USE OF REFRACTOMETRY TO IDENTIFY OPIOID-CONTAINING SOLUTIONS

The purpose of this laboratory study was to assess the value of refrac tometry in identifying the contents of a variety of opioid-containing solutions. A handheld refractometer was used to document the refractio n produced by the undiluted contents of alfentanil, fentanyl, morphine , sufentanil ampoules and by solutions of Ringers lactate, 0.9% saline , 3.3% dextrose in 0.3% saline, and distilled water. Each opioid was t hen serially diluted in serial 1:2, 1:4, and 1:8 dilutions in each of these solutions and the refractions of each determined. Based on this information, blinded identification of various diluted opioid solution s was attempted. Refractometer values for undiluted fentanyl and sufen tanil were identical with those for distilled water. Those for undilut ed alfentanil and morphine were almost identical with each other and w ith I:2 and 1:4 dilutions of either drug in Ringer's lactate or 0.9% s aline. We conclude that refractometry is an unreliable screening metho d to detect tampering with opioid solutions.