Comparative study of sample preparation methods; supported liquid membrane and solid phase extraction in the determination of benzimidazole anthelmintics in biological matrices by liquid chromatography–electrospray–mass spectrometry

Supported liquid membrane (SLM) and solid phase extraction (SPE) have been applied as clean-up and/or enrichment techniques for a mixture of five benzimidazole anthelmintics compounds, namely albendazole, fenbendazole, mebendazole, oxibendazole, and thiabendazole. Two biological matrices, mainly urine and milk, and ultra high purity (UHP) water were spiked with a mixture of these five compounds. Waters Oasis® MCX and International Sorbent Technology (IST) HCX SPE sorbents were used. The liquid membrane used for clean-up and/or enrichment of these compounds was 5% tri-n-octylphosphine oxide (TOPO) dissolved in n-undecane/di-n-hexyl ether (1:1). The SLM extraction efficiencies and SPE percentage recoveries ranged between 60 and 100%. The detection limits (DLs) for different benzimidazole compounds by SPE/LC–ES–MS for thiabendazole, oxibendazole, and albendazole was 0.1 ng/L, for fenbendazole and mebendazole was 1 and 10 ng/L, respectively. Similarly, the detection limits of SLM/LC–ES–MS for thiabendazole, oxibendazole, and albendazole was 0.1 ng/L and for fenbendazole and mebendazole was 1 ng/L. The results of optimization of various parameters of the SLM method are reported.