LC-MS/MS Method Optimization
We optimized all eight adrenal steroids in positive and negative
ionization mode; however, positive mode performed better for all
analytes and therefore negative mode data will not be discussed. Using
tuning mode, we optimized source (curtain gas = 276 kPa temperature =
600 ºC, ion source gas 1 = 209 kPa, ion source gas 2 = 414 kPa,
interface heater = Off, collision gas- High, ion spray voltage = 4000 V)
and compound parameters (Table 1). DHEAS did not ionize well in positive
mode and was later removed from the final positive ionization method.