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An ultrasound-assisted, one-pot cloud point extraction was developed for the determination of iron in vegetable samples by UV-Visible spectrophotometry. This method was based on the complexation of iron with an environmentally-friendly natural chelating agent extracted from Dipterocarpus intricatus Dyer fruit at pH 5.5 in the presence of Triton X-114. Reagent extraction, complexation, and preconcentration were performed simultaneously using ultrasound-assisted extraction at 45 °C. The surfactant-rich phase was diluted with ethanol and loaded through a syringe barrel packed with cotton that acted as a filter to trap the reagent powder. Analyte-entrapped on cotton was eluted using 0.1 mol·L -1 nitric acid solution. Filtrate and eluate solutions were measured absorbance of the dark-blue product at 575 nm. Influential parameters for the procedure were investigated. Under the optimum experimental conditions, the calibration curve was linear, ranging from 0.1 to 1.0 mg·L -1 with r 2 = 0.997. Limits of detection and quantification were 0.03 and 0.09 mg·L -1 ranged from 89.0 to 99.8%, while iron content in vegetable samples ranged from 2.45 to 13.36 mg/100 g. This method was cost-effective, reliable, eco-friendly, and convenient as a green analytical approach to determining iron content.-1 ranged from 89.0 to 99.8%, while iron content in vegetable samples ranged from 2.45 to 13.36 mg/100 g. This method was cost-effective, reliable, eco-friendly, and convenient as a green analytical approach to determining iron content.

Simple simultaneous determination of iron and manganese by sequential injection spectrophotometry using astilbin extracted from Smilax china L. root is proposed. It is based on the kinetic difference of the complexation of the ions and astilbin. With a simple sequential injection system, the simultaneous determination can be performed at pH 10 and can be followed at a wavelength of 440 nm. A throughput of 12 samples per hour was obtained with detection limits (3σ) of 0.05 mg L -1 iron(III) and 0.20 mg L -1 manganese(II), respectively. Application of the proposed system to real ground water sample was demonstrated. The results agreed with that of the atomic absorption spectrophotometric reference method., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Green analytical methods employing flow analysis with simple natural reagent extracts have been exploited. Various formats of flow based analysis systems including a single line FIA, a simple lab on chip with webcam camera detector, and a newly developed simple lab on chip system with reflective absorption detection and the simple extracts from some available local plants including butterfly pea flower, orchid flower, and beet root were investigated and shown to be useful as alternative self indicator reagents for acidity assay. Various tea drinks were explored to be used for chromogenic reagents in iron determination. The benefit of a flow based system, which allows standards and samples to go through the analysis process in exactly the same conditions, makes it possible to employ simple natural extracts with minimal or no pretreatment or purification. The combinations of non-synthetic natural reagents with minimal processed extracts and the low volume requirement flow based systems create some unique green chemical analyses., (Copyright © 2011 Elsevier B.V. All rights reserved.)

A green flow injection spectrophotometric technique for the determination of ascorbic acid was described based on the redox and complexation reactions. Iron(III) was reduced to iron(II) by ascorbic acid with subsequent complexation reaction of remaining iron(III) with a natural reagent extracted from Areca catechu L. at pH 5.0 yielding a dark-blue color. Absorbance decreased with increasing ascorbic acid concentration. A linear range of 1–10 mg/L for ascorbic acid was obtained with r2 of 0.9986. Limit of detection and limit of quantification were 0.3 and 0.9 mg/L, respectively. Relative standard deviation was less than 5.0%. This method was utilized to quantify ascorbic acid in pharmaceuticals and soft drinks with a sampling rate of 40 h−1. Ascorbic acid contents of 96–100% in pharmaceutical samples were obtained, while recoveries for spiked ascorbic acid standard at 3 mg/L in soft drinks were 92–113%. [ABSTRACT FROM AUTHOR]

An environmentally friendly field-portable approach based on small-scale ultrasound-assisted extraction and micro-volume colorimetry was proposed for the determination of iron using natural reagent extracts from pomegranate peels. Ultrasound technology was utilized for the extraction of pomegranate peels in acetate buffer pH 5.5. Sonication parameters influencing the extraction process of natural reagents from pomegranate peel were investigated, including the type of solvent, mass/volume ratio of solvent, sonication time, temperature, and power. The efficiency of the ultrasound-assisted procedure for the extraction of iron from pharmaceutical formulations was evaluated by comparing to their label value and the reference method for pharmaceutical formulations. A linear calibration graph ranging from 1.0 to 10.0 mg L−1 Fe(III) was obtained from micro-volume colorimetric determination (at 530 nm) with limits of detection and quantification of 0.31 and 0.78 mg L−1, respectively. The reproducibility for 3.0 mg L−1 Fe(III) was 3.8% as the relative standard deviation. This developed system was successfully applied to determine the iron content in pharmaceutical formulations and the results agreed well with those obtained by a reference method. Good recoveries between 97 and 105% were obtained. [ABSTRACT FROM AUTHOR]

Exploiting natural reagents derived from plant extracts to develop analytical methods promote green chemistry. Betel nut (Areca catechu Linn.) was utilized as a natural reagent for determination of iron(III) by sequential injection spectrophotometry. This method was based on the reaction of iron(III) with natural reagent as betel nut in acetate buffer at pH 5.5, forming an iron(III)-betel nut complex that showed maximum absorption at 565 nm. A linear calibration graph in the range 0.2–10.0 mg L−1 iron(III) gave a correlation coefficient (r2) of 0.9995. Limit of detection and limit of quantification were 0.06 and 0.20 mg L−1, respectively. Relative standard deviation of the repeatability and reproducibility was less than 5.0%. The proposed method was successfully applied for determination of iron(III) content in rice samples, with recoveries ranging from 83.06 to 99.05%. Results agreed well with those obtained from the FAAS technique at the 95% confidence level. [ABSTRACT FROM AUTHOR]

