like d.s. said, you would end up with straight test, no ester attached. it would just be test suspension. you don't need to add an ester, and you couldn't unless you could acquire propionic acid, or cypionic, etc. and those chemicals are very strictly regulated. if you tried to order them from some chemical supply house, you'd probably have some men in suits knocking on your door. anyway, you don't need to add an ester to use the test.