GC-ECD : which system recommended

[Bibi]

Hi Everyone,


We plan to buy a GC-ECD system for the first time.

We want to use it for environmental analyses, i.e. organic contaminants
(THm, HAA, PCBs in soil, waste and water.

Any idea on the best choice between Thermo, agilent and perkin ?


Thanks

[haiedc]

Agilent 7890A with micro ECD is very good for your purposes. I have recently analyzed organochlorine pesticides and the calibration can go down to 1 - 2 ppb.

[CE Instruments]

Biased answer but whenever I ran a direct comparison of the Thermo ECD vs 6890 ECD Thermo always won on performance. This may not however be the complete story as you should take into account the best injector for your sample type, local service support , data system etc.

[AICMM]

bibi,

I think CE's comment is most appropriate. I have found very similar performance with ECD's although I will say that the micro-ECD of Agilent is a vast improvement on their older design. It really comes down to what you are used to (who's GC's and software do you currently use), service and support in your area.

I will say this, you will have a hard time doing HAA's/THM's and PCB's on the same instrument without flipping columns in and out. I currently use two separate instruments to play with these components since I am working on a non-radioactive ECD. One is a thicker film volatiles column (HAA's/THM's) and the other a narrow bore, thin film pesticide column.

Best regards.

[bhahn]

bibi,
I agree with all that has been said here, especially with the assessment that running Pest/PCB's and switching for HAA's and THM's will be a bear! You are better off with 2 instruments if you do these, depending on your sample load. Personally, I like the Agilent software.

We sell new and used equipment, service and support.
bhahn@aoti.net

[gpronger]

I would look closely at maintaining the inlet on the two systems. The Agilent inlet is very straight-forward to maintain, while I do not believe this to be the case with the Thermo system. My understanding is that the latest model GC is improved, but I would look into this aspect of the two systems very carefully. My impression of the two vendors is that the Thermo has designed their system first to be design"purity" (if theoretically the gap between inlet wall and liner needs to be 0.001 mm, then make it that way) to the theory and secondarily to maintenance while I would reverse this for Agilent. They will err towards serviceability (if making the inlet 0.001 mm will make it near impossible to service, open up the spec a bit and we'll live with a little loss in sensitivity). Neither is correct, just different perspectives in manufacturing.

[CE Instruments]

Thermo injectors designed for what ? The Thermo injectors are Grob designed (both generations) The Cold On column is unsurpassed by any other thanks to its patented secondary cooling and it will always outperform any other; but that's no use if your samples are not applicable to COC. The BEST PTV (Brightly Enhanced Sample Transfer ) is a pretty standard PTV and should perform fine along with the rest. The Split/splitless was optimised by Grob for the launch of the 8000 series in 1991. It was designed to be discrimination free and capable of larger injection volumes than other injectors. This means there are a number of liner sizes and options from Thermo plus all the other special ones from other suppliers. It offers discrimination free analysis but at the cost of keeping the same temperature from top to bottom of the injector, this has the effect of boiling Septa especially if users do not reduce the injector temperature by 20C when transfering from another manufacturers method. The other complication of this injector is that people think that the liner cap removal tool can be used to tighten the septum cap leading to compressed septa and damaged caps. It should only ever be tighted finger tight !
Routine maintenance should not be that much more troublesome than any other make injector, if the septa are trouble , buy the Merlin Microseal kit

[Rick]

GC-Agilent are the best, quality of valve, EPC gas control,precision, number of ramp, support and service ect.....Thermo like Perkin, are good but cheaper.