Elements in cultured fishes in Chittagong, Bangladesh and risk assessment.

The concentrations of manganese, iron, copper, lead, nickel, cadmium, arsenic, copper and mercury were determined in 10 cultured fish species, which were collected from local markets of Chittagong, Bangladesh, in June 2021. Measurements were performed by atomic absorption spectrophotometry, after acid digestion of the samples. In some cases, the concentration of the investigated elements was more than the maximum limit set by the WHO. Although the concentration of toxic elements in fishes was relatively high in some species, no health risk has been identified in comparison to the estimated daily intake and the maximum limit. Calculated hazard indices were below 1, which indicates the investigated fish would not cause human health risks. Carcinogenic risk indices for Cr, As, and Cu in all species were considered to be significant.

A highly sensitive and selective spectrofluorimetric method for the determination of cerium at pico-trace levels in some real, environmental, biological, soil, food and bone samples using 2-(α-pyridyl)-thioquinaldinamide.

A very simple, ultra-sensitive and highly selective non-extractive new spectrofluorimetric method is presented for the determination of cerium at pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA). PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of cerium(iv). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.0005-0.0015 M H2SO4) solution with cerium(iv) in absolute ethanol to produce a highly fluorescent oxidized product (λ ex = 303 nm; λ em = 370 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.0005-0.0015 M H2SO4) for the period between 5 min and 24 h. Linear calibration graphs were obtained for 0.001-600 µg L-1 of Ce, having a detection limit of 0.1 ng L-1; the quantification limit of the reaction system was found to be 1 ng L-1 and the RSD was 0-2%. A large excess of over 60 cations, anions and complexing agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN- etc.) do not interfere in the determination. The developed method was successfully used in the determination of cerium in several certified reference materials (alloys, steels, noodles, ores and sediments) as well as in some environmental waters (potable and polluted), biological fluids (human blood, urine and milk), soil samples, food samples (vegetable, rice, corn and wheat), bone samples (human, cow, bull, fish, hen, goat, sheep), solutions containing both cerium(iii) and cerium(iv) and complex. The results of the proposed method for assessing biological, food and vegetables samples were comparable with ICP-OES and were found to be in excellent agreement.