Xevo tq xs mass spectrometer

Plasma concentrations of TXA were determined by ultrahigh-performance liquid chromatography-tandem mass spectrometry. 4-Aminocyclohexanecarboxylic acid was used as the internal standard^{41 (link),42} with modifications. Specifically, plasma samples were prepared for analysis using protein precipitation with acetonitrile. Sample extracts were analyzed using normal phase chromatography with a Waters BEH HILIC column (2.1 × 100 mm, 1.7 μm, Waters Corp.) followed by detection with a Waters Xevo TQ-XS mass spectrometer. The mobile phase was A (10 mmol/L ammonium formate in water/isopropanol/formic acid 50/50/0.1):B (10 mmol/L ammonium format in acetonitrile/water/formic acid 90/10/0.1) = 40:60 with 0.25 mL/min flow rate. The mass spectrometer used an electrospray ionization source and a positive ion multiple reaction monitoring mode. For quantification of TXA, mass-to-charge ratios were set to 158.2 > 95.2 for TXA and 144.2 > 109.1 for the internal standard, respectively. Measurements for samples containing over 25 μg/mL TXA were obtained after diluting the samples into control plasma. The lower limit for TXA quantification was 0.04 μg/mL. Intra-assay (within-day) precision (% coefficient of variation [% CV]) and accuracy (% bias) were 1.3% to 8.7% and 0.9% to 7.6%, respectively. Inter-assay (between-day) % CV and % bias were 0.7% to 6.7% and 1.2% to 15.2%, respectively.

The Waters Xevo TQ-XS mass spectrometer was operated in electrospray positive ionization mode using multiple reaction monitoring mode. The capillary voltage was set at 3.00 kV, and desolvation temperature was set at 500°C. Gas flow parameters were optimized to 1000 L/h for desolvation, 150 L/h for cone, and 7.0 bar for nebulizer. The dwell time was set at 50 ms. Cone voltage and collision energy were optimized at 60 V and 38 eV for pamiparib, and 70 V and 42 eV for [¹³C₂,¹⁵N₂]pamiparib. The most sensitive MS transitions of m/z 299.0 → 133.0 and 303.0 → 134.9 were selected for monitoring pamiparib and [¹³C₂, ¹⁵N₂]pamiparib, respectively (Figure 1).

Liquid-chromatography tandem mass-spectrometry (LC-MS/MS) was used to quantify the following vitamin D metabolites in serum and SF; 25(OH)D3, 3-Epi-25(OH)D3, 25(OH)D2, 24,25-dihydroxyvitamin D3 (24,25(OH)₂D3) and 1,25(OH)₂D3 as described previously [32 (link)–34 ] with slight modifications. In brief, samples were prepared for analysis by protein precipitation and supported liquid-liquid extraction, followed by derivatization with 4-(2-(6,7-dimethoxy-4-methyl-3-oxo-3,4-dihydroquinoxalinyl)ethyl)-1,2,4-triazoline-3,5-dione (DMEQ-TAD) as previously described [35 (link)]. Analysis of extracted sera and SF vitamin D metabolites was performed on a Waters ACQUITY ultra performance liquid chromatography (UPLC) coupled to a Waters Xevo TQ-XS mass spectrometer. The LC-MS/MS method has been validated on US Food and Drug Administration guidelines for analysis of these metabolites.