a reagent test paddle includes a contamination detection medium , a reference color bar , at least one chemical test medium , and a unique identifier . the contamination detection medium includes a reagent that changes color in the presence or when exposed to a hostile or inhospitable environment . each chemical test medium includes a regent that is responsive to a respective analyte in a biological sample . the reference color bar includes reference color samples of different colors . the unique identifier , like a serial number , identifies the particular paddle and its chemical test medium so it can be uniquely and anonymously associated with a user . a method includes capturing and interpreting digital images of a biologically unexposed and subsequently exposed reagent test paddle at various delay times within an automatically calibrated environment ; locating the paddle in a plurality of digital images , extracting the reference color bar and locating the contamination detection medium and chemical test medium in each digital image . color changes of the chemical test medium and contamination medium are detected at various delay times after sample exposure . to determine validity of test results , the method further compares the detected colors of the contamination detection medium with predetermined colors expected for no contamination and contamination .