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Journal Article


Nickley J, Pesce AJ, Krock K. Drug Test. Anal. 2016; 9(8): 1214-1216.


Precision Diagnostics LLC, Laboratory, San Diego, California.


(Copyright © 2016, John Wiley and Sons)






Cocaine is a common drug of abuse. To detect its use, a screening detection concentration for the cocaine metabolite benzoylecgonine is commonly set at 150 ng/mL and its confirmatory cutoff is set at 100 ng/mL [1]. Studies have suggested that these cutoffs may be set too high, allowing some patients with this substance abuse problem to be missed [2,3] or improperly monitored. With the advent of LC-MS/MS technology it is possible to reliably detect and quantify lower concentrations of its metabolite benzoylecgonine [4] as part of a larger drug panel. One purpose of the study was to establish if there was a significant increase in detection of cocaine use with a tenfold more sensitive cutoff. A very sensitive dilute and shoot assay for benzoylecgonine was developed with a lower limit of quantitation of 5 ng/mL. Validation of the 5 ng/mL cutoff was achieved by plotting all the positive cocaine observations as a frequency distribution on a logarithmic scale. The number of positive results with measurable concentrations below the typical industry 100 ng/mL cutoff level but above the high sensitivity 5 ng/mL cutoff level was observed to be 51.9% of the observed positives. The lower cutoff also allowed a re-evaluation of the window of detection after cessation of use. It was observed to be between 17 to 22 days.

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Language: en


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