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In this study, simple, new and functional silky nanostructures of Co3O4 are prepared by hydrothermal method. These nanostructures are successfully used for the enzyme free sensing of uric acid in 0.1 M phosphate buffer solution of pH 7.3. Physical characterization experiments were carried out to explore the morphology, composition and crystalline phase of the newly prepared Co3O4 nanostructures. Scanning electron microscopy (SEM) shows a silk like morphology and energy dispersive spectroscopy (EDS) revealed the presence of Co and O as the main elements. Powder X-ray diffraction (XRD) demonstrates a cubic crystallography with well resolved diffraction patterns. The electrochemical activity of these silky Co3O4 nanostructures was evaluated by cyclic voltammetry (CV) in a 0.1 M phosphate buffer solution at pH 7.3. The high purity and unique morphology of Co3O4 shows a highly sensitive and selective response towards the non-enzymatic sensing of uric acid. This uric acid sensor exhibits a linear range of 0.5 mM to 3.5 mM uric acid and a 0.1 mM limit of detection. The anti-interference capability of this uric acid sensor was monitored in the presence of common interfering species. Furthermore, electrochemical impedance spectroscopy confirms a low charge transfer resistance value of 5.11 K Ω cm2 for silky Co3O4 nanostructures which significantly supported the CV results. The proposed modified electrode is stable, selective and reproducible which confirms its possible practical use. Silky Co3O4 nanostructures can be of great importance for diverse electrochemical applications due to their excellent electrochemical activity and large surface area.

In this study, a simple approach was used to produce nonprecious, earth abundant, stable and environmentally friendly NiCo2O4/CuO composites for the oxygen evolution reaction (OER) in alkaline media. The nanocomposites were prepared by a low temperature aqueous chemical growth method. The morphology of the nanostructures was changed from nanowires to porous structures with the addition of CuO. The NiCo2O4/CuO composite was loaded onto a glassy carbon electrode by the drop casting method. The addition of CuO into NiCo2O4 led to reduction in the onset potential of the OER. Among the composites, 0.5 grams of CuO anchored with NiCo2O4 (sample 2) demonstrated a low onset potential of 1.46 V vs. a reversible hydrogen electrode (RHE). A current density of 10 mA cm−2 was achieved at an over-potential of 230 mV and sample 2 was found to be durable for 35 hours in alkaline media. Electrochemical impedance spectroscopy (EIS) indicated a small charge transfer resistance of 77.46 ohms for sample 2, which further strengthened the OER polarization curves and indicates the favorable OER kinetics. All of the obtained results could encourage the application of sample 2 in water splitting batteries and other energy related applications.

Summary In this study, a total of 84 milk samples (60 nonbranded and 24 branded) were analysed for occurrence of oxytocin (OT) residues by ELISA. OT level was detected in the range of 39.29–456.55 pg mL−1 with mean value of 138.53 ng L−1. In branded milk samples, OT residues were minimal as compared to nonbranded milk samples. Nonbranded milk samples had higher prevalence of OT residues; 16.67% had OT level in the range of ≤500 ng L−1. The average daily intake of OT was found 0.087 μg day−1 per person. It was concluded that the OT concentration was relatively higher in samples obtained from dairy farm, dairy shop and milk man than that in ultra-high temperature (UHT) and powder milk samples. In addition, there are no reports subjected to standardising a permissible OT level in dairy milk category, although OT is considered detrimental to both human and animal life.

An efficient and simple in situ ultrasonic assisted esterification method has been developed for gas chromatographic determination of benzoic acid (BA) in raw and processed milk samples. For optimization of variables, chemometric approach was employed using Plackett–Burman design (PBD) and face-centered central composite design (FCCCD). Firstly, major factors affecting benzoic acid methyl ester (BAME) yield, i.e., BA concentration, volume of methanol, sonication time, amount of milk, and sulfuric acid, were studied with PBD. After screening significant factors, further optimization was carried out with FCCCD. Analysis of variance (ANOVA) of the quadratic model demonstrated that BA concentration, interaction factors of BA with sulfuric acid, and methanol volume significantly (p < 0.05) affect the BAME %yield. The proposed in situ method has better BAME limit of detection (0.02 mg/L) and quantification (0.07 mg/L) for the rapid determination of BA in milk samples avoiding the use of sample pretreatment and solvent extraction step.

In the present studies efforts are made to develop a low cost method to remove pesticides from water streams. Low cost walnut shells after chemical and thermal treatment are used to remove carbofuran and Chloropyriphos pesticides from aqueous solutions. The adsorption parameters i.e. pH, contact time, shaking speed and initial concentration have been studied. The adsorption was found to be rapid 97-99% within 30 min. The adsorption of pesticides on the adsorbent surface was found to be pH dependent. The adsorbent material was characterized by scanning electron microscopy (SEM) analysis and FT-IR spectroscopy. Elution experiments were performed to recover the adsorbed pesticide from the adsorbent surface. The Freundlich, Langmuir, D-R and Thomas models were used to study the partitioning behavior for the adsorption system along with kinetic and thermodynamic studies. The proposed adsorption method was utilized to remove carbofuran and Chloropyriphos pesticides from environmental water samples. Key word: Adsorption; pesticides; Walnut shell; Isotherms, Kinetics; thermodynamics.