Skip to main content
. Author manuscript; available in PMC: 2009 Aug 15.
Published in final edited form as: J Chromatogr B Analyt Technol Biomed Life Sci. 2008 Apr 29;871(2):236–242. doi: 10.1016/j.jchromb.2008.04.031

Figure 2.

Figure 2

Chromatographic traces for methionine standard at 50 ng/mL in positive ionization mode (a) and NAD+ in a biological sample in negative mode (b), on identical TSQ Quantum Ultra (Thermo Fisher Scientific ) triple quadrupole instruments but with different ion sources, the unheated electrospray source (sold line) and the heated electrospray source (HESI, dashed line). The insets show the corresponding noise/background region. The LC method was HILIC as reported previously [10]. The source conditions for the unheated ESI were: spray voltage +3500 V or −3000 V, sheath gas 30 psi, auxiliary gas 10 psi. The source conditions for the HESI were: spray voltage +2555 V or −2555 V, vaporizer temperature 230 °C, sheath gas 22 psi, auxiliary gas 37 psi.