Tasneem Gul Kazi

Heavy metals are among the most hazardous chemical pollutants, present in trace amounts in various samples. Prior to the quantitative measurement of heavy metals in a sample, an effective sample preparation technique is usually adopted. Among the various techniques, dispersive liquid–liquid microextraction (DLLME) is regarded as one of the most effective sample preparation strategies for heavy metal preconcentration due to its simplicity, speed, low cost, high extraction recovery, enrichment factor, and minimal solvent use. Various DLLME modes have been introduced, including ultrasound‐assisted DLLME, vortex‐assisted DLLME, air‐assisted DLLME, spray‐assisted DLLME, and effervescence‐assisted DLLME, to improve extraction efficiency. In addition, traditional organic solvents are being replaced with alternative solvent systems such as supramolecular solvents (SUPRAs), switchable solvents (SSs), and deep eutectic solvents (DESs) to improve the greenness of these DLLME approaches. Based on the benefits of various DLLME approaches and the use of these environmentally friendly solvents, this review briefly presents the extraction mechanisms and applications of various DLLME modes for heavy metal extraction. In addition, the use of the aforementioned alternative solvents in various DLLME approaches is discussed, along with their benefits. Moreover, the review presents a comparative assessment of different DLLME approaches and environmentally friendly solvents and critically examines limitations, including the use of chlorinated organic solvents in air‐assisted DLLME (AA‐DLLME), the use of organic solvents for analyte‐rich phase dilution, and the use of THF. Furthermore, a table summarizes the figures of merit for all DLLME methods reported (2021–2025) for heavy metal extraction.

Background: Tuberculosis is spreading throughout the globe, and it is a main cause of death especially children in developing countries. Disturbances in the concentrations of essential trace elements are associated with impaired immunity in pulmonary tuberculosis infection. Objective: In this study, the alterations in concentrations of essential trace elements, copper (Cu), iron (Fe), and zinc (Zn) in biological sample (blood serum) were determined in children with pulmonary tuberculosis (PTB), age 5 to 10 years, before and after a 6-month anti-tuberculosis treatment period. Methods: An environmentally friendly methodology was used to treat the serum sample by means of a deep eutectic solvent, composed of oxalic acid and choline chloride (Ox–ChCl) at diverse molar ratios, and then shaking the sample mixture was sonicated in ultrasonic bath at different temperatures (40–85°C). Subsequently, dilute HNO3 (0.5 M) was added and tubes centrifuged. The supernatant solution was subjected to inductively coupled emission plasma spectrophotometry. The effects of various factors on the efficiency of digestion of the serum samples to determine Cu, Fe, and Zn, including volume of deep eutectic solvent and its mole ratio, temperature and shaking time of ultrasonic bath (sonication time) were checked. Results: The data indicate that the PTB patients have a changed profile of all three metals in their sera and this could be more due to the active disease rather than underlying deficiencies. Compared with the non-diseased children, the levels of Fe and Zn in the serum samples of PTB-affected children were considerably lower (P < 0.05), while the Cu/Zn ratio was much higher (P < 0.05). Conclusion: After 6-month treatment, the levels of Fe and Zn were enhanced about 16% and 30%, respectively, while 23% Cu was decreased in serum samples of PTB children. These values were slightly lower than reference values. Highlights: Disturbances of essential trace elements levels are associated with impaired immunity. A deep eutectic solvent, composed of choline chloride and oxalic acid, was used for digestion of serum. The levels of Fe and Zn in the serum samples of PTB-affected children were significantly lower (P < 0.05). Negative correlations of Zn and Fe with Cu in serum samples of PTB-infected children were observed.

Green sol–gel synthesis of Na ₂ Fe ₄ O ₇ nanoparticles using tamarind extract and their incorporation into a sodium alginate composite (AG/Na ₂ Fe ₄ O ₇ -NC).

Petrochemical facilities, including oil well drilling, are discharging resources of extensive noxious waste into the environment. The workers in different sections might be exposed to vanadium (V) through different routes (groundwater and soil), which is linked with extensive physiological disorders, hypertension, respiratory disorders, anemia, skin, and gastrointestinal disorders. This study determined the contents of V in a biological sample (scalp hair) of workers of different categories (outdoor and office workers) in an oil drilling field in Sindh, Pakistan. The environmental samples, groundwater, bottled mineral water, and soil samples were also analyzed for V. For comparative purposes, the scalp hair of age-matched male subjects residing in domestic areas of Hyderabad city, Pakistan, was also analyzed. Generally, the concentrations of V in groundwater near the oil drilling field and drilled soil illustrated significant variations. The results show that the vanadium concentration in the scalp hair of non-exposed referents (controls) and office workers (exposed referents) was 62% and 45% lower than those observed for outdoor drilling and cleaning mud workers. It was observed that high exposure to V in outdoor workers might be linked with different physiological disorders such as anemia, eye problems, and bronchial disorders. Graphical Abstract

Solid-phase extraction (SPE) has attracted the attention of scientists because it can increase the selectivity and sensitivity measurements of analytes. Therefore, this study is designed to synthesise magnesium oxide nanoparticles (D-MgO-NPs) by an eco-friendly method using biogenic sources Duranta erecta followed by fabricating its chitosan-based polymeric composite (D-MgO-NC) for the SPE of heavy metals (HMs), i.e., arsenic (As), cadmium (Cd), and lead (Pb) from drinking water. Various analytical techniques were used for the surface characterization of D-MgO-NPs and D-MgO-NC. FTIR findings confirmed the formation of D-MgO-NC based on MgO association with the –OH/–NH₂ of the chitosan. D-MgO-NC showed the smallest size of particles with rough surface morphology, followed by the crystalline cubic structure of MgO in its nanoparticle and composites. The synthesised D-MgO-NC was used as an adsorbent for the SPE of HMs from contaminated water, followed by their detection by atomic absorption spectrometry. Various experimental parameters, including pH, flow rate, the concentration of HMs, eluent composition, and volume, were optimised for the preconcentration of HMs. The limits of detection for As, Cd, and Pb of the proposed D-MgO-NC-based SPE method were found to be 0.008, 0.006, and 0.012 μm L⁻¹, respectively. The proposed method has an enrichment factor and relative standard deviation of >200 and −1, respectively.