Supported Liquid Membrane Extraction of Anabolic Androgenic Compounds in Biological Matrices and Detection by LC-ESI-MS

A sample work-up and enrichment technique involving the use of supported liquid membrane (SLM) and detection by high performance liquid chromatography coupled to a mass spectrometer operating under positive ion electrospray mode (LC-PI-ESI-MS) has been developed for the determination of six anabolic androgenic compounds in different biomatrices; mainly urine, kidney, liver and milk. Anabolic androgenic compounds analysed included 17α-trenbolone, 17β-trenbolone, 19-nortestosterone, testosterone, 4-androstene-3,17-dione and testosterone benzoate. Several factors affecting the extraction efficiency during SLM enrichment, such as donor pH were studied. The detection limits (DL) were 0.08 μg L–1 for 4-androstene-3,17-dione, 0.7 ng L–1 19-testosterone, 1.1 ng L–1 for testosterone, 0.1 ng L–1 for 17β-trenbolone, 1.6 ng L–1 for 17α-trenbolone and 0.03 μg L–1 for testosterone benzoate. Modification at C17 in the structures of 4-androstene-3,17-dione and testosterone benzoate affected their recoveries with SLM and explained their observed high detection limits.Keywords: Anabolic androgenic compounds, supported liquid membrane, liquid chromatography, electrospray ionization, massspectrometr

Determination of persistent cyclic organochlorine residues in sediment slurry by microporous membrane liquid-liquid extraction and gas chromatography-mass spectrometry

A method, using microporous membrane liquid-liquid extraction technique (MMLLE) and gas chromatography with an electron capture detector (GC-ECD) and gas chromatograph coupled to a mass spectrometer, was developed for the analysis of cyclic organochlorine pesticides (OCPs) and polychlorinated biphenyls (PCBs) in sediment slurry. The MMLLE extraction employed isooctane as the organic liquid that was immobilised in the hollow fibre pores and in the lumen, at optimal sample pH value of 2.0 for OCPs and 7 for PCBs. The effect of triton x-100, in enhancing the dissolution of the compounds from sediment, was found to be optimal at a value of 0.15%, while the ionic strength was optimal at a value of 0.01 M. Samples from coastlines along the Indian Ocean in the southern parts of South Africa were found to be contaminated with cis and trans chlordane at concentrations of up to 0.003 mg/kg, while samples from northern parts were contaminated with 2,2’,4’,4-tetrachloro-1,1’biphenyl at concentrations of up to 0.02 mg/kg.Keywords: Organochlorine pesticides, polychlorinated biphenyls, hollow fibre liquid phase micro-extraction, high performance liquid chromatography, mass spectrometr

Sample preparation using liquid membrane extraction techniques

A brief review is given of membrane extraction techniques that are seen as suitable for the extraction of various chemicals in water samples. Membrane-based extraction methods have now gained popularity as methods of choice in the extraction of both ionisable and non-ionisable molecules from different samples. The main attractive features for these techniques include the use of minimal organic solvents, high selectivity and clean-up efficiency, with high enrichment factors. In most cases the overall cost involved is low due to the simplicity of the techniques which normally involve relatively fewer steps and handling procedures as compared to many other sample-preparation techniques. The various forms and the configurations of membrane-based techniques are another attractive feature which allows the possibility of hyphenation with separation instruments such as gas/liquid chromatographs and even capillary electrophoresis.Keywords: liquid membrane extraction techniques, sample preparation, water monitoring, organic and inorganic compound

Effect of natural blue-green algal cells lysis on freshwater quality

Blue-green algae grow in freshwater bodies when they are provided with suitable factors such as nutrients and appropriate weather conditions. Their cell lysis occurs naturally when they encounter unfavourable conditions.  This study reports on the types and amounts of fatty acids added into freshwater due to the algal cell lysis. The investigation on the amount of fatty acids released into water due to algal cells lysis was performed by placing samples in two compartments, one with no light allowing the algae cells to die while the other compartment was kept in favourable conditions enough to sustain the life of algae. Fatty acids were then extracted from both dead and living cells as well as their respective water filtrates. Determination of fatty acids was performed using GCxGC-TOF-MS. Identified fatty acids were mainly; tetradecanoic acid, 7-hexadecenoic acid, hexadecanoic acid, 9,12,15-octadecatrienoic acid, 6,9,12,15-octadecatetraenoic acid, 9,12-octadecadienoic, 9-octadecenoic and octadecanoic acids. It was found that water from the dead cells had higher amounts of fatty acids than water samples from the living cells. Unsaturated fatty acids increased from 0.85 mg/L to 2.70 mg/L in filtrate water from the dead algae. The pH of water samples from the dead cells decreased from 6.8 to 6.1. Keywords: Algae, cells lysis, Fatty acids, gas chromatography time-of-flight mass spectrometry, water qualit

