Ultrasonic Nebulization-Accelerated Gas-Phase Enrichment Following In Situ Microplasma Desorption for Analysis of Trace Heavy Metals by Optical Emission Spectrometry

Abstract

Despite the great potential of microplasma optical emission spectrometry (OES) for on-site analysis, it remains a challenge to achieve the fast, sensitive, batch, and multielement analysis of trace heavy metals in a complex matrix. Herein, a novel ultrasonic nebulization-accelerated gas-phase enrichment (GPE) following in situ microplasma desorption sampling approach is employed for the determination of trace heavy metals by a miniature dielectric barrier discharge (DBD)-OES device. The volatile heavy metal species obtained by hydride generation (HG) can be quickly separated from the complex matrix under the action of ultrasonic nebulization, adsorbed on the surface of the activated carbon electrode tip for GPE, and then in situ desorbed and excited by DBD microplasma to achieve multielement OES analysis. With an array nebulizer plate, a batch of 10 samples can be handled for GPE in 40 s, and DBD-OES analysis is maintained at a rate of 6 s per sample. Under the optimized conditions, the detection limits for simultaneous determinations of Hg, Cd, Cu, and Sn are 0.005, 0.01, 0.03, and 0.04 μg L–1, respectively, and the detection sensitivities are about 164, 157, 132, and 91-fold improved with respect to those of the conventional HG-DBD-OES mode, respectively. The accuracy and practicability are verified by measuring several certified reference materials. This fast GPE plus in situ DBD-OES analysis strategy possesses the features of simple operation, time-savings, and low cost, contributing to volatile species transport, matrix interference elimination, and device miniaturization for field applications.

One-Pot Pretreatment Coupled to Microplasma Optical Emission Spectrometry for Field and Sensitive Determination of Inorganic Mercury and Methylmercury in Fish

“…The one-pot pretreatment unit achieved the functions of extraction, separation, and enrichment of Hg­(II) and MeHg in fish, which was composed of 12 quartz reactors (15 mm o.d., 14 mm i.d., 65 mm height, ALFAQUARTZ), a UV lamp (254 nm/30 W, Hot Light Shanghai), two 3D-printed orifice plates for quartz reactors and UV lamp fixation (CL133, Shenzhen Creality 3D Technology Co., Ltd.) (Figure S1), and 12 headspace enrichment devices with activated carbon electrode tips (Figure S2). The activated carbon electrode tips were made according to previous works. , In brief, a commercially available activated carbon rod (0.9 mm diameter, 4 mm length) was inserted into a hollow stainless-steel tube (1 mm o.d., 0.9 mm i.d., 80 mm length) and protruded 3 mm from one end of the stainless-steel tube, serving as the trapping tip. The quartz reactors were treated according to the reported method to reduce the memory effect and blank .…”

“…The activated carbon electrode tips were made according to previous works. 36,38 In brief, a commercially available activated carbon rod (0.9 mm diameter, 4 mm length) was inserted into a hollow stainless-steel tube (1 mm o.d., 0.9 mm i.d., 80 mm length) and protruded 3 mm from one end of the stainless-steel tube, serving as the trapping tip. The quartz reactors were treated according to the reported method to reduce the memory effect and blank.…”

“…In this respect, microplasmabased OES systems can provide an ideal tool for field analysis of mercury. 36,37 Therefore, the development of convenient and efficient methods for the extraction, separation, and preconcentration of mercury species in seafood is the key to solving the existing problems.…”

“…In addition, the portable atomic spectroscopic instrument is essential for field analysis of mercury species in seafood under routine conditions. In this respect, microplasma-based OES systems can provide an ideal tool for field analysis of mercury. , Therefore, the development of convenient and efficient methods for the extraction, separation, and preconcentration of mercury species in seafood is the key to solving the existing problems.…”

Battery-Operated and Self-Heating Solid-Phase Microextraction Device for Field Detection and Long-Term Preservation of Mercury in Soil

“…Among the methods used for the field detection of mercury, microplasma optical emission spectrometry (MP-OES) is the most promising one since it not only retains the advantages of conventional atomic spectrometry such as elemental specificity and low matrix interference but also provides several unique advantages of compact setup and low power consumption. − Despite considerable improvements achieved in MP-OES, its sensitivity is still too low to accomplish the detection of trace-level mercury in real samples. , As with conventional atomic spectrometry, sample introduction remains a common impediment to obtain the optimum performance of MP-OES. Correspondingly, MP-OES has been coupled with a variety of sampling techniques to enhance its sensitivity and alleviate matrix interference, including chemical vapor generation (CVG), ,,, electrothermal vaporization (ETV), and headspace solid-phase microextraction (HS-SPME). , …”