Determination of several psychiatric drugs in whole blood using capillary gas-liquid chromatography with nitrogen phosphorus detection: comparison of two solid phase extraction procedures

A simple and reliable gas chromatographic method with nitrogen-phosphorus detection without derivatization was developed for the detection of several psychiatric drugs in whole blood as part of systematic toxicological analyses (STA). Drugs included mirtazapine, chlorpromazine, methotrimeprazine (levomepromazine), clothiapine, olanzapine, clozapine, haloperidol, and thioridazine. All drugs were studied at concentrations of 100-2,000 microg/L, except haloperidol that was studied at concentrations of 400-8,000 microg/L. In order to select the best blood purification procedure and therefore increase the signal to noise ratio we have compared two solid-phase extraction (SPE) columns, Chem Elut and Bond Elut Certify, for their recovery, precision, sensitivity and matrix purification efficiency. Recoveries for these drugs using Chem Elut columns at 500 and 2,000 microg/L (2,000 and 8,000 microg/L for haloperidol) were in the range 21-65%, with intra-assay and inter-assay precisions of less than 17% and 19%, respectively. Limits of detection (LODs) and limits of quantitation (LOQs) for mirtazapine, chlorpromazine, methotrimeprazine, clothiapine, olanzapine, clozapine, and thioridazine ranged from 62 to 161 microg/L and from 205 to 531 microg/L, respectively. LOD and LOQ for haloperidol were 442 and 1,458 microg/L, respectively. Recoveries of these compounds using Bond Elut Certify columns at 500 and 2,000 microg/L (2,000 and 8,000 microg/L for haloperidol) were in the range 44-97%, with intra-assay and inter-assay precisions of less than 7% and 14%, respectively. LODs and LOQs for mirtazapine, chlorpromazine, methotrimeprazine, clothiapine, olanzapine, clozapine, and thioridazine ranged from 37 to 66 microg/L and from 122 to 218 microg/L, respectively. LOD and LOQ for haloperidol were 156 and 515 microg/L, respectively. Linearity was observed in the studied range for all compounds with r(2) values of >0.999. The use of the mixed-mode bonded-silica Bond Elut Certify columns showed advantages comparing with Chem Elut columns for the screening of these psychotropic agents such as higher recoveries, cleaner extracts, better sensitivity, better precision and less solvent consumption and subsequent disposal.     

Tacit Collusion in the Frequently Repeated Multi-Unit Uniform Price Auction for Wholesale Electricity in England and Wales

Tacit collusion between National Power and PowerGen, the dominant generators in England and Wales for most of the 1990s, was widely speculated but was not definitively proven. In the event of a legal determination, the best available evidence is a test of suspicious patterns of bidding behavior. The methodology has two stages: the first is to show that the suspects behave differently from the rest, which are assumed competitive; the second stage is to ask whether or not strategies of suspects affect one another. Results: the impact of suspects on the aggregate bid function can not be explained away by costs and common market events, and a seemingly unrelated regression (SUR) on strategies of the suspects reveals bid inter-dependence and co-ordination on demand trends. A quarter of the dynamic indicators support an inference of tacit collusion. The existence of multiple equilibria in supergames, however, prevents a conclusive statement.     

Unveiling the Price of Obscenity: Evidence From Closing Prostitution Windows in Amsterdam

Does legitimating sinful activities have a cost? This paper examines the relationship between housing demand and overt prostitution in Amsterdam. In our empirical design, we exploit the spatial discontinuity in the location of brothel windows created by canals, combined with a policy that forcibly closed some of the windows near these canals. To pin down their effect on housing prices, we apply a difference-in-discontinuity (DiD) estimator, which controls for the precise location of brothel windows and the effect of other policies and local developments. Our results show that the housing prices are discontinuous at the bordering canals, and this discontinuity nearly disappears after closures. The discontinuity is also found to decrease with the distance to brothels, disappearing after 300 yards. Our estimates indicate that homes right next to sex workers were 30 percent cheaper before the closures. This result seems unrelated to the presence of other businesses, such as bars and cannabis shops. Instead, the price discount is partly explained by petty crimes. However, 73 percent of the effect remains unexplained after controlling for many forms of crime and risk perception. Our findings suggest that households tend to be against the visible presence of sex workers and related nuisances, reaffirming their marginalization.