This study proposes a performance appraisal framework for agricultural water distribution systems based on the Water-Food-Energy Nexus perspective. To analyze and evaluate agricultural water distribution systems with this framework, various methods of improving the operational management were developed and tested under the conventional and water shortages in operational scenarios. The Water-Food-Energy Nexus indicators were then calculated for performance appraisal of the water distribution systems in a study area, located in central Iran. The results indicated that by upgrading the manual operation to an automatic control system, gave the best results from the nexus indicators perspectives. The Bayesian Network model was used to present a probabilistic approach that could assist managers and decision-makers in evaluating the performance of the system, based on the nexus perspective. For this purpose, various configurations of the Bayesian Network structures were developed based on an export-oriented approach, and the most appropriate model was determined for the test case. The calibration and validation process of the selected configuration approved a high accuracy in fulfilling the objective of the study. The developed framework can be employed as a decision support model to prioritize options for modernizing agricultural water distribution systems.

A rapid planar chromatographic method for identification and quantification of 25 water-soluble dyes in food was developed. In a horizontal developing chamber, the chromatographic separation on silica gel 60F(254) high-performance thin-layer chromatography plates took 12 min for 40 runs in parallel, using 8 mL ethyl acetate-methanol-water-acetic acid (65 + 23 + 11 + 1, v/v/v/v) mobile phase up to a migration distance of 50 mm. However, the total analysis time, inclusive of application and evaluation, took 60 min for 40 runs. Thus, the overall time/run can be calculated as 1.5 min with a solvent consumption of 200 μL. A sample throughput of 1000 runs/8 h day can be reached by switching between the working stations (application, development, and evaluation) in a 20 min interval, which triples the analysis throughput. Densitometry was performed by absorption measurement using the multiwavelength scan mode in the UV and visible ranges. Repeatabilities [relative standard deviation (RSD), 4 determinations] at the first or second calibration level showed precisions of mostly <or=2.7%, ranging between 0.2 and 5.2%. Correlation coefficient values (R >= 0.9987) and RSD values (<or=4.2%) of the calibration curves were highly satisfactory using classical quantification. However, digital evaluation of the plate image was also used for quantification, which resulted in RSD values of the calibration curves of mostly <or=3.0%, except for two <or=6.0%. The method was applied for the analysis of some energy drinks and bakery ink formulations, directly applied after dilution. By recording of absorbance spectra in the visible range, the identities of the dyes found in the samples were ascertained by comparison with the respective standard bands (correlation coefficients >or= 0.9996). If necessary for confirmation, online mass spectra were recorded within a minute.

A new, efficient, and sensitive cloud point methodology was developed for preconcentration of trace quantities of cobalt and nickel in water and food samples prior to their determination by flame atomic absorption spectrometry (FAAS). The metals react with 2-(benzothiazolylazo)-4-nitrophenol (BTANP) at pH 7.0 and micelle-mediated extraction using the nonionic surfactant Triton X-114 medium. The surfactant-rich phase was diluted with acidified methanol and the cobalt and nickel content was determined by FAAS. The optimum conditions (e.g. pH, reagent and surfactant concentrations, temperature and centrifugation times) were evaluated and optimized. The proposed CPE method showed linear calibration within the ranges 5.0–100 and 5.0–150 ng mL⁻¹ of cobalt and nickel, respectively, and the limits of detection of the method was 1.4 and 1.0 ng mL⁻¹ of cobalt and nickel, respectively. The interference effect of some cations and anions was also studied. The method was applied to the determination of both metals in water and food samples with a recovery from the spiked water samples in the range of 95–102%. The validation of the procedure was carried out by analysis of a certified reference material.

