Spectral signature drug detection

Description (excerpt)

CROSS-REFERENCE TO RELATED APPLICATIONS The present application claims benefit of priority to U.S. Provisional Patent Application No. 62/042,667, entitled “Drug Detection Using Infrared Light” and filed on Aug. 27, 2014, which is specifically incorporated by reference herein for all that it discloses or teaches. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT This invention was made with government support under NCRADA-NRL-13-534 awarded by The Naval Research Laboratory (NRL). The government has certain rights in the invention. BACKGROUND Drug abuse is costly to society in terms of increased healthcare cost, lost productivity, loss of life, and property damage, for example. Rapid detection of drugs, both legal and illegal, with potential for abuse and/or their corresponding psychoactive compounds within the human body is useful to monitor, deter, and/or reduce drug abuse. A suite of relatively compact and portable devices (e.g., handheld devices) and bench-top devices for breath and blood specimens exists for alcohol detection, monitoring, and measurement within the human body. These devices have been deployed by law enforcement and in workplace environments for decades, with proven results. However, the development of similarly compact, portable, and reliable devices for detecting other drugs with potential for abuse has proven more elusive. At least two challenges for detecting and quantifying various drugs within a human subject are: 1) the relatively low concentration levels present in the human subject after ingestion, inhalation, injection, or other form of entry of the drug into the human subject; and 2) the relative difficulty in discriminating between psychoactive (or parent) drug compounds, which cause impairment of normal activities (e.g., driving) and byproducts or metabolites produced within the body, which may or may not be psychoactive. Liquid or gas chromatography may be capable of meeting these challenges, but is generally limited to use in laboratory environments by trained scientists and is time-consuming and/or costly. Marijuana, for example, is in the midst of a shift from illegal to legal status across the United States and elsewhere around the world. With marijuana's changing legal status brings increased availability and potentially increased risk of abuse, with potentially broad adverse societal impacts. Delta-9-tetrahydrocannabinol (THC) is the primary psychoactive compound responsible for marijuana intoxication, however, the Delta-9-THC level present in a human subject after ingestion of cannabis smoke or cannabis -infused edibles is quite low, often ranging from several nanograms per mL, in the case of blood or saliva, to several picograms per square inch for exhaled breath condensate. Furthermore, the human subject rapidly metabolizes the Delta-9-THC to 11-Hydroxy-Delta-9-THC and 11-nor-9-Carboxy-Delta-9-THC, which possess very similar chemical structures as the Delta-9-THC, but have reduced or non-existent psychoactive effects on the human subject by comparison to Delta-9-THC. There is a need for new methods and devices to detect drugs with the potential for abuse which address some or all of the aforementioned challenges. SUMMARY Implementations described and claimed herein address the foregoing problems by providing an infrared drug detector comprising: a bodily fluid collector directed at a discrete location on a substrate and configured to deposit a bodily fluid specimen on the substrate; an infrared source directed at the discrete location on the substrate and configured to emit a source beam at the bodily fluid specimen; and an infrared detector configured to receive a spectral signature of the bodily fluid specimen following interaction of the bodily fluid specimen with the infrared source beam to detect the presence of an analyte within the bodily fluid specimen. Implementations described and claimed herein address the foregoing problems by further providing a method comprising: depositing a bodily fluid specimen at a discrete location on a substrate; directing an infrared source beam at the discrete location on the substrate; detecting a spectral signature of the bodily fluid specimen on the substrate following interaction of the bodily fluid specimen with the infrared source beam; and identifying one or more analytes within the bodily fluid specimen using the detected spectral signature. Implementations described and claimed herein address the foregoing problems by still further providing a method of infrared drug detection comprising: directing an infrared source beam at a discrete location on a substrate; detecting a control spectral signature of the substrate following interaction of the substrate with the infrared source beam; depositing a bodily fluid specimen at the discrete location on the substrate following detection of the control spectral signature of the substrate; directing the infrared so