Determination of Cadmium in Brown Rice Samples by Fluorescence Spectroscopy Using a Fluoroionophore after Purification of Cadmium by Anion Exchange Resin

Electrochemical Sensors for Heavy Metal Ion Detection in Aqueous Medium: A Systematic Review

Heavy metal ions (HMIs) are very harmful to the ecosystem when they are present in excess of the recommended limits. They are carcinogenic in nature and can cause serious health issues. So, it is important to detect the metal ions quickly and accurately. The metal ions arsenic (As3+), cadmium (Cd2+), chromium (Cr3+), lead (Pb2+), and mercury (Hg2+) are considered to be very toxic among other metal ions. Standard analytical methods like atomic absorption spectroscopy, atomic fluorescence spectroscopy, and X-ray fluorescence spectroscopy are used to detect HMIs. But these methods necessitate highly technical equipment and lengthy procedures with skilled personnel. So, electrochemical sensing methods are considered to be more advantageous because of their quick analysis with precision and simplicity to operate. They can detect a wide range of heavy metals providing real-time monitoring and are cost-effective and enable multiparametric detection. Various sensing applications necessitate severe regulation regarding the modification of electrode surfaces. Numerous nanomaterials such as graphene, carbon nanotubes, and metal nanoparticles have been extensively explored as interface materials in electrode modifiers. These nanoparticles offer excellent electrical conductivity, distinctive catalytic properties, and high surface area resulting in enhanced electrochemical performance. This review examines different HMI detection methods in an aqueous medium by an electrochemical sensing approach and studies the recent developments in interface materials for altering the electrodes.

A novel dual-function probe for fluorescent turn-on recognition and differentiation of Al3+ and Ga3+ and its application

In this study, a novel dual-function probe BMP based on benzothiazole was easily synthesized and characterized through common optical technique. In the system consisting of DMF/H₂O (v/v, 2/3), probe BMP showed azure and blue-green to Al³⁺ and Ga³⁺, respectively. Besides, the binding ratios of BMP to Al³⁺ and Ga³⁺ were determined as 1:1, which confirmed by Job's plot. Furthermore, for Al³⁺ and Ga³⁺, the limit of detection (LOD) was determined to be 1.51 × 10^-6 M and 4.28 × 10^-6 M, respectively. Moreover, it was worth noting that BMP showed good performances in paper colorimetry, cell phone colorimetric identification and cell imaging.

A new bio-compatible Cd2+-selective nanostructured fluorescent imprinted polymer for cadmium ion sensing in aqueous media and its application in bio imaging in Vero cells

Schematic representation of Cd²⁺ recognition by the imprinted polymer and fluorescence signal creation as a result of the mentioned recognition process.

Mass-producible disposable needle-type ion-selective electrodes for plant research

Easily mass-producible needle-type Na⁺ and K⁺ ion-selective electrodes (ISEs) were developed for the direct and indirect measurement of Na⁺ and K⁺ ion concentrations in live plants. A polyimide strip with a silver layer on one side and Ag/AgCl formed at one end was used to construct two types of ISEs. For the type I ISE, an electrolyte layer was formed on the layer of silver and Ag/AgCl, which was then covered with a protecting layer. Subsequently, an ion-selective membrane (ISM) was formed at the truncated end with Ag/AgCl. For the type II ISE, a syringe needle was used as a container and an ISM was formed at the sharp end. Then, the polyimide strip with Ag/AgCl at one end was inserted and an electrolyte solution was injected to complete the ISE. Reference electrodes (REs) with similar structures were fabricated by forming a liquid junction instead of the ISM. The electrode responses and the relationship between the ISE potential and the Na⁺/K⁺ ion concentration agreed with those predicted by the Nernst equation. The Na⁺ and K⁺ ion concentrations in different parts of the rice plant (Oryza sativa L.) were measured using the Na⁺ and K⁺ ISEs, respectively. The results obtained using these devices agreed well with those obtained using inductively coupled plasma atomic emission spectrometry, thus confirming the practical applicability of the developed ISEs.

Comparative study on the nutrients, heavy metals and pesticide composition of some locally produced and marketed rice varieties in Nigeria

The nutrients, heavy metals and pesticide concentrations of an imported (Gold) and three locally produced and marketed rice varieties (Samples B-mass, C-R8 and D-CP) in Nigeria were investigated using standard techniques. All the rice varieties contained considerable amounts of moisture, ash, protein, lipid and carbohydrate but were low in crude fibre. The local rice varieties contained higher (P < 0.05) amounts of tryptophan and tyrosine than the imported rice. Sample C had the highest amino acids contents compared with other rice varieties. The threonine contents of the control and sample B were higher than WHO standards. Lead and mercury were not detected in all the rice varieties while the levels of cadmium, arsenic, chromium and thallium were within permissible range. The rice varieties contained considerable amounts of selenium, calcium, iron, manganese, zinc, phosphorous, boron, cobalt, Vitamins A, D, B6, thiamine, riboflavin, niacin and cobalamin with insignificant amounts of pesticide residues.