If I drank 10 drinks every Friday for several months but don't drink any otherday and have not drank in 9 days will this show up on a PEth test?

Probably so. Phosphatidylethanol (PEth) has been investigated for a number of years as a biomarker of alcohol consumption (1). EtG proponents recommend it as a complementary test (3, 4).

PEth is a blood test and is present only following heavy or frequent consumption of alcohol, 7 drinks or more within a 7 day period according to most estimates.

However, it is detectable for about 14 days after no alcohol intake. (3, 4)

I'm aware of one major testing lab that began offering PEth tests in 2010 but haven't heard anything more about actual use of the test.

Where are you being tested? (I'm interested in type of agency doing testing, i.e. treatment, etc)

1) Wurst, 2002
2) Aradottier, 2006
3) Skipper (EtG blog)
4) Hartmann, 2007

Concentra labs in Texas