Syringe injection pump

Samples were analyzed by a hybrid quadrupole time-of-flight mass spectrometer (maXis Impact, Bruker Daltonics, Billerica, MA, USA) equipped with an electrospray ionization (ESI) source. The mass spectrometer was set up and calibrated by using ES Tuning Mix (Agilent Technologies, Santa Clara, CA, USA) to detect ions with a mass-to-charge ratio (m/z) ranging from 50 to 1000 and a mass accuracy of 1–3 parts per million (ppm) in the positive ion charge detection mode. The samples were injected into the ESI source with a flow of 180 µL/h using a glass syringe (Hamilton Bonaduz AG, Bonaduz, Switzerland) and a syringe injection pump (KD Scientific, Holliston, MA, USA). All samples were analyzed in random order. The internal standard Losartan (C22H23ClN6O, m/z = 423.169) added to each sample before MS analysis was used for monitoring of matrix suppression, reproducibility, and stability of the method. Tandem mass spectrometry (MS/MS) analysis of selected precursor ions with an intensity ≥ 5000 was performed at collision energy from 10 to 40 eV.

Mass spectrometry analysis of the samples was carried out by direct injection to a hybrid quadrupole time-of-flight mass spectrometer (maXis Impact, Bruker Daltonics, Bremen, Germany) equipped with an electrospray ionization (ESI) source. The mass spectrometer was set up to detect ions with the mass-to-charge ratio (m/z) in the range from 50 to 1000 Da and mass accuracy up to three parts per million (ppm). The appropriate mass range of the mass spectrometer was calibrated by using ES Tuning Mix (Agilent Technologies, Santa Clara, CA, USA). Spectra were acquired in the positive ion mode detection. The samples were injected into the ESI source using a glass syringe (Hamilton Bonaduz AG, Bonaduz, Switzerland) and a syringe injection pump (KD Scientific Inc., Holliston, MA, USA) with flow rate of 180 µL/h for one minute. All samples were analyzed in random order and in three-five technical replicates. MS/MS spectra of selected precursor ions with the intensity threshold of 5000 were acquired at collision energy from 10 to 40 eV.

Samples were analyzed by a hybrid quadrupole time-of-flight mass spectrometer (maXis Impact, Bruker Daltonics, Billerica, MA, USA) equipped with an electrospray ionization (ESI) source. The mass spectrometer was set up to prioritize the detection of ions with a mass-to-charge ratio (m/z) ranging from 45 to 900 Da, with a mass accuracy of 1–3 parts per million (ppm). The spectra were recorded in the positive ion charge detection mode. The samples were injected into the ESI source using a glass syringe (Hamilton Bonaduz AG, Bonaduz, Switzerland) connected to a syringe injection pump (KD Scientific, Holliston, MA, USA). The rate of sample flow to the ionization source was 180 µL/h. Technical replicates were not performed. Mass spectra were obtained using DataAnalysis version 3.4 (Bruker Daltonics, Billerica, MA, USA) to summarize one-minute signals.