Bruno Rollmann

Degradation of Poly (isobutyl Cyanoacrylate) Nanoparticles

Poly(isobutyl cyanoacrylate) nanoparticles were prepared. They were degraded in two enzyme-free media at pH 7 and 12 in the presence of rat liver microsomes. The conventional formaldehyde-producing degradation route was studied, and showed a very low efficiency. Another pathway, consisting of ester hydrolysis, was identified and studied. In contrast to the formaldehyde pathway, ester hydrolysis was shown to be catalysed by enzymes. Finally, the release rate of adsorbed actinomycin from nanoparticles was proved to correlate exactly with the degradation rate of the polymer.

Quantitative estimation of heterocyclic aromatic amines by ion-exchange chromatography and electrochemical detection

Conditions for the quantitative determination of three heterocyclic aromatic amines (HAAs), produced by heat processing of protein-rich food products, were established for a HPLC-electrochemical detection system. The separation of 2-amino-3-methylimidazo[4,5-f]quinoline (IQ), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) and 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQ(x)) was achieved on an ion-exchange column with acetonitrile-80 mM phosphate buffer (30:70) mobile phase at pH 5.6. The figures of merit were calculated. Reproducibility gave a relative standard deviation of 1.6-2.4% when measured by peak area. Detection limits (signal-to-noise ratio 3) ranged from 35 pg for MeIQ(x) to 70 pg for MeIQ. The method was applied to the determination of HAAs in a commercial beef extract sample.

Role of residual solvents in the formation of volatile compounds after radiosterilisation of cefotaxime

Radiation sterilisation is a promising method to sterilise pharmaceutical products. However, this process is accompanied by a modification of odour due to volatile compounds formation. The origin of malodorous compounds produced during solid cefotaxime radiosterilisation has been investigated and several mechanisms are proposed to explain their appearance. Moreover, some quantitative data are given. Analysis of the degradation products was performed using a GC-ITD system with an injection by the static headspace technique. It appeared that some of the radio-induced compounds (such as carbon oxide sulfide and carbon disulfide) came from the degradation of the drug itself, whereas the formation of others required the presence of residual solvents which are volatile impurities already present before irradiation. Acetaldehyde directly came from impurities but the appearance of esters and acetaldehyde O-methyloxime was due to the presence of both cefotaxime and residual solvents together. Thus, the residual solvents play a key role in the radiolysis compounds formation (six of eight require the presence of them) and consequently in the modification of odour as well.

Quantitation of levamisole in plasma using high performance liquid chromatography

SummaryA rapid and sensitive procedure is described for the quantitation of levamisole in plasma using high-performance liquid chromatography (HPLC). The procedure involves sample preparation using a reverse-phase C18 cartridge prior to chromatography and quantitation using peak area ratios (UV absorbance detection, 225 nm) of levamisole to the internal standard, quinine.The limit of detection was 21 ng/ml and the limit of quantification was 72 ng/ml, both contained in 1 ml of plasma. The recoveries were sufficiently high (73.1%) and overall coefficient of variation of the procedure was 0.25%. This procedure has been used to determine levamisole levels in human and cattle plasma. A comparison of using two C18 columns (Nova-pak®, Puresil®) was also studied and discussed.

The mutagenicity of cassava (Manihot esculenta Crantz) preparations.

Different cassava products were found to contain mutagenic activities in the Ames test. This paper describes how the flavonol quercetin is released during the cooking of fresh cassava leaves, following a process very similar to culinary habits. The hydrolysis of the glucoside(s) and the release of free quercetin has been followed by the monitoring of mutagenic activities with a simultaneous isolation and purification by thin-layer chromatography. The fluorodensitometric method applied revealed that fresh leaves contained about 1300 mg quercetin per kg wet weight, of which 800 mg were released during a normal cooking process.

Dibekacin assay in serum by automated fluorescence polarization immunoassay (Abbott Tdx): Comparison with high-performance liquid chromatography, substrate-labelled fluorescent immunoassay and radioimmunoassay.

An immunoassay based on fluorescence polarization detection (FPIA) has been recently adapted for dibekacin. This has been compared with a reference method (high-performance liquid chromatography), and two other methods used in clinical laboratories for monitoring this aminoglycoside, namely substrate-labelled fluorescent immunoassay (SLFIA) and radioimmunoassay (RIA). FPIA was fast and more reliable than SLFIA or RIA, and offered therefore superior performance. However, its nominal cost per assay is high.