A novel efficient and accurate ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the detection of 13 diuretics in animal-derived foods was developed. The samples were extracted with acetonitrile or 90% acetonitrile solution and cleaned up on a PRiME HLB pass-through solid phase extraction (SPE) column. Then, an ACQUITY HSS T3 column (100 mm × 2.1 mm, 1.8 μm) was used for chromatographic separation by gradient elution using a mobile phase consisting of 5 mmol/L aqueous ammonium acetate and acetonitrile, and an electrospray ionization source (ESI) operated in both positive and negative ion scanning modes with multiple reaction monitoring (MRM) was used to detect the diuretics qualitatively and quantitatively. The results showed that the calibration curves for all the analytes exhibited good linearity with correlation coefficients above 0.9970. The limits of quantification ranged from 2.0 to 5.0 μg/kg. The recoveries of the proposed method ranged between 68.3% and 118.0%, with relative standard deviations (RSDs) between 0.47% and 9.5% (n = 6). This method is a fast, simple, accurate, and practical one for the detection of diuretics.

An analytical method was established for the determination of the residues of 11 sulfonamides and five quinolones in infant formula milk powder using ultra-performance liquid chromatography tandem triple quadrupole mass spectrometry (UPLC-MS/MS). Acidified acetonitrile was used for sample extraction and the extract was purified and concentrated by solid phase extraction (SPE) using a PRiME hydrophilic lipophilic balance (HLB) column, then separated on an XBridge BEH C₁₈ column, detected in the positive ion mode using an electrospray ionization source, and quantified by the calibration curve method with matrix matching. The calibration curves of all analytes showed a good linear relationship in the concentration range of 2–100 ng/mL with correlation coefficients greater than 0.9950. The limit of detection (LOD) and the limit of quantification (LOQ) were 0.1-0.2 and 0.3-0.5 μg/kg, respectively. Recoveries for spiked samples were between 84.8% and 108.0%, with relative standard deviations (RSDs) between 0.36% and 5.41%. The proposed method is simple, efficient, reliable and sensitive.

The aim of this work was to develop an automated on-line solid phase extraction (SPE) with liquid chromatography-tandem mass spectrometry method for the detection of fifteen sulfonamides in pork and fish samples. Samples were extracted with 0.2% formic acid acetonitrile solution, purified by on-line SPE device with HLB column, then separated by XBridge C₁₈ column, using 0.1% formic acid solution and acetonitrile as the mobile phase. Mass spectrometric data was acquired under multiple reaction monitoring (MRM) mode using positive ionization electrospray. Internal standard method was used in the quantification, good linear relationship was got in range of 0.1–100 ng/mL and correlation coefficient was higher than 0.9990. The limits of detection were in the range of 0.125–2.00 μg/kg and the limits of quantitation were in the range of 0.250–5.00 μg/kg. Recoveries of the method were in range of 78.3%–99.3%, relative standard deviation were lower than 10%. The method was simple, sensitivity, and could be used for routine supervision and analysis of fifteen sulfonamides in pork and fish.