title: Picogram-level quantification of some growth hormones in bovine urine using mixed-solvent bubble-in-drop single drop micro-extraction.
abstract: Growth hormones are important biologically active compounds. However, they can cause deleterious effects if not used with care and their use in farmed animals is banned in the European Union. This study presents the development and application of a mixed-solvent "bubble-in-drop single drop micro-extraction" (BID-SDME) method for enrichment of stilbene hormones in bovine urine samples. The hormones are quantified using GC-MS showing good linearity with the coefficient of determination (R(2)) of 0.999 and 0.999 for hexestrol and diethylstilbestrol, respectively, in the concentration range 0.05-10 ng mL(-1). Excellent precision (RSD<10%) and accuracy (using a bovine urine certified reference material) were obtained. The observed detection capability (CCα, or LOD) values were 0.01 ng mL(-1) (hexestrol), 0.03 ng mL(-1) (cis-diethylstilbestrol) and 0.02 ng mL(-1) (trans-diethylstilbestrol), respectively, while the decision limit (CCβ, or LOQ) values were 0.03 ng mL(-1), 0.08 ng mL(-1) and 0.07 ng mL(-1), which are comparable to or better than those reported in literature. Importantly, sample handling is significantly simplified by our method and enrichment values are greatly enhanced. The results show that a 3:1 chloroform/toluene mixture gave the highest extraction efficiency with a drop-bubble ratio of 2:1. We highlight the importance of solvent density on the success of the BID-SDME method.
authors.affiliation: Department of Chemistry, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa; Department of Chemistry and Chemical Technology, National University of Lesotho, P.O. Roma 180, Lesotho.
authors.forename: Mosotho J
authors.initials: MJ
authors.lastname: George
authors.affiliation: Department of Chemistry, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa.
authors.forename: Ljiljana
authors.initials: L
authors.lastname: Marjanovic
authors.affiliation: Department of Chemistry, University of Johannesburg, P.O. Box 524, Auckland Park 2006, South Africa; Ferrier Research Institute, Victoria University of Wellington, Gracefield Research Centre, 69 Gracefield Rd, Lower Hutt 5010, New Zealand. Electronic address: bradley.williams@vuw.ac.nz.
authors.forename: D Bradley G
authors.initials: DB
authors.lastname: Williams
mesh_terms: D000818:Animals; D002417:Cattle; D002725:Chloroform / Q000737:chemistry; D004054:Diethylstilbestrol / Q000737:chemistry / Q000652:urine*; D008401:Gas Chromatography-Mass Spectrometry; D006589:Hexestrol / Q000737:chemistry / Q000652:urine*; D006728:Hormones / Q000652:urine; D057230:Limit of Detection; D012997:Solvents / Q000737:chemistry; D014050:Toluene / Q000737:chemistry
chemical_list: D006728:Hormones; D012997:Solvents; D006589:Hexestrol; D014050:Toluene; D004054:Diethylstilbestrol; D002725:Chloroform
keywords: Bovine; Diethylstilbestrol; Growth hormone; Hexestrol; Microextraction; Urine