Robert Linke | PubMed Health

PubMed2004

Trimethylsulfonium hydroxide as derivatization reagent for the chemical investigation of drying oils in works of art by gas chromatography.

A procedure for the determination of fatty acids (FA) and glycerol in oils has been developed. The method includes a derivatization step of the FAs into their methyl esters or a transesterification of the triacylglycerols with trimethylsulfonium hydroxide (TMSH), respectively. The analysis is carried out by gas chromatography with parallel flame ionization and mass spectrometric detection. The parameters involved in the transesterification reaction were optimized. Only the stoichiometric ratio of TMSH:total FA amount showed a significant influence on the reaction yield. Relative standard deviations for 10 replicates were below 3% for all FAs studied and their linearity range was 0.5-50 mmol/L, when using heptadecanoic acid as an internal standard. The final procedure was rapid and required little sample handling. It was then tested on fresh oil samples and presented satisfying results, in agreement with previous works.

Art↗

PubMed2002

Multislice computed tomographic imaging in temporal bone dysplasia.

OBJECTIVES: To evaluate the impact of multislice computed tomographic (MSCT) imaging, a recently developed computed tomographic technique, on imaging of temporal bone malformations. STUDY DESIGN: Retrospective case review. SETTING: The study was performed at a tertiary referral center. PATIENTS: High-resolution temporal bone studies of 168 consecutive patients were reviewed for various temporal bone malformations. MAIN OUTCOME MEASURES: Visualization of various dysplastic conditions of the temporal bone without the need for supplementary scan procedures or additional imaging techniques. INTERVENTION: MSCT imaging was performed on a scanner with four detector rows by using the following parameters: 120 kV, 50 mA/s, 0.5-mm slice thickness, 0.2-mm reconstruction increment, pitch factor of 0.75, and a field of view of 160 mm. Two-dimensional and three-dimensional image reconstructions were performed subsequent to data transfer to a workstation. In one patient suspected of having a vascular dysplasia, high-resolution MSCT imaging was supplemented by multislice computed tomographic angiography. RESULTS Temporal bone dysplasias were encountered in 28 patients (16.7%), affecting the external auditory canal (n = 15), the middle ear (n = 18), the inner ear (n = 5), and the vascular system (n = 3). All temporal bone dysplasias were visualized by two-dimensional and three-dimensional images of excellent detail resolution. In none of the patients were supplementary computed tomographic scans necessary, except for one patient with evidence of an aberrant course of the internal carotid artery. Multislice computed tomographic angiography obviated the need for invasive diagnostic procedures. CONCLUSION: MSCT imaging of the temporal bone allows for comprehensively assessing various dysplasias through high-quality two-dimensional and three-dimensional image reconstructions.

Adolescent↗