High-performance liquid chromatographic determination of morphine and its 3- and 6-glucuronide metabolites: improvements to the method and application to stability studies

Improvements to previously reported methods for the determination of morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in human plasma are described. The improved methods involve the use of a solid-phase extraction cartridge and a chromatographic system which uses paired-ion reversed-phase high-performance liquid chromatography with a radially compressed column. Only one cartridge is used to prepare each sample for chromatography and each cartridge may be used for at least fourteen 1-ml plasma samples. The recovery is greater than 85%. The improvements to the method of sample pretreatment and in the chromatographic conditions have allowed determination of morphine, M3G and M6G in human plasma down to 13.3 nmol/l (coefficient of variation = 9.3%), 108 nmol/l (6.6%) and 41 nmol/l (6.7%), respectively, using ultraviolet detection alone. It was shown that all three compounds were stable in plasma for up to 101 weeks when stored at -20 degrees C.     

Elucidating the mode of action of a corrosion inhibitor for iron

Two polymetallic iron(III) complexes 1 and 2 have been synthesised from the known corrosion inhibitor 3-(4-methylbenzoyl)-propionic acid HL1 and their crystal structures determined. Coordination geometries extracted from these structures have been used as the basis for molecular modelling onto idealised iron(III) oxide surfaces as an aid to understanding the efficacy of inhibitors of the 4-keto acid type. The proposed mode of action involves 1,3-bridging didentate coordination of the carboxylate function of L1 to two FeIII ions, hydrogen-bond formation between the 4-keto group of L1 and a bridging surface hydroxy group, as well as close packing of the aromatic end groups, which should generate a hydrophobic barrier on the surface. Adsorption isotherm experiments have been used to compare the strengths of binding of related carboxylic acids onto iron(III) oxide surfaces and indicate that the presence of the 4-keto function leads to the formation of significantly more stable surface complexes.     

Simple method for the assay of linezolid in Brain Heart Infusion broth by high-performance liquid chromatography

A simple HPLC method was developed and validated for quantification of linezolid in Brain Heart Infusion (BHI) broth. Eperezolid was employed as internal standard and the sample pre-treatment procedure was simple. Calibration standards ranged from 0.05 to 16 mg/L. Accuracy was within 7.8% and reproducibility (RSD) was less than 8.3%. Recovery was approximately 100% at all concentrations examined. Linezolid was stable in the autosampler insert for at least 24 h at ambient temperature and in BHI for 72 h at 37 degrees C. This assay is rapid and ideal for analysis of a large number of samples.     

Electron beam generation using a ferroelectric cathode

Data is presented on the production of electron beams from a ferroelectric cathode at voltages of order 0.5 MV and current densities of order 100 A/cm². In comparison with data at lower voltages, the beam current scales as the three-halves-power of the voltage. An interpretation of the voltage dependent scaling, based on the coupling of electrostatic energy from the ferroelectric to the gun, is presented     

Results from an X-band coaxial extended length cavity

Experiments and simulations demonstrate high-power microwave generation at 9 GHz in a coaxial geometry. The 9 cm diameter annular electron beam is propagated between inner and outer drift tube conductors, a configuration which increases the beam current and reduces the structure fields from existing high-power sources, Since the TEM mode of the coaxial guide reduces the quality factor of small-gap cavities, especially at high frequency, the interaction is provided by an extended length cavity loaded with dielectric. A single 16 cm cavity generates 200 MW of power from the 400 keV, 7 kA electron beam. Although the cavity can oscillate at a number of resonances, a single mode is selected with 10-30 kW of input power from a magnetron. A coupler samples 25 MW of the power from the interaction region, precisely measured using a single-shot calorimeter. Simulations indicate that the efficiency of the device is limited to 7% by saturation effects, and can be improved by reducing the length of the cavity     

Inflation of Finite Lattices Along All-or-nothing Sets

We introduce a new generalization of Alan Day’s doubling construction. For ordered sets \(\mathcal {L}\) and \(\mathcal {K}\) and a subset \(E \subseteq \ \leq _{\mathcal {L}}\) we define the ordered set \(\mathcal {L} \star _{E} \mathcal {K}\) arising from inflation of \(\mathcal {L}\) along E by \(\mathcal {K}\). Under the restriction that \(\mathcal {L}\) and \(\mathcal {K}\) are finite lattices, we find those subsets \(E \subseteq \ \leq _{\mathcal {L}}\) such that the ordered set \(\mathcal {L} \star _{E} \mathcal {K}\) is a lattice. Finite lattices that can be constructed in this way are classified in terms of their congruence lattices.A finite lattice is binary cut-through codable if and only if there exists a 0?1 spanning chain \(\left \{\theta _{i}\colon 0 \leq i \leq n \right \}\) in \(Con(\mathcal {L})\) such that the cardinality of the largest block of ?? _i /?? _i?1 is 2 for every i with 1≤i≤n. These are exactly the lattices that can be constructed by inflation from the 1-element lattice using only the 2-element lattice. We investigate the structure of binary cut-through codable lattices and describe an infinite class of lattices that generate binary cut-through codable varieties.     

Alan Day's doubling construction

Presented by J. Sichler.