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A very simple, ultra-sensitive and highly selective non-extractive spectrofluorimetric method is presented for the determination of manganese at nano-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA).

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A sensor for the determination of orthophosphate (PO4 3–) concentration in water was developed that utilizes the enzymatic cleavage of maltose in the presence of PO4 3– to generate an equivalent amount of glucose. The glucose produced from this reaction was quantified using a commercial glucometer test strip coupled to a miniature potentiostat using amperometry. This sensing approach yielded a limit of detection of 1.45 μM (0.1 ppm) glucose/PO4 3–, which is lower than that of a commercial glucometer (≥600 μM glucose), and a dynamic range of 10 μM–3 mM. The selectivity of the approach to PO4 3– was evaluated by determining the device’s response to known components in natural water samples. Finally, we showed that the approach can be used to determine PO4 3– in tap and river water samples.

Dynamic viscosities (η exp ) for the binary mixtures of methanol with isomeric (o-, m-, and p-derivatives) xylenes were measured at T = (303.15, 308.15, 313.15, 318.15, and 323.15) K and atmospheric pressure (p = 101 kPa). The viscosity deviation (Δη) that has been derived from the η exp was correlated using a Redlich− Kister-type equation. The η exp values were compared with the calculated viscosities (η cal ) obtained using generalized correlation models, such as Bingham, Arrhenius, Kendall−Monroe, Grunberg−Nissan, and Andrade/DIPPR. The changes in the η exp of solvent mixtures rather than in the pure fluids, or deviations from η cal , have been discussed in terms of the molecular interactions and structural effects due to the component molecules. Furthermore, the quantum chemical density-functional theory calculations were used to predict the optimized geometry and total energies of the pure fluids and their binary mixtures.

A simple, ultra-sensitive, and highly selective spectrophotometric method has been established for the trace quantification of zinc (Zn), using 2-hydroxynaphthaldehyde benzoylhydrazone (HNABH). Zn forms a pale yellowish-green complex (maximum absorption at 426 nm) with HNABH (1:1, v:v) in a marginally acidic solution (0.00005-0.00023 M H2SO4). The average molar absorption coefficient and Sandell’s sensitivity were found: 2.87×105 L/mol.cm and 12 ng/cm2 of Zn, respectively. The observed linearity range for Zn was 0.01-50 mg/Lwith a detection limit of 1 µg/L. The analysis of biological, food, and vegetable samples using the suggested method were found to be in tremendous accord with those acquired by Atomic Absorption Spectroscopy (AAS) and Inductively Coupled Plasma-Optical Emission Spectroscopy (ICP-OES). The method has high precision and accuracy (s = ±0.01 for 0.5 mg/L). The limit of quantification of the proposed method was 10 µg/L.

Introduction Genistein is one of the isoflavones found in soy and soy products 1, 2. It has extraordinary advantages for its antioxidant 1 3 , anticancer 1, 2, 4 and estrogen effects 5, 6. Three hydroxyl groups in the aromatic rings of genistein contribute to its excellent antioxidant capacity 3. Moreover, genistein can inhibit the induction of stress proteins on tumor cells and retard the action of tyrosine kinase. This ultimately contributes to its anticarcinogenic benifits 4, 6. Genistein is also a kind of phytoestrogen contained in plants and is capable of showing estrogen effect. The structure of 17β-estradiol is similar to genistein therefore has the ability to bind to the estrogen receptor. Furthermore, genistein acts as a weak agonist or antagonist of estradiol depending its amount 5, 6. Despite having greater beneficial effects on the human body, genistein is hard to use because of its poor water-solubility 1. Therefore, it requires a novel solubilization treatment when genistein is intended to use in