Monolayer-Protected Noble-Metal Clusters as Potential Standards for Negative-Ion Mass Spectrometry

• Published in: Analytical chemistry (Washington) Vol. 90; no. 19; pp. 11351 - 11357
• Main Authors: Baksi, Ananya, Chakraborty, Papri, Nag, Abhijit, Ghosh, Debasmita, Bhat, Shridevi, Pradeep, Thalappil
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 02-10-2018
• Subjects: Calibration; Chemistry; Ionic mobility; Low molecular weights; Mass spectrometers; Mass spectrometry; Mass spectroscopy; Materials science; Metal clusters; Metals; Mobility; Molecules; Monolayers; Negative ions; Noble metals; Polymers; Salts; Shape recognition; Spectrometers; Spectroscopy
• ISSN: 0003-2700; 1520-6882
• DOI: 10.1021/acs.analchem.8b02280

A detailed mass-spectrometric study of atomically precise monolayer-protected clusters revealed the potential application of such materials as mass-spectrometric standards, mostly in negative-ion mode and in the high-mass range. To date, very few molecules are known that can be efficiently ionized and detected at lower concentrations as negative ions with high signal intensities beyond m/z 3000. Noble-metal clusters are molecules with definite masses, sizes, and shapes, which makes them excellent candidates to choose as standards over conventional low-molecular-weight polymers or clusters of ionic salts. They may be used as calibrants in all possible modes, including tandem mass spectrometry and ion mobility. With the advancement in materials science, more and more molecules are being added to the list that are inherently negatively charged in solution and can be examined by mass spectrometry. In this report, we demonstrate the use of three such model cluster systems for their potential to calibrate mass spectrometers in negative-ion mode. This idea can be extended to many other clusters known so far to achieve calibration in extended mass ranges.