The Forensic Services Chemistry section of the National Forensic Science Technology Center (NFSTC) evaluated the RxSpec 700Z spectrometer manufactured by ASD, Inc., in order to determine whether it is currently suitable for the analysis and identification of controlled substances when being used in traditional and nontraditional laboratory environments.
The RxSpec 700Z spectrometer is a field-portable visible/near infrared (Vis/NIR) spectrometer that is currently being used to conduct fast, nondestructive qualitative or quantitative analysis on solids, powders, and other material in a variety of industries. The RxSpec 700Z is housed in a durable protective aluminum case that allows for easy instrument relocation and setup. The unit is capable of using a 110-120V AC or a 12V DC internal or external power source. It uses a halogen lamp as the excitation incident light source; the light focuses on the unknown sample from underneath the sampling window. During the analysis, the instrument collects digitized data on the vibrations that result from the molecular excitation of the sample, which in turn provides a spectra or unique chemical "fingerprint" of the material. The evaluation of the instrument found that chemometrics models developed by the evaluator with assistance from a representative from ASD, Inc., failed to properly identify even standard samples. If a chemometrics model is properly developed, it should account for most of the molecular variability that occurs within a given collection of reference spectra for each of the compounds of interest, thus statistically reducing the occurrence of misidentification errors. The evaluation was thus reduced in scope as a result of these findings, excluding the assessment of sensitivity, reproducibility, portability, and environmental effects. Areas for improvement, training requirements, and health and safety issues are discussed. Tables and graphs