Chromatography Forum

The teaser I read in my e mail promped me to check it out. Claims to help recoveries of difficult compounds with 525.2.
My worst player is hexachlorocyclopentadiene and no data is included in the method except to say that acceptance levels for HCCPD will be widened.
The other question I have is what advantage would be gained by adding internal standards post extraction?

At this time the only advantage offered to me iis that all method preservatives are in the bottle prior to sampling.

I don't think I'll be trying it soon.

Bigbear,

I'm fairly unfamiliar with 525.? but I have experience with 8270. What exactly do you (or the method mean) by adding internal standards post extraction? I guess 8270 already does this as well as adding surrogate standards prior to extraction. In 8270 the analytes are quantified from the IS spiked after the extraction just prior to analysis. The surrogates are only used to determine relative extraction efficiency for that sample. IS spiked at the end of processing correct for injection variations etc. In my opinion it would be better to quantify from the surrogates and then calculate %rec using Surrogates relative to the final spiked IS. This is how isotopic dilution works (and it works really well).

So I think the only added benefit would be that you would know a relative extraction efficiency for each sample. If you currently use only surrogates (spiked prior to extraction) there is no way of telling extraction efficiency from injection irreproducibility. They are both affecting your overall area of your surrogates. Spiking IS at the end isolates the difference in injection recovery and extraction recovery.

Sorry if I got a little off topic.