Voltammetric Determination of a Benzimidazole Anthelmintic Mixture at a Poly(3-methylthiophene)-modified Glassy Carbon Electrode

The voltammetric determination of benzimidazole anthelmintics at a glassy carbon rotating-disk electrode modified with poly(3-methylthiophene) is presented. The purpose of surface modification was to improve the sensitivity and limits of detection for determination of the compounds in a standard mixture. Thus, five compounds, namely thiabendazole, mebendazole, albendazole, fenbendazole and oxibendazole have been studied using square wave voltammetry. It has been possible to resolve four of the compounds, mebendazole, fenbendazole, oxibendazole and thiabendazole, in a mixture. Investigations of a number of parameters, including the mode of potential application, cathodic reduction versus anodic oxidation, the type of electrode, effect of pH and speed of electrode rotation, among others, are reported. South African Journal of Chemistry Vol.56 2003: 5-

Determination of Lipophilic Extractives in Ionic Liquid Extracts of Eucalyptus Pulp by Gas Chromatography - Mass Spectrometry

Lipophilic wood extractives composition is currently a big concern of pulp and paper industries as well as for the environmentalists due to their negative impacts on the quality of pulp and the environment. Because of the shortcomings of different extraction procedures using volatile organic solvents in capturing residual lipophilic extractives in pulp, this study reports on the use of ionic liquids as an effective approach for such extraction. The capacity of two ionic liquids; 1- butyl-3-methylimidazolium acetate and 1-butyl-3-methylimidazolium chloride to recover wood extractives was compared and it was observed that ionic liquid with chloride anion recovered a higher amount of extractives. The effect of temperature of the added precipitating solvent during cellulose regeneration on the recovery of extractives was also studied. Recovery of extractives increased with increasing temperature of the added precipitating solvent and equilibrium was reached at 90oC. Fatty acids (saturated, unsaturated and α-hydroxyl acids), sterols (β-sitosterol and stigmastanol), steroid hydrocarbons and ketones were the main compounds determined from bleached pulp using gas chromatography mass spectrometry. On the basis of the fact that ionic liquids are biodegradable and non-volatile, this approach of analysis is definitely a highly green process for the determination of lipophilic extractives in pulp.Key words: Dissolving pulp, Extractives, Gas chromatography-mass spectrometry, Green solvent, Ionic liqui

Synthesis and characterization of molecularly imprinted polymers for the remediation of PCBs and dioxins in aqueous environments

This paper, reports on the approach devised to remediate water sources contaminated with PCBs and dioxins. The approach reported is based on the synthesis of highly selective molecularly imprinted polymers (MIPs). The paper elaborates the materials, procedures and protocols devised and followed for the synthesis of MIPs..

Measurements of distribution coefficients and lipophilicity values for oleanolic acid and betulinic acid extracted from indigenous plants by hollow fibre supported liquid membrane

Hollow fibre supported liquid membrane (HFSLM) has been applied in the measurements of distribution constants, KD and lipophilicity (log P) values for the isomeric triterpenic acids, betulinic acid (BA) and oleanolic acid (OA) isolated from indigenous plants. The results have shown that BA had an optimum pH of 3.5 while the optimum sample pH for OA was ranging from 0.5 to 2.5. The log P values obtained for BA and OA were 6.61 and 6.12, respectively. The KD value obtained for BA was 0.29 while that for OA 0.16. The method has advantages of simplicity, use of minimal organic solvents and the ability to selectively extract only one isomer (OA) in the mixture with BA by optimizing pH conditions.KEY WORDS: Betulinic acid, Oleanolic acid, Hollow fibre supported liquid membrane, Distribution coefficient, Lipophilicity Bull. Chem. Soc. Ethiop. 2011, 25(3), 321-332