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A new, fast and simple analytical method that is able to identify and quantify simultaneously 17 steroid hormones and metabolites (pregnenolone, 17-OH-pregnenolone, progesterone, 17-OH-progesterone, androsterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, cortisol, corticosterone, aldosterone, 11-deoxycortisol, 11-deoxycorticosterone, dihydrotestosterone, estrone and estradiol) has been developed in equine serum using the ultrahigh- performance liquid chromatography-tandem mass spectrometry technique. A total of 400 μl of sample was deproteinized with 1000 μl of acetonitrile, evaporated, restored with 50 μl of a solution of 25% methanol and injected in ultrahigh- performance liquid chromatography-tandem mass spectrometry triple quadrupole. The recovery percentage obtained by spiking the matrix at two different concentrations with a standard mixture of steroid hormones was in all cases higher than 85.60% and with the percentage of coefficient of variation lower than 8.37%. The range of the correlation coefficients of the calibration curves of the analyzed compounds was 0.9922-0.9986, and the limits of detection and limits of quantification were in the range of 0.002-2 and 0.0055-5.5 ngml-1, respectively. The detected limit of quantification for testosterone (i.e. 50pgml-1) is twofold lowerwith respect to its threshold admitted in geldings plasma (100pgml-1 free testosterone). The high sensitivity and the quantitative aspect of the method permitted to detect most of the steroids in equine serum. Once validated, the method was used to quantify 17 steroid hormones in mare, stallion and gelding serum samples. The main steroids detected were corticosterone (range 37.25-51.26 ngml-1) and cortisol (range 32.57-52.24 ngml-1), followed by 17-OH-pregnenolone, dihydrotestosterone and pregnenolone. [ABSTRACT FROM AUTHOR]

In recent decades, mass spectrometry techniques, particularly when combined with separation methods such as high-performance liquid chromatography, have become increasingly important in pharmaceutical, bio-analytical, environmental, and food science applications because they afford high selectivity and sensitivity. However, mass spectrometry has limitations due to the matrix effects (ME), which can be particularly marked in complex mixes, when the analyte co-elutes together with other molecules, altering analysis results quantitatively. This may be detrimental during method validation, negatively affecting reproducibility, linearity, selectivity, accuracy, and sensitivity. Starting from literature and own experience, this review intends to provide a simple guideline for selecting the best operative conditions to overcome matrix effects in LC-MS techniques, to obtain the best result in the shortest time. The proposed methodology can be of benefit in different sectors, such as pharmaceutical, bio-analytical, environmental, and food sciences. Depending on the required sensitivity, analysts may minimize or compensate for ME. When sensitivity is crucial, analysis must try to minimize ME by adjusting MS parameters, chromatographic conditions, or optimizing clean-up. On the contrary, to compensate for ME analysts should have recourse to calibration approaches depending on the availability of blank matrix. When blank matrices are available, calibration can occur through isotope labeled internal standards and matrix matched calibration standards; conversely, when blank matrices are not available, calibration can be performed through isotope labeled internal standards, background subtraction, or surrogate matrices. In any case, an adjusting of MS parameters, chromatographic conditions, or a clean-up are necessary. [ABSTRACT FROM AUTHOR]

• An accurate quantitative analysis of craft beers by LC–MS/MS identified phenolic acids and flavonoids mostly coming from malt, and bitter acids and prenylflavonoids coming from hop. • Dilution 1:2 of the sample with the mobile phase offered a very fast and simple method to minimize the matrix effect. • Most polyphenols are absorbed into the yeast added for the fermentation. • Spent yeast can be considered a source of polyphenols coming from beers ingredients. An accurate quantification of phenolic compounds present in several kind of craft beers, corresponding worts, ingredients and spent products was performed by LC–MS/MS in this study. The dilution 1:2 of the sample with the mobile phase gave the best results, offering a very fast and simple method to reduce the matrix effect. A validated method was applied to six different types of craft beers, their worts, starting and spent products, such as barley malts and barley husks, starting hops and spent hops, and finally, starting yeast and spent yeasts to quantify the selected phenolic compounds. The Total Phenol Content (TPC) of barley malts is not negligible and it results almost prevalently due to trans- p -coumaric acid, which ranges from 76.4 μg/Kg for Mais to 672.6 μg/Kg for Munich. The trans- p -coumaric acid is transferred to the worts during the must preparation and is responsible for the not negligible TPC of worts, that was between 131.1 μg/Kg for Ego to 2041.6 μg/Kg for Alter beer. Bitter acids and prenylflavonoids are mainly present in the starting hops (TPC 323.8 μg/Kg and TPC 500.3 for Saaz and Perle hops, respectively). Their concentration strongly decreases in the spent hops where the TPC ranges between 8.0 μg/Kg for Triplo Malto to 24.4 μg/Kg for Alter, suggesting that they are transferred to the intermediate of production. Phenolic compounds, originally present in the starting barley malts and hops, are limitedly present into the final beers, and their TPC ranges approximately from 65.6 μg/Kg for Fiat lux to 105.3 μg/Kg for Alter. Actually, most phenolic compounds are absorbed into the yeast added for the fermentation, as it is clearly evident from the observation that spent yeasts contain a higher phenolic compounds amount with the respect to the starting yeast, and several phenolic compounds, in particular those coming from hops, are originally absent into the yeast and are only present in the spent ones. [ABSTRACT FROM AUTHOR]