Quantitative analysis of delta9-tetrahydrocannabinol in preserved oral fluid by liquid chromatography-tandem mass spectrometry

A rapid and sensitive method for the analysis of delta9-tetrahydrocannabinol (THC) in preserved oral fluid was developed and fully validated. Oral fluid was collected with the Intercept, a Food and Drug Administration (FDA) approved sampling device that is used on a large scale in the U.S. for workplace drug testing. The method comprised a simple liquid-liquid extraction with hexane, followed by liquid chromatography-tandem mass spectrometry (LC-MS-MS) analysis. Chromatographic separation was achieved using a XTerra MS C18 column, eluted isocratically with 1 mM ammonium formate-methanol (10:90, v/v). Selectivity of the method was achieved by a combination of retention time, and two precursor-product ion transitions. The use of the liquid-liquid extraction was demonstrated to be highly effective and led to significant decreases in the interferences present in the matrix. Validation of the method was performed using both 100 and 500 MicroL of oral fluid. The method was linear over the range investigated (0.5-100 ng/mL and 0. 1-10 ng/mL when 100 and 500 microL, respectively, of oral fluid were used) with an excellent intra-assay and inter-assay precision (relative standard deviations, RSD <6%) for quality control samples spiked at a concentration of 2.5 and 25 ng/mL and 0.5 and 2.5 ng/mL, respectively. Limits of quantification were 0.5 and 0.1 ng/mL when using 100 and 500 microL, respectively. In contrast to existing GC-MS methods, no extensive sample clean-up and time-consuming derivatisation steps were needed. The method was subsequently applied to Intercept samples collected at the roadside and collected during a controlled study with cannabis.     

Degradation of cellulosic key chromophores by ozone: a mechanistic and kinetic study

Cellulose - Chromophores, colored substances of rather high stability that reduce brightness, are present in all kinds of cellulosic products, such as pulp, fibers, aged cellulosic material, and...     

Gas chromatography-mass spectrometry as a tool for estimating odour concentrations of biofilter effluents at aerobic composting and rendering plants

The relationship between chemical concentrations (gas chromatography–mass spectrometry analysis) and odour concentrations (olfactometry) was studied for biofilter emissions from four aerobic vegetable, fruit and garden waste (VFG) composting plants and one animal rendering plant. For the VFG composting plants, the study revealed a good linear relationship of the odour concentration with the total volatile organic compounds (VOC) concentration (R²=0.97, n=16) as well as with the concentration of esters and ketones (R²=0.9, n=19). For biofilter emissions of the animal rendering plant, the total VOC concentration was a poor estimator for odour concentration. However, for this type of odour, concentrations of organic sulphur containing compounds correlated well with odour concentrations (R²=0.94, n=8). The results of the study also showed that the relationship between chemical and odour concentrations is specific for each type of odour and cannot be generalized.     

Explicit portfolio for unit-linked life insurance contracts with surrender option

Introducing a surrender option in unit-linked life insurance contracts leads to a dependence between the surrender time and the financial market. [J. Barbarin, Risk minimizing strategies for life insurance contracts with surrender option, Tech. rep., University of Louvain-La-Neuve, 2007] used a lot of concepts from credit risk to describe the surrender time in order to hedge such types of contracts. The basic assumption made by Barbarin is that the surrender time is not a stopping time with respect to the financial market.The goal of this article is to make the hedging strategies more explicit by introducing concrete processes for the risky asset and by restricting the hazard process to an absolutely continuous process.First, we assume that the risky asset follows a geometric Brownian motion. This extends the theory of [T. Møller, Risk-minimizing hedging strategies for insurance payment processes, Finance and Stochastics 5 (2001) 419–446], in that the random times of payment are not independent of the financial market. Second, the risky asset follows a Lévy process.For both cases, we assume the payment process contains a continuous payment stream until surrender or maturity and a payment at surrender or at maturity, whichever comes first.     

The impact of metrological traceability on the validity of creatinine measurement as an index of renal function

When the calibration of a routine measurement procedure is traced back to metrological higher order, a significant discrepancy can occur between the analytical conditions of the routine measurement and the analytical conditions that were used in the clinical studies upon which the decision-making criteria are based. This can lead to serious interpretation errors with possible dramatic consequences for patients. The calibration of the creatinine Jaffé method is an excellent example of the importance of medical traceability. The compensated Jaffé method correlated accurately with the reference method and the compensated Jaffé creatinine clearance (CrCl), Cockroft and Gault and MDRD with the ⁵¹Cr EDTA clearance. The Schwartz estimate based upon the compensated Jaffé and enzymatic method overestimated, while uncompensated Jaffé slightly underestimated glomerular filtration rate (GFR). The situation in children is complex since serum creatinine concentrations are much lower in infants, rendering tubular secretion relatively more important. Low-molecular weight proteins have been suggested to replace serum creatinine as a marker for GFR. -trace protein, cystatin C, and ₂-microglobulin showed good correlation with GFR. However, care should be taken in patients presenting with some malignant tumors, since significant increases of cystatin C in patients with metastatic melanoma or colorectal cancer has been reported.Presented at the 9th Conference on Quality in the Spotlight, 18-19 March 2004, Antwerp, Belgium     

In Situ Incorporation of Praziquantel in Polymer Microparticles through Suspension Polymerization for Treatment of Schistosomiasis

Schistosomiasis is one of the major public health problems worldwide. Even though this is a common illness among preschool children in poor countries, treatment is carried out mainly through the administration of praziquantel tablets, which has some disadvantages, such as the strong bitter taste. As an alternative to overcome this problem, the development of new encapsulated praziquantel formulations is demanded. For this reason, suspension polymerizations are carried out for the in situ encapsulation of praziquantel into polymer microparticles, using methyl methacrylate (MMA) and cationic compounds (diethylaminoethyl methacrylate, DEAEMA, and dimethylaminoethyl methacrylate, DMAEMA) as comonomers. This technique allows for the preparation of polymer microparticles with high encapsulation efficiencies (>90%) with characteristic sizes ranging from 0.5 to 1500 µm. Drug release profiles show that praziquantel is released from poly(methyl methacrylate) microparticles slowly due to the existence of strong diffusional resistance. On the other hand, the addition of cationic comonomers renders polymer particles sensitive to pH variations, allowing for faster release of praziquantel in acidic environments, as found in the stomach.     

Development of reference materials for microbiological analysis

The reliability of reference materials (RMs) depends on properties such as fitness, robustness, commutability, stability and homogeneity. The development of RMs for microbiological analysis is especially challenged through questions around the stabilisation and recovery of viable cells, the dispersion of precise numbers of cells, matrix effects and, when using molecular techniques, the presence of nucleic acids (e.g. DNA) of dead and live target organisms. However, RMs are indispensable tools for quality control in microbiological analysis. The Institute for Reference Materials and Measurements (IRMM), as part of the European Commission, concentrates its efforts on the development of RMs to support the development, implementation and monitoring of EU legislation. A special focus is given to highly precise RMs for presence/absence and enumeration tests in microbiological food and water analysis. Another group of new RMs certified by the IRMM comprise DNA-based materials to control the identity of micro-organisms in qualitative assays. All of these activities serve to improve quality control in microbiological analysis. Presented at ‘BERM-10’, April 2006, Charleston, SC, USA.