Integrating the MasSpec Pen with Sub-Atmospheric Pressure Chemical Ionization for Rapid Chemical Analysis and Forensic Applications.

Analytical methods that allow rapid, sensitive, and specific chemical measurements are central to forensic analysis and essential to accelerating compound screening and confirmation. We have previously reported the development of the MasSpec Pen technology as an easy-to-use and disposable hand-held device integrated to a mass spectrometer for direct analysis and molecular profiling of biological samples. In this Technical Note, we describe a new apparatus that integrates the MasSpec Pen device with a subatmospheric pressure chemical ionization (sub-APCI) source and an ion trap mass spectrometer for detection and semiquantitative analysis of forensic-related compounds. Coupling the MasSpec Pen device to a sub-APCI source allowed semiquantitative analysis of the drugs cocaine and oxycodone, the agrochemicals atrazine and azoxystrobin, and the explosives trinitrotoluene and dinitroglycerin in under 20 s. Using chemical ionization, improved reproducibility and sensitivity for targeted chemical detection and compound identification was achieved while maintaining the user-friendly features of the hand-held MasSpec Pen device. Limits of detection in the high picogram to low nanogram range were obtained for the compounds analyzed, which are within the range of federal screening cutoffs and those reported for other ambient ionization MS techniques. Altogether, the MasSpec Pen sub-APCI system described enabled rapid and semiquantitative chemical analysis for forensic applications and could be further adapted and applied to other areas of chemical testing.

Rapid Analysis and Authentication of Meat Using the MasSpec Pen Technology.

Food authenticity and safety are major public concerns due to the increasing number of food fraud cases. Meat fraud is an economically motivated practice of covertly replacing one type of meat with a cheaper alternative raising health, safety, and ethical concerns for consumers. In this study, we implement the MasSpec Pen technology for rapid and direct meat analysis and authentication. The MasSpec Pen is an easy-to-use handheld device connected to a mass spectrometer that employs a solvent droplet for gentle chemical analysis of samples. Here, MasSpec Pen analysis was performed directly on several meat and fish types including grain-fed beef, grass-fed beef, venison, cod, halibut, Atlantic salmon, sockeye salmon, and steelhead trout, with a total analysis time of 15 s per sample. Statistical models developed with the Lasso method using a training set of samples yielded per-sample accuracies of 95% for the beef model, 100% for the beef versus venison model, and 84% for the multiclass fish model. Predictors of meat type selected included several molecules previously reported in the skeletal muscles of animals, including carnosine, anserine, succinic acid, xanthine, and taurine. When testing the models on independent test sets of samples, per-sample accuracies of 100% were achieved for all models, demonstrating the robustness of our method for unadulterated meat authentication. MasSpec Pen feasibility testing for classifying venison and grass-fed beef samples adulterated with grain-fed beef achieved per-sample prediction accuracies of 100% for both classifiers using test sets of samples. Altogether, the results obtained in this study provide compelling evidence that the MasSpec Pen technology is a powerful alternative analytical method for meat analysis and investigation of meat fraud.