How best to dispense P&T Methanol

Discussions about sample preparation: extraction, cleanup, derivatization, etc.

5 posts Page 1 of 1
I've been thinking for some time that there must be a way to safely dispense Purge and Trap grade Methanol with a repipettor. My formative years expertise is with metals and I don't bat an eye at using a couple of 'BrandTech 4731140 Dispensette Organic 1-10ml Analog Adjustable Bottletop Dispenser, with a SafetyPrime Valve' to dispense my trace metal grade Nitric and Hydrochloric acids.

I frequently need to extract high volatile soils into methanol for 8260 VOC analysis. I keep eyeing my acid dispensors and wondering if I can get away with ordering one for my P&T Methanol instead of preparing empty VOA's ahead of time with manual pipetting.

Can I use one of these organic dispensers without picking up 8260 VOC's as contaminants? What sort of filter is adaquate on the vent to prevent contamination?
I've been using one for >10 years with no contamination issues. Methanol and water left out in the same hood will pick up acetone and acetonitrile.

If I am measuring a specific volume for a VOA extraction I always check it first with a volumetric flask.
One issue has been that our solvent supplier, B&J, likes to change the bottle cap size and the cap in the correct size has wandered off somewhere.
Steve Reimer wrote:
I've been using one for >10 years with no contamination issues. Methanol and water left out in the same hood will pick up acetone and acetonitrile.

If I am measuring a specific volume for a VOA extraction I always check it first with a volumetric flask.
One issue has been that our solvent supplier, B&J, likes to change the bottle cap size and the cap in the correct size has wandered off somewhere.

Alright! Thank you for responding; I am going to do this. I did not realize that "organic" dispensers were able to prevent VOC contamination.

Oddly, "organic" dispensers are the best ones for dispensing trace metal and higher purity grade nitric and hydrochloric acids and I am guessing its not just material compatibility but that the piston mechanism is isolated from outside air and possible contamination by airborne dust.
We have had ones to dispense concentrated sulfuric acid, but the acid kills the plastic parts over time.
I have been using one for 20+ years(I think it is the same one) and have no problems with it. I do keep it separate from any other solvents, because the air inlet to the bottle is a porous teflon plug in the side of the dispenser and it could allow other solvent vapors in. Also have the problem with different bottle threads, the size is the same but threads can differ and keep it from sealing as tightly as possible.
The past is there to guide us into the future, not to dwell in.
5 posts Page 1 of 1

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