The success of other field deployable devices in identifying designer benzodiazepines is limited by their poor detection in samples of, or prepared from, tablet material. Lactose monohydrate and microcrystalline cellulose are the primary excipients used in pharmaceutical benzodiazepine tablets and are compounds previously reported as producing strong interfering signals in both Raman spectroscopy and FTIR instruments . Having already validated the effectiveness of resolving benzodiazepine standards via HSF, Figures S3 show the comparative absorbance spectra taken for four compounds (clonazepam, diazepam, nitrazepam and zopiclone) when extracted from pharmaceutical tablets. We find that spectra are highly reproducible across tablet extracts and standard solutions, where no additional peaks are present, and all absorbance maxima are preserved. From Figure , the HSFs are essentially identical whether from a standard or extracted from a tablet. That is, the approach is not affected by the presence of typical excipients and they do not contribute to the measured HSFs. Unlike licensed medication, street BZDs are manufactured with little regard for quality control and are frequently cut with over-the-counter painkillers including paracetamol and ibuprofen, in addition to stimulants such as caffeine . Many of these adulterants contain conjugated ring structures that are known to exhibit intrinsic fluorescence , therefore, we sought to examine the potential impact of these compounds on benzodiazepine FSF. Figures show the resultant FSFs of 1mg/mL diazepam tablet extract combined with caffeine, paracetamol, and ibuprofen. The ratio of cutting agents to benzodiazepine is typical of what could be expected for a street tablet (~20:1), excluding caffeine which was added at a lower concentration owing to solubility in EtOH, recapitulating realistic extraction from street tablet material . Diazepam fluorescence is readily resolved across these samples where emission contributions from caffeine, paracetamol (λex 275nm, λem = 310 nm) and ibuprofen (λex 265, 275, 285 nm, λem = 290 nm) are also partially preserved. In Figures and, we show how the spectral features of clobazam, are also resolved in the presence of diazepam. These data highlight that spectral features arising from the presence of multiple fluorescent species within a scanned sample are generally additive in nature. We therefore posit that positive identification of multiple benzodiazepines is essentially additive with additional emissive compounds, the reflected LED light varies in a more complex manner. Moreover, we do not anticipate that it will always be the case that emission spectra will be additive, and so we advocate for careful analysis of known contaminants and likely, or observed mixtures. Discrimination of complex drug mixtures beyond BZDs.