Use a Refractometer to Validate Narcotic Waste

October 2019 - Vol. 16 No. 10 - Page #8

Identifying and preventing diversion are critical responsibilities of every health system. Ascertaining whether controlled substance waste has been tampered with is a particularly effective method of detecting possible diversion. Adopting a refractometer to reveal tampering is a useful strategy to enhance a facility’s diversion prevention efforts.

Essentia Health is an integrated health system serving patients in Minnesota, Wisconsin, North Dakota, and Idaho. Headquartered in Duluth, Minnesota, Essentia Health has 14,400 employees, including more than 2000 physicians and advanced practitioners. The organization operates 15 hospitals, 76 clinics, six long-term care facilities, three assisted living facilities, three independent living facilities, five ambulance services, and one research institute. Essentia Health St. Mary’s-Detroit Lakes, a 34-bed hospital and Level III trauma center, has been using refractometry on a regular basis for more than 20 years to detect tampering of medication waste.

Detecting Diversion Using Refractometry

All witnessed waste is returned to pharmacy via the return bins, and samples are screened via refractometry prior to proper disposal. Pharmacy utilizes a handheld, digital refractometer on 2 random days each week to sample controlled substance waste; approximately 25% of our total controlled substance waste transactions are sampled. Waste is screened for evidence of tampering from locations throughout the hospital, including the emergency room, ICU, medical/surgical units, endocrinology, obstetrics, and the ORs.

Dozens of products can be tested. (See the TABLE for the refractometer sample testing process.) The refractometer is calibrated prior to each test, and it is thoroughly cleaned with alcohol swabs in between each sample tested. When there are non-standard readings or suspicion of possible diversion, the pharmacy manager reviews the results to determine if samples should be sent to an outsourced laboratory for definitive testing. For example, if a product that should test at 1.3 returns a result of 2.0 or even 0, that product is sent to the outsourced laboratory. Approximately 2-3 samples are sent to our contracted lab vendor for definitive testing each month, at a cost of about $100 per sample. When this occurs, the diversion-prevention team is alerted, and a diversion investigation begins.

In one instance, definitive testing for fentanyl, and the ensuing comprehensive diversion investigation, led to the discovery that poor practice was responsible for non-standard test results: The sample had been diluted in the vial prior to administration by EMS personnel. This situation ultimately served as an excellent educational tool to improve practice. After an event such as this, staff may be placed on a watch list for a number of months, wherein their work receives increased scrutiny and all of their waste is tested via refractometry.

Selecting a Refractometer

When choosing a refractometer, the most important considerations are accuracy of the validation and ease of calibration. In addition, robust staff training is critical to proper refractometer use. Our training encompasses calibration steps and the process for internal sampling. Moreover, developing and implementing a refractometer policy and procedure is key to effective use.

Benefits of Refractometer Use

Generally inexpensive, refractometers may provide an economical first line of defense in identifying diversion. In fact, the ASHP guidelines on perioperative pharmacy services, published in June 2019, state that verification of waste content should occur both randomly and when diversion is suspected.1 See the SIDEBAR for more on ASHP’s guidance on refractometer use.

The refractometer has proven to be an effective screening tool at Essentia Health. We have found it to be both accurate and easy to calibrate in addition to successfully identifying suspicious activity. One investigation found that fentanyl waste had been replaced with normal saline, which prompted a full diversion investigation.

Limitations to this Approach

Although an effective screening tool, there are limitations to refractometer use. For example, refractometry alone cannot distinguish between fentanyl and sterile water, as the refractive indices of undiluted fentanyl and water are identical. However, using the refractometer is still useful as many diverters are not aware of this fact and will dilute the fentanyl vial with normal saline, which tests at 1.1, while fentanyl is supposed to test at 0. In this scenario, it is clear the product tested is not fentanyl and adulteration is likely.

When testing a new product that does not yet have a defined refraction, we aim to establish a narrow refraction range, keeping in mind that some lot variability exists. As such, we test multiple vials from different lots of a single manufacturer and then establish the standard deviation from those results. In addition, each strength of a manufacturer’s product must be tested separately.

Finally, it is important to note that although refractometry plays a valuable role in screening for potential diversion, it does not eliminate the need for definitive testing. One of the benefits of definitive testing is that it can be used in court should the need arise.

Results and Future Goals

Looking to the future, we are considering additional uses for the refractometer; for example, the device could be used to validate that sterile compounding techniques are safe and accurate (similar to the idea of utilizing gravimetrics to validate CSPs).

Using a refractometer to validate controlled substance waste has proven extremely beneficial to our diversion-prevention program, as it assists in diversion investigations involving suspicious activity and facilitates additional monitoring of certain individuals. In addition, utilizing refractometry increases our confidence that we are taking proactive steps to identify and prevent diversion within our hospital.


  1. Bickham P, Golembiewski J, Meyer T, et al. ASHP Guidelines on Perioperative Pharmacy Services. Am J Health-System Pharm. 2019;76(12):903-920.

Nicholas Helbling, PharmD, BCPS, is the pharmacy operations senior manager for Essentia Health St. Mary’s-Detroit Lakes inpatient pharmacy in Detroit Lakes, Minnesota. He graduated from North Dakota State University in 2011. Cole’s professional interests include health care administration, project management, and process excellence.


ASHP Guidance on Verifying Waste Content1

A comprehensive and interdisciplinary approach to diversion surveillance for anesthesia should include . . . Verification of waste content by the pharmacy on a random basis and when suspect. Analysis of the contents may be done with the use of a refractometer standard or a spectrophotometric device that measures the refractive index of a substance relative to a reference standard (eg, the dispensed product).

The guidance goes on to state that:

Many refractometers are relatively inexpensive and easy to use . . . however, the refractive index of undiluted fentanyl is identical to that of water, and the diluent can affect the refractive reading of a diluted drug . . . Suspect or random syringes may be definitively analyzed internally or sent to an outside laboratory for analysis. If a controlled substance is sent to a laboratory for analysis, a clear chain of custody for the sample, as well as any required internal standard, must be maintained.


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