A simple cost-effective device for downscaling chemical analysis with microliter-scale dropwise handing and smartphone detection is proposed. The platform was made from easily available materials. Drops of constant volume of analyte and reagent were placed onto a channel then moved by gravity force to mix and react with each other. The color change due to reaction was monitored with a smartphone. Assays of iron, copper and phosphate employing the platform were demonstrated with 1,10-phenanthroline, bicinchoninic acid and molybdate reagents, respectively. Kinetic study was also demonstrated for this simple device. Image 1 • A platform with moving micro drops is proposed for green chemical analysis. • This simple platform is an alternative cost-effective downscaling portable device. • The platform is made from easily available materials. • The platform was able to apply for kinetics study of both fast and slow reactions. • Assays were demonstrated for Fe2+, Cu2+ and phosphate using 1,10-phenanthroline, BCA and molybdate. [ABSTRACT FROM AUTHOR]

Paper-based analytical devices (PADs) with four new designs could be fabricated using commercially available home-based scan-and-cut printer. They serve for miniaturised platforms for chemical analysis. Replication analysis of a sample together with the calibration (using the analyte standards at different concentrations) can be completed in a single run, by utilising smartphone as the detector. Some new approaches for choosing detection zones were suggested. The four proposed PAD designs here were used as models in microliter scale operation to demonstrate the well-known chemistries of colorimetric determinations of iron, phosphate, and hardness using 1,10-phenanthroline and simple aqueous guava leaf extract; molybdate, and EBT-EDTA complexometric titration, respectively, through calibrations: where Blue (B) value = 88.2log [Fe3+] - 80.8, R2 = 0.989; B value = 1.75 [Fe3+] + 0.198, R2 = 0.999; Grey scale (I) value = 1.77 [Fe3+] – 1.22, R2 = 0.997; Red (R) value = 16.1log [PO 4 3−] + 8.95, R2 = 0.999; Hue (H) value = 43.3log [Ca2+] + 233, R2 = 0.994, respectively. For the hardness, using one of the PAD designs, true titration was also possible. Applications of the proposed devices and procedures were demonstrated for real world samples with validation. Additionally, kinetic study of the molybdenum blue for phosphate was demonstrated using one of the PADs. [Display omitted] • New designs of paper based analytical devices (PADs) by simple fabrication. • The PADs for replication analysis of a sample within a single run with smartphone. • Via video recorded by smartphone allows new way for optimisation. • Demonstrated for real world uses with iron, phosphate, and hardness as model assays. • Reengineered PADs as powerful analytical tools in low resource settings. [ABSTRACT FROM AUTHOR]

Abstract: A sequential injection (SI) method in a lab-on-valve (LOV) format for simultaneous spectrophotometric determination of copper and iron has been devised. The detection chemistry is based on the complex formation of 2-(5-bromo-2-pyridylazo)-5-[N-n-propyl-N-(3-sulfopropyl)amino]aniline (5-Br-PSAA) with copper(II) and/or iron(II) at pH 4.6. Copper(II) reacts with 5-Br-PSAA to form the complex which has an absorption maximum at 580nm but iron(III) does not react. In the presence of a reducing agent only iron(II)–5-Br-PSAA complex is formed and detected at 558nm. Under the optimum experimental conditions, the determinable ranges are 0.1–2mgl−1 for copper and 0.1–5mgl−1 for iron, respectively, with a sampling rate of 18h−1. The limits of detection are 50μgl−1 for copper and 25μgl−1 for iron. The relative standard deviations (n =15) are 2% for 0.5mgl−1 copper and 1.8% for 0.5mgl−1 iron when determined in standard solutions. The recoveries range between 96 and 105% when determining 0.25–2mgl−1 of copper and 0.2–5mgl−1 of iron in artificial mixtures at copper/iron ratios of 1:10 to 5:1. The proposed SI-LOV method is successfully applied to the simultaneous determination of copper and iron in multi-element standard solution and in industrial wastewater samples. [Copyright &y& Elsevier]

Abstract: Guava leaf extract is utilized as an alternative natural reagent for quantification of iron. The flow injection technique enables the use of the extract in acetate buffer solution without the need of further purification. Some properties of the extract such as its stability and ability to form a colored complex with iron were studied. The proposed system is an environmentally friendly method for determination of iron with less toxic chemical wastes. [Copyright &y& Elsevier]

• Simple aqueous extract of L. leucocephala leaf contains mimosine (hydroxypyridinone). • Use as natural color reagent for iron assays that is different from so far reported. • The performance similarly to that of commercial mimosine but with much less cost. • Demonstrated for real blood tonic samples. • Offering an alternative green chemical analysis. A simple extract of Leucaena leucocephala (Lam.) de Wit leaf containing mimosine is proposed as a natural color reagent for the determination of iron. The extract exhibited the formation of Fe(III) with mimosine similarly to that of the commercially available mimosine. A linear calibration: A 460 = 6.8 × 10−2 [Fe(III)] + 8.2 × 10−2, R2 = 0.99 was obtained for 0–10 mg.L−1, with LOD (3σ), LOQ (10σ) and %RSD being 0.2 mg.L−1, 0.7 mg.L−1 and less than 5, respectively. The proposed procedure was demonstrated for real samples of blood tonic. The results agreed with that of the FAAS method. [ABSTRACT FROM AUTHOR]