Alan R. Hayman

Physicochemical characterization and dissolution properties of meloxicam-cyclodextrin binary systems.

The objective of the work is physicochemical characterization of meloxicam (ME)-cyclodextrin (CD) binary systems both in solution and solid states and to improve the dissolution properties of meloxicam via complexation with alpha-, beta- and gamma-cyclodextrins. Detection of inclusion complexation was done in solution state by means of phase solubility analysis, mass spectrometry and 1H nuclear magnetic resonance (NMR) studies, and in solid state using differential scanning calorimetry (DSC), powder X-ray diffractometry, and in vitro dissolution studies. Phase solubility, mass spectrometry and 1H NMR studies in solution state revealed 1:1M complexation of meloxicam with all CDs. A true inclusion of ME with gamma-CD at 1:1 and 1:2M in solid state was confirmed by DSC, powder XRD and scanning electron microscopy (SEM) studies. Dissolution properties of ME-CDs binary systems were superior when compared to pure ME.

Physicochemical characterization and dissolution properties of nimesulide-cyclodextrin binary systems

The objective of this work is physicochemical characterization of nimesulide-cyclodextrin binary systems both in solution and solid state and to improve the dissolution properties of nimesulide (N) via complexation with α-, β, and γ-cyclodextrins (CDs). Detection of inclusion complexation was done in solution by means of phase solubility analysis, mass spectrometry, and 1H nuclear magnetic resonance (1H-NMR) spectroscopic studies, and in solid state using differential scanning calorimetry (DSC), powder x-ray diffractometry (X-RD), scanning electron microscopy (SEM), and in vitro dissolution studies. Phase solubility, mass spectrometry and 1H-NMR studies in solution revealed 1∶1 M complexation of N with all CDs. A true inclusion of N with β-CD at 1∶2 M in solid state was confirmed by DSC, powder X-RD and SEM studies. Dissolution properties of N-CD binary systems were superior when compared to pure N.

Super-Microporous Silicate Molecular Sieves

A new synthesis of supermicroporous silica (1.6–2.0 nm diameter), using micelles of a quaternary ω-hydroxyalkylammonium salt, is presented by the authors. The material exhibits highly ordered pore arrays (see Figure). Details on pore size determination by adsorption techniques are given. In an outlook, the effects of template chain length and of Al or Ti doping (catalytic centers) on pore size and array stability are discussed.

Correlation of geographical location with stable isotope values of hydrogen and carbon of fatty acids from New Zealand milk and bulk milk powder.

The aim of this study was to investigate the correlation of δ²H and δ¹³C of bulk milk powder and milk powder fatty acids to their production region. A total of 46 milk powder samples from across New Zealand were collected and analyzed. Principal component analysis (PCA) showed that the δ²H and δ¹³C of four fatty acids (C4:0, C14:0, C16:0, C18:1) and bulk milk powder were found to be correlated with regional production area. Linear discriminant analysis (LDA) models were prepared using different combinations of bulk and fatty acid δ²H and δ¹³C. All models were effective in discriminating samples from the North and South Islands. The LDA model using just fatty acid δ²H and δ¹³C provided the best separation. Therefore, the isotopic composition of the aforementioned fatty acids can be utilized as a good biomarker in milk powder that conveys reliable isotopic information to track milk powders to their regional origin.

Isotope fractionation during precipitation of methamphetamine HCl and discrimination of seized forensic samples

Methamphetamine is a widely abused illicit drug. Increasingly, studies have focused on stable isotope analysis by isotope ratio mass spectrometry (IRMS) to link samples of methamphetamine synthesized together or from the same source of precursor. For this reason, it is important to understand potential sources of isotope fractionation that could cause variability in forensic data sets. In this study, methamphetamine free base samples were synthesized from (-)-ephedrine HCl using the HI/red phosphorus synthetic route and then precipitated as HCl salts by bubbling with HCl gas. The entire sample did not precipitate when first bubbled with gas, and multiple precipitation steps were required. Fractions of precipitate were individually analyzed for delta(13)C, delta(15)N and delta(2)H by IRMS. Both delta(15)N and delta(2)H were found to become more negative, with the heavy isotopes depleted, in successive fractions of precipitate. Homogenizing the precipitate fractions together could eliminate this fractionation. However, in a clandestine situation this fractionation could lead to greater than expected delta(15)N and delta(2)H variability between illicit samples of methamphetamine HCl that have been synthesized from the same sample of ephedrine. This needs to be taken into account when interpreting forensic IRMS data. We also present an analysis of four separate seized case lots of methamphetamine HCl, taking into account the possible sources of fractionation and available intelligence information.

