This is an academic paper that evaluates emerging technologies to test for the presence of fentanyl, including fentanyl test strips, a hand-held Raman Spectrometer, and a desktop Fourier-Transform Infrared Spectrometer. Fentanyl test strips were found to be the most sensitive and specific and were also able to detect minute amounts of fentanyl in the sample.
Green, T.C., Park, J.N., Gilbert, M., McKenzie, M., Struth, E., Lucas, R., Clarke, W., Sherman, S.G. (2020). An assessment of the limits of detection, sensitivity and specificity of three devices for public health-based drug checking of fentanyl in street-acquired samples. International Journal of Drug Policy, 77, 102661.