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Featured Application: Optimized Volatiles Analysis on an Rtx-VMS Column with Restek CRMs Means Better VOC Data in Less Time

Fast, Optimized GC Purge-and-Trap Analysis of Volatiles for Soil and Water Methods


  • Save set-up time—we’ve optimized volatiles analysis for you!
  • Fit-for-purpose Rtx-VMS column separates early eluting gases and critical VOCs, ensuring rugged, accurate volatiles analysis.
  • Precisely formulated CRMs ensure accurate quantitation and are backed by Restek’s ISO accreditation and rigorous documentation.

Volatile organic compounds (VOCs) pose human health risks and can enter the environment and water supplies through a number of avenues, such as the improper disposal of industrial chemicals (e.g., chlorinated solvents) or the leaking of fuel components from underground storage tanks. Monitoring programs often utilize GC purge-and-trap analysis of volatiles in soil and water samples in order to track VOC contamination. The first fused silica columns used for this analysis were based on diphenyl/dimethyl polysiloxane stationary phases. However, resolution of gases has always been problematic with these columns. In support of labs conducting purge-and-trap analysis of volatiles, Restek designed the Rtx-VMS column specifically to optimize the separation of commonly analyzed VOCs of environmental concern. The Rtx-VMS column features a stationary phase that is selective for VOCs, a film thickness sufficient to retain and resolve the low boiling volatiles, and enough thermal stability to elute the high boiling VOCs.

Since the Rtx-VMS column has been optimized for volatiles analysis, it provides excellent resolution of critical VOCs, which ensures more accurate quantification in fast analysis times. As shown in the chromatograms below, data quality and lab productivity can be increased using an Rtx-VMS column paired with Restek certified reference materials (CRMs). In the first example, excellent resolution of the 82 drinking water contaminants listed in EPA Method 524.3 was obtained—including o-xylene and styrene, which often coelute on other columns. Labs that include the seven volatiles listed in the Unregulated Contaminant Monitoring Rule 3 (UCMR3) in their drinking water analyses will benefit greatly from this application and these products. Having all VOCs packaged in only three ampuls with CRM documentation simplifies the task of calibration. In addition, separating and detecting volatiles using the Rtx-VMS column delivers the best quality data for purge-and-trap analysis of volatiles in drinking water.

The second chromatogram shown below demonstrates the performance of the Rtx-VMS in separating a longer list of volatiles, specifically the 102 VOCs listed in EPA Method 8260. While EPA Method 524.3 was written for purgeable organic compounds in water samples, EPA Method 8260 can be used for purge-and-trap analysis of volatiles in a much more diverse array of sample types (soil, water, solid waste, etc.) In this example, good chromatographic results are again obtained for both early- and late-eluting volatiles, but the separation of oxygenates is particularly noteworthy. Oxygenates are added to gasolines to enhance fuel performance, and they are target compounds in leaking underground storage tank monitoring. Purge-and-trap GC-MS analysis with a highly selective Rtx-VMS column is recommended for this method because key oxygenates—such as methyl tert-butyl ether (MTBE) and tert-butyl alcohol (TBA)—coelute on other GC columns and they also share the ions used for identification. In addition to separating these components in the reference standards shown below, the Rtx-VMS column can resolve MTBE and TBA as well as additional oxygenates from other target compounds and potentially interfering matrix components in gasoline. To see the separation and identification of 5 ppb oxygenates in a gasoline sample, read our application note.

As shown in the chromatograms below, Restek’s combination of CRMs and the Rtx-VMS column are highly effective tools that are optimized for GC purge-and-trap analysis of volatiles. The unique Rtx-VMS column phase offers the best separation of critical compound pairs on the market. In addition, Restek CRMs are comprehensive, manufactured and QC-tested in our ISO-accredited labs, and come complete with all necessary documentation to make your job easier.


