A quantity test is performed on a skin print received on a substrate to determine a quantity score for the skin-print. A chemical analysis of the skin-print is subsequently performed to detect one or more chemical species or analytes to provide a chemical test result. The quantity score and chemical test result are stored or transmitted. In another embodiment, the chemical test is performed only if the quantity score meets a predefined threshold. The quantity test may involve determining a volume or mass of skin-print deposited on the substrate. The volume or mass may be calculated by measuring one or more attributes of the skin-print. The quantity test may involve an optical analysis of the skin-print and may be calibrated using a secondary quantity test. The quantity test may comprise measuring the influence of a skin-print on light transmission into/out of the substrate (figure 2a), and the second quantity test may comprise performing white light interferometry. The quantity score may be used to scale the chemical analysis. The substrate may comprise a unique identifier, such as an RFID tag or barcode, which is transmitted with the quantity score and chemical test result. An image of the skin-print may be compared with a database of user skin-print images to identify the donor prior to the chemical analysis.
