SWIM - Soil water interface monitoring: development of automatic analysis tools

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Sequential injection system with in-line solid phase extraction and soil minicolumn for determination of zinc and copper in soil leachates

Publication . Paluch, Justyna; Mesquita, Raquel B. R.; Cerdà, Victor; Kozak, Joanna; Wieczorek, Marcin; Rangel, António O. S. S.

A sequential injection (SI) system equipped with in-line solid phase extraction column and in-line soil minicolumn is proposed for determination of zinc and copper in soil leachates. The spectrophotometric determination (560 nm) is based on the reaction of both analytes with 1-(2-Pyridylazo)-2-naphthol (PAN). Zinc is determined after retaining copper on a cationic resin (Chelex100) whereas copper is determined from the difference of the absorbance measured for both analytes, introduced into the system with the use of a different channel, and zinc absorbance. The influence of several potential interferences was studied. Using the developed method, zinc and copper were determined within the concentration ranges of 0.005–0.300 and 0.011–0.200 mg L−1, and with a relative standard deviation lower than 6.0% and 5.1%, respectively. The detection limits are 1.4 and 3.0 μg/L for determination of zinc and copper, respectively. The developed SI method was verified by the determination of both analytes in synthetic and certified reference materials of water samples, and applied to the determination of the analytes in rain water and soil leachates from laboratory scale soil core column and in-line soil mini-column.

2018-01-30Journal article

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Microsequential injection lab-on-valve system for the spectrophotometric bi-parametric determination of iron and copper in natural waters

Publication . González, Alba; Mesquita, Raquel B. R.; Avivar, Jessica; Moniz, Tânia; Rangel, Maria; Cerdà, Víctor; Rangel, António O. S. S.

The determination of iron and copper exploiting a microsequential injection lab-on-valve system with online spectrophotometric detection is described. A new, environmental friendly 3-hydroxy-4-pyridinone chelator, functionalized with a polyethylene glycol chain (MRB12) to improve water solubility, was used for iron determination. For copper determination, 1-(2-pyridylazo)-2-naphthol (PAN) was used. Different parameters affecting the formation of the complexes were studied, namely sample volume, reagent concentration, and buffer composition and concentration. The optimized conditions, 150 mu L of sample volume and 250 mg L-1 of MRB12 for iron determination, and 200 mu L of sample and 120 mg L-1 of PAN for copper determination, enabled an LOD of 15 and 18 mu g L-1 for iron and copper, respectively. The robustness of the developed procedure was assessed by the calculation of the relative standard deviation (RSD), 5% for iron determination and 2% for copper determination. The accuracy of the method was assessed comparing the results with two certified samples (RD < 7.5%) and calculating recovery percentages with five river water samples (average < 107%).

2017Journal article

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A solid phase extraction flow injection spectrophotometric method for the zinc determination in plants

Publication . Ribas, Tânia C. F.; Tóth, Ildikó V.; Rangel, António O. S. S.

A solid phase extraction flow injection system for the spectrophotometric determination of total zinc in plant digests was developed. Solid phase extraction was chosen as a strategy for zinc preconcentration and removal of some interferences. The determination of zinc was based on the colorimetric reaction with Zincon. As detection system, a multi-reflection flow cell coupled with a light emitting diode was used. The analytical characteristics of the methodology such as pH of standard/sample solution, nitric acid concentration, the placement of SPE column within the manifold and preconcentration flow rate were studied. The interference of some metals present in plants was also assessed. The limits of detection and quantification achieved were 0.04 mg L−1 and 0.12 mg L−1, respectively. The corresponding Zincon consumption was 0.17 mg for each determination. The developed system was applied to plant digests and the results obtained were in agreement with those obtained with reference procedure.

2017Journal article

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Monitoring the impact of fertilizers on soil leachates using sequential injection analysis for multiparametric determination

Publication . Costa, Carolina F. F. A.; Rocha, Filipa V.; Mesquita, Letícia S.; Mesquita, Raquel B. R.; Rangel, António O. S. S.

2018Conference object

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Microfluidic paper-based devices as disposable, easy-to-use, real time quantification methods

Publication . Mesquita, Raquel B. R.; Rangel, António O. S. S.

2018-03Conference object

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