QuEChERS experience with OPs

[vichrom]

Hello everyone.

We're going to purchase some QuEChERS kits for pesticide analysis, and I wonder what are your experiences with this extraction/cleanup method for OPs pesticides. How good are your recoveries?

[Don Shelly]

QuEChERS recoveries for OPs are generally very good. Much depends on your matrix and determinative method. Normalization and matrix matching is recommended for difficult matrices.

[richiekichi]

I use QuEChERS extensively and as Don has said, recoveries are generally pretty good for a wide range of pesticide residues. That said, the method can require some "fiddling" to ensure acceptable recoveries in difficult matrices. If you are planning to analyze a variety of sample types I would recommend you purchase the salts and buffers, C18, PSA, GCB etc separately, rather than buy the commercially available kits. Although weighing everything out can get a little tedious.

[lovemymoe]

If those are made by UCT, I haven't used the Quechers but I do like UCT. They're one of the few vendors left that I give a true benefit of the doubt to because I haven't been let down yet. I don't know what other people's experiences are, but I have experienced a fair share of excessively back-ordered items and in one instance, a shameful reduction in quality that ended up costing my lab quite a bit of money in me investigating why recovery went from 80% to 11%. That to me is particularly irritating since I automatically assume I've made a mistake somewhere and also because it's just another thing to try and juggle/compensate for. Bottom line, I'd waiger you'll like them.

[Alexandre]

We analyze by QuEChERS foods for few years now, validated and ISO 17025 accredited.
We make QuEChERS manually, it is very slow. We are trying now 3 vendors Agilent, Waters and Macherey-Nagel.
OPs are OK for most foods, but garlic and onion are a nightmare when analysed on u-ECD and FID, too much interference. SPE gives you much lower background for difficult samples.
Alexandre

[Camisotro]

Bumping this because of the mention of back-ordered products. The delays are compounded by the fact that shipping to Canada usually requires going through a local distributor.

My lab is using QuEChERS for a method we're including as part of ISO 17025 accreditation. We started out with kits from Agilent. When we began to run out of kits leading up to our first audit, we ordered more and it all went on back-order. We were unable to complete some additional validation in time for the audit due to lack of supplies. My manager is currently juggling about 4-5 different suppliers trying to get anyone who can deliver us some kits soon, but this is dragging into weeks and weeks. This is ridiculous for a method that is supposed to be "quick".

We had some MgSO4 and sodium acetate lying around, which we tried to weigh out manually for use, but it mustn't have been the right purity (or dryness) as the GC-MS results were dismal (didn't try that on LC-MS yet). We are a small lab and don't actually have an oven or desiccator right now, so if we want the right level of dryness we're stuck with pre-packaged for the time being.

Are there any suppliers that seem to be on the more bountiful side for these kits rather than always back-ordered?

[Don Shelly]

We currently don't have any QuEChERS kits on backorder, although, if you are looking for something custom, that takes us a couple of days to assemble. If you are having trouble with the distributor, we have been known to ship directly to Canada.

Don

[Camisotro]

We currently don't have any QuEChERS kits on backorder, although, if you are looking for something custom, that takes us a couple of days to assemble. If you are having trouble with the distributor, we have been known to ship directly to Canada.

Don

Hi Don, thanks for letting me know. I see you are with UCT which goes through Chromspec in Canada. We have ordered Restek and AccuStandard through them before among others, so I did present the UCT part numbers to my boss as one option.

[Don Shelly]

Great! If you need any help, let me know.

Thanks for the kind words "lovemymoe"!

Don

[Pepter]

We analyze by QuEChERS foods for few years now, validated and ISO 17025 accredited.
We make QuEChERS manually, it is very slow. We are trying now 3 vendors Agilent, Waters and Macherey-Nagel.
OPs are OK for most foods, but garlic and onion are a nightmare when analysed on u-ECD and FID, too much interference. SPE gives you much lower background for difficult samples.
Alexandre

What you mean by "we make QuEChERS manually, it is very slow".
Duno how big is your laboratory and how many kits you use per day but
in some situations its cheaper to hire person to do "kits" than order them from vendors.

[Alexandre]

It was about 150 tubes/day (tube I and tube II together).
I wanted consistency and speed.
Surprisingly with so many vendors of QuEChERS kits the results (%Rec) were unacceptable for some.
Is it a homogeneity or moisture issue?
What are US prices for QuEChERS?

[Pepter]

It was about 150 tubes/day (tube I and tube II together).
I wanted consistency and speed.
Surprisingly with so many vendors of QuEChERS kits the results (%Rec) were unacceptable for some.
Is it a homogeneity or moisture issue?
What are US prices for QuEChERS?

Will check prize of our (europen) kits tomorrow.
But iam sure its gona be cheaper to hire somone. Its not hard to make 100 small kits per hour.