Preconcentration, Speciation, and Determination of Mercury by Solid Phase Extraction with Cold Vapor Atomic Absorption Spectrometry

Preconcentration and speciation analysis of mercury: 3D printed metal scavenger-based solid-phase extraction followed by analysis with inductively coupled plasma mass spectrometry

A selective method for preconcentration and determination of methylmercury (MeHg) and inorganic mercury (iHg) in natural water samples at the ng L^-1 level has been developed. The method involves adsorption of Hg species into a 3D printed metal scavenger and sequential elution with acidic thiourea solutions before ICP-MS determination. Experimental parameters affecting the preconcentration of MeHg and iHg such as the sample matrix, effect of the flow rate on adsorption, eluent composition, and elution mode have been studied in detail. The obtained method detection limits, considering the preconcentration factors of 42 and 93, were found to be 0.05 ng L^-1 and 0.08 ng L^-1 for MeHg and iHg, respectively. The accuracy of the method was assessed with a certified groundwater reference material ERM-CA615 (certified total iHg concentration 37 ± 4 ng L^-1). The determined MeHg concentration was below MDL while iHg concentration was determined to be 41.2 ± 0.5 ng L^-1. Both MeHg and iHg were also spiked to natural water samples at 5 ng L^-1 concentration and favorable spiking recoveries of 88-97% were obtained. The speciation procedure was successfully applied to two lake water samples where MeHg and iHg concentrations ranged from 0.18 to 0.24 ng L^-1 and 0.50-0.62 ng L^-1, respectively. The results obtained demonstrate that the developed 3D printed metal scavenger-based method for preconcentration and speciation of Hg is simple and sensitive for the determination of Hg species at an ultra-trace level in water samples.

New modified cellulose nanoparticles for solid-phase extraction of some metal ions in biological and water samples

A preconcentration procedure for heavy metal ions in biological and water samples has been presented. The procedure is based on the sorption of Cu2+, Cd2+, Hg2+, and Pb2+ on cellulose nanoparticles modified with folic acid. The prepared adsorbent was characterized by FT-IR, SEM, TEM, and BET measurements. Potentiometric titration is used to prove the complexation between metal ions and the modified cellulose as well as to calculate the cation-exchange capacity of the sorbent. The influences of the analytical parameters including pH, amount of adsorbent, shaking time, temperature, conditions of desorption, and the effects of matrix ions were studied. Under the optimized conditions, the calibration curves for Cu2+, Cd2+, Hg2+, and Pb2+ were linear in the range of 2.7–200, 0.5–50, 0.37–150, and 10–300 μg L−1, respectively. The detection limits (3s, n = 10) for Cu2+, Cd2+, Hg2+, and Pb2+ were 0.81, 0.15, 0.11, and 3.9 μg L−1, respectively. The proposed method offers a preconcentration factor of 200 for all of the ions studied and an enhancement factor for Cu2+, Cd2+, Hg2+, and Pb2+ of 40.0, 30.8, 40.4, and 34.2, respectively. The accuracy of the suggested method was tested by analyzing spiked samples. The method was successfully applied to the determination of these metal ions in water and blood samples.

Fluorescent carbon nanoparticles for the fluorescent detection of metal ions

Fluorescent carbon nanoparticles (F-CNPs) as a new kind of fluorescent nanoparticles, have recently attracted considerable research interest in a wide range of applications due to their low-cost and good biocompatibility. The fluorescent detection of metal ions is one of the most important applications. In this review, we first present the general detection mechanism of F-CNPs for the fluorescent detection of metal ions, including fluorescence turn-off, fluorescence turn-on, fluorescence resonance energy transfer (FRET) and ratiometric response. We then focus on the recent advances of F-CNPs in the fluorescent detection of metal ions, including Hg(2+), Cu(2+), Fe(3+), and other metal ions. Further, we discuss the research trends and future prospects of F-CNPs. We envision that more novel F-CNPs-based nanosensors with more accuracy and robustness will be widely used to assay and remove various metal ions, and there will be more practical applications in coming years.