Portable LC becomes much more practical by simply switching from conventional 4.6-1.0 mm i.d. columns to 0.250-0.075 mm i.d. capillary columns because the amount of mobile phase required is reduced by as much as three orders of magnitude. This greatly simplifies transport and disposal of organic solvents used as or in the mobile phase. Interest in mobility arises from the desire to perform LC analyses at or near the sample source, to easily move the LC from one laboratory bench to another, to place it in a hood or near a reaction vessel (e.g., for reaction monitoring), and to position it as close as possible to other sampling devices or detection systems such as a mass spectrometer (MS). For these reasons, we are continually developing and enhancing a hand-portable capillary LC system that has a small footprint, is easy to carry (even while in operation), can be operated using a smart phone or tablet (as well as laptop or other computer), and produces consistent low to sub-microliter per minute flow rates at pressures up to approximately 700 bar. In its basic design, UV-transparent capillary columns and single-wavelength on-column UV-absorbance detectors (235, 255 and 275 nm LEDs) are housed in cartridges that can be easily exchanged using a leak-tight compression mechanism. In recent months, other detection options, based on MS, variable wavelength UV-absorption, and fluorescence have been investigated. Relatively fast analysis of mixtures of polycyclic aromatic hydrocarbons, pharmaceuticals, enantiomers, drugs of abuse and hemp extracts are representative of samples to which the portable LC has been advantageously applied. The performance characteristics of the portable LC are similar to those obtained using conventional LC systems, except care must be exercised to ensure that samples are particle-free, extra-column volumes are minimized, and capillary columns are not overloaded with sample.

Features and applications of portable capillary LC

ACS Spring Meeting 2021

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