title: Time-of-flight-secondary ion mass spectrometry method development for high-sensitivity analysis of acid dyes in nylon fibers.
abstract: A minimally destructive technique for the determination of dyes in finished fibers provides an important tool for crime scene and other forensic investigations. The analytical power and the minimal sample consumption of time-of-flight-secondary ion mass spectrometric (TOF-SIMS) analysis provides the ability to obtain definitive molecular and elemental information relevant to fiber identification, including identification of dyes, from a very small volume of sample. For both fiber surface analysis and, with the aid of cryomicrotomy, fiber cross-section analysis, TOF-SIMS was used to identify various dyes in finished textile fibers. The analysis of C.I. Acid Blue 25 in nylon is presented as a representative example. The molecular ion of C.I. Acid Blue 25 with lower than 3% on weight-of-fiber (owf) dye loading cannot be identified on dyed nylon surfaces by TOF-SIMS using a Bi(3)(+) primary ion beam. Sputtering with C(60)(+) provided the ability to remove surface contamination as well as at least partially remove Bi-induced damage, resulting in a greatly improved signal-to-noise ratio for the Acid Blue 25 molecular ion. The use of C(60)(+) for damage removal in a cyclic manner along with Bi for data acquisition provided the ability to unambiguously identify Acid Blue 25 via its molecular ion at a concentration of 0.1% owf from both fiber surfaces and cross sections.
authors.affiliation: Analytical Instrumentation Facility, College of Engineering, North Carolina State University, Campus Box 7531, Room 318 MRC, 2410 Campus Shore Drive, Raleigh, North Carolina 27695, United States. czhou@ncsu.edu
authors.forename: Chuanzhen
authors.initials: C
authors.lastname: Zhou
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Roberto
authors.initials: R
authors.lastname: Garcia
authors.forename: Anne
authors.initials: A
authors.lastname: Crawford
authors.forename: Keith
authors.initials: K
authors.lastname: Beck
authors.forename: David
authors.initials: D
authors.lastname: Hinks
authors.forename: Dieter P
authors.initials: DP
authors.lastname: Griffis