Determination of elemental composition of metals using ambient organic mass spectrometry

Rapid detection of metal impurities on the surfaces of intact objects with irregular shapes using electrochemical mass spectrometry

New approaches are demanded in daily life and industry for the rapid inspection of chemical impurities on various objects, particularly those with irregular shapes. Herein, an analytical strategy combining electrochemistry (EC) and mass spectrometry (MS) has been developed for the direct inspection of metal impurities on various objects which are commonly used in daily life and industry. An intact object (e.g., necklace, bearing, ring) was immersed in an electrolytic cell containing EDTA/acetonitrile/water solution at appropriate potentials to form metal ions. The formed metal ions were instantly chelated with specific ligands (e.g. ethylenediaminetetraacetic acid) and sampled for online electrospray ionization (ESI) with high-resolution MS detection. The unique feature of the method is that metal speciation information can be obtained even when just a metal impurity (e.g., Pb, Ni) is localized on a hard-to-reach tiny spot on the inner surface of objects with extremely irregular shapes. A single sample analysis requires less than 10 minutes, regardless of the object shape. The limit of detection is 0.05 ppb with sample consumption on the nanogram level. The experimental results demonstrate that the method is promising for the non-destructive quality and safety inspection of metal impurities on virtually any kinds of objects with high chemical sensitivity.

MS-Based Analytical Techniques: Advances in Spray-Based Methods and EI-LC-MS Applications

Mass spectrometry is the most powerful technique for the detection and identification of organic compounds. It can provide molecular weight information and a wealth of structural details that give a unique fingerprint for each analyte. Due to these characteristics, mass spectrometry-based analytical methods are showing an increasing interest in the scientific community, especially in food safety, environmental, and forensic investigation areas where the simultaneous detection of targeted and nontargeted compounds represents a key factor. In addition, safety risks can be identified at the early stage through online and real-time analytical methodologies. In this context, several efforts have been made to achieve analytical instrumentation able to perform real-time analysis in the native environment of samples and to generate highly informative spectra. This review article provides a survey of some instrumental innovations and their applications with particular attention to spray-based MS methods and food analysis issues. The survey will attempt to cover the state of the art from 2012 up to 2017.

Diethyldithiocarbamate enhanced chemical generation of volatile palladium species, their characterization by AAS, ICP-MS, TEM and DART-MS and proposed mechanism of action

Comprehensive investigation of chemical generation of volatile species (VSG) of palladium for detection by analytical atomic and mass spectrometry and, specifically, the mechanistic aspects of their formation and tentative identification are presented. VSG was achieved in a flow injection mode using a generator that permitted rapid mixing of acidified sample with NaBH₄ reductant. Atomization in a diffusion flame with detection by atomic absorption spectrometry was exclusively used for optimization of generation conditions while inductively coupled plasma mass spectrometry was utilized to investigate overall system efficiency and analytical metrics of the VSG system for potential ultratrace analysis. Sodium diethyldithiocarbamate (DDTC) served as a crucial reaction modifier, enhancing overall system efficiency 9-fold. Combinations of modifiers, Triton X-100 and Antifoam B surfactants provided a synergistic effect to yield a further 2-fold enhancement of VSG. The overall system efficiency was in the range 16-22%, with higher efficiencies correlating with higher Pd concentrations. The contribution of co-generated aerosol to the overall system efficiency, determined by means of concurrent measurement of added Cs, was negligible - less than 0.1%. The nature of the volatile species was investigated using several approaches, but principally by transmission electron microscopy (TEM) after their collection on a grid, and by direct analysis in real time (DART) using high resolution orbitrap mass spectrometry. These experiments suggest a parallel but dual-route mechanism of VSG of Pd, one attributed to generation of a volatile DDTC chelate of Pd and a second to nanoparticle formation.