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Environmental Article

8-Minute Dual Column Analysis of Organochlorine Pesticides

Using Rtx®-CLPesticides / Rtx®-CLPesticides2 Columns

By Jason Thomas, Environmental Chemist
  • Analysis and confirmation of 20 pesticides in 8 minutes.
  • Baseline resolution of all compounds, for improved accuracy.
  • Low-bleed columns, for reliable data.

Analyses for organochlorine pesticides are among the most common pesticide methodologies in use today. US EPA Method 8081, for example, requires separation of 20 organochlorine pesticides, some of which are isomers or are otherwise structurally similar and, therefore, are difficult to separate. Restek introduced two proprietary phases to address this issue, the Rtx®-CLPesticides phase and the Rtx®-CLPesticides2 phase, which have proven very popular within the environmental community. The unique selectivities of this column pair allow laboratories to significantly reduce analysis times for Method 8081.

There is a constant need for faster analyses to help increase sample throughput and, thereby, to increase productivity. Fast GC is a good solution, but the reduced column internal diameters and thinner phase film coatings associated with fast GC have been deterrents, due to concerns about the columns’ ability to cope with the harsh sample matrices often encountered in environmental samples, and shortened column lifetimes.

Using a 0.53mm ID guard column at the inlet end of a dual column configuration protects the analytical columns downstream. This configuration allows 20m x 0.18mm ID thin film columns to be used, with their associated high efficiency, to greatly reduce analysis time without the reduction of column lifetime usually associated with introducing “dirty” samples into small bore columns.

Figure 1 shows separation of the 20 target pesticides in EPA Method 8081 in 8 minutes using 20m x 0.18mm ID Rtx®-CLPesticides/Rtx®-CLPesticides2 columns with a 0.53mm ID guard column. In addition to rapid, baseline resolution, the pesticides are eluted as sharp, symmetric peaks. This, in turn, helps assure reliable quantification data for these analytes. Clearly the Rtx®-CLPesticides/Rtx®-CLPesticides2 columns, in conjunction with a 0.53mm ID guard column, are an excellent choice for analyzing EPA Method 8081 pesticides, or equivalent target lists of these pesticides.


Figure 1  20 organochlorine pesticides resolved and confirmed in 8 minutes,
using Rtx®-CLPesticides/Rtx®-CLPesticides2 columns.

  1. 2,4,5,6-tetrachloro-m-xylene (surr.)
  2. α-BHC
  3. γ-BHC
  4. β-BHC
  5. δ-BHC
  6. heptachlor
  7. aldrin
  8. heptachlor epoxide

  1. γ-chlordane
  2. α-chlordane
  3. endosulfan I
  4. 4,4’ DDE
  5. dieldrin
  6. endrin
  7. 4,4’ DDD
  8. endosulfan II

  1. 4,4’ DDT
  2. endrin aldehyde
  3. endosulfan sulfate
  4. methoxychlor
  5. endrin ketone
  6. decachlorobiphenyl (surr.)

GC_EV00892

GC_EV00893

Column:

Rtx®-CLPesticides, 20m, 0.18mm ID, 0.18µm (cat.# 42102) (top) and Rtx®-CLPesticides2, 20m, 0.18mm ID, 0.14µm (cat.# 42302) with 5m x 0.53mm ID intermediate-polarity deactivated guard tubing (cat.# 10045), connected using SeCure™ “Y” Connector Kit (cat.# 20276) with Universal “Y” Press-Tight® Connector

Sample:

Organochlorine Pesticide Mix AB #2 (cat.# 32292), 8-80µg/mL each component in hexane/ toluene,
Pesticide Surrogate Mix (cat.# 32000), 200µg/mL each component in acetone

Inj.:

0.5µL splitless (hold 0.75 min.), 2mm single gooseneck inlet liner (cat.# 20795)

Inj. temp.:

250°C

Carrier gas:

helium, constant flow

Linear velocity:

20cm/sec. @ 140°C

Oven temp.:

140°C (hold 1 min.) to 250°C @ 35°C/min. (hold 1 min.) to 330°C @ 35°C/min. (hold 3 min.)

Det.:

ECD @ 350°C