8260 + 8270, how to improve surrogate recovery?

Discussions about GC and other "gas phase" separation techniques.

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1. What are the most widely used evaluation criteria? Iirc the methods suggest 70-130% but say that the lab can use their own quality objectives if they're justified.

2. 8260 with static headspace, usually getting into range, but not always, that's indication of incomplete extraction, but what can I improve in order to remedy this.

3. 8270, solids with ultrasonic extraction and liquids with LLEx, same as with 8260 but here I'm getting really low recoveries.

Any tips would be very welcome.
See method 8000, section 9.6

"Data quality objectives" depend on who is using the data, and for what. Only you (or your bosses/customers) can answer that.

I'm guessing your problem isn't limited to just surrogate compounds.
I do 8270 with an ultrasonic extraction. My control limits are much wider than 70-130, but that applies to a lot of analytes in my LCS and MB as well.

If you're looking for advice on how to improve recovery in a method, you're going to have to explain what you're doing now, first.
I would be very happy with 70% recoveries for most surrogates by 8270.

2,4,6-Tribromophenol 40-87
2-Fluorobiphenyl 18-97
2-Fluorophenol 35-79
Nitrobenzene-d5 24-150
Phenol-d6 22-95
Terphenyl-d14 35-128

These are more typical limits which have been derived over time using the statistical formula listed in the method using recoveries in ongoing samples. (several hundred used each time they are evaluated)

Those are for water samples, soils can be even lower depending on technique.

If you are running just blanks, recoveries can be in that 70-130 range, but even then the 70% can be difficult to hit for some surrogates due to loss in concentration or extraction efficiency. Real world samples with dirty matrix normally pull those recoveries down so that is why they suggest using the statistical method to set ranges to better represent what you would find in real world samples.

8260 usually has better recoveries since normally the internal standard and surrogate are in the same mixture when injected, especially if using automated addition in the autosampler. For 8260 waters our recovery limits are in the 80-120 range but for soils the BFB drops into the mid 60%s on the lower end. Any soil with clay in it can adsorb it quite well.
The past is there to guide us into the future, not to dwell in.
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