An environmentally friendly, sensitive, easy and fast ultrasound-assisted ionic liquid-based dispersive liquid-liquid microextraction technique (UA-IL-DLLME) was developed to preconcentrate trace quantities of nickel Ni(II) ion in water, food and tobacco samples prior to detection by FAAS. The proposed technique based on utilisationthe of ionic liquid (IL) (1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate [HMIM][FAP]) as an extraction solvent for Ni(II) ions after the complexation with quinalizarin (Quinz) at pH 6.0. The impact of different analytical parameters on the microextraction efficiency was investigated. In the range of 2.0–300 µg L⁻¹, the calibration graph was linear. Limit of detection and preconcentration factor were 0.6 µg L⁻¹ and 100. Relative standard deviation (RSD%) as precision at 50 and 100 µg L⁻¹ of Ni(II) were 2.4% and 3.6%, respectively (n = 10). The validation of the proposed procedure was verified by a test of two certified reference materials (TMDA-51.3 fortified water, TMDA-53.3 fortified water and SRM spinach leaves 1570A) applying the standard addition method. Finally, the proposed UA-IL-DLLME method was developed and applied to preconcentrate and determine of trace quantities of Ni(II) in real water, food and tobacco samples with satisfactory results.

This study reports a simple, rapid and greener method based on ultrasound assisted-cloud point extraction coupled with inductively coupled plasma-optical emission spectroscopy (ICP-OES) for preconcentration and determination of antimony (Sb), tin (Sn) and thallium (Tl) in food and water samples. Factors affecting the preconcentration procedure were optimized using fractional factorial design and response surface methodology based on Box-Behnken design. Under optimum conditions, the calibration graphs were linear over the concentration range of 0.023–700 μg L−1 with correlation coefficients up to 0.9994, the limits of detection ranged from 0.007–0.010 μg L−1, the limits of quantification were from 0.023 to 0.033 μg L−1 and the relative standard deviations (n = 15) were between 1.3% and 4.1%. In addition, the preconcentration factors were found to be 150, 145 and 160 for Sb, Sn and Tl, respectively. Finally, the developed method was successfully applied in various food and water samples as well as certified reference materials for rapid determination of Sb, Sn and Tl.

A preconcentration procedure based on cloud point extraction and back-extraction (CPE-BE) was proposed for speciation of inorganic vanadium (V⁴⁺ and V⁵⁺) followed by determination by inductively coupled plasma-optical emission spectrometry (ICP-OES). Two consecutive steps are used in this technique. The traditional CPE technique was applied as a first step, V⁵⁺ reacts with bis(3,4-dihydroxybenzylidene)isophthalohydrazide (DHBIP) forming a hydrophobic complex at pH 7.0. The formed complex is then entrapped in a surfactant-rich phase of Triton X-114, while V⁴⁺ kept in the aqueous phase. Following this stage, a back-extraction step was performed to minimize the deteriorating effect of the organic matrix on the plasma performance. For this purpose, the surfactant-rich phase containing the analyte was incubated at 45 °C with 1.0 mL of 1.0 mol L⁻¹ of HNO₃ solution for 15 min. Finally, the analyte in the aqueous phase was determined by ICP-OES. The total vanadium was determined as V⁵⁺ after oxidation of V⁴⁺ by using hydrogen peroxide. The calibration graph is linear from 0.4–750.0 μg L⁻¹ for V⁵⁺ at the optimum conditions (pH 7.0, 10⁻⁴ mol L⁻¹ DHBIP, 0.1 % (v/v) Triton X-114 and 45 °C). The detection and quantification limits of V⁵⁺ were 0.12 μg L⁻¹and 0.40 μg L⁻¹, respectively, with an enrichment factor of 49.5, and the relative standard deviation was less than 2.5 % (n = 7, c = 10 μg L⁻¹). The method has been used for speciation of inorganic V in water samples and determination of total V in cabbage, carrots, mint, and tomato samples with satisfactory results.

