44 May / June 2019
Figure 7. Reconstructed ion chromatograms (RICs) for 9 drugs spotted onto a TLC plate and analysed by DART compared to fluorescence detection (inset). The RICs are normalised to the same scale with relative scale factors as shown in the inset table. The plate is scanned at a rate of 3 mm s-1 spots at 1.35 minutes and 1.98 minutes, respectively.
. Mass spectra are shown for the
the simplicity of the interface: a zero dead volume connection, stainless steel capillary, mounting brackets and a solvent drain, it is not clear why a commercial interface has not been offered. The problem may be circular: the development may be waiting for customer demand, yet customer demand will not occur until an interface is available. Perhaps this situation will change in the near future and DART will find a place among LC/ MS detection methods.
Conclusion
Direct Analysis in Real Time (DART) mass spectrometry can be used for more than simply exposing a sample to the heated DART gas stream. When combined with simple sample handling and sample preparation methods such as in-situ derivatisation, solid-phase microextraction, and thermal desorption and pyrolysis, DART selectivity and detection limits can be greatly improved. Dopant-assisted argon DART and oxygen adduct formation are two
variations on DART that permit the selective detection of nonpolar compounds such as saturated hydrocarbons. While DART is often used as a stand-alone ion source, it has been combined with the most common forms of chromatography with characteristics that complement other mass spectrometric detection methods.
References
1. Cody, R. B.; Laramee, J. A.; Durst, H. D. Versatile New Ion Source for the Analysis of Materials in Open Air under Ambient Conditions; Analytical Chemistry 2005, 77, 2297-2302.
2. Domin, M. A.; Cody , R. B. Ambient Ionization Mass Spectrometry; Royal Society of Chemistry, 2015.
3. Penning, F. M. Über Ionisation durch Metastabile Atome; Naturwissenschaften 1927, 15, 818.
4. Pierce, C. Y.; Barr, J. R.; Cody, R. B.; Massung, R. F.; Woolfitt, A. R.; Moura, H.;
Thompson, H. A.; Fernandez, F. M. Ambient generation of fatty acid methyl ester ions from bacterial whole cells by direct analysis in real time (DART) mass spectrometry; Chem. Commun. 2007, 807 - 809.
5. Fraser, D.; DeRoo, C. S.; Cody, R. B.; Armitage, R. A. Characterization of blood in an encrustation on an African mask: spectroscopic and direct analysis in real time mass spectrometric identification of haem; Analyst 2013, 138, 4470-4474.
6. Kim, H. J.; Park, S. R.; Jang, Y. P. Extraction-free In situ Derivatisation of Timosaponin AIII Using Direct Analysis in Real Time TOF/MS; Phytochemical Analysis 2014, 25, 373-377.
7. Zeng, S.; Wang, L.; Chen, T.; Qu, H. On- line coupling of macroporous resin column chromatography with direct analysis in real time mass spectrometry utilizing a surface flowing mode sample holder; Analytica Chimica Acta 2014, 811, 43-50.
8. JEOL USA Inc. Using Solid Phase Microextraction with AccuTOF-DART® for
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