Impact of Gas–Liquid Interface on Photochemical Vapor Generation

Abstract

Interfacial effect has attracted increasing interest as the inherent asymmetric environment of a gas–liquid interface leads to different chemical and physical properties between this region and the bulk phase, resulting in enhanced chemical processes, specific reactions, and mass transfer at the interface. Photochemical vapor generation (PVG) is regarded as a simple and green sample introduction method in atomic spectrometry. However, the photochemical behavior of elements with the interface is not known. Herein, we report the PVG of elements at the gas–liquid interface along with a possible mechanism investigated for the first time. Enhancement and/or suppression effects from the gas–liquid interface were observed on the PVG of 17 elements, which was correlated with the properties of analytes and the generated intermediate substances/products of PVG and the applied conditions. Enhancement from 1.1- to 7.3-fold in analytical sensitivity was found for 12 elements in the system with gas–liquid interface(s) compared to the results obtained in previous reports of PVG using traditional flow injection with inductively coupled plasma mass spectrometry measurement. The introduction of gas–liquid interface(s) and the resultant elevated temperature inside the PVG reactor likely facilitated the generation of radicals, the subsequent radical-based reactions, and the separation/transport/detection of volatile species of elements. In contrast, intermediate substances/products generated in PVG with poor thermostability will readily decompose at elevated temperatures, leading to a decreased signal response of analytes. The finding is helpful to understand the transport of elements under UV irradiation in the environment and has potential for analysis of trace elements in environmental and biological samples.

GC-MS exploration of photochemically generated species of Os, W and Ru from reductive and oxidative media

“…Apart from the above, there is no doubt as to the concluded identity of the PVG species being W(CO) 6 , in line with earlier identification of same group VI Mo(CO) 6 being produced by PVG of Mo( vi ) from a similar medium. 10,49…”

“…It is self-evident that knowledge of the analytical reaction products is fundamentally crucial to furthering our understanding and validation of possible PVG mechanisms. Many systems have been successfully characterized using gas chromatography mass-spectrometry (GC-MS) techniques, including As, 9,10 Bi, 11–13 Br, 14,15 Cl, 15,16 Co, 13,17 I, 18 F, 19 Fe, 20,21 Hg, 22 Mo, 10 Ni, 23 Sb, 10 Se 24 and Te. 25…”

Vanadium Species-Assisted Photochemical Vapor Generation for Direct Detection of Trace Tellurium with Inductively Coupled Plasma Mass Spectrometry

“…The main parameters affecting PVG of Te were investigated independently. An X-band electron paramagnetic resonance (EPR) spectrometer (EMXplus, Bruker, Germany) was used for identification of radicals and the intermediate generated during PVG. , All the EPR spectra were simulated by the Easyspin program in Matlab. Volatile species collected from the headspace of GLSs were identified by gas phase chromatography–mass spectrometry (GC–MS).…”

Atomic spectrometry update: review of advances in atomic spectrometry and related techniques

“…A different focus was provided by Yu et al , 41 who investigated the gas–liquid interface by using a segmented flow system. They found no difference in the PVG of As, Sn, Ir, Os, Cd, Ni, Hg, and Mo regardless of whether air or Ar was used before/after the solution slug.…”

“…Re PVG was enhanced by a combination of Cd 2+ , Co 2+ , formic acid and acetic acid; 38 Os with acetic acid; 39 and I with ethanol. 40 A different focus was provided by Yu et al, 41 who investigated the gas-liquid interface by using a segmented ow system. They found no difference in the PVG of As, Sn, Ir, Os, Cd, Ni, Hg, and Mo regardless of whether air or Ar was used before/aer the solution slug.…”