Fabrication of permanent silver cement frit at the inlet of micro-columns: a significant progress toward realization of disposable micro-columns

The advent of disposable micro-columns will be a hope of workers of chromatography-related laboratories. A very critical and important requirement is the formation of affordable inlet frits. Welding a metal screen to a column inlet is not recommended because of the risk of damage to stationary phase. In this study, the Tollens probe (silver mirror reaction) was adopted to make affordable frits. Silver is reduced on the particle surface and in an empty space among the particles, forming a solid silver network structure at the column inlet area by injecting the reaction solution into the packed column at a depth of one third (10 cm) of the packed bed (0.5 mm × 300 mm). The silver cement structure was successfully formed, and the silver cement frit endured mobile phase flow well when C18 modified ground silica monolith particles were used to make the packed bed. The formation of the silver cement frit was not successful when the stationary phase based on conventional spherical silica particles was used. Negligible reduction of chromatographic performance by the silver cemented frit was observed. This study serves as the first step toward realization of disposable micro-columns.

Packed column inlet as a direct injection capillary inlet

Discrimination is a known problem when analyzing high-boiling compounds, which considerably hinders their analysis at trace levels. This problem can be solved by using either direct or on-column injection. Modification of a standard injection port liner and a micro-syringe is presented, so that a direct injection with in-column evaporation can be easily done. The proposed changes are compatible with any packed column injection port, simple to implement, and inexpensive. The changes are described and the analysis of acyloglycerols in diesel oil spiked with 50 % FAME is used to demonstrate the utility of the proposed injection technique.