In the field of chemistry, monitoring the reaction process and rate of chemical reactions is very important in order to accurately understand the type of reaction that is occurring.
Probe electrospray ionization (PESI) is a direct ionization technique that uses a probe to ionize sampled target components by sampling a sample at a constant frequency with high voltage applied to the probe tip. This technique enables rapid monitoring of sample changes without the need for a chromatograph. The DPiMS-2020, which combines PESI with a mass spectrometer, enables accurate understanding of the progression of chemical reactions through real- time monitoring of changes in the molecular weight information of components targeted for analysis. This article introduces the result of using the DPiMS- 2020 to perform real-time analysis of the deprotection reaction of a peptide protecting group that was produced on a sample plate.

When a solution of 23.0 mg of Fmoc-Tyr(tBu)-OH(N-(9- Fluorenylmethoxycarbonyl)-O-tert-butyl-L-tyrosine) dissolved in 5 mL of DMF is mixed together with a solution of piperidine and DMF mixed at a 1:4 ratio , a deprotection reaction of the Fmoc group will occur at room temperature (Fig. 2).

Fig 1 Deprotection Reaction of Fmoc-Tyr(tBu)-OH


Direct Probe Ionization Mass Spectrometer "DPiMS-2020"



The DPiMS-2020 is a single quadrupole mass spectrometer based on using probe electrospray ionization. It uses a probe to remove a micro quantity of liquid from the sample placed on the sample plate and inject it into the MS unit for mass analysis. It is extremely easy to operate and it is able to measure samples such as chemical products, food materials, and biological samples, directly or with very minimal sample pretreatment.