Novel analytical procedures for screening of drug residues in water, waste water, sediment and sludge

Traces of pharmaceuticals are continuously introduced into the aquatic environment mainly by sewage treatment plant effluents. Final data about their impact on the ecosystem are still partly missing. Progress in instrumental analytical chemistry has resulted in the availability of methods that allow a monitoring of these pollutants at ng L⁻¹ levels. In this review the state-of-the-art of residue analysis of pharmaceuticals by chromatographic and electrophoretic techniques is summarized. Improvements in detection limits over the past years have mainly been due to sophisticated mass spectrometric detection techniques. Furthermore, robust sample preparation and preconcentration protocols based on solid-phase extraction and related procedures have contributed significantly to the achievements observed so far. This review also covers several immunochemical approaches which may serve as an inexpensive alternative for quick screening of samples.     

Quantitative Analysis of Polymer Additives with MALDI-TOF MS Using an Internal Standard Approach

MALDI-TOF MS is used for the qualitative analysis of seven different polymer additives directly from the polymer without tedious sample pretreatment. Additionally, by using a solid sample preparation technique, which avoids the concentration gradient problems known to occur with dried droplets and by adding tetraphenylporphyrine as an internal standard to the matrix, it is possible to perform quantitative analysis of additives directly from the polymer sample. Calibration curves for Tinuvin 770, Tinuvin 622, Irganox 1024, Irganox 1010, Irgafos 168, and Chimassorb 944 are presented, showing coefficients of determination between 0.911 and 0.990.     

Determination of quaternary alkylammonium compounds by capillary zone electrophoresis and indirect UV detection as a real alternative to ion chromatography with suppressed conductivity detection

A capillary electrophoretic (CE) method for the determination of residual mid-chain alkyltrimethylammonium compounds in the pharmaceutical product Welchol™ (an alkylated, crosslinked polyallylamine) was developed, validated and compared with the existing ion chromatographic (IC) method with suppressed conductivity detection. Excellent reproducibilities of migration times (RSD<0.5% within a series of 55 sample injections) and relative peak areas (RSD<2%) make the method suitable for quality control as a real alternative to IC. Limits of quantification of 0.01% w/w of each impurity in the active substance were achieved. Buffer systems for indirect UV detection based on creatinine as visualization reagent with different inorganic and organic acids (phosphoric, sulfuric, formic, acetic, oxalic and citric acid) and their effect on selectivity to ten quaternary ammonium compounds were studied. Selectivity changes were observed for the di- and trivalent analytes depending on the buffer applied. Also, the influence of acetonitrile, methanol, 1,4-dioxane and tetrahydrofuran on selectivity was investigated. In addition, CE–MS experiments were carried out in order to identify several impurities in the product.     

Selective determination of bromide and iodide in serum and urine by gas chromatography

A gas chromatographie method with electron capture detection is described for the simultaneous determination of bromide and iodide in biological matrices such as serum and urine. Samples are purified by passing them through a disposable C-18 reversed phase silica cartridge; bromide and iodide are derivatized in acid medium to 2-bromoethanol and 2-iodoethanol by ethylene oxide and the derivatives are extraced into ethyl acetate. Detection limits are in the low ng/ml-range.     

Improved high-performance liquid chromatographic determination of guanidino compounds by precolumn dervatization with ninhydrin and fluorescence detection

Ninhydrin has been investigated as a pre-column derivatization reagent for guanidino compounds. The reaction takes place under strongly alkaline conditions, followed by a second step at low pH and elevated temperature. This procedure yields derivatives with favourable fluorescence properties (excitation at 390 nm, emission at 470 nm). Amino acids do not react with ninhydrin under these conditions so that the method can easily be used for biological samples. Reversed-phase HPLC separations of the derivatives of several representative guanidino compounds in human blood have been achieved with gradients consisting of aqueous formic acid and methanol. Fluorescence detection yields quantification limits of about 20 microg L(-1). Hyphenation with electrospray mass spectrometry has been used to confirm the identity of the derivatives.     

Metal ion capillary zone electrophoresis with direct UV detection: Separation of metal cyanide complexes

Mixtures of cyanide complexes of iron(III), copper(I), iron(II), nickel(II), chromium(III), mercury(II), palladium(II), silver(I), cadmium(II), zinc(II), cobalt(II), and cobalt(III) have been separated by capillary zone electrophoresis using a fused silica capillary and 20 mM phosphate buffers containing 1–2 mM sodium cyanide. The complexes were detected by direct UV absorpticn at 214 nm; detection limits are in the mid ppb range for all metals except cadmium and zinc. The different detectability of various metal cyanide complexes enables the application of the method to the analysis of complex matrices such as cyanide plating bath solutions.     

Determination of glutathione in biological material by high-performance liquid chromatography with electrochemical detection

Glutathione in biological samples is extracted by perchloric acid and separated by ion-paier chromatography on a RP-18 phase. In a post-column reaction, glutathione is converted to an isoindole derivative by reaction with o-phthalaldehyde and detected at a galssy carbon electrode at 800 mV v. Ag/AgCl/3 M KCl. The detection limit is 40 pmol of glutathione injected.     

Determination of free fatty acids by capillary zone electrophoresis

Capillary zone electrophoresis was investigated for the separation of free fatty acids as an alternative to well established techniques such as GC or HPLC. The analysis was performed with indirect UV detection in a counterelectroosmotic flow mode using a diethylbarbiturate carrier electrolyte at a pH between 10 and 11 in a mixed aqueous-organic solvent. Separation of saturated and unsaturated fatty acids could be achieved after bromination of the double bonds. Problems with wall adsorption of fatty acids could be overcome by increasing the temperature and using a high concentration of a zwitterionic reagent to inactivate the silica surface. Increased sensitivity could be achieved after preconcentration on alumina. The method was applied to the determination of free fatty acids in dairy products. The advantages compared to traditional methods include short analysis times and simple preparation steps.Dedicated to Univ. Prof. Dr. Karl Winsauer on the occasion of his 70th birthday     

Evaluation of a microwave assisted extraction prior to high performance liquid chromatography for the determination of additives in polyolefins

This work presents a method for the reliable determination and quantitation of frequently used stabilizers in polyolefins. The extraction of the stabilizers from the polymeric matrix was investigated for several different solvents and solvent mixtures in a monomode microwave reaction system. Ethyl acetate showed the best extraction performance with respect to easy and rapid sample preparation. For this solvent, a systematic and comprehensive survey of time- and temperature-dependence of extraction efficiency was carried out. Extractions utilizing ethyl acetate for 30 min at 130 °C showed the best overall performance for all investigated analytes. Additionally, the influence of the physical form of the sample was investigated. The extraction of pellets and powder was compared and, regardless of the physical form, the reproducibility for the whole method developed for all chosen analytes was below 2%.