Synthesis of novel super-microporous silicates by ω-hydroxy alkyl ammonium halide bolaform surfactant templating

Abstract Using a new family of ω-hydroxy alkyl ammonium bromide bolaform surfactants as supramolecular templates we have prepared a range of novel templated super-microporous (1.0–2.0 nm) SiO 2 , Al– and Ti–SiO 2 molecular sieve materials. The unique bi-functional molecular structure of the template induces smaller micelle diameters of the template assemblies along with interesting aggregation symmetries. These properties allow templating of porous materials that exhibit technologically important small pore sizes and interesting pore symmetries that bear similarity to Lα, P6 3 /mmc and Mα (cmm) phases.

Juvenile-adult chemical dimorphism in foliage of Dacrydium biforme☆

Abstract Phyllocladene was the major diterpene in 15 specimens of Dacrydium biforme adult foliage. The major sesquiterpenes, which vary considerably in level from tree to tree, have been identified. Juvenile and adult foliage extracts from the same trees differed greatly. 8α-Isopimara-9(11),15-diene was the major diterpene in juvenile foliage. (Z)-5-Ethylidene-2(5H)-furanone was an artefact of steam-distillation of juvenile leaves.

Terpenes of foliage oils fromHalocarpus bidwillii

Abstract A study of the foliage oils of 24 specimens of Halocarpus bidwillii revealed considerable infraspecific variation. The compounds identified comprised two monoterpene hydrocarbons (α-pinene and myrcene), six sesquiterpene hydrocarbons (α-longipinene, longifolene, caryophyllene, germacrene-D, bicyclogermacrene and δ-cadinene), three oxygenated sesquiterpenes (longicamphenylone, spathulenol, and t-cadinol), six diterpene hydrocarbons [8α-isopimara-9(11),15-diene, sclarene, isophyllociadene, isokaurene, phyllocladene and kaurene] and one oxygenated diterpene (kaur-16-en-19-al). Marked differences between the constitution of the mature and juvenile foliage were noted.

Assessing Carbon and Hydrogen Isotopic Fractionation of Diesel Fuel n-alkanes During Progressive Evaporation

Compound‐specific isotope analysis offers potential for fingerprinting of diesel fuels, however, possible confounding effects of isotopic fractionation due to evaporation need to be assessed. This study measured the fractionation of the stable carbon and hydrogen isotopes in n‐alkane compounds in neat diesel fuel during evaporation. Isotope ratios were measured using a continuous flow gas chromatograph/isotope ratio mass spectrometer. Diesel samples were progressively evaporated at 24 ± 2°C for 21 days. Increasing depletion of deuterium in nC12–nC17 alkanes in the remaining liquid with increasing carbon chain length was observed. Negligible carbon isotope fractionation was observed. Preferential vaporization was measured for the shorter chain n‐alkanes and the trend decreased with increasing chain length. The decrease in δ2H values indicates the preferential vaporization of the isotopically heavier species consistent with available quantitative data for hydrocarbons. These results are most important in the application of stable isotope technology to forensic analysis of diesel.

Significant Determinants of Isotope Composition During HI/Pred Synthesis of Methamphetamine

Methamphetamine HCl was synthesized using three variations of the hydriodic acid/red phosphorus (HI/Pred) synthetic route. A Plackett-Burman experimental design was used to determine how reaction parameters affected the isotopic composition of the product. Isotope ratio mass spectrometry results showed only the source of precursor 13 C was significant in determining product δ 13 C; the manufacturer, reaction temperature, time, scale, and source of HI were not significant. The precursor was also the main determinant of product δ 2 H, with smaller contributions from the HI source for one method. From precursor to product, large δ 2 H depletion occurred for most samples. Deuterium nuclear magnetic resonance spectroscopy ( 2 H NMR) was used to investigate the specific site of this. Significant fraction of deuterium was observed only at the benzylic position, the site of hydrogen addition during synthesis. Methamphetamine synthesized from ephedrine was shown to be depleted in this position.