Dr. Bronner's Soap
I wouldn't carry liquid detergent if I were worried about the field tests.
If you google Dr. Bronner's Soap and drug test, you'll find out that, at least since 2007 or so, they are trying to make the police stop using their field tests because, according to Dr. Bronner's manufacturer, "the field test is *much* better at detecting soap/detergent than actual drugs".
A ton of people ended up having to explain why their babies "tested positive" for drug use when all they were using was Aveno lotion or some soap or another.
Our law enforcement branches don't care that they have been illegally jailing innocent people, as long as their report can claim they arrested a bunch of people.
I'm hoping that having to pay a lot of money to people they unjustly jail will end up fixing the problem.