Parallel Pseudo-MRM on the 'brick' miniature mass spectrometer for high throughput multi-target screening

With increasingly improved analytical performances, miniature mass spectrometers are expandingly applied in more application scenarios. The capability of high throughput analysis of multi-targets is a crucial function of a miniature mass spectrometer, especially for in-situ applications. As a powerful method for target screening, multiple reaction monitoring (MRM) was conventionally realized on triple quadrupole (QQQ) mass spectrometers. Previously, pseudo-multiple reaction monitoring (pseudo-MRM) operation mode has been realized on a "brick" mass spectrometer equipped with a single ion trap. However, pseudo-MRM on an ion trap was realized through the tandem-in-time fashion, and the throughput of pseudo-MRM was still limited. As a continuous effort to boost performances of the "brick" miniature mass spectrometer, parallel pseudo-MRM mode was developed, and the throughput could be raised up to 10 times for multi-target screening. To achieve better isolation and collision induced dissociation (CID) efficiencies, the mass range of interest was divided into several segments based on optimized Mathieu q value. The fast screening of 10 different drugs was used as an illustrative example. Furthermore, parallel quantitative analysis was also demonstrated and verified using the internal standard calibration method.