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

A Rapid and Sensitive LC-MS/MS Method for the Determination of Multi-class Residues of Antibiotics in Chicken Liver

A very sensitive, simple and cost-effective liquid chromatography–mass spectrometry/mass spectrometry (LC-MS/MS) method for the determination of multi-class antibiotics in chicken liver was developed. The drugs under consideration were sulfaguanidine and sulfamethazole, trimethoprim, tetracycline, chlortetracycline and tylosin. Linear calibrations were established for all the analytes and the R2 values ranged between 0.9990 and 0.9997. The limits of quantitation (LOQs) varied between 0.025 and 78.8 μg kg–1. The limit of detections (LODs) were better than those that have been reported for the same antibiotics in many instances in other studies and ranged between 0.010–31.5 μg kg–1 with the sulfonamides exhibiting lower sensitivity compared to others. This was attributed to poor response factors, low S/N ratios and matrix interferences. A contrast between the relative responses towards mass spectrometer and ultra-violate/visible (UV/VIS) detection of the analytes is also reported. Sulfonamides exhibited higher response factors towards UV/VIS than mass spectrometer detection and the opposite was true for the rest of the analytes.KEYWORDS: Quadrupole ion trap, LC-MS, sulfonamides, tetracycline, tylosin, antibiotics, chicken liver, LC-MS/MS

Supported liquid membrane extraction of 17&#223- estradiol

A sample purification and enrichment technique involving the use of supported liquid membrane (SLM) has been developed for the selective extraction of 17b- estradiol and its metabolites, namely 17b-estriol and estrone in various biological matrices and water. The biological matrices in which extraction was done included bovine kidney and liver tissues, milk and urine. The liquid membrane used to trap these compounds was made of 5% tri-n-octylphosphine oxide (TOPO) dissolved in a mixture of di-nhexylether and n-undecane (1:1, v/v). Separation and detection of the analytes obtained after SLM enrichment was done by liquid chromatography-electrospray mass spectrometry (LC-ESI-MS). The extraction efficiencies (E) for 1 ng/L estradiols mixture spiked in various biological matrices were in the order of 61–80%, 52–74%, 67–89% and 61–82% for kidney tissue, milk, urine and liver tissue, respectively. For spiked water sample, the extraction efficiencies were of the order 82–96% from a 1 ng/L sample mixtures. LC-ESI-MS gave the detection limits of 0.3 ng/L, 1.8 ng/L and 2.4 mg/L for 17bestradiol, estrone and 17b-estriol, respectively