An evaluation of low benzoylecgonine concentrations in urine

Abstract

Introduction: In federally-regulated workplace urine drug testing, benzoylecgonine is analyzed
to detect cocaine use. Cocaine has been detected on surfaces of paper currency and school
desks, indicating the possibility of passive exposure. Indeed, benzoylecgonine concentrations
up to 11 ng/mL have been observed in end-of-shift urine samples from individuals working in
forensic laboratories.
Objectives: The aim was to determine the prevalence of benzoylecgonine in urine at
concentrations below the U.S. Department of Health and Human Services (HHS) initial test cutoff
of 150 ng/mL.
Methods: Deidentified negative urine samples (n=2,809) from federally-regulated drug testing
were analyzed using liquid chromatography quadrupole Time-of-Flight mass spectrometry (LCQTOF-
MS). Samples were extracted using mixed mode cation exchange (MCX) solid phase
extraction (SPE) followed by separation on a biphenyl column (Restek Raptor 100x2.1 mm, 1.8 μm).
Data was collected in MSE mode with a Waters Xevo G2-XS. The panel contained 75 analytes,
including common drugs of abuse, emerging drug trends, and prevalent novel psychoactive
substances (NPS). Samples were deemed positive for benzoylecgonine if they met identification
criteria (retention time, accurate mass, fragments present). The estimated limit of detection (LOD)
was 5,000 area counts, corresponding to ~1 ng/mL, depending on the run (range 0.2-4.9 ng/mL).
Semi-quantitative benzoylecgonine concentrations were estimated using area ratios with reference
samples at 5, 10, and 50 ng/mL, included in each run.
Results: In 7.4 million federally-regulated workplace urine specimens tested at HHS-certified
laboratories, the positivity, compared to federal cutoffs, for benzoylecgonine was 0.15% in 2025
(≥150 ng/mL), and the total drug positivity was 2.26%. By comparison, 3.6% (n=100) of the
specimens in this study were positive for benzoylecgonine, using the criteria described above.
While quantifications cannot be made, most estimated concentrations were well below 150 ng/mL.
The median estimated concentration was 4.1 ng/mL with a majority of results (74/100) in the
1-10 ng/mL range.
Discussion: While it is expected that some benzoylecgonine concentrations in urine from people
who use cocaine will be below the 150 ng/mL initial test cutoff, but the positivity in the study is
striking. These results were obtained using significantly more sensitive methods than routinely
used in workplace drug testing. As such methods become increasingly prevalent in post-mortem
and driving under the influence laboratories, forensic toxicologists should consider multiple
possibilities for low benzoylecgonine concentrations in urine.
Most estimated benzoylecgonine concentrations were less than 10 ng/mL (79/100, including 5