Handheld Spatially Offset Raman Spectroscopy for rapid non-invasive detection of ethylene glycol and diethylene glycol in medicinal syrups.

We investigate the potential of Spatially Offset Raman Spectroscopy (SORS) as a rapid, non-invasive screening tool deployable in the field to detect diethylene glycol (DEG) and ethylene glycol (EG) in medicinal syrups within closed containers. Measurements were performed on neat propylene glycol (PG) and glycerol, key components of many medicinal syrups, as well as marketed medicinal syrup formulations spiked with DEG and EG at various concentration levels to assess the technique's limit of detection in real-life samples. SORS was able to detect these down to ∼0.5 % concentration level in neat PG for both DEG and EG compounds and ∼1 % concentration level for DEG and EG in neat glycerol. The DEG and EG detection thresholds for the marketed formulations measured through original bottles was ∼1 %, for Benylin (active ingredient: Glycerol) and Piriteze (active ingredient: Cetirizine Hydrochloride). For Calpol (active ingredient: Paracetamol) the detection limit was higher, ∼2 % for EG and ∼5 % for DEG. Although not reaching the International Pharmacopeial 0.1 % detection threshold currently required for purity checks for human consumption, the method can still be used to detect products where DEG or EG has been wrongly used instead of PG or glycerol or if present in large quantities. The technique could also be used for raw material identification testing to ensure no mislabelling has occurred in pre-production stages and as a screening device in distribution chains to detect major deviations from permitted content in non-diffusely scattering, clear formulations, to help prevent serious adverse outcomes, such as acute renal failure and deaths.