Chromatography Forum

Please Help me to over come the Endrin/DDT degradation problem.give me some tips. i changed my column , inlet liner,gold seal,clean the injection port.please give me the conditions of GC. I have agilent 7890a gc with micro ECDs.

Please Help me to over come the Endrin/DDT degradation problem.give me some tips. i changed my column , inlet liner,gold seal,clean the injection port.please give me the conditions of GC. I have agilent 7890a gc with micro ECDs.

What are the conditions you are operating now? To what extent the compounds degrade?

At my laboratory our DDT/Endrin breakdown is usually < 3% but we have to change the inlet liner to achieve this. We use a liner with glass wool and that is usually the only maintenance required to meet the breakdown criteria. It's a little more expensive but relatively easy to spend about a minute changing a liner vs cooling down the instrument and clipping columns and replacing gold seals.

Watch your injector temp. >197 will cause significant breakdown. Clean and silanize your liners and if you use glass wool, make sure it's not crappy glass wool. Make sur your injector temp is being read properly too, I've found variations in temperature probes. Just for fun, put a thermometer in the injection port and see what you get.. I've seen a few surprises. If these things don't work, shoot me an e-mail.
Good luck,
Bill

At my laboratory our DDT/Endrin breakdown is usually < 3% but we have to change the inlet liner to achieve this. We use a liner with glass wool and that is usually the only maintenance required to meet the breakdown criteria. It's a little more expensive but relatively easy to spend about a minute changing a liner vs cooling down the instrument and clipping columns and replacing gold seals.

Can you please give me the part number for the liner.

Watch your injector temp. >197 will cause significant breakdown. Clean and silanize your liners and if you use glass wool, make sure it's not crappy glass wool. Make sur your injector temp is being read properly too, I've found variations in temperature probes. Just for fun, put a thermometer in the injection port and see what you get.. I've seen a few surprises. If these things don't work, shoot me an e-mail.
Good luck,
Bill

Instrument 1: Agilent 7890A Gas Chromatograph
Detectors: Electron Capture Detector (ECD)
Auto sampler: Agilent 7683
Column 1: RTX-CL Pesticides 1, 30m x 0.32mm x 0.32µm
Column 2: RTX-CL Pesticides 2, 30m x 0.32mm x 0.25µm

Flow Rate: He @ 4 mL/min.
GC Conditions: Initial Temp: 120oC
Initial Time: 0.3min
Injector: 200C
Det:330C
Rate A: 45o/minute
Temp. A: 200oC
Time A: 0.0 min.
Rate B: 15o/minute
Temp. B: 230oC
Time B: 0 min.
Rate C: 30o/minute
Final Temp: 320oC
Final Time: 2.0 min.

Please Help me to over come the Endrin/DDT degradation problem.give me some tips. i changed my column , inlet liner,gold seal,clean the injection port.please give me the conditions of GC. I have agilent 7890a gc with micro ECDs.

What are the conditions you are operating now? To what extent the compounds degrade?

more than 30% degradation

nstrument 1: Agilent 7890A Gas Chromatograph
Detectors: Electron Capture Detector (ECD)
Auto sampler: Agilent 7683
Column 1: RTX-CL Pesticides 1, 30m x 0.32mm x 0.32µm
Column 2: RTX-CL Pesticides 2, 30m x 0.32mm x 0.25µm

Flow Rate: He @ 4 mL/min.
GC Conditions: Initial Temp: 120oC
Initial Time: 0.3min
Injector: 200C
Det:330C
Rate A: 45o/minute
Temp. A: 200oC
Time A: 0.0 min.
Rate B: 15o/minute
Temp. B: 230oC
Time B: 0 min.
Rate C: 30o/minute
Final Temp: 320oC
Final Time: 2.0 min.