On-line solid-phase extraction and multisyringe flow injection analysis of Al(III) and Fe(III) in drinking water

A naked-eye visible aluminium (III)-based complex fluorescence sensor for sensitive detection of mesotrione

Mesotrione, which is a kind of herbicide to control broad-leaved weeds, has been increasingly used due to its excellent selectivity, rapid process and low toxicity. However, the excessive application of mesotrione have led to widespread contamination. Herein, a turn-on competitive coordination-based fluorescent probe, 2-hydroxy-1-(9-purin)-methylidenehydrazinenaphthalene (HPM), has been successfully synthesized. HPM could effectively detect Al3+ in CH3OH/HEPES (1/9, v/v) with low limit of detection (LOD) being 0.2 µM via coordination. HPM also exhibited excellent imaging capabilities for Al3+ in living cells with low cytotoxicity. On the basis of the competitive coordination of HPM with Al3+, the [HPM-Al3+] complex could also serve as a potential fluorescence sensor for detecting mesotrione with the LOD of 0.2 µM. Furthermore, [HPM-Al3+] complex was applied for the detection of mesotrione in real samples and test paper. Finally, the mechanism of [HPM-Al3+] for sensing mesotrione was investigated deeply as well. This work designed a new convenient method for on-site detection of mesotrione without the large-scale equipment or complicated pre-treatment.

Greener and wide applicability range flow-based spectrophotometric method for iron determination in fresh and marine water

A flow-based method for the spectrophotometric determination of iron in recreational waters, both fresh and marine (variable salinity content), was developed. For that purpose, 3-hydroxy-4-pyrydinone ligand functionalized with an ether function was synthetized and used as chromogenic chelator (1-(3'-methoxypropyl)-2-methyl-3-benzyloxy-4-(1H)pyridinone - MRB13) for iron quantification. This water-soluble reagent was previously reported as a greener alternative to quantify iron, due to its low toxicity and a more environmental friendly synthesis. Furthermore, it also displayed a high affinity and specificity for iron. With the main objective of quantifying iron in a variety of water types (different matrices and iron content), two strategies were developed, one of them including on-line solid-phase extraction (SPE), and the other without resorting to a SPE process. Water matrix clean-up and iron enrichment was achieved using a nitrilotriacetic acid resin column. The potential interference of metal ions usually present in water samples was assessed and no significant interference (<10%) was observed. The limits of detection were 11 and 2.9 μg L^-1 without and with SPE, respectively. For one determination (three replicates), the corresponding consumption of MRB13 is 90 μg, sodium hydroxide is 1.4 mg, and boric acid is 5.6 mg. The method was applied to certified water samples and the results were in agreement with certified values. The developed method was also applied to fresh and marine water, and recovery ratios of 103 ± 4 and 101 ± 7 without and with SPE, respectively, were achieved.

A built-in self-calibrating luminescence sensor based on RhB@Zr-MOF for detection of cations, nitro explosives and pesticides

A RhB@Zr-MOF composite with dual-emission properties was demonstrated as a self-calibrating sensor for cations, nitro explosives and nitenpyram.

A lysosome-targetable fluorescent probe for imaging trivalent cations Fe3+, Al3+ and Cr3+ in living cells

An effective morpholine-type naphthalimide chemsensor, N-p-chlorophenyl-4-(2-aminoethyl)morpholine-1,8-naphthalimide (CMN) has been developed as a lysosome-targeted fluorometric sensor for trivalent metal ions (Fe³⁺, Al³⁺ and Cr³⁺). Upon the addition of Fe³⁺, Al³⁺ or Cr³⁺ ions, the probe CMN showed an evident naked-eye color changes which pale yellow solution of CMN turned deepened and it displayed turn-on fluorescence response in methanol. CMN showed a significant selective and sensitive toward Fe³⁺, Al³⁺ or Cr³⁺ ions, while there was no obvious behavior to other monovalent or divalent metal ions from the UV-vis and fluorescence spectrum. Based on the Job's plot analyses the 1:1 coordination mode of CMN with Fe³⁺, Al³⁺ or Cr³⁺ was proposed. The limit of detection (LOD) observed were 0.65, 0.69 and 0.68 μM for Fe³⁺, Al³⁺ and Cr³⁺ ions, respectively. The N-atom of morpholine directly involved in complex formation, CMN emitted fluorescence through inhibition of photoinduced electron transfer (PET). This probe exhibited excellent imaging ability for Fe³⁺, Al³⁺and Cr³⁺ ions in living cells with low cytotoxicity. Significantly, the cellular confocal microscopic research indicated that the lysosome-targeted group of morpholine moiety was introduced which realized the capability of imaging lysosomal trivalent metal ions in living cells for the first time.

A Green Sequential Injection Spectrophotometric Approach Using Natural Reagent Extracts from Heartwood of Ceasalpinia sappan Linn. for Determination of Aluminium

A cost-effective and environmentally friendly approach using a simple sequential injection spectrophotometric system with a non-synthetic reagent from plant extracts was proposed for a green analytical-chemistry methodology. The crude aqueous extracts from heartwood of Ceasalpinia sappan Linn. in acetate buffer pH 5.5 were utilized as an alternative natural reagent for the quantification of aluminium. The extracts contained homoisoflavonoid compounds, brazilin, and brazilein, which reacted with Al(3+) to form reddish complexes with the maximum absorption wavelength at 530 nm. The optimum conditions for the sequential injection parameters, such as sequential profile, sample and reagent volumes, and the pH effect, were investigated. Under the optimum conditions, a linear calibration graph in the range of 0.075 - 1.0 mg L(-1) Al(3+) was obtained with limits of detection and quantification of 0.021 and 0.072 mg L(-1) Al(3+), respectively. Relative standard deviations of 3.2 and 2.4% for 0.1 and 0.25 mg L(-1) Al(3+) (n = 11), respectively, and sampling rate of 128 injections h(-1) were achieved. The developed system was successfully applied to pharmaceutical preparations, water, and beverage samples. The results agreed well with those obtained from the ICP-AES method. Good recoveries between 87 and 104% were obtained.

Research on a spectral recognition method for on-line measurement of COD in dyeing wastewater based on SIMCA

A novel instrument and a method using multi-wavelength spectra combined with a pattern recognition method (SIMCA) were developed and evaluated.

A glance into aluminum toxicity and resistance in plants

Aluminum toxicity is an important stress factor for plants in acidic environments. During the last decade considerable advances have been made in both techniques to assess the potentially toxic Al species in environmental samples, and knowledge about the mechanisms of Al toxicity and resistance in plants. After a short introduction on Al risk assessment, this review aims to give an up-to-date glance into current developments in the field of Al toxicity and resistance in plants, also providing sufficient background information for non-specialists in aluminum research. Special emphasis is paid to root growth and development as primary targets for Al toxicity. Mechanisms of exclusion of Al from sensitive root tips, as well as tolerance of high Al tissue levels are considered.