Spectrophotometric determination of zinc and copper in a multisyringe injection analysis system using a liquid waveguide capillary cell: Application to natural waters

This work exploits a multisyringe injection analysis (MSFIA) system coupled with a long liquid waveguide capillary cell for the spectrophotometric determination of zinc and copper in waters. A liquid waveguide capillary cell (1.0mpathlength, 550mmi.d. and 250mL internal volume) was used to enhance the sensitivity of the detection. The determination for both ions is based on a colorimetric reaction with zincon at different pH values. The developed methodology compares favourably with other previously described procedures, as it allows to reach low detection limits for both cations (LODs of 0.1 and 2mg L−1, for copper and zinc, respectively), without the need for any preconcentration step. The system also provided a linear response up to 100mg L−1 with a high throughput (43 h−1) and low reagent consumption and effluent production. The developed work was applied to natural waters and three certified reference water samples.info:eu-repo/semantics/acceptedVersio

Sequential injection trace determination of iron in natural waters using a long-pathlength liquid core waveguide and different spectrophotometric chemistries

We developed a sequential injection analysis (SIA) method for the determination of iron in coastal, ground, and surface fresh waters using two different reagents (ferrozine and 1,10-phenathroline). The methodology uses a double-line SIA system to improve mixing conditions between sample and reagent solutions. A liquid waveguide capillary cell (LWCC) with 1.0 m pathlength, 550 μm i.d., and 250 μL internal volume was used to enhance the sensitivity of the determination. The detection limits for the ferrozine and 1,10-phenanthroline reagent were 0.15 and 0.35 μg L–1, respectively. The system provides a linear response up to 20 μg L–1 and has a high throughput rate (41 h–1), low reagent consumption, and also low effluent production for both reagents. The developed method was applied to natural waters (river, well, ground, potable, and sea waters) and one reference water sample

A multi-syringe flow injection system for the spectrophotometric determination of trace levels of iron in waters using a liquid waveguide capillary cell and different chelating resins and reaction chemistries

A method integrating a long waveguide capillary cell with a preconcentration resin in a multi-syringe flow injection analysis (MSFIA) system for iron determination in waters was developed. The determination of iron is based on a colorimetric reaction and two reagents were tested, ferrozine and ammonium thiocyanate. A liquid waveguide capillary cell (1.0 m pathlength, 550 μm i.d. and 250 μL internal volume) with a preconcentration resin were used to improve the sensitivity of the determination. Two different preconcentration resins were also tested, Chelex 100 and NTA Superflow. The developed method employing the NTA Superflow with ferrozine colorimetric reagent provided a detection limit of 0.05 μg L−1 with a linear response up to 8 μg L−1 and a sample throughput rate of 12 per hour. The developed system presents low reagents/sample consumptions. The accuracy was assessed using a certified reference water sample.info:eu-repo/semantics/acceptedVersio

Spectrophotometric sensor system based on a liquid waveguide capillary cell for the determination of titanium: Application to natural waters, sunscreens and a lake sediment

An analytical procedure for the spectrophotometric determination of titanium at trace levels was developed. The procedure involves the use of a multipumping flow system (MPFS) coupled with a liquid waveguide capillary cell (LWCC) with 1.0 m path length, 550 mm i.d. and 250 mL internal volume, which enabled to enhance the sensitivity of the determination and thus avoid complex and timeconsuming preconcentration steps. The determination is based on the colorimetric reaction of titanium with chromotropic acid. The limit of detection (3 ) was 0.4 mg/L and a linear response up to 100 mg/L with a sample throughput of 46 h−1, and a low reagent consumption/effluent production was achieved. The developed procedure was applied to natural waters, sunscreen formulations and one certified lake sediment sample.info:eu-repo/semantics/submittedVersio

Searching for the most variable m/z values in grape development in a Portuguese vineyard

Each vineyard is known to have a strong impact on the metabolic compounds of grapes due to its external factors, named terroir [1]. Furthermore, knowledge on the metabolic behavior of vines in response to the terroir effect can help to assess, in advance, the optimal maturity of grapes. The aim of this work was to obtain a metabolic profile of vines in different locations and consequently associate it with the external conditions present during grapes’ development using an untargeted approach. Samples were collected in eight sites of a Portuguese vineyard during different developmental stages and analyzed using a metabolomic protocol based on liquid chromatography coupled to tandem mass spectrometry [2]. Briefly, samples were grounded and extracted using a mixture of water/methanol/chloroform (20:40:40, v/v/v). The aqueous methanol fraction was used for further analysis. An Agilent Eclipse plus C18 column (RRHD 1.8 µm, 2.1 mm × 100 mm) was used for chromatographic separation and elution was achieved in gradient mode. Water and acetonitrile both containing 0.1% (v/v) formic acid were used as mobile phase. Mass spectrometry analysis was performed in positive and negative ionization mode and data were acquired in scan mode to maximize the number of detected m/z values. MZmine software was chosen for data analysis due to its robustness in fragment selection. A baseline correction was applied to equalize baselines and an alignment algorithm was used to equalize retention times aiming to compare m/z values from different samples. Statistical and chemometric tools were used to exclude m/z values attributed to blanks and to establish a metabolic profile, respectively. Preliminary results confirm that the methodology chosen for data analysis is fast and accurate for the viable selection of the most significant m/z features. Regarding currently analyzed samples, the proposed methodology allowed the identification of several m/z features presenting a statistically significant variation among sampling points, which will be further investigated as indicators of the maturity state.info:eu-repo/semantics/publishedVersio