Method Development

[lusi]

Hello,
Can someone offer some information on the following?
We are basically using validated methods and adapting them for our systems. How long does it take to validate these methods on the lab's LC MS and GC MS systems?

[tlahren]

Please give some more information: eg.

-Which methods (EPA, ASTM etc.)
-Are your analyses regulated by a governing agency (local or government agency etc.)?

For example, Here in MN, USA environmental labs are regulated by the Minnesota Department of Health (MDH) and the Minnesota Pollution Control Agency. The MDH requires that we have a Standard Operating Procedure (SOP) of our own written that is consistent with the specific analytical method (i.e., different ones for each EPA 8260 and EPA 8270). They also require documentation in this SOP or current analytical method detection limits and reporting limits (MDLs and RLs). These usually have to be updated every year (you analyze them to determine the capabilities of your system). You also have to show reproducibility of the entire method by demonstrating a Lower and Upper limit for acceptability. On top of all of this you have to order from a vendor a Performance Test sample (PT) of which only the vendor and the agency (MDH in this case) know the results. If you complete all of this and pass the PT test then you have successfully validated that you are able you accurately and precisely run the specified method on the exact equipment listed in the SOP.

Each state, country, governing body has different requirements. I only know about the environmental field in the USA but I'm sure there are quite similar requirements in any other type of field.

If you really have no governing agency (i.e., University Research etc.) I would suggest you run a series of injections (eg., same standard analyzed about 10 times) and see if they are statistically similar (Q-test etc.) and close to the expected result (student T-test etc.). Also do this for some Analyte-spiked samples or blanks and put them through the entire analytical process (i.e., extractions, cleanups, evaporation etc.) as you would an actual sample and perform the same statistics on them. In other words, do everything you can to convince yourself and anyone around you that your results are as accurate as possible.

In any case, provide us with a little more info and you may get some more relevant responses from others who know more than I.

Hope this helps.

[lusi]

Thanks so much Ty. We have CIPAC methods for some pesticide products. The methods here in most cases were developed on a different brand of the instrument and in some cases use consumables we can not find for our instrument. We also use different flow rates and injection volumes. However, for the residues we do not have any standard methods. We will try those published in journals etc.

We do not have any regulated procedures we need to follow, but we are hoping to one day get accredited to ISO 17025.

I have never worked with these instruments before so I am unsure what is the protocol for adapting methods and ensuring that they are fit for use and also in keeping with the ISO 17025 standard.

I read somewhere that the method development and validation can take months. Also I got the impression that each method must be validated on the specific instrument.

Can you tell me if the MDH does proficiency testing for pesticide residues and products? Also would they offer those services to overseas clients?

[tlahren]

I don't think the MDH would be able to help over seas or even out of state. As far as proficiency testing you might try http://www.accustandard.com. You can order a PT sample and analyze it. They post the results online and I think they also mail them to you with your score (how many analytes you correctly quantitated). They also carry pesticide standards for standard methods.

For GC/MS try starting with the U.S. EPA method 8270. It's at least a good reference for GC/MS analysis of semi-volatile analytes. The list for this method contains numerous pesticides and the quality check criteria included a check for degradation of DDT (must be very low) and peak tailing for pentachlorophenol and benzidine (also needs to be low). AccuStandard also has most EPA methods available for download at http://www.accustandard.com/asi/epa_downloads.php3. I'm not familiar with the CIPAC methods but the EPA 8270 method has enough info to get you down the right path of putting out good, reliable data. I'm not sure which is the method for LC/MS but I think it's an 8300 number. There are many so take a look at the link above.

You are right in that it can take months for method development for each method on each instrument and that proficiency must be shown on each specific instrument (2 different GC/MS systems must both be tested for same method proficiency). The info in the EPA methods usually has a basic GC/MS setup scheme complete with GC and MS parameters that should get you at least seeing and identifying compounds in your first couple analyses. Also ordering mixes of standards from vendors like AccuStandard, Restek etc., they usually will provide you with a chromatogram of the standard along with the analytical parameters and conditions in which they analyzed it. They will go one step further if you call them and probably chat with you about how to optimize methods for specific analytes as well. They are very helpful during method development usually.

Hope this further helps your goals.

[lusi]

Thanks Ty. We had ordered one set of Standards from Accustandards, but it came with no chromatographs and when we inquired about that we basically did not received any.

Is there a specific department that is helpful for that information?

[tlahren]

I don't remember exactly who I have talked to in the past but I think it was the manager of their technical support group. The were able to send me some additional chromatograms. If they are still no help go to Restek.com and see if they have a similar standard. They might be able to provide some chromatograms and conditions either online or by request.

[lusi]

Thanks Ty