Comparative Investigation of Six Different Searching Techniques for Seminal Stains The comparison of six searching methods showed, that the phosphatase test has the highest, the choline test a sufficient and the other tests a poor sensitivity. Stains of seven body secretions and excretions, 13 fruit and 17 vegetables have been investigated by damp filter paper method. The spermine-, gamma-glutamyltranspeptidase-, and the zinc test had an insufficient specificity. The phosphatase test had false positive results with kiwi fruit, cauliflower, pea, and potato; the choline test with cauliflower, pea, broccoli, leek, and tomato; the leucineaminopeptidase test with feces and strawberry.