Methods for sampling into an atmospheric pressure inlet mass spectrometer

Provided herein are systems and methods for sampling analytes into an atmospheric pressure inlet mass spectrometer using ultrasonic nebulization-assisted atmospheric pressure chemical ionization. The systems can include a mass spectrometer having an input and an ultrasonic nebulizer chip. The ultrasonic nebulizer chip can be operatively coupled to the mass spectrometer, such that when the ultrasonic nebulizer chip nebulizes the analyte to provide a nebulized analyte, at least some of the nebulized analyte enters the input of the mass spectrometer.