technology developed at Valco’s capillary column development center where VICI takes polyimide-coated fused silica (FST) and removes the polyimide layer. Then the (FST) is electroplated with nickel. As a result of the superior heat transfer of the electroplated nickel, we are able to rapidly and efficiently heat and achieve excellent resolution for a 30M capillary column. These columns can be programmed faster (hundreds of degrees/min)- save 50-90% The columns can be reliably started a few degrees above ambient These columns cool down faster because of their low mass so savings> 50% Stearns et al (J. Chromat.) have looked at high MW HC but we are looking at applications for gases & semivolatiles with thick film (5-10 ) capillary columnsPID Analyzers, LLC

Resistively Heated Column 4 There are two types:  a wire wrapped- where a Ni wire is wrapped with a fused silica column and covered with an insulator  B. where the column is coated with Ni then coated with polyimide The performance of the latter is somewhat better but the former has a lower cost These are available in short (5M) or long (30M) capillary columns in a variety of bonded liquid phases They are also available as PLOT column with various Hayesep packingsPID Analyzers, LLC

Photo GC 301 C 5PID Analyzers, LLC

Applications 6  Our applications at PID are in lower MW HC up to C6 solvents and semivolatiles. Here we have to start just above to ambient, a difficult task for most GC’s, w/o subamb. We were able to start @ 23oC (reproducibly), hold 1 min, then prog. to 200oC (at 40C/min.) & hold for 1-2min. to complete. With a thick film column (5 ), we could easily separate gases and light solvents.  For larger molecules, we would need a thin film 0.5 resistively heated column.  Since these columns can be controlled separately, it is possible to have two different columns and two detectors running at the same time.PID Analyzers, LLC

Fast GC Chromatogram for C1 to C6 alkanes 7PID Analyzers, LLC

PID FID Ratios 8 PID/FID Ratios PID/FID Series Schematic (f) # of Double BondsPID Analyzers, LLC

Complex LNG sample GC PID/FID (Packed column) 9PID Analyzers, LLC

PID FID Rations for LNG Sample 10 Peak # Type PH-PID PH-FID PID/FID Ratio 1 IP> 10.2 eV NR OR -- 2 IP> 10.2 eV NR OR -- 3 IP> 10.2 eV NR OR -- 4 Aliphatic 220 54 4 5 Aliphatic 180 57 3.2 6 Aliphatic 88 17 5.1 7 Olefin 52 4 13 8 Aliphatic 104 17 6.1 9 Aromatic- Bz 256 5 51.2 10 Aromatic- Tol 308 4 77 11 Aromatic 132 3 44 12PID Analyzers, LLC Aromatic 64 2 32

PID/FID Capillary Chromatograms of Aromatics 11PID Analyzers, LLC

PID/FID Ratios (note PID scale is set 80x less sensitive than the FID) 12 # Component PID FID PID/FID Ratio 1 toluene 33 28 94 2 ethyl benzene 20 37 43.2 3 m- xylene 28 36 62 4 tmbenz 39 35 89 5 styrene 27 38 78 6 i prop Tol 15 32 37.5 7 1,2,4 TMT 19 36 42 8 but benz 23 39 47 9 br- benz 29 18 128 10 1,2,4 TMB 13 12 87 11 1,2,3 TMB 12 12 80 12PID Analyzers, LLC naphthalene 26 29 72

Solvents (BTX + MeOH) GC-PID/FID 13PID Analyzers, LLC

Conclusions 14 We have shown that with low MW HC- there is a >50% reduction in analysis times There are eight different ramps that can be programmed so that separations can be improved in different sections of the chromatograms Although we have worked with thick films, these columns are available with thin films for high MW compounds and with PLOT columns for separation of low MW gases. Note that two columns can be run simultaneously for volatiles & semivolatiles or polar and non polar compounds to expand the detection of multiple compounds PID/FID analyses provides an opportunity to positively identify the solutes during the analytical process. Note the large differences in PID/FID rations in slide #12. These can be used for positive identification of a HAP in the chromatogramPID Analyzers, LLC

Monitoring and identification of hazardous air pollutants by fast capillar…

by Jennifer Maclachlan on Aug 25, 2012

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Monitoring and identification of hazardous air pollutants by fast capillar… Presentation Transcript