Douglas E. Raynie

Kinetic performance comparison of a capillary monolithic and a fused-core column in micro-scale liquid chromatography.

The kinetic performance of monolithic and fused-core capillary C(18) columns was compared in isocratic-elution liquid chromatography. Heptanophenone was chosen as a test compound. The (u(0), H) couple obtained in a column with permeability K(v0) was transferred into a plate number, dead time (N, t(0)) couple and the kinetic plots were achieved by using a Kinetic Method Plot Analyzer template. The u(0,opt) (0.98 mm/s for the monolith and 1.05 mm/s for the fused-core column) and H(min) (17.58 μm for the monolith and 18.08 μm for the fused-core column) values determined from the van Deemter curve were found to be almost identical, whereas the N(opt) (the plate number for which the support achieves its best analysis time/pressure cost ratio) (150,000 for monolith and 41,000 for fused-core column), maximal plate number, N(max) (the maximum plate number that can ever be reached with a support) (550,000 for monolith and 120,000 for the fused-core column) and optimal analysis time, t(opt) (the time needed to obtain N(opt) plates) (18,583 s for the monolith and 4,068 s for the fused-core column) performance numbers determined from the kinetic plots were found to be significantly different.

Evaluation of microbore and packed capillary column chromatography with an ethylvinylbenzene-divinylbenzene polymeric packing material and supercritical ammonia as the mobile phase

Abstract An investigation into the use of ammonia as a mobile phase for high-resolution supercritical fluid chromatography was conducted. A highly cross-linked ethylvinylbenzene—divinylbenzene polymeric packing material (5-μm diameter) in microbore stainless-steel and nickel capillary tubing demonstrated reasonable efficiencies ( ca. 10 000–15 000 plates m −1 , after initial exposure to ammonia) without phase degradation as previously observed when using open-tubular capillary columns. However, ammonia treatment caused an initial rapid loss in efficiency ( ca. 42%) for reasons as yet undetermined. The polymeric packing materials were much more inert than conventional silica-based packing materials. Separations of polar drugs, underivatized amino acids and defoliant herbicides are shown.

Alkaloids of Arctomecon species (Papaveraceae). 12-methoxyallocryptopine, a new protopine-type alkaloid

Abstract The alkaloid content was determined, mainly by GCMS, for three rare western United States species of the Papaveraceae: Arctomecon californica, A. humilis and A. merriamii . Allocryptopine and protopine were major alkaloids in all species, along with lesser quantities of a new alkaloid, 12-methoxyallocryptopine. Eleven other alkaloids, especially benzophenanthridines, were detected in minor amounts. The pattern of alkaloid structures in Arctomecon , one of the few remaining genera of the Papaveraceae left to be studied in detail, is briefly discussed.

Models for integrating toxicology concepts into chemistry courses and programs

ABSTRACT Toxicology and related concepts are being taught within chemistry education programs to enable students to (1) develop an awareness of toxicological principles and concepts that are otherwise absent from the chemistry curriculum for undergraduates and (2) design chemical products and processes that have reduced health and environmental hazards. This manuscript presents three model courses from different higher education institutions, presenting different approaches for introducing toxicology concepts to students. The models are presented not as prescriptive approaches, but as inspirational models for others to use to generate their own unique approaches to integrating and teaching toxicology concepts. GRAPHICAL ABSTRACT

Compositional Analysis of Microwave Chemically Treated Biomass Samples

The compositional analysis of slurries generated from the microwave-assisted pretreatment of switchgrass, prairie cordgrass, and distillers dried grains with solubles were investigated. The biomass samples were treated under acidic, alkali or neutral conditions at 1200 W and 200°C for 10 min. The supernatants were analyzed for sugars, whereas the compositional analysis of the remaining solid fractions was performed using an integrated scheme based on the Standard Laboratory Analytical Procedures for raw biomass developed at the National Renewable Energy Laboratory. The experimental results show that little to no arabinose was found in these treated substrates. Substrates treated under alkaline conditions resulted in the highest carbohydrate content with the lowest lignin amount, whereas acidic pretreatments with 0.5 % H2SO4 resulted in hemicellulose-free biomass. A minute amount of hemicellulose was still present in prairie cordgrass and switchgrass after treatment with 0.2 % H2SO4 and this amount increased for pretreatments with H2O and 0.3 % H2O2. Pretreatments under alkaline conditions with 1 % NaOH were the least aggressive treatments methods because they retained the most carbohydrates in the biomass pulp while having the lowest lignin amount.

15 Method development for biomolecules

Abstract Various modes of high-performance liquid chromatography (HPLC) are often applied to the separation of large biomolecules, including reversed-phase liquid chromatography (RPLC), hydrophobic interaction chromatography (HIC), ion-exchange chromatography (IEC), and size-exclusion chromatography (SEC). Sample complexity not only makes these separations difficult but also renders HPLC method development an arduous task. At best, the bioanalyst must first use knowledge of the sample to decide the separation goals, and then a separation mode can be selected. Once the separation mode is chosen, specific method development steps are often little more than trial and error. While general HPLC method development guidelines are a useful starting place, additional characteristics that must be considered are presented. We discuss the varying nature of biomolecule sample properties and the role of solute hydrophobicity in achieving adequate liquid chromatography (LC) resolution in each of the common modes of LC. Emphasis is placed on the separation of peptides and proteins for purely analytical (rather than preparative) purposes.