Determination of para red, Sudan dyes, canthaxanthin, and astaxanthin in animal feeds using UPLC.

A simple high-performance liquid chromatography method was developed for quantitative determination of para red, Sudan I, Sudan II, Sudan III, Sudan IV, canthaxanthin, and astaxanthin in feedstuff. The sample was extracted using acetonitrile and cleaned up on a C(18) SPE column. The residues were analyzed using ultra-performance liquid chromatography coupled to a diode array detector at 500 nm. The mobile phase was acetonitrile-formic acid-water with a gradient elution condition. The external standard curves were calibrated. The mean recoveries of the seven colorants were 62.7-91.0% with relative standard deviation 2.6-10.4% (intra-day) and 4.0-13.2% (inter-day). The detection limits were in the range of 0.006-0.02 mg/kg.

Validation of a solid-phase extraction and ultra-performance liquid chromatographic tandem mass spectrometric method for the detection of 16 glucocorticoids in pig tissues.

A sensitive analytical method has been developed and validated for simultaneous determination of 16 glucocorticoid (fluorometholone, flumethasone, triamcinolone, aldosterone, clobetasol propionate, methylprednisolone, fluocinolone acetonide, hydrocortisone, prednisone, dexamethasone, beclomethasone, prednisolone, budesonide, triamcinolone acetonide, fludrocortisone acetate, and cortisone) residues in pig tissues (muscle, liver, and kidney). These biosamples were hydrolyzed with beta-glucuronidase/arylsulfatase enzyme and passed through a Supelclean ENVI-Carb graphitized carbon black solid-phase extraction cartridge, followed by further purification using aminopropyl cartridges. Analytes were separated on an ultra-performance liquid chromatography BEH C18 column followed by tandem mass spectrometry (MS) with an electrospray ion source. The MS data acquisition was performed in the negative multireaction monitoring mode by a time-scheduled multireaction monitoring program. The assay for the 16 glucocorticoids were linear over the range of 1-250 microg/L for pork, liver, and kidney, with correlation coefficient >0.99. Estimated detection limits for the target analytes ranged from 0.03 to 0.30 microg/kg, and limits of quantitation ranged from 0.10 to 1.00 microg/kg. Recoveries of the glucocorticoids (spiked at levels of 0.4 and 2.0 microg/kg) ranged from 81.0 to 112.3%, with relative standard deviations between 2.6 and 16.6%.