Mingyue Lin

A tin-bismuth alloy electrode for the cathodic stripping voltammetric determination of iron in coastal waters

We employed a home-made tin–bismuth alloy electrode (SnBiE) as the working electrode with 1-(2-piridylazo)-2-naphthol (PAN) as the complexing ligand to detect trace iron. This method is based on the cathodic reduction of Fe(III)–PAN complex to Fe(II)–PAN complex at the SnBiE by using adsorptive cathodic stripping voltammetry. The experimental parameters, such as the pH value, concentration of buffer solution, accumulation potential, accumulation time and the concentrations of PAN, were optimized, and the interference by other ions was investigated in detail. The response of Fe(III) was linear in the range of 1 nM to 900 nM with a detection limit of 0.2 nM (after 60 s of accumulation, s/n = 3). This method can also be applied to the determination of iron in coastal rivers and seawater with satisfactory results.

Cathodic stripping voltammetric determination of chromium in coastal waters on cubic Nano-titanium carbide loaded gold nanoparticles modified electrode

The novel cubical nano-titanium carbide loaded gold nanoparticles modified electrode for selective and sensitive detection of trace chromium (Cr) in coastal water was established based on a simple approach. Nano-titanium carbide is used as the typical cubical nanomaterial with wonderful catalytic activity towards the reduction of Cr(VI). Gold nanoparticles with excellent physical and chemical properties can facilitate electron transfer and enhance the catalytic activity of the modified electrode. Taking advantage of the synergistic effects of nano-titanium carbide and gold nanoparticles, the excellent cathodic signal responses for the stripping determination of Cr(VI) can be obtained. The detection limit of this method is calculated as 2.08 μg L-1 with the linear calibration curve ranged from 5.2 to 1040 μg L-1. This analytical method can be used to detect Cr(VI) effectively without using any complexing agent. The fabricated electrode was successfully applied for the detection of chromium in coastal waters collected from the estuary giving Cr concentrations between 12.48 and 22.88 μg L-1 with the recovery between 96% and 105%.

Determination of iron in seawater: From the laboratory to in situ measurements

The marine biogeochemistry of iron plays a significant role in regulating climate change. Trace dissolved iron in oceanic surface water can limit phytoplankton growth which in turn limits the carbon dioxide flux at the air/sea interface. To better understand the relationship between iron and its different species with phytoplankton, as well as the biogeochemical cycle of iron in seawater, accurate, sensitive, and in situ methods are needed for iron determination. This paper reviews the methods for determining iron in seawater from the laboratory, shipboard to in situ measurements, including such strategies as atomic spectrometry, spectrophotometry, chemiluminescence, and voltammetry, which will provide the foundation for developing reliable long-term iron monitoring and sensing platforms in the future.

Speciation determination of iron and its spatial and seasonal distribution in coastal river

In this study, the speciation of iron (Fe), including total Fe (TFe) and acidified dissolved Fe (ADFe), was assessed by fast cathodic absorption stripping voltammetry, using a gold electrode and 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP) as a novel complexing agent for Fe. The validity and accuracy of this method were compared with the standard spectrophotometry and tested by the standard samples. Under optimized conditions, the Fe response was linear within the range of 0.01 to 1 μM with a detection limit of 1.2 nM. To further validate this method, the variation in concentrations of TFe and ADFe were investigated at twelve sampling stations in a local coastal river, in both the dry and wet season. Additionally, to further understand the interaction between Fe and environmental factors, the relationships between the concentration of Fe species and dissolved oxygen (DO) and salinity were also discussed.