Generally: What analytical methods are used to determine the
concentration of alcohol in a urine sample. What is the minimum
quantity (in milliliters) for the sample to provide accurate results ?

Specifically: What analytical method is used by the medical bureau of
road safety in the republic of Ireland, and the minimum sample
quantity they need for accurate results.

I recommend you break your question up into two equally priced
questions. It may be that someone can find an answer to part 1 of your
question but be unable to answer part 2. This will likely prevent
anyone from answering your question at all. On the other hand, with
two separate questions, one of them may very well be answered even
though the answer to the other remains elusive.

Regards;
Tutuzdad-ga

Urine testing requires less then a drop of urine (my best guess would be 1 ml) 

Alcohol however is hardly ever tested using urine samples , more
common and faster are breath analyzers and saliva tests

The cutoff for most products governmental agencies use is 0.02%

From:
http://www.nsc.ie/road_safety/advice.cfm

The limits are set out in Road Traffic Act, 1994 as follows:

* over 107 milligrammes of alcohol per 100 millilitres of urine

So technically, the minimum amount of urine required would be 100
millilitres to determine accurately that 107 milligrammes of alcohol
are present.

http://toxicology.lsumc.edu/ethanol.htm

http://www.blackwell-synergy.com/links/doi/10.1046/j.1359-6357.2003.00605.x/full/

Hi corwin: One mililiter = 1 ml = one cubic centimeter. One drop would
be about twenty micro liters = 20 cubic milimeters. I'm guessing on
the 20.  Neil