Speciation analysis of lead in marine animals by using capillary electrophoresis couple online with inductively coupled plasma mass spectrometry

Lead, Mercury and Cadmium in Fish and Shellfish from the Indian Ocean and Red Sea (African Countries): Public Health Challenges

The main aim of this review was to assess the incidence of Pb, Hg and Cd in seafood from African countries on the Indian and the Red Sea coasts and the level of their monitoring and control, where the direct consumption of seafood without quality control are frequently due to the poverty in many African countries. Some seafood from African Indian and the Red Sea coasts such as mollusks and fishes have presented Cd, Pb and Hg concentrations higher than permitted limit by FAOUN/EU regulations, indicating a possible threat to public health. Thus, the operationalization of the heavy metals (HM) monitoring and control is strongly recommended since these countries have laboratories with minimal conditions for HM analysis.

Photoelectrochemical aptasensor for lead(II) by exploiting the CdS nanoparticle-assisted photoactivity of TiO2 nanoparticles and by using the quercetin-copper(II) complex as the DNA intercalator

A photoelectrochemical (PEC) aptasensor for Pb(II) detection is described. A nanocomposite consisting of CdS (2.5 μm) and TiO₂ nanoparticles (10 nm) was used as a photoactive material, and gold nanochains (Au NCs) as the support for immobilization of the Pb(II)-binding aptamer. The quercetin-copper(II) complex was further employed as the intercalator for the improvement of the photoactivity by embedding it into dsDNA. In the presence of Pb(II), a Pb(II)-stabilized G-quadruplex was formed between Pb(II) and DNA S1. This is accompanied by unwinding of the dsDNA and the release of the quercetin-copper(II) complex from the surface of the sensor. This results in a decrease of the photocurrent that drops linearly from 5.0 × 10^-12 to 1.0 × 10^-8 mol·L^-1 Pb(II) concentration range with a detection limit of 1.6 × 10^-12 mol·L^-1. The method was applied to the determination of Pb(II) in various samples and gave satisfactory results. Graphical abstractA photoelectrochemical aptasensor was fabricated for the detection of Pb(II) based on CdS-TiO₂ nanocomposite modified indium tin oxide (ITO) electrode. Gold nanochains (AuNCs) were used as anchor to immobilize the aptamers S1 and S2 that form a double helix structure by DNA hybridization. After embedding of quercetin-copper(II) complex as intercalator and electron donor, the concentrations of Pb(II) were determined by the changes of photocurrents.

Species characteristics of lead in sea foods collected from coastal water of Fujian, Southeastern of China

Various sea foods including fish, shellfish and shrimp were collected from different coastal areas of Fujian in China, and their Pb species characteristics were investigated in detail. The results indicated that there are two different species characteristics of Pb existing in sea food samples. About half of samples were detected to have only Pb(2+), and another half of samples were detected to have both Pb(2+) and trimethyl lead (TML). The results also revealed that Pb species characteristics in the sea foods rather depend on the species of sea food than the sampling area. In comparison with shellfish/shrimp samples, fish samples have higher concentrations of TML and Pb(2+). Especially, the average concentration of TML in the TML-detected fish samples is about 3 times of that in the TML-detected shellfish/shrimp samples, indicating that fish has stronger ability to uptake and accumulate TML. The concentrations of total lead in all samples are lower than the maximum allowable limit of national standard, suggesting that the sea foods collected from Fujian are safe for consumption. By considering that TAL has more toxicity than Pb(2+), the effect of TML in sea foods on the human health should be paid more attention in the future.

Capillary electrophoresis coupled with in-column fiber-optic laser-induced fluorescence detection for the rapid separation of neodymium

In this study, in-column fiber-optic (ICFO) laser-induced fluorescence (LIF) detection technique is coupled with capillary electrophoresis (CE) for the rapid separation of neodymium for the first time. The effects of buffer concentration, buffer pH, and separation voltage on the CE behaviors, including electrophoretic efficiency and detection sensitivity, are investigated in detail. Under the optimal condition determined in this study (15 mM borate buffer, pH 10.50, separation voltage 24 kV), neodymium could be separated effectively from the neighboring lanthanides (praseodymium and samarium) within several minutes, and the limit of detection for neodymium is estimated to be at the ppt level. The ICFO-LIF-CE system assembled in this study exhibits unique performance characteristics such as low cost and flexibility. Meanwhile, the separation efficiency and detection sensitivity of the assembled CE system are comparable to or somewhat better than those obtained in the previous traditional CE systems, indicating the potential of the assembled CE system for practical applications in the fields of spent nuclear fuel analysis, nuclear waste disposal/treatment, and nuclear forensics.

Toxic trace elements at gastrointestinal level

Many trace elements are considered essential [iron (Fe), zinc (Zn), copper (Cu)], whereas others may be harmful [lead (Pb), cadmium (Cd), mercury (Hg), arsenic (As)], depending on their concentration and chemical form. In most cases, the diet is the main pathway by which they enter our organism. The presence of toxic trace elements in food has been known for a long time, and many of the food matrices that carry them have been identified. This has led to the appearance of legislation and recommendations concerning consumption. Given that the main route of exposure is oral, passage through the gastrointestinal tract plays a fundamental role in their entry into the organism, where they exert their toxic effect. Although the digestive system can be considered to be of crucial importance in their toxicity, in most cases we do not know the events that occur during the passage of these elements through the gastrointestinal tract and of ascertaining whether they may have some kind of toxic effect on it. The aim of this review is to summarize available information on this subject, concentrating on the toxic trace elements that are of greatest interest for organizations concerned with food safety and health: Pb, Cd, Hg and As.