Anders Hagman

Analysis of volatile organic compounds in polymers by dynamic headspace—multi-dimensional gas chromatography —mass spectrometry

Abstract The use of dynamic headspace—multi-dimensional gas chromatography—mass spectrometry in studies of volatile organic compounds in plastics is described. The results demonstrate the utility of this technique to increase the resolution of selected compounds, to generate less overlapped mass spectra and to obtain a higher confidence of the analysis results. Some construction features of the laboratory-assembled system are discussed.

Studies on contamination of intravenous solutions from PVC-bags with dynamic headspace GC-MS and LC-diode array techniques

Abstract The contamination of intravenous solutions from PVC-bags was studied by: (1) dynamic headspace GC-MS of the PVC-material; and (2) screening and identification of the impurities in the intravenous solution by gradient liquid chromatography with a diode array UV-detector (LC-UV-DAD). In the study of the PVC-material, the plastic was heated to 120°C for 5–20 min in an oven, conditions similar to the heat sterilization process of the product. The volatile compounds were transferred into a GC-MS system. The intravenous solution in the PVC-bag was studied by injecting 1 ml of the solution into a gradient LC-UV-DAD system. Both studies show that a wide range of compounds including many unidentified are released from the PVC-material. The following compounds have been identified in a brand of Swedish intravenous solutions in 100 ml PVC-bags: di(2-ethylhexyl)phthalate, mono(2-ethylhexyl)phthalate, phthalic acid, 2-ethylhexanol, phthalide, butylhydroxyanisol, benzaldehyde, benzole acid and phenol. In solutions from another manufacturer bisphenol-A and cyclohexanon were detected as well. The components were present at μg/l levels except for cyclohexanon which was in the mg/1 level.

Study of Preprocessing Methods for the Determination of Crystalline Phases in Binary Mixtures of Drug Substances by X-ray Powder Diffraction and Multivariate Calibration:

In this paper, various preprocessing methods were tested on data generated by X-ray powder diffraction (XRPD) in order to enhance the partial least-squares (PLS) regression modeling performance. The preprocessing methods examined were 22 different discrete wavelet transforms, Fourier transform, Savitzky–Golay, orthogonal signal correction (OSC), and combinations of wavelet transform and OSC, and Fourier transform and OSC. Root mean square error of prediction (RMSEP) of an independent test set was used to measure the performance of the various preprocessing methods. The best PLS model was obtained with a wavelet transform (Symmlet 8), which at the same time compressed the data set by a factor of 9.5. With the use of wavelet and X-ray powder diffraction, concentrations of less than 10% of one crystal from could be detected in a binary mixture. The linear range was found to be in the range 10–70% of the crystalline form of phenacetin, although semiquantitative work could be carried out down to a level of approximately 2%. Furthermore, the wavelet-pretreated models were able to handle admixtures and deliberately added noise.

Trapping efficiency of capillary cold traps

Abstract The ability to retain a series of n -alkanes (C 3 C 6 and C 12 ) by cryogenic trapping in different types of simple capillary trap has been studied. The traps were either capillary tube packed with glass beads or open-tubular capillary cold traps. The trapping efficiency was studied as a function of the amount of alkane and the temperature gradient of the trap. The trapping efficiency of open-tubular cold traps is dependent on both these factors, but the packed cold trap retained the alkanes quantitatively.

Thermal degradation of polychlorinated alkanes

Abstract Thermal degradation products of two polychlorinated alkanes (PCA) containing 59 % and 70 % chlorine, respectively, and also a commercial chlorinated paraffin (CP) containing 70 % chlorine were determined by gas chromatography and mass spectrometry. Thermolyses were performed in both inert atmosphere and air at different temperatures and times. Aliphatic and aromatic hydrocarbons and minor amounts of chlorinated substances were identified products of the medium chlorinated PCA. The highly chlorinated PCA and the commercial CP in addition gave products such as polychlorinated benzenes, toluenes, biphenyls and naphthalenes.

Chemical composition analysis of carrageenans by infrared spectroscopy using partial least squares and neural networks

Abstract The use of partial least squares and neural networks is described for the multivariate analysis of the chemical composition of carrageenans by infrared spectroscopy. The content of κ-, ι- and λ-carrageenan is determined in standard mixture samples and in production batches of carrageenans. Various models of PLS and neural networks are examined using a designed ternary mixture of different carrageenan forms and the use of up to 36 independent variables selected from the infrared spectrum of the carrageenans. Both models can be applied for an accurate and rapid chemical composition analysis, although the neural networks model performs slightly better and appears to be more consistent.

Extractive pentafluorobenzylation of formic, acetic, levulinic, benzoic and phthalic acids, studied by liquid chromatography and dual-oven capillary gas chromatography

Abstract Extractive pentafluorobenzylation of different short-chain carboxylic acids, including formic acid and a dicarboxylic acid, phthalic acid, was examined. Extractive alkylations were carried out in two different two-phase systems, viz., dichloro methane-water and methyl isobutyl ketone-water, at a reaction temperature of 25°C. Quantitative yields were obtained within 50 min for both solvent systems, except for phthalic acid, which required an alkylation time exceeding 65 min in the dichloromethane-water system. Extractive pentafluorobenzylation of the monocarboxylic acids followed second-order rate kinetics. The derivatives formed have good liquid and gas chromatographic properties. In order to utilize fully the electron-capture properties of the esters formed, a dual-oven capillary gas chromatographic separation procedure with electron-capture detection was developed.

Applications of Chemometrics for Characterization of Macromolecules

AbstractThe possibilities of employing methods of chemometrics in order to characterize macromolecules are described. The review has been limited to chemometric methods concerning multivariate data analysis. Principal component analysis (PCA) has shown to be very useful for pattern recognition problems arising from chromatographic and spectroscopic data. An example of using a classification technique, SIMCA (Soft Independent Modelling of Class Analogy), as a product control method is presented. The suitability of Partial Least Squares (PLS) for relating data of different natures, e.g. chemical data with biological data, is discussed. Moreover, examples ranging from spectroscopic determinations to QSAR (Quantitative Structure Activity Relationships) are illustrated.

Characterization of Polymers Used as Pharmaceutical Excipients by Dynamic Headspace Gas Chromatography — Mass Spectrometry

AbstractThe use of dynamic headspace, a continuous gas extraction technique, for the analysis of volatile compounds in polymers is discussed. The present work presents the principles of dynamic headspace and its use in combination with capillary gas chromatography - mass spectrometry. The merits of dynamic headspace sampling in comparison to static headspace, the predominantly used headspace sampling method, are also discussed. To illustrate the technique, analyses of volatile compounds in three different carbohydrate polymers, commonly used as pharmaceutical excipients, are carried out.

Rapid reversed-phase high-performance liquid chromatography method for quantitation, at high pH, of the recombinant apolipo-protein A-IMilano in Escherichia coli fermentation broth

An automated reversed-phase high-performance liquid chromatography method for quantitative determination of recombinant apolipoprotein A-IMilano (r-Apo A-IM) in E. coli fermentation broth has been developed and evaluated. The use of a unique matrix (Poros IIR/H) makes it possible to achieve rapid separation and good resolution at high pH. The r-Apo A-IM-containing fraction is well separated from other proteins allowing a reliable quantification. The automation and high sample throughput of this method makes it very useful for routine determination of r-Apo A-IM in fermentation broth and in eluates from the various purfication steps. With suitable modifications and adaptions this method is likely to be useful for similar rapid analytical determination of recombinant proteins in complex solutions.