Most Sensitive ECD's

[MarkRob]

Hi there,

we have a small lab and currently we're using a 5890 II with dual ECD's for our PCBs. I'm consistantly having trouble reaching new required MDL's.

Can you tell me which are the most sensitive ECD's. Agilent? Thermo? Shimadzu? We would be interested in used equipment, so what systems would be good in the used category?

thanks.

M

[aldehyde]

Agilent's website claims that their micro-ECD is the most sensitive on the market. Obviously not the most impartial source, but I do a lot of work on Agilent GCs with uECD and have many customers doing environmental/pesticide analysis. I don't think I've spoken with anyone who has trouble meeting detection limits with it.

Here are the specifications they list:

Maximum operating temperature 400 ºC
Data acquisition rate Up to 50 Hz
MDL <6 fg/mL Lindane
Linear dynamic range >5 x 104 with lindane
Dynamic range >5 x 105 with lindane

I work exclusively with Agilent products so hopefully some people with experience with other vendors can weigh in.

[JTM]

I've had experience with a couple brands of uECDs. While I don't really think that there's ALL that much of a difference, Agilent does indeed make the prettiest one.

The one we use in house is an old 5890/uECD from back when HP still made them... Agilent products are the old HP products + 3 generations of models. These uECDs are extremely sensitive and should give 3 ranges of sensitivity:

0.5 pg/s Cl
1-2 pg/s S
2-4 pg/s N

PCBs MDL is somewhere in the 1 ppb range? I'm surprised you aren't able to hit that even with an aged machine.

[Peter Apps]

Sulphur and nitrogen compounds with an ECD ?

Peter

[aldehyde]

Amines are roughly as responsive on ECD as something with one fluorine or chlorine, I would assume thiols and other sulfur containing stuff would be on the same order.

[JTM]

Nitro groups are slightly better than amines.

Sulfite group > sulfate > thiol.

[Peter Apps]

Thanks aldehyde and JTM, if you have any references easily to hand I would be interested, if not, no problem, I'll google it.

Peter

[JTM]

References for traditional ECD sensitivity? This is going to be in old textbooks, etc...

Amine sensitivity

Stuff like that. This is just what I remember.

Here's Agilent's ECD page

[Peter Apps]

Thanks, JTM.

By the time the detector sees them those amines are not amines any more ! Specifically I'm interested in any kind of detector selectivity that can pull peaks out of very complex mixtures, and help with confirming identities from low resolution MS. Derivatization just makes the messy chromatograms even messier.

I'm just so used to ECD = halogen that the sulphur and nitrogen selectivity had slipped into the background.

Peter

[AICMM]

Peter,

I too am very interested in ECD relative sensitivity. Some things it is very sensitive to, viscinal diketones, disulfides, dinitro-trinitro compounds (explosives). I have experience running all of these classes of compounds and ppb sensitivity is very do-able.

I have one article citation: Bulletin of chemical society of japan 51(8), pp 2249, and I can send you the table if you are interested.

If you do go this route, I would be very interested in further exchange of data....

Best regards.

[Peter Apps]

Hi AICMM

Yes, I would like to see the table. I am in the process of specifying a GC with some extra bits for analysing wild dog scent marks. I am already looking at FID, and pulsed flame photometric for sulphurs. Adding an ECD as well might make things a bit crowded, because I have to fit an in-house inlet on top somewhere, but the extra independent confirmation for some compound classes might be worth it. If I do go that route I'll keep you posted.

Peter

[AICMM]

Peter,

Send me your e-mail address (aicmm at flash.net) and I will send you what little I have of relative sensitivities.

Best regards.