Trace level detection of select opioids (fentanyl, hydrocodone, oxycodone, and tramadol) in suspect pharmaceutical...

The opioid crisis in the USA has resulted in over 702,000 overdose fatalities between 1999 and 2017 and can be attributed to over-prescription of opioids and abuse of synthetic opioids in combination with other illicit drugs. A rapid and sensitive SERS method has been developed for trace detection of opioids including fentanyl, hydrocodone, oxycodone, and tramadol in low-dosage suspect tablets using two different handheld Raman spectrometers equipped with 785 and 1064 nm lasers. The method involves a micro-extraction procedure using 10% methanol in deionized water, followed by filtration and addition of colloidal silver and aqueous KBr, resulting in a mixture that can be measured directly via a glass vial. The lowest concentration (C_min ) of fentanyl, tramadol, oxycodone, and hydrocodone standards that yielded a positive match was 250 ng/ml, 5, 10, and 10 μg/ml using the 1064 nm laser device and 100 ng/ml, 1 μg/ml, 500 ng/ml, and 750 ng/ml using the 785 nm laser device, respectively. For the analysis of suspect tablets containing these opioids, the C_min ranges between 5 and 75 µg/ml for 1064 nm laser device and 1 and 50 µg/ml for 785 nm laser device. The overall positive identification rate for all the opioids studied in the suspect counterfeit tablets analyzed ranged from 80% to 100%. The use of SERS for rapid chemical identification at remote sampling sites, such as international mail facilities (IMFs) and express courier hubs (ECHs), provides a rugged, simple, and practical method applicable for point-of-entry sampling and analysis.