2026 Volume 74 Issue 2 Pages 47-51
In liquid chromatography-mass spectrometry (LC/MS), non-volatile buffers such as phosphate or ion-pairing reagents enhance chromatographic performance but interfere with mass spectrometric detection. On-line desalination tubes, which contain ion-exchange resin, have been developed to remove these additives prior to MS detection. However, each tube has a limited usage time (～15 minutes) and must be replaced frequently, making them unsuitable for high-throughput analysis. An automated switching device capable of sequentially using up to 100 on-line desalination tubes was developed to overcome the limitation. The device features a novel nozzle mechanism and software-controlled switching system that ensures consistent operation. Leaf extract sample was analyzed by LC/MS to evaluate the device’s performance. Peak diffusion of m/z 507.365 was assessed under three conditions. The full width at half maximum (FWHM) increased by approximately 1.4-fold when both on-line desalination tube and the device were used, compared to the peak without either. However, the peak shape remained acceptable for practical use. This device enables continuous LC/MS analysis with on-line desalination tubes for 24 hours or longer and is particularly useful for analyzing complex biological samples that require non-volatile additive.
