Evaluation of Antipsychotic Drugs’ Stability in Oral Fluid Samples

Antipsychotics have narrow therapeutic windows, and their monitoring in biological fluids is therefore important; consequently, stability in those fluids must be investigated during method development and validation. This work evaluates the stability of chlorpromazine, levomepromazine, cyamemazine, clozapine, haloperidol, and quetiapine in oral fluid (OF) samples, using the dried saliva spots (DSS) sampling approach and gas chromatography coupled to tandem mass spectrometry. Since many parameters can influence the stability of the target analytes, design of experiments was adopted to check the crucial factors that affect that stability in a multivariate fashion. The studied parameters were the presence of preservatives at different concentrations, temperature, light, and time. It was possible to observe that antipsychotic stability improved when OF samples in DSS were stored at 4 °C, with a low ascorbic acid concentration, and in the absence of light. With these conditions, chlorpromazine and quetiapine were stable for 14 days, clozapine and haloperidol were stable for 28 days, levomepromazine remained stable for 44 days, and cyamemazine was stable for the entire monitored period (146 days). This is the first study that evaluates the stability of these antipsychotics in OF samples after application to DSS cards.info:eu-repo/semantics/publishedVersio

Wear behavior of a new composite formulation, with TEOS addition, for abrasive vitrified grinding wheels

Vitrified grinding wheels are used in many manufacturing industries to shape and finish metals and other materials in an efficient way. This work addresses a new approach with the use of tetraethyl orthosilicate solution (TEOS solution or silica sol), as an additive, in vitrified abrasive composites for grinding wheels. Different types of composite were produced using always the same materials and processing methods, but with different TEOS contents. Compared with a reference abrasive grinding wheel, the addition of TEOS promoted an improvement in the abrasive tool performance. The new formulation for vitrified abrasive composites showed better dimensional stability during processing (drying and sintering), and could be applied to the production of grinding tools with high dimensional accuracy. With the addition of 3.75 wt% of TEOS there was an increase in the strength of the matrix bonds. The porosity of the composite increased by 7% (from 43.6 to 46.9%), also improving its wear properties, with the quadrupling of the grinding ratio of the abrasive composite. In addition, the surface roughness of the composite decreased (from Ra = 22.9 to 8.4 μm) allowing to improve the surface finish of the workpieces.This work was supported by Programa Operacional Competitividade e Internacionalização , with the code POCI-01-0247-FEDER-038492. This work was supported by FCT national funds, under the national support to R&D units grant, through the reference project UIDB/04436/ 2020 and UIDP/04436/2020