Chromatography Forum

but there should be standard way of doing things

I see no particular advantage to everyone doing it the same way,

I see no particular advantage to everyone doing it the same way,

Until a methods robustness is known, it is essential that labs (who want results comparable to other labs) follow the same procedure - Sorry, but this is just not true. The highest possible level of accuracy and precision in chemical measurements is reached in the international intercomparisons between national metrology labs, and it is the exception rather than the rule that all the labs that submit results for an intercomparison use the same methods, and certainly it is extremely rare for them to all follow exactly the same procedure (in the sense of an "official" method). In GC analyses for example results from extractions will be compared with results from purge and trap or headspace, and wet chemistry will be compared with instrumental analyses. Indeed, a high level certification of a reference material requires its properties to be measured using different, independent techniques different operators, reagents, room temperature, humidity (to name a few) can have a tremendous effect on the outcome True, but if a method is properly calibrated each time that it is applied then these extraneous influences will fall away, or be shown explicitely to render the results invalid - NB that I am talking here about chemical analyses, not tests such as the foaming ability of soap which I agree have to be done under a fixed set of conditions . The methods that I am referring to are used for long-term studies (1-2 years) so tracking method robustness is EXTREMELY important. I don't care if a method works today, it also has to work 6-12 months from now and give EXACTLY the same results for a known standard The same argument applies - it is not necessary for every analysis to follow exactly the same procedure, as long as every analysis is properly calibrated and properly carried out.

I am mainly talking about QA/QC labs the ultimate QA/QC labs are national metrology laboratories - and they do not use standard "official" methods such as are disseminated by the AOAC, of course R&D lab environments are different both R&D and QC labs need results that are fit for purpose, no difference at all there- they are supposed to be. But if a lab wants to label itself as a QA/QC regulated environment, they should act like oneyou seem to think that precise, accurate results can only be generated if everyone uses the same standard methods of analysis, as I argue above, this is simply not true. There is a time and place for innovation and a regulated lab is not one of them unless the innovation that they carry out is properly documented, uses equipment whose performance is validated, is carried out by appropriately trained and experienced people, etc etc.

Peter Apps are you a member of a scientific organization? If so, which one and why did you choose it? Southern African Zoological Society, Southern African Association for Wildlife Management, chosen so that I can access their journals. I analyse large carnivore excrement for a living: http://www.bpctrust.org/, remarkably there is no scientific organization whose official methods cover that area

both R&D and QC labs need results that are fit for purpose, no difference at all there

different operators, reagents, room temperature, humidity (to name a few) can have a tremendous effect on the outcome True, but if a method is properly calibrated each time that it is applied then these extraneous influences will fall away, or be shown explicitely to render the results invalid

is properly documented, uses equipment whose performance is validated, is carried out by appropriately trained and experienced people, etc etc.

It is good to see more chemists in PacNW AOAC . I stopped participating in the regional meeting as the number of chemists dropped and the biologist took over.
As one who has assembled a compendium of laboratory methods for use by others, it is very hard to get chemists to even agree on what level of effort is required for something as basic as method validation. Those with backgrounds in highly regulated areas have different ideas than those who are more interested in monitoring or risk assessment.
AOAC does have a procedure for method validation that is accessable, whether it meets the needs of potential users is for them to determine. One size does not fit all.

Say Hi to Carlos and Jim for me!

A lot of the AOAC methods are very archaic, they waste a lot of solvent, are long and obnoxious in terms of sample prep. I use them as a starting point.

so that results from a lab in US match results from a lab in say, Porturgal.