A composite of MCM-41 silica with rice husk was modified with dithizone with the aid of microwave radiation. The modified composite was characterized by different techniques and utilized for preconcentration of Cu²⁺, Zn²⁺ and Pb²⁺ prior to determination by flame atomic absorption spectrometry (FAAS). The adsorption process is optimized to attain the maximum efficiency. The procedure presented satisfying uptake characteristics with maximum adsorption capacity of 142.7, 102.9 and 228.8 mg g⁻¹ towards Cu²⁺, Zn²⁺ and Pb²⁺, respectively. The calibration graphs were linear up to 400 μg L⁻¹ for Cu²⁺ and Zn²⁺ and up to 800 μg L⁻¹ for Pb²⁺ with preconcentration factor of 240. The limits of detection were 0.28, 0.21 and 0.48 μg L⁻¹ for Cu²⁺, Zn²⁺ and Pb²⁺, respectively. The optimized procedure was utilized for the preconcentration of Cu²⁺, Zn²⁺ and Pb²⁺ in water and food samples prior to determination by FAAS with accepted precision and accuracy.

A simple and green ultrasound liquid-liquid microextraction method based on low viscous hydrophobic deep eutectic solvent (ULLME-LV-HDES) was proposed for the preconcentration and separation of selenium prior to HG-AAS detection. Six different DESs were prepared for the extraction of selenium. Quercetin was used complexing agent for Se(IV) ions. Various analytical parameters such as pH, quercetin amount, DES type and its volume, sonication time, sample volume were optimized. Tolerance limits of anion, cation and transition metal ions were studied. Preconcentration and enhancement factor were found 62.5 and 121. Under the optimum conditions, limit of detection was found 0.25 ng L⁻¹ with calibration range of 0.8–120 ng L⁻¹. Relative standard deviation was found 3.2%. The accuracy of the method was confirmed with certified reference materials (NIST 1567a Wheat flour and NIST 1548a Typical diet). Finally, the developed method was successfully applied to food and water samples.

A novel green solvent-based ultrasonic assisted dispersive liquid–liquid microextraction (GS-UADLLME) method was developed for the preconcentration of cadmium and lead ions in various real samples prior to determination by graphite furnace atomic absorption spectrometry (GFAAS). In order to extract trace amounts of cadmium and lead ions, 2-amino-3-sulfhydrylpropanoic acid (l-cysteine) (as a green ligand), tetrafluoroborate ion (BF₄⁻) (as an ion pair agent) and 1-butyl-3-methylimidazolium tetrafluoroborate [BMIM][BF₄] (as acceptor phase) were used. Different effective factors in the microextraction procedure such as pH of the sample solution, sample solution volume, acceptor phase volume, l-cysteine and tetrafluoroborate concentrations, centrifugation conditions and salting addition were thoroughly optimized. Under the optimum conditions, the calibration graphs were linear in the range of 0.8–180 and 2.5–190 ng L⁻¹ with a correlation coefficient (r²) higher than 0.9967 for the measurement of cadmium and lead ions, respectively. The limits of detection for the determination of Cd(ii) and Pb(ii) for the proposed method were 0.2 and 0.7 ng L⁻¹, respectively. The relative standard deviations (n = 5) for the analyte determination were lower than 3.4%. In order to investigate the method’s accuracy, cadmium and lead contents of a certified reference material, SRM 1643e (NIST), were determined and the results from the proposed method were in very good agreement with the certified values. The suggested method was successfully applied to the determination of cadmium and lead ions in real samples such as real water, soil, rice and tea samples.

In our work, hydrophobic thymol-based deep eutectic solvents (DESs) with strong reducibility, a lower density than water, and a slightly higher melting point than room temperature were synthesized. Based on these solid DESs, one-step derivatization and temperature-controlled vortex-assisted liquid-liquid microextraction based on the solidification of a floating DES (TC-VA-LLME-SFDES) via UV–Vis spectrophotometry for the rapid determination of total iron was developed. The derivatization and TC-VA-LLME were carried out simultaneously by the addition of DES as both the reducing agent and extraction solvent. After optimization, the calibration curve (5–250 μg L⁻¹, R² = 0.9982), limit of detection (1.5 μg L⁻¹), limit of quantitation (5.0 μg L⁻¹), precision (≤4.0%) and enrichment factor (92) was obtained. This method was applied for the determination of total iron in water and food samples with satisfactory recoveries (85.4–106.2%). One-step derivatization and TC-VA-LLME only required 2 min. Furthermore, this method opened up the application of solid DESs in liquid–liquid microextraction.