Determination of total iron in food samples after flow injection preconcentration on polyurethane foam functionalized with N,N-bis(salicylidene)-1,3-propanediamine

Quantification of Minerals in Edible Mushrooms via Optimized Microwave-Assisted Digestion: Nutritional Contributions of Fe, Mg, Na, K, and Ca

The intake of mushrooms provides numerous beneficial properties for the correct functioning of the human body due to their rich content in carbohydrates, proteins, fibers, vitamins, and minerals. However, most of the reports are focused on the determination of bioactive compounds and only a few regarding the essential mineral content and the evaluation of the RDI. Thus, the aim of this study was to determine the mineral composition of different cultivated (A. bisporus and P. ostreatus) and wild edible mushrooms (A. crocodilinus, A. arvensis, A. silvicola, A. impudicus, M. mastoidea, M. rhacodes, and P. ostreatus) collected in the south of Spain and north of Morocco. First, the optimization of a microwave-assisted digestion method was carried out using a Box-Behnken design with a response surface methodology to quantify the total content of five metals: Fe, Mg, Na, K, and Ca in mushrooms. The samples were analyzed by FAAS and ICP-OES. The percentage of the RDI of each mineral covered by the intake of mushrooms was calculated. It was observed that a high percentage of RDI levels are covered and just exceeded for Fe. Thence, due to their beneficial properties and high content of essential minerals, mushrooms would be proposed as a valuable source of nutrients to manufacture some food supplements.

Determination of Lead Employing Simple Flow Injection AAS with Monolithic Alginate-Polyurethane Composite Packed In-Valve Column

A simple flow injection FlameAAS for lead determination with an alginate-polyurethane composite (ALG-PUC) monolithic in-valve column has been developed. The ALG-PUC monolithic rod was prepared by mixing methylene diphenyl diisocyanate with polyol and sodium alginate with the ratio of 2:1:1 by weight for a 5 min polymerization reaction. It was then put into a column (0.8 cm i.d × 11 cm length) situated in a switching valve for the FI set up. A single standard calibration could be obtained by plotting the loaded µg Pb²⁺ vs. FI response (absorbances). The loaded µg Pb²⁺ is calculated: μg Pb²⁺ = FR_load × LT × C_Pb²⁺, where the FR load is the flow rate of the loading analyte solution (mL min⁻¹), LT is the loading time (min), and C_Pb²⁺ is the Pb²⁺ concentration (µg mL⁻¹). A linear calibration equation was obtained: FI response (absorbances) = 0.0018 [µg Pb²⁺] + 0.0032, R² = 0.9927 for 1–150 µg Pb²⁺, and RSD of less than 20% was also obtained. Application of the developed procedure has been demonstrated in real samples.

Structure–properties relationship of the polyurethanes that contain Schiff base in the main chain

This article studies the diversification of useful properties of polyurethane (PU) structures by the inclusion of new components. PUs containing a Schiff base in the main chain were synthesized by using N, N′-bis(salicylidene)-1,3-propanediamine as a chain extender. Novel Schiff base PUs were synthesized via a two-step polymerization starting from a Schiff base derivative diol chain extender with different molar ratios or by cross-linking with various natural raw materials. The sought after structures was confirmed by Fourier transform infrared spectra that showed the disappearance of the signals of both the hydroxyl and isocyanate groups. The thermal properties of these PUs were investigated by thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA). The initial degradation temperatures of the obtained PUs were found to be in the range of 300–350°C. Based on the results from DMA, the rigid structure of the Schiff base from the backbone of the PUs presented a higher storage modulus, results which may be connected to the physical cross-linking process of the macromolecules. Their optical properties were determined by fluorescence spectroscopy. The incorporation of Schiff base structures into the main PU chain generates new PU structures with improved thermomechanical properties, which includes possible bioactive Schiff base moieties, widening the range of practical applications for such polymers.

Optimization of a methodology for determination of iron concentration in aqueous samples using a newly synthesized chelating agent in dispersive liquid-liquid microextraction

The aim of this study was to establish a new dispersive liquid-liquid microextraction (DLLME) technique for the determination of iron concentration in aqueous solutions and fruit juices based on the reaction between iron and 3-hydroxy-1-(3-hydroxyphenyl)-2-methylpyridin-4(1H)-one (3-OH-PMPO) as a chelating agent. A central composite design (CCD) was applied to optimize the effects of independent parameters (pH, volume of disperser solvent and extractant solvent and chelating agent concentration) on extraction efficiency. Under the optimized conditions, the analytical curve is linear in a concentration range of 10-750 μgL^-1 with a detection limit of 5 μgL^-1. The relative standard deviation (RSD) for ten repeated determinations of iron concentrations at 40 and 200 μgL^-1 was calculated to be 4.2% and 1.2%, respectively. Relative recovery of iron in several water samples was investigated and the average was obtained in the range of 91-108%.

Determination of trace iron in the boiler water used in power generation plants by solid-phase spectrophotometry

A sensitive, simple and low-cost determination method for the total iron concentration in boiler water systems of power generation plants was developed by solid phase spectrometry (SPS) using 2,4,6-tris(2-pyridyl)-1,3,5-triazine (TPTZ) as a coloring agent. The reagents and 0.08 cm(3) of a cation exchanger were added to a 50-cm(3) boiler water sample, then mixed for 30 min to adsorb/concentrate the produced Fe(TPTZ)2(2+) colored complex on the solid beads, resulting in a 625 times concentration of the target analyte without any other procedure. The detection limit of 0.1 μg dm(-3) was obtained, and the optimum conditions for the digestion procedure and color developing reaction was investigated and reported. According to the application of this method to real samples, the present SPS method is the best one because of the shorter analysis time, simpler operation and use of very low-cost equipment compared to the conventional methods, such as TPTZ solution spectrophotometric method after a 16 times concentration, ICP-MS and AAS.

Synthesis, characterization of carbon polyurethane powder and its application for separation and spectrophotometric determination of platinum in pharmaceutical and ore samples

A new chelating sorbent was synthesized by covalently linking carbon nano-fiber with ion exchange polyurethane foam (CNF-PUFIX). CNF-PUFIX was characterized using different tools e.g. elemental analysis, IR spectrum and SEM. The functional groups of PUF have disappeared. The phenolic, carboxylic, quaternary ammonium salt and tertiary amine groups are detected in the CNF-PUFIX. The sorption properties of platinum (IV) onto CNF-PUFIX were investigated, the maximum sorption of platinum ions (~100%) was at the pH ranges 4-5, shaking for 18 min and sample flow rate 1.3 mL min(-1). The experimental data was fitted by kinetic models, the pseudo-second order is predominant (R(2)=0.998), the values of h and k2 are 4.4 mmol g(-1)min(-1) and 0.15 g mmol(-1)min(-1), respectively. The sorption capacity of CNF-PUFIX and the recovery percentage of Pt (IV) were 0.19 mmol g(-1) and 99-103%, respectively (RSD=1.72%, n=5). The CNF-PUFIX could be used many times without decreasing their capacities significantly. The equilibrium process is well described by the Langmuir isotherm model (R(2)=0.857), which is attributed to the homogeneous surface structure of the CNF-PUFIX. The values of ΔG and ΔH were -3.5 and -26.1 kJ mol(-1), respectively, which indicate that the sorption of platinum onto CNF-PUFIX is spontaneous and exothermic. The lower detection limit of platinum using spectrophotometric method is 2.4 µg L(-1) (RSD~3.8%, n=6). The accuracy of the procedure was verified by the analysis of standard reference materials of pharmaceutical and granite samples.