Detection of Δ9-tetrahydrocannabinol in exhaled breath collected from cannabis users.
Exhaled breath has recently been proposed as a new possible matrix for drugs of abuse testing. A key drug is cannabis, and the present study was aimed at investigating the possibility of detecting tetrahydrocannabinol and tetrahydrocannabinol carboxylic acid in exhaled breath after cannabis smoking. Exhaled breath was sampled from 10 regular cannabis users and 8 controls by directing the exhaled breath by suction through an Empore C(18) disk. The disk was extracted with hexane/ethyl acetate, and the resulting extract was evaporated to dryness and redissolved in 100 μL hexane/ethyl acetate. A 3-μL aliquot was injected onto the LC-MS-MS system and analyzed using positive electrospray ionization and selected reaction monitoring. In samples collected 1-12 h after cannabis smoking, tetrahydrocannabinol was detected in all 10 subjects. The rate of excretion was between 9.0 and 77.3 pg/min. Identification of tetrahydrocannabinol was based on correct retention time relative to tetrahydrocannabinol-d(3) and correct product ion ratio. In three samples, peaks were observed for tetrahydrocannabinol carboxylic acid, but these did not fulfill identification criteria. Neither tetrahydrocannabinol or tetrahydrocannabinol carboxylic acid was detected in the controls. These results confirm older reports that tetrahydrocannabinol is present in exhaled breath following cannabis smoking and extend the detection time from minutes to hours. The results further support the idea that exhaled breath is a promising matrix for drugs-of-abuse testing.
Drug abuse screening with exhaled breath and oral fluid in adults with substance use disorder.
In the treatment of substance use disorder, regular laboratory-based testing has the dual purpose of monitoring compliance with the prescribed medication and abstention from medically non-motivated substances (ie, drug abuse screening). The principal specimen for testing is urine, but collection of urine has some disadvantages, for example being more time-consuming and more intrusive compared to other matrices. There is also the risk of adulteration. This project compared exhaled breath and oral fluid as alternative matrices for drug abuse screening in patients with substance use disorder. All 51 subjects included in the study were enrolled at the Drug Addiction Emergency Unit in Stockholm. Exhaled breath, oral fluid, and urine samples were collected together with a self-report. Of all 117 self-reported drug intakes during the previous week, 72% were confirmed in urine, 73% in oral fluid and 39% in exhaled breath. In 31% of the subjects, additional substances other than those self-reported were detected analytically. For substance abuse screening, urine had the highest detection rate for buprenorphine, cannabis, and benzodiazepines, while oral fluid had the highest detection rate for amphetamines and methadone. Exhaled breath showed the highest detection rate of all matrices for cocaine. To identify significant differences in detection rates between the matrices future studies with larger sampling sizes are needed. Both oral fluid and exhaled breath are viable alternative specimens to urine, depending on the circumstances and purpose of the testing.
Photoinduced spin-state transition of Co3+ in the layered perovskite manganite thin film
The photoinduced effect, at different temperatures, on layered perovskite manganite La1.2Sr1.8Mn1.8Co0.2O7 thin film deposited on a SrTiO3(100) substrate has been studied using a He–Ne laser (632.8 nm) with the power of output 25 mW at low temperatures. The electrical transport and magnetic properties of the film are investigated systematically in the temperature region from 20 to 300 K. The resistance shows a significant decrease at low temperatures (T<90 K) under laser irradiation, which can be interpreted in terms of the spin-state transition of Co3+ ions. The magnetic field combined with the laser is also used to detect the photoinduced effect of the spin-glass state. The time dependence of the metastable system under several applied fields was also discussed. The system has the ability to keep a persistent memory of the magnetic history imprinted in its zero-field resistance.