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Diffuse reflectance spectrometry is shown to be useful for the quantitative determination of small amounts of pollutants. The relation between sample concentration and reflectance is described by the Kubelka-Munk equation. The experiments were performed with a laboratory constructed diode array spectrophotometer. We can obtain the quantitative reflectance values of different precipitates like ammonium...
A simple and sensitive extraction-spectrophotometric method for the determination of ammonium, barium and potassium in a mixture solution is reported. The DC18C6-ammonium-Orange II (DC18C6-NH 4 -OR II), DC18C6-Barium-Orange II (DC18C6-Ba-(OR II) 2 ) and DC18C6-Potassium-Orange II (DC18C6-K-OR II) ternary complexes are quantitatively extracted into dichloromethane and their absorbances...
A flow injection method on the basis of gas phase molecular absorption is described for the sequential determination of ammonium and nitrate. Two hundred microliters of sample solution is injected into the flow line. For ammonium determination, the sample zone is directed to a line in which reacts with NaOH (13M) and produces ammonia. But for nitrate determination, the sample zone is passed through...
This work has evaluated the influence of humic acid and/or surfactants in the quantification of ammonium in waters with the indophenol-type reaction method. Thymol has been employed with the colorimetric method for sample ammonium concentrations between 0.25 and 1mgL −1 . In addition, SPE/diffuse reflectance method has been used for quantification of ammonium at low concentrations (between...
The synthesis of CH 2 CHCH 2 OCH 2 [15-crown-5] (III) is achieved by the treatment of HOCH 2 – [15-crown-5] (I) with equimolar amounts of CH 2 CHCH 2 Br (II) in the presence of KOH. The hydrosilylation of III with Si(CH 2 CH 2 CH 2 SiMe 2 H) 4 (IV) in the presence of the Karstedt catalyst affords the crown ether...
A multi-parameter probe was used for in situ chloride, nitrate and ammonium measurements in a temporary stream (Ribeira da Pardiela, in the South of Portugal). Comparison with standard analytical methods was performed for all elements. For chloride, the results of the probe depicted the same behaviour as that obtained with the standard method, although it is clear that the matrix effects were present...
The determination of ammonium (NH 4+ ) in concentrations ranging from nanomolar to micromolar in fresh and brackish waters often loaded in high suspended particulate matter and dissolved organic acids is presented. The newly described microplate-based fluorometric technique is allowing quick automated readings of different groups of samples with different background fluorescence and matrix...
Colourimetric methods for the determination of NO 3− , NH 4+ and total N in water extracts of soils using 96-well microplate techniques are described. Nitrate was determined by azo dye formation after reduction to NO 2− using a solution of hydrazine sulphate. Ammonium in the soil extracts was purified and concentrated by diffusion as NH 3 from small volumes...
A strong post chemiluminescence (PCL) phenomenon was observed when ammonium was injected into the reaction mixture after the finish of CL reaction of N-bromosuccinimide (NBS) and dichlorofluorescein. Based on this, a sensitive flow injection PCL method was established for the determination of ammonium. The possible CL mechanism of the reaction was proposed based on a series of experiments. The PCL...
A new design of a membraneless gas-diffusion (MGD) unit coupled to a multisyringe flow injection system is proposed. The spectrophotometric determination of ammonium using an acid–base indicator was chosen to show the feasibility of this approach. Hence, in alkaline medium, ammonium ions are transformed into ammonia (donor channel) which diffuses through the headspace into the acceptor stream (bromothymol...
In this article, a simple, economic, and miniature flow analyzer for ammonium in seawater based on the solenoid micropumps is presented. A single reagent of sodium tetraborate, ortho-phthaldialdehyde (OPA), and sodium sulfite was used and optimized applying the modified SIMPLEX method. A special-made detection cell for fluorescence detection of the reaction product isoindol-1-sulfonat was made and...
In this work, a simple, economic, and miniaturized flow-based analyzer based on solenoid micropumps is presented. It was applied to determine two parameters of high environmental interest: ammonium and total inorganic carbon (TIC) in natural waters. The method is based on gas diffusion (GD) of CO 2 and NH 3 through a hydrophobic gas permeable membrane from an acidic or alkaline donor...
A simple, rapid and reliable gas-diffusion flow injection (GD-FI) method for ammonium determination in building materials has been developed. It is based on leaching ammonium from a ground solid sample into an alkaline solution with subsequent ammonia gas generation. Ammonia is then transported in a nitrogen stream to the GD cell of the FI system where it is absorbed into its acceptor solution containing...
We describe a highly sensitive colorimetric method for the determination of nanomolar concentrations of ammonium in seawater based on the indophenol reaction with o-phenylphenol [(1,1′-biphenyl)-2-ol, abbreviated as OPP]. OPP is available as non-toxic, stable flaky crystals with no caustic odor and has some advantages over phenol in practical use. The method was established by using a gas-segmented...
A simple sequential injection (SI) system with capability to determine multi-parameter has been developed for the determination of iron, manganese, phosphate and ammonium. A simple and compact colorimeter was fabricated in the laboratory to be employed as a detector. The system was optimized for suitable conditions for determining each parameter by changing software program and without reconfiguration...
Use of membraneless vaporization (MBL-VP) unit with two cone-shaped reservoirs is presented for on-line separation and detection of non-volatile species. A flow system comprising two sets of MBL-VP units with a single in-house capacitively coupled contactless conductivity detector (C4D) was developed for dual determination of ammonium and sulfide ions. Using the continuous-flow section, two zones...
The indophenol blue (IPB) method based on Berthelot's reaction is one of the most widely used methods for the determination of ammonium in natural waters. This study comprehensively optimized the kinetics of the IPB reaction under different reagent concentrations, temperature and salinity. The normally used toxic and odorous phenol was replaced by the less toxic, stable flaky crystalline compound,...
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