The direct detection and identification of staining dyes from security inks in the presence of other colorants, on currency and fabrics, by laser desorption mass spectrometry

Laser desorption mass spectrometry (LDMS) is useful for the direct desorption and MS analysis of dyes off materials such as paper. Here it is shown that staining dyes, produced by currency degradation devices, such as those used by financial institutions or armored transport companies, can be detected by LDMS. These staining dye packs are commonly used in bank security programs to deter theft or unauthorized removal of currency from teller stations or from ATM cash cassettes. Working automatically, these technologies release a security dye to degrade the surface of the notes and possibly mark the assailant involved in the attack. These dyes can be characterized and identified directly from paper currency, and from fabrics, and uniquely identified in the presence of other dyes that are used in the printing and dying of such materials, by LDMS. In these experiments, no extraction step is required. A pulsed UV laser directly irradiates a paper or fabric sample--colorants are desorbed, ionized and detected using time-of-flight MS. Results shown here suggest that dyes such as Basic Red 1:1 and Basic Violet 11:1 are used in such devices.