Learning from Headspace Sampling: a Versatile High-Throughput Reactor for Photochemical Vapor Generation.

Inspired by the headspace sampling (HS) device, a versatile high-throughput photochemical reactor with twenty vessels serving as both the photochemical vapor generator and the HS device was developed for the rapid and sensitive determination of mercury, nickel, and selenium by coupling photochemical vapor generation (PVG) to atomic fluorescence spectrometry (AFS) or point discharge optical emission spectrometry (µPD-OES). The photochemical reactor utilized a specially designed annular UV lamp around which the vessels containing sample solution were automatically rotated and irradiated to yield gaseous analyte species. Subsequently, the species escaped into the headspace of vessels prior to introduction to the atomic spectrometer. Compared with the conventional flow injection (FI) or continuous flow (CF) PVG, the developed PVG-HS method possesses several unique advantages including high throughput (260 pcs h-1), high sensitivity, and the elimination of matrix interference from transition metal ions and the memory effect associated with the quantification of mercury. Limits of detection (LODs) of 0.002, 0.007, and 0.01 µg L-1 were obtained for Hg (II), Ni (II), and Se (IV) by PVG-HS-AFS, respectively, and 0.02 and 0.2 µg L-1 were obtained for Hg (II) and Ni (II) by PVG-HS-µPD-OES, respectively. The practicality of the reactor was evaluated by the detection of Hg (II), Ni (II), and Se (IV) in five certified reference materials, including water (GBW08603, GBW08607, and GBW(E)080395), National Research Council Canada dogfish liver (DOLT-5), fish protein (DORM-4), and three river water samples with good recoveries (92-106%).