Premium
Direct analysis of surface chemicals using vibrating sharp‐edge spray ionization mass spectrometry
Author(s) -
Ranganathan Nandhini,
Lozier Austin M.,
Rawson Michael C.,
Johnson Matthew B.,
Li Peng
Publication year - 2020
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.8902
Subject(s) - chemistry , desorption electrospray ionization , ambient ionization , electrospray ionization , mass spectrometry , ionization , analytical chemistry (journal) , thermal ionization , chemical ionization , direct electron ionization liquid chromatography–mass spectrometry interface , chromatography , detection limit , electron ionization , organic chemistry , ion
Rationale Direct analysis of chemicals on a surface using mass spectrometry (MS) is of great importance in forensics, food and drug safety, environmental monitoring, and defense. Solvent extraction–based surface analysis offers a convenient way of controlling the desorption conditions and applying internal standards. To date, it mainly relies on a separate electrospray process to nebulize and ionize the solvents. Here, we report a simple and stand‐alone ionization system for the solvent extraction–based surface analysis without the need for high voltage, based on vibrating sharp‐edge spray ionization (VSSI). Methods We modified the original VSSI device and developed a stand‐alone, integrated surface sampling, and ionization system for MS analysis. By incorporating a micropipette‐based solvent dispenser with the VSSI device, the new system performs solvent extraction and ionization, and still maintains a small footprint. Results We demonstrated a four order‐of‐magnitude linear response for glucose spotted on a glass surface with a limit of detection (LOD) of 0.1 pg/mm 2 . We further characterized the performance of this method with a series of compounds and demonstrated a similar LOD to literature values obtained by desorption electrospray ionization. Finally, we applied this method to quantitatively measure the concentration of a pesticide ametryn on spinach surfaces. We demonstrated good linearity ( R 2 = 0.99) for ametryn with surface densities in the range of 8–800 pg/mm 2 and an LOD of 9 pg/mm 2 . Conclusions We have demonstrated a simple, effective, direct ambient‐ionization method that is highly sensitive to molecules on a wide range of surfaces. The flexibility, small footprint, low cost, and voltage‐free nature of this method make it an attractive technique for direct surface sample analysis using MS.