An Effective Acid-Base-Induced Liquid-Liquid Microextraction Based on Deep Eutectic Solvents for Determination of Testosterone and Methyltestosterone in Milk

Simultaneous determination of methyltestosterone and its metabolite in fish by gas chromatography-mass spectrometry

Methyltestosterone is one of the banned drugs in aquaculture, and it should be monitored in food-producing animals. 17α-Methyl-5β-androstane-3α,17β-diol, as the main metabolite of methyltestosterone in vertebrates, could be used as another marker for controlling the administration of methyltestosterone, due to its high residual concentration and slow elimination rate. In this study, an analytical method based on gas chromatography-mass spectrometry (GC-MS) was developed and validated for the simultaneous determination of methyltestosterone and its main metabolite in fish. After pretreatment by liquid-liquid extraction with n-hexane and solid phase extraction with C18 and NH2 columns, the target analytes in the muscle tissues were extracted and concentrated, and the influence of the sample matrix was eliminated. Then, the prepared samples were separated and detected with GC-MS in the selected ion monitoring (SIM) mode. Methyltestosterone-D3 was chosen as the internal standard for quantitation. After optimization, the limits of detection for methyltestosterone and 17α-methyl-5β-androstane-3α,17β-diol were 20 μg kg-1 and 15 μg kg-1, respectively. The limits of quantitation were both 50 μg kg-1. The calibration curves showed good linearity in the concentration range from 50.0 ng mL-1 to 500.0 ng mL-1. The correlation coefficients of methyltestosterone and 17α-methyl-5β-androstane-3α,17β-diol were more than 0.9990. The recoveries of the analytes in real samples were in the range of 99.7-116.6% with the relative standard deviation of 5.2-8.3%. The established method could meet the demand for simultaneous detection of methyltestosterone and its major metabolite, and it could be used to provide more information on the abuse of methyltestosterone in food-producing animals.

Tb3+-atorvastatin doped in poly(ethylene glycol) optical biosensor for selective determination of progesterone and testosterone in serum samples

An innovative, simple and cost effective Tb3+-atorvastatin photo probe was designed and used as a core for a spectrofluorometric approach to sensitively determine two vital biological compounds in serum samples. Tb3+-atorvastatin complex displays a characteristic electrical band with λ em at 545 nm with significant luminescence intensity, which is quenched in the presence of progesterone and testosterone at two variant sets of pH; 6.2 and 7.5, respectively. The conditions were optimized and the best solvent for operation was found to be acetonitrile with λ ex at 320 nm. Progesterone and testosterone were assessed in serum samples using the same optimal conditions within concentration ranges of 2 × 10-9 to 2.9 × 10-6 and 3.1 × 10-9 to 4.8 × 10-6 mol L-1, respectively. The proposed luminescence method was validated in accordance to ICH guidelines and found to be accurate, precise and specific and free from any interference. The cost effectiveness and applicability of the method make it a good choice for routine analysis of the two compounds and early diagnosis of chronic diseases associated with abnormalities in their physiological levels.

New Tb3+–simvastatin optical biosensor for sensitive determination of folic acid, progesterone, testosterone and vitamin D3 in biological fluids

An innovative, simple and cost effective Tb3+–simvastatin photo probe was designed and used as a core for a spectrofluorometric approach to sensitively determine four vital biological compounds in different matrices.