Tq tandem mass spectrometer

The concentrations of organic acids (i.e., citric acid, gluconic acid, lactic acid, malic acid, and succinic acid) were quantified in the aqueous extracts in triplicate by ultra-performance liquid chromatography with tandem mass spectrometry (UPLC-MS/MS), using an Acquity UPLC system equipped with a HSS T3 column coupled to a TQ tandem mass spectrometer (Waters, Milford, MA, United States), as described previously, except for the mobile phase used (De Bruyn et al., 2017 ). The latter consisted of an ultrapure water (MilliQ)-methanol (Merck) mixture (980:20, v/v) with 0.2% (v/v) formic acid (Merck) (eluent A) and an ultrapure water-methanol mixture (50:950, v/v) with 0.2% (v/v) formic acid (eluent B). Quantification was performed by external calibration.

Urinary cathinone and cathine concentration was determined as described previously^{57 (link)} using LC–MS/MS system consisted of a Waters Acquity UPLC (ultra-performance liquid chromatography) with a vacuum degasser, binary pumps, autosampler (12 °C) and sample manager connected to a Xevo TQ tandem mass spectrometer with MassLynx™/Target Lynx™ Software version 4.1 (Waters Co., Milford, MA, USA). In brief, a 50 μL aliquot of urine was added to an autosampler vial with 200 μL of IS working solution (40 ng). The vials were capped, vortexed for ~10 sec, and loaded onto the sample manager kept at 4 °C. Amphetamine, MDMA and metamphetamine (LGC Standards) in 100 µg mL⁻¹ concentration were diluted to 500 ng mL⁻¹ in double-distilled water and used as internal standards. The reference standards, cathinone-HCl and Phenylpropanolamine-HCl in 1 mg mL⁻¹ ampoules (LGC Standards) were diluted in 0.1% formic acid to give 100 mg mL⁻¹ solutions. Quality control (QC, 100 ng mL⁻¹) and standards for calibration curves covering a 0–10000 ng mL⁻¹ concentration range were prepared by dilution of working solutions of the analytes with blank urine. Lower limits of detection for cathinone and phenylpropanolamine was 100 ng mL⁻¹ and 300 ng mL⁻¹ respectively.

The concentrations of organic acids (i.e., citric acid, fumaric acid, gluconic acid, isocitric acid, lactic acid, malic acid, oxalic acid, quinic acid, and succinic acid) in the processing waters and acidic bean extracts were determined by ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC-MS/MS), using an Acquity UPLC system equipped with an HSS T3 column and a TQ tandem mass spectrometer (Waters; Milford, MA, United States), as described previously (Zhang et al., 2019 (link)). Quantification was performed through external calibration in triplicate. All samples were mixed with methanol, microcentrifuged (19,400 × g for 15 min at 10°C), and filtered (Chromafil 0.2 μm PTFE filters) before injection (10 μL) into the column.