Method 508.1: Determination of Chlorinated Pesticides and Herbicides Analysis by Liquid-Solid Extraction and Electron Capture GC

Seven EPA Methods on One Column EPA Method 508.1 includes many of the same components as Method 505, but it also contains several other compounds, including chlorinated pesticides, herbicides, and organohalides. In order to increase sample throughput, an optimized method is shown here using a dual column configuration with the Rtx-CLPesticides/Rtx-CLPesticides2 column pair. These columns, used under the conditions shown, offer a unique selectivity that allows the target analytes to be resolved in approximately half the analysis time of the original method. Further, both columns easily passed the comprehensive system performance criteria adapted from 508.1 (see table below). The unique selectivity of the Rtx-CLPesticides/Rtx-CLPesticides2 column pair offers an ideal balance of speed and resolution for chlorinated pesticide, herbicide, and organohalide analysis.

Rtx-CLPesticides and Rtx-CLPesticides2 columns easily pass Method 508.1 performance criteria.

Test/Requirement Analyte Concentration (ppb) Rtx-CLPesticides2 Rtx-CLPesticides
Inertness (breakdown <20%) endrin 50 0.9% 1.4%
Inertness (breakdown <20%) 4,4'-DDT 100 1.0% 1.1%
Sensitivity (S/N>3) chlorpyrifos 2 12.0 6.2
Chromatographic performance (0.8<PGF<1.15) DCPA 50 1.03 1.06
Column performance (resolution>0.50) delta-BHC/
chlorothalonil
40/50 9.9 26.8

Vendor Column Pair Analysis Time (min) Coelutions Restek Advantage
Restek Rtx-CLPesticides /
Rtx-CLPesticides2
23.5 / 24 2 / 2
  • Good balance of speed and resolution.
Competitor A column 1 / column 2 21 / 23 0 / 3
Competitor B column 1 / column 2 18 / 17 2 / 4
Comparison based on published competitor data. All columns tested were 0.32 mm ID.

24-minute analysis of Method 508.1 chlorinated pesticides, herbicides, and organohalides using Rtx-CLPesticides columns and a micro-ECD. View larger

Peaks
1.Hexachlorocyclopentadiene
2.Etridiazole
3.Chlorneb
4.Propachlor
5.Trifluralin
6.Hexachlorobenzene
7.α-BHC
8.Simazine
9.Atrazine
10.Pentachloronitrobenzene (IS)
11.γ-BHC
12.β-BHC
13.δ-BHC
14.Heptachlor
15.Chlorothalonil
16.Metribuzin
17.Alachlor
18.Aldrin
19. 4,4'-Dibromobiphenyl (SS)
Peaks
20.Metolaclor
21.DCPA methyl ester (Chlorthal-dimethyl)
22.Heptachlor epoxide
23.trans-Chlordane*
24.Cyanazine
25.cis-Chlordane*
26.Endosulfan I
27.4,4'-DDE
28.Dieldrin
29.Endrin
30.Chlorobenzilate
31.4,4'-DDD
32.Endosulfan II
33.4,4'-DDT
34.Endrin aldehyde
35.Endosulfan sulfate
36.Methoxychlor
37.cis-Permethrin
38.trans-Permethrin
* For information regarding the nomenclature used for cis-chlordane and trans-chlordane, visit www.restek.com/chlordane-notice
Pesticides & Herbicides U.S. EPA Method 508.1 Rtx-CLPesticides & Rtx-CLPesticides2
GC_EV01022
ColumnsRtx-CLPesticides2 30 m, 0.32 mm ID, 0.25 µm (cat.# 11324)
and Rtx-CLPesticides 30 m, 0.32 mm ID, 0.32 µm (cat.# 11141)
using Rxi guard column 5 m, 0.32 mm ID (cat.# 10039)
with deactivated universal “Y” Press-Tight connector (cat.# 20405-261)
Sample50 ng/mL 508.1 calibration mix #1 (cat.# 32094)
100 ng/mL 508.1 calibration mix #2 (cat.# 32095)
100 ng/mL 508.1 calibration mix #3 (cat.# 32096)
50 ng/mL pentachloronitrobenzene (cat.# 32091)
250 ng/mL 4,4'-dibromobiphenyl (cat.# 32092)
500 ng/mL atrazine (cat.# 32208)
500 ng/mL simazine (cat.# 32236)
Diluent:Ethyl acetate
Injection
Inj. Vol.:2 µL splitless (hold 0.75 min)
Liner:Cyclo double taper (4 mm) (cat.# 20896)
Inj. Temp.:250 °C
Oven
Oven Temp.:80 °C (hold 0.5 min) to 155 °C at 19 °C/min (hold 1 min) to 210 °C at 4 °C/min to 310 °C at 25 °C/min (hold 0.5 min)
Carrier GasHe, constant flow
Linear Velocity:26 cm/sec
DetectorMicro-ECD @ 325 °C
NotesThis chromatogram was obtained using an Agilent micro-ECD. To obtain comparable results, you will need to employ a micro-ECD in addition to confirmational dual columns connected to a 5-meter guard column using a “Y” Press-Tight connector.

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