[Ninhydrin permeability tests of common packaging materials in the field of fingerprint examination]

With a simple experimental set-up, common packaging materials were tested for their ninhydrin permeability. The packaging material was loaded with a ninhydrin treated paper on the inside and covered with an amino acid treated paper on the outside. If ninhydrin penetrates through the packaging film, "Ruhemann's purple" will form on the amino acid treated paper. In all, 28 packaging materials were tested over a period of 24 weeks. It turned out that all the films made of polyethylene (PE) showed ninhydrin permeability. With one exception, this permeability occurred after three days already. All packages made of other film material were not permeable to ninhydrin.