Lcms 8050 liquid chromatograph mass spectrometer

Shimadzu LCMS-8050 liquid chromatograph mass spectrometer (Shimadzu Corporation, Japan) equipped with binary pump, autosampler and electrospray ionization (ESI) source was used for the analysis. The specimens were injected into the LC-MS/MS system through ESI source for atmospheric pressure ionization and specimen analysis was performed using flow injection analysis-electrospray ionization-tandem mass spectrometry (FIA-ESI-MS/MS) method.

LC-MS/MS was performed using an LCMS-8050 Liquid Chromatograph Mass Spectrometer (Shimadzu, Kyoto, Japan) and Shimadzu HPLC System (system controller (CBM-20A), pump (LD-20AD), degasser (DGU-20As), UV detector (SPD-20A), and auto injector (SIL-20AC HT)). Separations were performed on a CAPCELL PAK C18 UG120 (3 μm, 2.0 mm × 100 mm, Shiseido Co., Ltd., Tokyo, Japan) using a mobile phase of 10 mmol/L ammonium acetate and 0.1% acetic acid in methanol and water (97:3) at a flow rate of 0.4 mL/min. Column temperature was maintained at 40 °C. The mass spectrometer was equipped with an electrospray ionization and was run in positive ion mode. Identification and quantitation were based on MS/MS-multiple reaction monitoring mode using transition ions as follows: m/z 445 → 187 for the [M+H]⁺ MK-4 adduct, m/z 445 → 187 for the [M + H]⁺ chromenol adduct, 619 → 58 for the [M + H]⁺ MKH-DMG adduct, m/z 532 → 58 for the [M + H]⁺ MKH-mono-DMG adduct, m/z 664 → 187 for the [M + H]⁺ MKH-SUC adduct, m/z 564 → 187 for the [M + H]⁺ MKH-mono-SUC adduct, and m/z 461 → 81 for the [M + H]⁺ MKO adduct. Retention times were: MK-4, 3.3 min; MK-4 chromenol, 2.0 min; MKH-DMG, 1.7 min; MKH-mono-DMG, 1.6 min; MKH-SUC, 1.1 min; MKH-mono-SUC, 1.2 min; and MKO, 2.5 min.

Methanol solutions
of diruthenium complexes (3a or 3b, 10 μM)
were mixed with an equal volume of an aqueous solution of either l-cysteine (to produce the final concentration of 120 μM)
or GSH (to produce the final concentration of 10 mM). The resulting
solutions were maintained in the dark. Afterward, aliquots of the
final solutions were injected, using the autosampler of the LC–MS
system with bypassed separation column, into the stream of 1:1 v/v
methanol/water at 0.2 mL/min flow rate and immediately analyzed by
ESI-MS in a positive ionization mode (mass range 100–1500 m/z). Samples from l-cysteine
were analyzed on a Bruker amaZon SL mass spectrometer, while samples
from GSH were analyzed on a Shimadzu LC–MS 8050 Liquid Chromatograph
Mass Spectrometer. The obtained data were processed using the dedicated
software provided by each respective manufacturer (Bruker, Data Analysis
4.4; Shimadzu, LabSolutions Connect software).