Hand-powered ionization methods for the mass spectrometric detection of small molecules

Miniaturization of ambient ionization source is of great importance to the popularization of mass spectrometry . However, current ambient ionization sources are typically connected to several accessory equipment such as high voltage power supply, gas cylinders, and injection pumps. We report hand-powered ionization methods for mass spectrometric detection of small molecules based on a piezoelectric element that transforms hand mechanical energy into electrical energy. The piezoelectric element only weighs 39 g and lengths 9 cm, and no extra accessory equipment is needed. Paper spray , nanoelectrospray, and pin-to-funnel discharge powered by the piezoelectric elements were achieved, and several small molecule standards, including drugs, herbicides, etc., were detected and confirmed using these devices with a benchtop mass spectrometer . In addition, terbuthylazine (a herbicide) on the surface of a tomato was detected using the hand-powered pin-to-funnel discharge coupled with a miniature mass spectrometer , which indicates a potentially broader application of these methods in the on-site detection field. The methods described here are low-cost, user-friendly, miniatured, and versatile. Although efforts are still needed for the improvement of the performance, the piezoelectric element shows the alternative pathway of the miniaturization of ambient ionization.