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Topic: MEK Transdermal absorption quantity question  (Read 5191 times)

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Offline IUPG

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MEK Transdermal absorption quantity question
« on: December 04, 2011, 09:08:32 AM »
I'm hoping to determine, within reasonable error, the quantity of methyl ethyl ketone that was absorbed through my skin when I spilled a significant quantity of PVC glue (similar to rubber cement) on my hand.  All glue sniffing jokes aside, this has some pretty serious repercussions for me, as I am being falsely accused of consuming alcoholic beverages orally.

So I've found most of the info I need (other than an evaporation rate) but having never made it past my community college principles of chemistry class I require some help with the conversions and piecing it all together.

First, the Absorption rate for MEK is either:  0.46 µgÊcm-2Êmin-1 or 5 to 10 micrograms/cm2/min. I can't figure out the first equation and the second one doesn't specify wether its wet or dry skin which makes a 20% difference (absorbs faster wet, mine was dry)

I'm guessing the spill covered 75cm2 of skin.

The weight to volume of MEK is 802.52 kg/cu.m

The evaporation rate is linked here: http://www.ilpi.com/msds/ref/evaporationrate.html but I can't find a standard to get an actual timeframe calculation based on the multiple variables of environment. the ambient temp was 25C (but it was on my skin so 35C) with little wind, 40% humidity and no solar radiation.

I guess I'd like to figure out how many milliliters would have been absorbed so I could determine the blood concentration once I figure out the alcohol volume of MEK and its relativity to whatever would trigger the device that reads the BAC. http://bi.com/sites/all/themes/BI/pdf/factsheet/Tad_factsheet.pdf

Maybe this is more of a medical question, but I figured I'd give this a try, I'd appreciate any ideas of where else I should try and figure this out.

Offline Borek

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Re: MEK Transdermal absorption quantity question
« Reply #1 on: December 04, 2011, 11:39:18 AM »
5 to 10 micrograms/cm2/min.

You said 75 cm2, assuming upper limit and a full minute (i guess you have not kept the glue on your hand forever), you could absorb 750 μg - we are in the mg range. 1 mg is in the microliter range, not milliliter. This is several orders of magnitude too low to explain measurable BAC, no matter what assumptions you try.
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Offline IUPG

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Re: MEK Transdermal absorption quantity question
« Reply #2 on: December 04, 2011, 06:34:50 PM »
I'm using the evaporation rate to determine how long it was on my skin. Have you ever tried to remove rubber cement from your skin? It doesn't go anywhere until the MEK has evaporated, and allowed the glue to become gummy, then you peel it off like a second skin.

I'm guessing it took 15 minutes for most of the MEK to evaporate and for the glue to "set up" before I could begin peeling it off.

Offline Borek

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Re: MEK Transdermal absorption quantity question
« Reply #3 on: December 05, 2011, 02:46:55 AM »
15 minutes will mean 15 mg, this is still way too small amount to be significant.

Assuming you weigh 70 kg, 15 mg gives something like 2x10-5%, while legal limits for BAC are (depending on where you live) in the 10-2% range. There is no way you can blame MEK for your problems.
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Offline opsomath

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Re: MEK Transdermal absorption quantity question
« Reply #4 on: December 05, 2011, 03:31:44 PM »
Did you get a breathalyzer test? Those are based on alcohol dehydrogenase and would not respond to MEK.

Offline IUPG

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Re: MEK Transdermal absorption quantity question
« Reply #5 on: December 05, 2011, 11:09:32 PM »
Did you get a breathalyzer test? Those are based on alcohol dehydrogenase and would not respond to MEK.

I did get a Breath test, and I blew .000, but it was 2 hours after the monitor device was triggered so they claimed the alcohol was out of my system and they continue to trust their device. unbeknown to me, I could have taken a UA, which would have proved my case and prevented me from going to frikkin jail for 2 months.

Borek, thanks for the response, I'm simply trying to find what triggered the sensor, I know that I did not drink, and the glue somehow set off the device as there were no other possible contributing factors.  They claim that by analyzing a graph of the sensors readings they can tell if it is a false positive due to environmental substances and not consumption. Apparently the graph reflects a sharp spike in alcohol readings when it is an environmental trigger as opposed to the gradual rise and fall that consumed alcohol would reflect as metabolized by the body after consumption. My graph reading is a pretty obvious gradual rise and fall within a 4+ hour timeframe, toping out at .042ish. The system activates a flag at .02bac. In my case, I'm trying to determine if the "consumption" was percutenious (through the skin).

Is it possible that the Devices sensor would misread MEK (or the methanol the body metabolizes MEK into; http://www.inchem.org/documents/ehc/ehc/ehc143.htm#SubSectionNumber:6.3.2 ) as a higher concentration of alcohol dehydrogenase? again this is a transdermal sensor and not a breathalyzer.

Offline Borek

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Re: MEK Transdermal absorption quantity question
« Reply #6 on: December 06, 2011, 04:50:20 AM »
I did get a Breath test, and I blew .000, but it was 2 hours after the monitor device was triggered so they claimed the alcohol was out of my system

Doesn't sound logical to me - speed with which BAC goes down is pretty well researched. No idea about exact numbers in your case, but if you were above legal limit at t=0, I don't think you can get down to zero BAC in two hours.

Note that test result has to come from the verified device, otherwise it has no legal meaning.
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Offline IUPG

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Re: MEK Transdermal absorption quantity question
« Reply #7 on: December 06, 2011, 11:37:49 PM »
Trust me, the lack of logic is abhorrent and they can claim pretty much whatever they want.  The legal limit is any thing over .000 but the transdermal sensor sends a flag at .02. They claim I went from a .o42 to .000 in a 2 hour period, which is speculative and conjecture, but what the sensor shows from the graph indicates consumption so they choose that.

Apparently the device is verified, I'm attempting to determine why my results were so extreme and how I can explain or recreate the same scenario to duplicate the results and exonerate my record to reflect the truth.

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