Peaks
1.Dichlorodifluoromethane
2.Chlorodifluoromethane
3.Chloromethane
4.Vinyl chloride
5.1,3-Butadiene
6.Bromomethane
7.Trichlorofluoromethane
8.Diethyl ether
9.1,1-Dichloroethene
10.Carbon disulfide
11.Methyl iodide
12.Allyl chloride
13.Methylene chloride
14.trans-1,2-Dichloroethene
15.Methyl acetate
16.MTBE-D3 (SS)
17.MTBE
18.tert-Butyl alcohol (TBA)
19.Diisopropyl ether (DIPE)
20.1,1-Dichloroethane
21.tert-Butyl ethyl ether (ETBE)
22.cis-1,2-Dichloroethene
23.Bromochloromethane
24.Chloroform
25.Carbon tetrachloride
26.Tetrahydrofuran
27.1,1,1-Trichloroethane
28.1,1-Dichloropropene
29.1-Chlorobutane
30.Benzene
31.tert-Amyl methyl ether (TAME)
32.1,2-Dichloroethane
33.Trichloroethene
34.1,4-Difluorobenzene
35.tert-Amyl ethyl ether (TAEE)
36.Dibromomethane
37.1,2-Dichloropropane
38.Bromodichloromethane
39.cis-1,3-Dichloropropene
40.Toluene
41.Tetrachloroethene
Peaks
42.trans-1,3-Dichloropropene
43.1,1,2-Trichloroethane
44.Ethyl methacrylate
45.Dibromochloromethane
46.1,3-Dichloropropane
47.1,2-Dibromoethane
48.Chlorobenzene-D5
49.Chlorobenzene
50.Ethylbenzene
51.1,1,1,2-Tetrachloroethane
52.m-Xylene
53.p-Xylene
54.o-Xylene
55.Styrene
56.Bromoform
57.Isopropylbenzene
58.4-Bromofluorobenzene (SS)
59.Bromobenzene
60.n-Propylbenzene
61.1,1,2,2-Tetrachloroethane
62.2-Chlorotoluene
63.1,3,5-Trimethylbenzene
64.1,2,3-Trichloropropane
65.4-Chlorotoluene
66.tert-Butylbenzene
67.Pentachloroethane
68.1,2,4-Trimethylbenzene
69.sec-Butylbenzene
70.4-Isopropyltoluene
71.1,3-Dichlorobenzene
72.1,4-Dichlorobenzene-D4
73.1,4-Dichlorobenzene
74.n-Butylbenzene
75.Hexachloroethane
76.1,2-Dichlorobenzene-D4 (SS)
77.1,2-Dichlorobenzene
78.1,2-Dibromo-3-chloropropane
79.Hexachlorobutadiene
80.1,2,4-Trichlorobenzene
81.Naphthalene
82.1,2,3-Trichlorobenzene
5 ppb Volatiles in Drinking Water on Rtx-VMS by EPA Method 524.3
GC_EV1297
ColumnRtx-VMS, 30 m, 0.25 mm ID, 1.40 µm (cat.# 19915)
Sample524.3 internal standard/surrogate mix (cat.# 30017)
524.3 gas calibration mix (cat.# 30014)
524.3 VOA MegaMix standard (cat.# 30013)
Diluent:RO water
Conc.:5 ng/mL (5 mL sample)
Injectionpurge and trap split (split ratio 30:1)
Liner:Premium 1.0mm ID straight inlet liner (cat.# 23333.1)
Inj. Temp.:200 °C
Purge and Trap
Instrument:EST Encon Evolution
Trap Type:Vocarb 3000
Purge: 11 min, flow 40 mL/min
Dry Purge: 1 min, flow 50 mL/min
Desorb: 1 min @ 260 °C, flow 30.9 mL/min
Bake: 8 min @ 265 °C
Interface Connection:injection port
Transfer Line Temp.:150 °C
Oven
Oven Temp.:45 °C (hold 4.5 min) to 100 °C at 12 °C/min to 240 °C at 25 °C/min (hold 1.32 min)
Carrier GasHe, constant flow
Flow Rate:0.9 mL/min
DetectorMS
Mode:Scan
Scan Program:
GroupStart Time
(min)
Scan Range
(amu)
Scan Rate
(scans/sec)
11.547–3005.4
22.935–3005.19
Transfer Line Temp.:240 °C
Analyzer Type:Quadrupole
Source Temp.:230 °C
Quad Temp.:150 °C
Electron Energy:70 eV
Solvent Delay Time:1.5 min
Tune Type:BFB
Ionization Mode:EI
InstrumentAgilent 7890A GC & 5975C MSD
AcknowledgementEST Analytical provided the Centurion robotic autosampler and Encon Evolution P&T concentrator.

