【国外标准】 Standard Guide for Fourier Transform Infrared Spectroscopy in Forensic Tape Examinations

5.1 This guide is designed to assist an examiner in the selection of appropriate sample preparation methods for the analysis, comparison, and identification of pressure sensitive adhesive (PSA) tapes. If no meaningful differences are noted between the known and unknown samples regarding physical appearance or measurements, then IR spectroscopy should be the next step in the analytical scheme.5.2 Infrared spectroscopy can provide molecular information regarding major organic and inorganic components. For various reasons, components in lesser amounts are typically more difficult to identify unequivocally. Reasons for this include interference of the absorption bands of the major components with the less intense bands of minor components and sensitivity issues whereby the minor components are present at concentrations below the detection limits of the instrument.5.3 Infrared spectroscopy can be used to obtain spectra for elucidation of the chemical composition of a tape and for comparison of two or more tape samples. When used for spectral comparisons, the objective is to determine whether any meaningful differences exist between the samples.1.1 Infrared spectroscopy (IR) is a valuable method for the identification and comparison of pressure sensitive tapes (1-20).2 This guide provides basic recommendations and information about infrared spectrometers and accessories, with an emphasis on sampling techniques specific to pressure sensitive tape examinations. The particular method(s) employed by each examiner or laboratory will depend upon available equipment, examiner training, sample suitability, and sample size.1.2 This guide is intended for examiners with a basic knowledge of the theory and proficiency in the use of infrared spectroscopy as well as experience in the handling and forensic examination of pressure sensitive tapes. Further, this guide is to be used in conjunction with a broader analytical scheme (21-23).1.3 Disclaimer: This guide offers a set of instructions for performing one or more specific operations. This standard cannot replace knowledge, skill, or the ability acquired through appropriate education, training, and experience and should be used in conjunction with sound professional judgment.1.4 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.