A fast and convenient sample preparation method for the analysis of cannabinoids in oral fluid

Cannabis is the world's most used illegal drug. The main psychoactive component is ∆-9-tetrahydrocannabinol (THC). To aid identification of cannabis-impaired individuals, a simple but effective workflow for reliable quantification of THC and its metabolites in oral fluid samples collected with the Greiner Bio-One Saliva Collection System is presented. Sampling involves rinsing the oral cavity with an extraction solution containing a citrate buffer stimulating salivary flow. Sample processing targeted the cannabinoid fraction interacting with proteins and other insoluble constituents that can be separated by centrifugation. Approximately 50% of the total cannabinoid amount included in oral fluid were recovered from the obtained pellet by extraction with acetonitrile. Liquid chromatography-tandem mass spectrometry was used for cannabinoid quantification. Fitness of the developed workflow for application in forensic and clinical cannabis testing was demonstrated by assessing multiple performance parameters, including selectivity, linearity, limits of quantification (LOQs), accuracy, precision, matrix effects, extraction recoveries, process efficiencies, and stability. Furthermore, sensitivity and specificity of the developed oral fluid-based cannabis test was demonstrated by analysing 195 samples collected either from opioid addicts or persons suspected of driving under the influence of drugs. The accuracy of identifying a person with presence of THC in blood was found to be 97.9%.

Development of a large-scale biocalorimeter to monitor and control bioprocesses

Calorimetry has shown real potential at bench-scale for chemical and biochemical processes. The aim of this work was therefore to scale-up the system by adaptation of a standard commercially available 300-L pilot-scale bioreactor. To achieve this, all heat flows entering or leaving the bioreactor were identified and the necessary instrumentation implemented to enable on-line monitoring and dynamic heat balance estimation. Providing that the signals are sufficiently precise, such a heat balance would enable calculation of the heat released or taken up during an operational (bio)process. Two electrical Wattmeters were developed, the first for determination of the power consumption by the stirrer motor and the second for determination of the power released by an internal calibration heater. Experiments were designed to optimize the temperature controller of the bioreactor such that it was sufficiently rapid so as to enable the heat accumulation terms to be neglected. Further calibration experiments were designed to correlate the measured stirring power to frictional heat losses of the stirrer into the reaction mass. This allows the quantitative measurement of all background heat flows and the on-line quantitative calculation of the (bio)process power. Three test fermentations were then performed with B. sphaericus 1593M, a spore-forming bacterium pathogenic to mosquitoes. A first batch culture was performed on a complex medium, to enable optimization of the calorimeter system. A second batch culture, on defined medium containing three carbon sources, was used to show the fast, accurate response of the heat signal and the ability to perfectly monitor the different growth phases associated with growth on mixed substrates, in particular when carbon sources became depleted. A maximum heat output of 1100 W was measured at the end of the log-phase. A fed-batch culture on the same defined medium was then carried out with the feed rate controlled as a function of the calorimeter signal. A maximum heat output of 2250 W was measured at the end of the first log-phase. This work demonstrates that real-time quantitative calorimetry is not only possible at pilot-scale, but could be readily applied at even larger scales. The technique requires simple, readily available devices for determination of the few necessary heat flows, making it a robust, cost-effective technique for process development and routine monitoring and control of production processes.

Biosurfactants from Bacillus licheniformis: structural analysis and characterization

The surface-active compounds of the strain Bacillus licheniformis were isolated and their structure was elucidated. The high surface-active capacity of the crude extract was basically due to traces of long-chain saturated fatty acids, especially of palmitic and stearic acids, to a mixture of small amounts of hydrocarbons with chain lengths of 20 and 22 carbons, and mainly to appreciable amounts of four slightly different lipopeptides. The lipopeptides were found to be a mixture of four closely related compounds. The lipophilic part consisting of i-, n-C14 or i-, ai-C15 beta-OH fatty acids was linked to the hydrophilic peptide moiety, which contained seven amino acids (Glu, Asp, Val, three Leu and Ile) by a lactone linkage. Fifteen milligrams per litre of the purified lipopeptide product decreased the surface tension of water from 72 mN m-1 to 27 mN m-1, characterizing the product as a powerful surface-active agent that compares favourably to other (bio)surfactants. Antibiotic activity was demonstrated against bacteria and yeasts.