Office Chromatography: Precise printing of sample solutions on miniaturized thin-layer phases and utilization for scanning Direct Analysis in Real Time mass spectrometry

Office Chromatography combines achievements in office technologies with miniaturized planar chromatography. In the life sciences, printing of materials became an accepted technique, whereas in separation science, the use of printers for chromatography is at its infancy. A bubble-jet printer was modified for exact application on miniaturized plates. Technical modifications included the removal of all unnecessary parts and the improvement of the positioning system, purge unit and sample supply system. Evaluation was performed via a slide scanner and image evaluation software. Printing of a food dye mixture solution (n = 5) led to a calculated mean deposition volume of 13 ± 1 nL/mm2 per print-cycle. A mean determination coefficient (R2; n = 5) of 0.9990 was obtained for application of increasing volumes, executed via increasing band widths of 50–200 μm (corresponding to 2–8 nL). Using larger band widths and multiple print jobs, deposition volumes of up to the microliter scale represented an alternative to cost-intensive standard equipment. After print, separation, detection and digital evaluation of five food dyes, mean R2 (n = 5) were obtained between 0.9977 and 0.9995. The accuracy of printing was proven by mean recovery rates of 101–105% with repeatabilities of 3–7% (%RSD, n = 5). The transfer to nanostructured ultrathin-layer plates proved the synergetic potential of these fields of research. First, this modified printer was suited for printing of finely graduated scales of three preservatives for determination of the spatial resolution of scanning Direct Analysis in Real Time mass spectrometry.