Agilent 6460 triple quadrupole ms

T3 was measured by isotope dilution LC-MS/MS using the Agilent 6460 triple quadrupole MS coupled with an ESI source and Agilent 1200 Infinity series HPLC (Agilent Technologies, Santa Clara, CA, USA) as previously described.^{16 (link),19 (link)} FT3 and FT4 were separated from protein-bound hormones by ultrafiltration at 37°C, followed by measurement by isotope dilution LC-MS/MS using an AB Sciex Triple Quad 6500 (AB Sciex, Concord, ON, Canada) and Shimadzu LC-20AD HPLC (Shimadzu Instruments, Columbia, MD, USA) as previously described.^{36 (link)} Complete method validation studies and diurnal reference intervals for thyroid hormones have been established.^{37 (link)}Cortisol was measured by isotope dilution LC-MS/MS using the Agilent 6490 triple quadrupole MS coupled with an atmospheric pressure photoionization source and Agilent 1200 Infinity series HPLC (Agilent Technologies, Santa Clara, CA, USA) as previously described.^{38 (link),39 (link)} Complete method validation studies and diurnal variations have been established.^{40 (link)}

Analysis of nucleosides
was performed with Agilent 1290 UHPLC and Agilent 6460 Triple Quadrupole
MS (both from Agilent Technologies Inc., Santa Clara, CA). The injected
sample volume was 5 μL. Chromatographic separation of adenosine
and N6-methylated adenosine was done with a reversed phase column
(2.1 × 100 mm, 1.7 μm Waters). UHPLC eluents were A, 10
mM ammonium formate at pH 5 and B, methanol. Gradient elution was
from 5 to 25% B in 5 min followed by 4 min at 5% MeOH, total flow
being 400 μL/min. Retention times of monitored adenosine nucleosides
were 3.6 and 5.6 min, respectively. A mass spectrometer was set to
the positive electrospray ionization mode with the daughter ion analysis
mode (MS/MS) (Ade 268 → 136 m/z and 6mAde
282 → 150 m/z) using collision energy 7 and
21, respectively. Ion optimization was done using automatic tuning
with source capillary temperature at 400, and 250 °C was used
as transfer line temperature. A mixture of nitrogen and air was used
as electrospray ionization gases, and argon was used as collision
gas. Quantification of sample analysis was done with the instrument’s
quantitation program for adenosine at 1–10,000 nM and for N6-methylated
adenosine at 0.5–3000 μM concentration ranges.