Ultrasensitive UHPLC-MS/MS Quantification

After the AT sample was pretreated [64 (link)], an EXIONLC System was used for UHPLC separation (Sciex). Formic acid at 1% in water served as mobile phase A, and acetonitrile served as mobile phase B. The temperature in the column was fixed at 40 °C. The injection volume was 2 L, and the autosampler’s temperature was set at 4 °C. For the development of the test, a Sciex QTrap 6500+ (Sciex Technologies) was used. The typical ion source settings were as follows: ion spray voltage: +5500/−4500 V; curtain gas: 35 psi; temperature: 400 °C; ion source gas 1:60 psi; ion source gas 2:60 psi; and DP: 100 V. Finally, SCIEX Analyst Work Station Software (Version 1.6.3) was employed for MRM data acquisition and processing. An in-house R program and database were applied for peak detection and annotation.