Automated printing technology as a new tool for liquid sample preparation for micro x‐ray fluorescence (MXRF)

Abstract

The focus of this study was to explore automated printing technology (APT) as an alternative means to manual methods for nanoliter dried spot sample preparation of liquid samples for micro x-ray fluorescence analysis (MXRF). APT was used successfully to dispense 20 and 50 nl volumes of multielemental standard solutions onto AP1 and Kapton film substrates. Automated droplet deposition was rapid and minimized operator skill and human error in the sample preparation process. Dried spots prepared by APT were generally circular in shape and similar in appearance to those prepared by manual dried spot deposition techniques. Furthermore, multiple dried spots could be accurately and reproducibly deposited in the same precise location on the film substrate surface, allowing for increased sample loadings within the MXRF analysis area for higher elemental sensitivity. The characteristics of the substrate did affect the quality of dried spot formation, with irregularly shaped spots forming on the thicker, more hydrophobic Kapton film, especially with higher droplet mass loadings. Adverse effects of irregular spot formation on quantitative analysis could be easily minimized by increasing the MXRF analysis area to encompass the entire dried spot residue. Nanoliter dried spot sample preparation is useful not only for MXRF analysis of liquid samples, but can also be applied to other analytical techniques such as IR, Raman or UV/fluorescence spectroscopy, the applications of which can benefit from rapid sample throughput and matrix reduction.

Measurement of Crystalline Silica Aerosol Using Quantum Cascade Laser–Based Infrared Spectroscopy

“…Method C offers the lowest MDL and demonstrates the superior measurement capability of QCL-based approach and can be coupled with different sample preparation methods. The low detection limits obtained using method C are also consistent with similar results obtained for other microspectroscopy techniques using the dried spot method 24 .…”

“…The resulting dried spot is then analyzed using QCL-IR. Similar dried spot methods have been successfully used before for other microspectroscopies 24 . To generate a calibration curve for method C, suspensions of quartz SRM were first prepared in ultrafiltered deionized water (CAS 7732-18-5, ThermoFisher Scientific, Rochester, NY, USA) with various predetermined aqueous concentrations ranging from 0.2 to 6 mg/ml.…”

Liquid-phase microextraction as an attractive tool for multielement trace analysis in combination with X-ray fluorescence spectrometry: an example of simultaneous determination of Fe, Co, Zn, Ga, Se and Pb in water samples

“…The recently proposed advanced nanolitre or even picolitre dried-spot sample preparation systems designed for m-XRF measurement in combination with LPME are promising tools, particularly for very small organic drops. [39][40][41] Because m-XRF measurement is easy to automate, the implementation of LPME on a lab-on-chip system with m-XRF is very promising microanalysis. Papers dedicated to microextraction on lab-on-chip systems for organic analysis have been recently published.…”

Atomic spectrometry update. X-ray fluorescence spectrometry

“…Miller et al built on their earlier work of using nanolitre dried spots that decreased reagent consumption and produced specimens of uniform shape to enable the detection of elements with picogram sensitivity by micro X-ray fluorescence and TXRF. Their current publication 161 overcame the major drawback in the preparation of nanolitre dried spots due to operator variables as the droplets were deposited manually through a contact injection method onto different analysis substrates. This technique, however, introduced sample preparation errors due to variations in the contact geometry of the injector tip with the substrate surface between droplet injections plus a human factor arising from differences in user technique.…”