[Peripheral analgesic effect of intra-articularly applied clonidine]. / Periphere analgetische Wirkung durch intraartikulär verabreichtes Clonidin.

BACKGROUND AND AIM: Clonidine applied intra-articularly into the knee joint has a peripheral analgesic effect. We examined intra-articularly injected clonidine to determine whether resorption with a measurable systemic concentration could be detected. METHODS: A randomised, placebo-controlled double-blind study was carried out on patients undergoing knee arthroscopies. The 69 patients were randomised into three groups: group 1 received 150 ug clonidine intra-articularly, group two 150 ug clonidine intravenously and group three a placebo. Postoperative pain therapy was carried out with i.v. morphine hydrochloride. Pain scores and side-effects were documented for 24 h. RESULTS: There were no significant differences between the three groups in demographics, duration of operation, duration of anaesthesia, diagnoses or type of operation. The pain score at rest was significantly lower in group 1. In the first 20 min, the systemic concentration of clonidine was significantly higher in the intravenous group than in the intra-articular group. CONCLUSION: Intra-articular clonidine has a postoperative analgesic effect after knee arthroscopies due to a peripheral action.

Comparative studies of the static and dynamic headspace extraction of saturated short chain aldehydes from cellulose-based packaging materials.

Aldehydes in cellulose-based materials such as cardboard are derived from lipid degradation. Depending on the production- and storage conditions of the cardboard, the aldehyde content changes. Owing to their sensorial properties, accurate control of their content is obligatory. The cardboard usually exhibits strong and even varying matrix effects and considerable inhomogeneity. The comparability of results of analysis after static and dynamic headspace extraction of short chained saturated aldehydes from cellulose-based matrices was studied. In the case of the static extraction technique, special attention was given to the establishment of the headspace equilibrium, which could be reached by the addition of water as a displacer. For dynamic headspace extraction, the volatiles were purged from the matrix by an inert gas and enriched on an adsorbent trap. In theory, the extraction yield should be 100%. Since there are no certified reference materials for verification of the extraction efficiency available, confirmation was achieved by determining the total amount of analytes in the sample by means of multiple headspace extraction.In comparison to the static operation mode, the major drawbacks of the dynamic technique were found to be based on a more complex parameter string and on limitations to the extractable sample quantities, which may result in enhanced uncertainty of the measurements. Nevertheless, the results of analysis pointed out that both headspace extraction techniques are suitable for the determination of volatile aldehydes from cellulose-based materials.

Reduction of adsorption phenomena of volatile aldehydes and aromatic compounds for static headspace analysis of cellulose based packaging materials.

Headspace analysis of solid samples is frequently hampered by severe matrix effects due to adsorption phenomena of the analytes on polar matrix surfaces. Since adsorption can give rise to incorrect results, a possible alternative can be provided by a transfer of the adsorption system into a partition system. This can be accomplished by the addition of substances, which exhibit higher affinity to the matrix than the analyte, thus acting as displacer or modifier. The effect of water as displacer for a quantitative static headspace analysis of straight chained saturated aldehydes and mononuclear aromatics (benzene, toluene, xylenes and ethylbenzene) in cellulose based packaging material has been investigated. Special emphasis was given to an establishment of distribution equilibrium conditions. For this, the influence of the amount of added displacer was studied by means of a multiple headspace extraction procedure coupled to gas chromatography with mass spectrometric detection and selected ion monitoring.

Microwave-assisted derivatization of volatile carbonyl compounds with O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine.

A method for the determination of carbonyl compounds, either directly from gaseous phase or following a volatilization from liquid or solid samples after trapping on Tenax TA is presented. Following solvent desorption, the carbonyls are derivatized using O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine. The reaction is accomplished in a microwave oven using closed vessels to minimize reaction time compared to conventional methodology. The solvent for the chemical reaction was selected according to the requirements of microwave energy interaction and solubility. After gas chromatographic separation of the corresponding oximes, they are detected using electron impact mass spectrometry in single ion monitoring mode. Quantification is carried out using internal standardization with 3-fluorobenzaldehyde, resulting in limits of detection in the ppm range following the calibration graph method. The optimized conditions provide for good recoveries and fast reaction rates for the volatile carbonyls studied so far.

Elimination of matrix effects for static headspace analysis of ethanol.

