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Most Sensitive ECD on the Market

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HP 6890 MICRO-ECD: GREATER LINEAR RANGE, LOWER MDLs

Most Sensitive ECD on the Market

The new HP 6890 Micro-ECD, designed particularly for capillary columns, has a linear range an order of magnitude greater and offers better sensitivity than any other ECD on the market today. It is also more robust than previous electron capture detectors.

HP 6890 Micro-ECD Diagram

Sensitivity and selectivity of the ECD have led to its adoption as the required detector for the analysis of polychlorinated biphenyls (PCBs) and organopesticides in several EPA Methods1 and CLP protocols.2 Disadvantages of the ECD include a limited linear range, often requiring extensive sample dilution and rework. In addition, most ECDs are designed for both packed and capillary columns, with a large internal cell volume that decreases the sensitivity obtainable with capillary columns.

Increased Sensitivity, Low Noise

The specially designed flow cell of the HP 6890 Micro-ECD is optimized for capillary columns. It offers an MDL for lindane of <8 fg/sec, a 5-fold improvement over the standard HP 6890 ECD (calculated by the ASTM E697-91 protocol3) and a performance that makes it the most sensitive ECD on the market. The closeup of the lindane peak in the chromatogram of a 500-ppt injection of CLP mixture A demonstrates the low noise level obtained.

Enhanced Linear Range

The HP 6890 Micro-ECD permits calibration from 0.4 to 1000 ppb,4 an almost 150-fold improvement over the required CLP range of 5-80 ppb.2 This range reduces the number of samples that require dilution and rework and increases throughput and laboratory efficiency. The EPA criteron of <20% RSD is met over a range of five orders of magnitude for several of the pesticides listed in CLP protocols.

Ideal with Fast GC

The small volume of the flow cell of the micro-ECD is ideal for fast GC. Figure 2 shows a fast-GC run of 5 ppb of CLP Mixture A, using a 5 m x 100 mm HP-5 column. Excellent peak shape is obtained with a 3.8-minute run, compared to 28 minutes under standard conditions (Figure 1). The HP 6890 Micro-ECD therefore is ideal for screening runs, where speed is a major requirement.

HP6890 Micro-ECD chromatogram for 500-ppt CLP A Mixture. Inset: Lindane peak showing peak shape and noise level.

Figure 1. HP6890 Micro-ECD chromatogram for 500-ppt CLP A Mixture. Inset: Lindane peak showing peak shape and noise level.		 Conditions
Column: HP-608; 30 m x 530 µm
Oven Program: 150°C (0.5 min);
5°C/min to 275°C (10 min)
Injection: Splitless; 2 µL with 1-min purge,
60 mL/min purge flow
Carrier gas: He, 5 mL/min
Makeup gas: N2, 60 mL/min
Inlet: 250°C
Detector: 300°


Peaks
  1. Tetrachloro-m-xylene
  2. alpha BHC
  3. Lindane
  4. Heptachlor
  5. Endosulfan
  6. Dieldrin
  7. Endrin
  8. DDD
  9. DDT
  10. Methoxychlor
  11. Decachlorobiphenyl
HP6890 fast GC with the HP 6890 Micro-ECD
Figure 2. HP6890 fast GC with the HP 6890 Micro-ECD.

Conditions
Column: HP-5; 5 m x 100 mm x 0.17 µm film thickness
Oven Program: 150°C (0.5min);
45°C/min to 275°C (1min)
Injection: Split; 10:1
50-ppb CLP Mixture A at 5 pg/mL
Carrier gas: He, 1 mL/min
Makeup gas: N2, 60 mL/min
Inlet: 250°C
Detector: 300°

EPC Enhances Stability and Reproducibility

Because an ECD detector is a concentration-sensitive device, response factors are dependent on the gas flows. The HP 6890 Micro-ECD precisely controls all flows with electronic pneumatics control (EPC); it therefore delivers enhanced stability and greatly simplifies setup and validation.

Improved Robustness

When changing methods, the Micro-ECD recovers faster than previous models. Overall system utility and laboratory productivity are therefore considerably improved, and switching between methods causes minimum downtime.

The HP 6890 Micro-ECD meets the CLP linearity specifications for all compounds over a much larger dynamic range than typical ECDs. Its improved sensitivity makes it the best choice for applications that require an extremely low detection limit (MDL), and its compatibility with high-speed GC makes it ideal for sample screening. In fact, the new micro-ECD easily sets new specification benchmarks for other ECDs on the market.

References

  1. EPA Methods 508, 608, 8080, 8081, 8061.
  2. USEPA Contract Laboratory Program, Statement of Work for Organic Analysis, OLM03.1, August 1994.
  3. Annual Book of ASTM Standards, Section 14, General Methods and Instrumentation, Section E 697-91, Page 206.
  4. Abdel-Rahman, M., Snyder, W. D., and Wilson, W. H. (in press).



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