Peaks
1.Dichlorodifluoromethane
2.Chloromethane
3.Vinyl chloride
4.Bromomethane
5.Chloroethane
6.Trichlorofluoromethane
7.Diethyl ether
8.1,1-Dichloroethene
9.Carbon disulfide
10.1,1,2-Trichloro-1,2,2-trifluoroethane
11.Iodomethane
12.Allyl chloride
13.Methylene chloride
14.Acetone
15.trans-1,2-Dichloroethene
16.Methyl-D3-tert-butyl-ether
17.Methyl acetate
18.Methyl tert-butyl ether
19.tert-Butyl alcohol
20.Acetonitrile
21.Diisopropyl ether
22.Chloroprene
23.1,1-Dichloroethane
24.Acrylonitrile
25.Ethyl tert-butyl ether
26.cis-1,2-Dichloroethene
27.2,2-Dichloropropane
28.Bromochloromethane
29.Chloroform
30.Carbon tetrachloride
31.Tetrahydrofuran
32.Methyl acrylate
33.1,1,1-Trichloroethane
34.Dibromofluoromethane
35.1,1-Dichloropropene
36.2-Butanone
37.Benzene
38.Propionitrile
39.Methacrylonitrile
40.1,2-Dichloroethane-D4
41.Pentafluorobenzene
42.tert-Amyl methyl ether
43.1,2-Dichloroethane
44.Isobutyl alcohol
45.Trichloroethene
46.1,4-Difluorobenzene
47.Dibromomethane
48.1,2-Dichloropropane
49.Bromodichloromethane
50.Methyl methacrylate
51.cis-1,3-Dichloropropene
Peaks
52.2-Chloroethyl vinyl ether
53.Toluene-d8
54.Toluene
55.2-Nitropropane
56.Tetrachloroethene
57.2-Bromo-1-chloropropane
58.4-Methyl-2-pentanone
59.trans-1,3-Dichloropropene
60.1,1,2-Trichloroethane
61.Ethyl methacrylate
62.Dibromochloromethane
63.1,3-Dichloropropane
64.1,2-Dibromoethane
65.2-Hexanone
66.Chlorobenzene-D5
67.Chlorobenzene
68.Ethylbenzene
69.1,1,1,2-Tetrachloroethane
70.m-Xylene
71.p-Xylene
72.o-Xylene
73.Bromoform
74.Styrene
75.Isopropylbenzene
76.4-Bromo-1-fluorobenzene
77.Bromobenzene
78.cis-1,4-Dichloro-2-butene
79.1,4-Dichlorobutane
80.n-Propylbenzene
81.1,1,2,2-Tetrachloroethane
82.2-Chlorotoluene
83.1,2,3-Trichloropropane
84.1,3,5-Trimethylbenzene
85.trans-1,4-Dichloro-2-butene
86.4-Chlorotoluene
87.tert-Butylbenzene
88.Pentachloroethane
89.1,2,4-Trimethylbenzene
90.sec-Butylbenzene
91.p-Isopropyltoluene
92.1,3-Dichlorobenzene
93.1,4-Dichlorobenzene-D4
94.1,4-Dichlorobenzene
95.n-Butylbenzene
96.1,2-Dichlorobenzene
97.1,2-Dibromo-3-chloropropane
98.Nitrobenzene
99.Hexachlorobutadiene
100.1,2,4-Trichlorobenzene
101.Naphthalene
102.1,2,3-Trichlorobenzene
*Carbon dioxide
Volatile Organics by EPA Method 8260 (80ppb Standard) on Rtx-VMS
GC_EV00685
ColumnRtx-VMS, 30 m, 0.25 mm ID, 1.4 µm (cat.# 19915)
Sample8260B MegaMix calibration mix kit (cat.# 30475)
California oxygenates mix (cat.# 30465)
VOA calibration mix #1 (ketones) (cat.# 30006)
8260A surrogate mix (cat.# 30240)
8260 internal standard mix (cat.# 30074)
Injectionpurge and trap split (split ratio 25:1)
Inj. Temp.:250 °C
Purge and Trap
Instrument:O.I. Analytical 4560 with 4551A Autosampler
Trap Type:#10 (Tenax/silica gel/carbon molecular sieve)
Purge: 11 min @ 20 °C, flow 38 mL/min
Desorb Preheat Temp.:150 °C
Desorb: 1.0 min @ 190 °C, flow 32 mL/min
Bake: 10 min @ 210 °C
Transfer Line Temp.:110 °C
Oven
Oven Temp.:35 °C (hold 7 min) to 90 °C at 4 °C/min to 220 °C at 45 °C/min (hold 1 min)
Carrier GasHe, constant flow
Flow Rate:1.3 mL/min
Dead Time:1.47 min @ 35 °C
DetectorAgilent 5971A GC-MS
Transfer Line Temp.:280 °C
Tune Type:PFTBA/BFB
Scan Range:35-260 amu
NotesSample Size: 10 mL
Sample Temp: 40 °C
Water Management: 110 °C purge, 0 °C desorb, 240 °C bake
6-Port Valve: 110 °C
Sparge Mount: 45 °C
Valve Manifold: 50 °C
Other Conditions: prepurge, preheat, dry purge OFF
AcknowledgementPurge & trap courtesy of O.I. Analytical

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