Determination of fipronil in bovine plasma by solid-phase extraction and liquid chromatography with ultraviolet detection

A fast and efficient method has been developed and validated for the determination of fipronil in bovine plasma. Samples were subjected to solid-phase extraction (SPE) followed by reversed phase liquid chromatography (LC) separation, using acetonitrile/water (60:40 v/v) as the mobile phase with a flow rate of 1.0 mL/min and ultraviolet (UV) detection at 210 nm. Ethiprole was used as the internal standard (IS). The method was found to be linear over the range 5-500 ng/mL (r = 0.999). The limit of quantitation (LOQ) was validated at 5 ng/mL. The method was successfully applied to monitor plasma concentrations following subcutaneous administration of fipronil in cattle

Simple high performance liquid chromatography method for determination of benzalkonium chloride homologues in nasal preparations

A High-Performance Liquid Chromatography method was developed for quantification of benzalkonium chloride (BAC) and separation of three major homologues, in nasal preparations. Chromatography separation was carried out on a CLC-cyano column, using 0.075M acetate buffer with acetonitrile (45:55, v/v) pH = 5.0, as mobile phase, in an isocratic elution. The total run time was 20 min at a flow rate of 1.0 mL/min. The retention times were of 10.0, 12.8 and 16.1 min, respectively, for homologs C12 , C14 and C16 of benzalkonium chloride. About precision, the method presented excellent repeatability and satisfactory precision intermediate, and the coefficients of variation found were 1.73 and 4.51%, respectively. The accuracy values were ranging from 100.86 to 110.99%. The lower limits of quantification and detection were 5 μg/mL and 2.5 μg/mL, respectively. Two out of seven analyzed lots contained less BAC than allowed.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Raman-scattered laser guide-star photons to monitor the scatter of astronomical telescope mirrors

The first observations of laser guide-star photons that are Raman-scattered by air molecules above the Very Large Telescope (VLT) were reported in June 2017. The initial detection came from the Multi-Unit Spectroscopic Explorer (MUSE) optical integral field spectrograph, following the installation of the 4 Laser Guide Star Facility (4LGSF) on Unit Telescope 4 (UT4) of the VLT. In this Letter, we delve further into the symbiotic relationship between the 4LGSF laser guide-star system, the UT4 telescope, and MUSE by monitoring the spectral contamination of MUSE observations by Raman photons over a 27-month period. This dataset reveals that dust particles deposited on the primary and tertiary mirrors of UT4, which are responsible for a reflectivity loss of ∼8% at 6000 Å, contribute (60 ± 5)% to the laser line fluxes detected by MUSE. The flux of Raman lines, which contaminates scientific observations that are acquired with optical spectrographs, thus provides a new, non-invasive means to monitor the evolving scatter properties of the mirrors of astronomical telescopes that are equipped with laser guide-star systems