High oven temperature — cold on-column injection for the automated CGC analysis of high molecular weight compounds such as triglycerides

Modification of the Carlo-Erba cold on-column injector for (automated) analysis of high molecular compounds at high oven temperature is described. The secondary cooling tube of the cold on-column injector is replaced by a lengthened tube through which a high air flow is directed. The injection site is maintained at 65–70 °C while the oven is at high temperature (? 300 °C). For automated injection, a short deactivated precolumn of 22 to 30 cm × 0.53 mm i.d. is coupled to the analytical column via a butt connector with make-up gas supply. For a triglyceride mixture, automatically injected at 300 °C, the mean % deviation for all peak areas was 1.8% and the mean % deviation for all retention times was 0.09 % for five consecutive runs.     

Some considerations to optimize the synthesis procedure and the structural quality of mesostructured silicas

Two methods for the preparation of highly ordered MCM-41 silica are discussed. The quality of the structure was optimized by adequate stirring of the reaction mixture containing low concentration of surfactant, followed by heating at 70 °C for 3 h under stirring. Besides this energetically favorable procedure allowed to obtain structures very stable upon calcination. The role of the ethanol and the hydroxide source in the synthesis process is also analyzed.     

Catalytic asymmetric hydrosilylation of acetophenone with new chiral thiourea ligands containing the (S)-α-phenylethyl group

New chiral thioureas 1–8 containing 1,2-ethylendiamine or trans-1,2-diaminocyclohexane as the carbon skeleton, and containing an (S)-α-phenylethyl group have been prepared (79–98% yield). Thioureas 1–8 were used as ligands for the zinc-based catalyzed asymmetric hydrosilylation of acetophenone with polymethylhydrosiloxane (PMHS). The best result was achieved with monothiourea 1 (up to 75% ee), in toluene and a catalyst load of 5 mol %.     

Determination of organometallic compounds in surface water and sediment samples with SPME-CGC-ICPMS

Organometal compounds of tin, mercury and lead were simultaneously determined in environmental water and sediment samples by CGC-ICPMS. Instead of classical liquid/liquid extractions, solid phase microextraction was used as sampling technique. In this method, the organometallic compounds arein situ derivatised in the aqueous phase and simultaneously extracted onto a polydimethylsiloxane fiber, so that organic solvents are no longer necessary. The sorbed organometals are subsequently released from the fiber in the GC injection liner by thermal desorption. By sampling from the headspace, only the species of interest are sampled and no interfering matrix components are coextracted. With this new method, derivatisation, extraction, preconcentration and injection into the GC takes only 10 min with a minimum of handling steps. Owing to the very low detection limits (0.13–3.7 ng/1 as metal) only small sample amounts (25 ml of water, 0.5 g of sediment) are needed for one analysis. Finally, SPME is an inexpensive sampling technique that can be used with standard split/splitless injection systems.     

Preparation of polymandelide by reaction of α-bromophenylacetic acid and triethylamine

Polymandelide was prepared in 77% yield by reaction of α-bromophenylacetic acid and triethylamine. The product was characterized by ¹H- and ¹³C-NMR and IR spectra and isolation and identification of mandelic acid from hydrolysis of the polymer. The NMR spectra indicate the presence of tacticity at CH in the polymer. Molecular weights were determined by GPC and viscosity measurements; n values of 12–20 are comparable to those reported for polymandelides prepared by other methods. The x-ray powder diffraction pattern showed the product to be completely amorphous. Thermal decomposition was studied using DSC.     

Surface characterization of a cross‐linked cytochrome c film on cysteamine‐modified gold electrodes

The aim of the present paper is to characterize a cross‐linked horse heart cytochrome c (HHC) film on cysteamine‐modified gold electrodes. The HHC film was deposited using 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) as a coupling agent. Attenuated total reflection infrared (ATR‐IR) spectroscopic analyses were performed to characterize the newly formed surface on a qualitative and conformational level. The film thickness was measured using a noncontact optical surface profiler, while quantitative data and information on the heterogeneity of the film were obtained by means of synchrotron radiation X‐ray micro fluorescence (SR micro‐XRF). Results indicate that, in addition to electrochemical studies, spectroscopic analysis methods are essential to gain insight in the effect of immobilization strategies on protein conformations. The latter is of relevance in the development and optimization of biosensors. Copyright © 2009 John Wiley & Sons, Ltd.