Pyridine - poor recovery (8270/3535)

[andrew ryder]

Pretty much what the title says - running 8270 TCLP by SPE (Horizon One Pass, with the in-line carbon cartridge) and pyridine recovery in the blank spikes is abysmal: 4-8% on average, enough to frequently fail even our very forgiving control charts. Interestingly it’s usually a bit better in the MS/MSD, more like 15%. The method suggests that the concentration step may be to blame - we use a Horizon Dryvap system and concentrate the three fractions (acid-base-carbon) in the same reservoir at the lowest heat setting.

Anyone else running this method have similar issues or guidance?

[James_Ball]

Pretty much what the title says - running 8270 TCLP by SPE (Horizon One Pass, with the in-line carbon cartridge) and pyridine recovery in the blank spikes is abysmal: 4-8% on average, enough to frequently fail even our very forgiving control charts. Interestingly it’s usually a bit better in the MS/MSD, more like 15%. The method suggests that the concentration step may be to blame - we use a Horizon Dryvap system and concentrate the three fractions (acid-base-carbon) in the same reservoir at the lowest heat setting.

Anyone else running this method have similar issues or guidance?

Have you tried raising the temperature a little and lowering the gas flow during evaporation? I know that works for PAH compounds sometimes. It is counter intuitive, but who knows.

To see if it is cartridge related or evaporation related, extract a blank then spike it just before evaporation and see how it recovers. If you get near 100% then it is the extraction step, if it is low then it is evaporation.

[andrew ryder]

Thanks James - I will just have to play around a bit. Hopefully not too much as those SPE disks and cartridges are pricey.

Makes sense for the PAHs, but pyridine is relatively volatile, so I'm worried a hotter coil will just burn it off even further.