Evaluation of the higher sensitive LC/MS/MS incorporates novel desolvation technologies to achieve low femto-gram LOQ

The triple quadrupole mass spectrometer is widely used in various application fields to quantify the trace amount of compounds in real world samples because of its excellent sensitivity and selectivity. In order to achieve lower limit of quantitation, many researchers have been developing new desolvation technologies at either ESI sprayer or MS inlet.
Here, we report the higher sensitive triple quadrupole mass spectrometer equipped with novel desolvation devices such as addition of the heated gas blowing along with electrospray and the heated multi-orthogonal ion path mounted at the inlet of mass spectrometer. The combination of the heated gas at ESI and heated multi-orthogonal ion path enhanced desolvation efficiency which resulted in low femto-gram limit of quantitation.
Several commercially available drug samples (Reserpine, Verapamil, Alprazolam, Carbamazepine, Cilostazol, Lidocaine, Fluticasone and Testosterone) were prepared for the sensitivity evaluation of higher sensitive triple quadrupole mass spectrometer equipped with the modified ESI source and the heated multi orthogonal ion path. All the samples were analysed by the Multiple Reaction Monitoring (MRM). MRM parameters including MRM transitions and collision energy as well as compound dependent ion transfer voltages were optimised through automatic MRM optimization functionality incorporated in LabSolution software (Shimadzu Corporation, Kyoto, Japan).The temperatures of heated gas and heated multi-orthogonal ion path were optimised for each sample.
Using modified ESI source and the heated multi orthogonal ion path helped to deliver a limit of quantitation for all eight drugs below 5 fg/uL. The temperature of heated gas and heated multi-orthogonal ion path were independently optimised for each sample with the range of 200 to 500 degree C and 150 to 300 degree C respectively. The ion intensity of reserpine was increased 8 times with the heated gas and 4 times with heated multi-orthogonal ion path operated at 300 degree C. Besides larger volume of Ion was introduced into the mass spectrometer by the effective desolvation, the base line noise was maintained at reasonably low level as the noise derived from neutral droplet or unwanted ions were strongly reduced in the multi orthogonal region heated at high temperature, and resulted in excellent signal to noise ratio which achieved low femto-gram sensitivity.