The intention of this work was to develop a simple and fast procedure for a determination of small amounts of ethanol in aqueous protein containing solutions based on combined headspace gas chromatography. In order to provide for short analysis time static headspace methodology was considered for this purpose. In this context the influence of the matrix composition onto the analytical results has been established and internal standardization as well as a full evaporation technique have been evaluated as promising alternatives for a compensation of matrix effects. With respect to speed of analysis, simplicity of sample handling as well as the quality of the analytical performance parameters, precision and accuracy, the full evaporation technique proved to be superior. Thus, the static equilibration of a 20 microliters sample aliquot in a conventional headspace sample vial for 5 min at 100 degrees C is sufficient to obtain equilibrium conditions for gas chromatographic analysis. The accuracy of this method was verified by robust regression analysis and exhibited excellent robustness within the required limits of sample composition ranging from 0 to 20% (w/w) protein content and up to 5 g/l salt content.

Stereospecific determination of D-thyroxin and L-thyroxin in serum.

A new method for separate determination of D-thyroxin and L-thyroxin in the serum was applied to study the response of serum levels of these isomers and of radioimmunologically determined total T3, total T4, free T4 and TSH upon administration of 2, 4 and 6 mg of a highly purified D-thyroxin preparation in six male patients with diffuse nontoxic goiter. D- and L-thyroxin are determined separately following extraction of the hormone from the serum and formation of diastereomeric dipeptides. The separation and final determination are accomplished by means of ion-pair chromatography on reversed-phase columns using an iodine-selective catalytic detector. A significant decrease in TSH takes place during the 3-days observation period. The values of D-T4, total T3 and free T4 are highest 4 hours after administration of the tablets and get to be to initial values after 24 hours. L-T4 shows no significant change. A direct suppressive effect of D-T4 on the pituitary gland may therefore be assumed as the cause of the suppression of TSH secretion.

Determination of D-penicillamine in serum by fluorescence derivatization and liquid column chromatography.

A simple and fast method for the determination of D-penicillamine in serum is described. The analysis is based o a fluorescence derivatization of the sulfhydryl group combined with a reversed-phase liquid chromatograhic separation and fluorescence detection. Before derivatization the serum proteins are precipitated with ethanol and removed by centrifugation. As derivatizing agent 5-dimethylaminonaphthaline-1-sulfonylaziridine is used which reacts selectively with thiols under defined reaction conditions. The detection limit is in the pmol range; 50-300 ng of D-penicillamine can be determined with a relative standard deviation of 7-8%. Thus the method permits a simple determination of D-penicillamine in serum at therapeutic levels.

[Serum levels od D-thyroxine in euthyroidism and hypothyroidism (author's transl)]. / Serumspiegel von D-Thyroxin bei Euthyreose und Hypothyreose.

Serum levels of D-thyroxine (D-T4) and L-thyroxine (L-T4) were determined by use of a newly developed method for the stereospecific determination of these isomers in 8 patients with diffuse non-toxic goiter and 2 hypothyroid patients following administration of increasing doses of D-thyroxine. During the 3-day observation period a significant decrease of serum-TSH takes place. D-T4 levels are highest 4 hours after administration of the tablets and approach basal values within 24 hours in euthyroid as well as hypothyroid patients. Serum half life of D-T4 was 5.7 hours on the average in the euthyroid group and was markedly prolonged in hypothyroidism. L-T4 levels show no significant changes. Since the D-T4 preparation used, contained only very little amounts of the L-isomer, it may be assumed that D-T4 exerts a direct suppressive effect on the pituitary TSH secretion, as evidenced by the observed significant decrease in basal and TRH-stimulated TSH serum levels.

Separation of enantiomeric iodinated thyronines by liquid chromatography of diastereomers.

A method for the separation of D,L-triiodothyronine and D,L-tetraiodothyronine optical isomers is described. The iodinated thyronines are coupled with L-leucine and the resulting diastereomers are separated by reversed-phase liquid chromatography. The derivatives are detected in the UV region at 230 nm. The technique can be used for the determination of the optical purity of thyroid hormones. It is possible to determine 0.2% of the L-isomer in D-tetraiodothyronine with a relative standard deviation of 8%. One complete analysis takes about 2 h. The results are in good agreement with those of an enzymatic method.