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Nowadays most metabolomic studies involve the analysis of large sets of samples to find a representative metabolite pattern associated to the factor under study. During a sequence of analyses the instrument signals can be subjected to the influence of experimental variability sources. Implementation of quality control (QC) samples to check the contribution of experimental variability is the most common...
The work presents the application of compositional data methodology to analytical results, taking as an example the study of the volatile profiles of green Spanish-style table olives according to cultivars and production areas. For this purpose, the volatile compounds (analysed by GC-MS and expressed as percentages of the total area) were considered as a compositional data set in the Simplex space...
Main drawbacks for silver determination in seawater are the effects of samples matrix and that Ag appears in the sub ng L−1. Available methods for sample preparation in Ag analysis are based on solid and liquid extraction using tedious process that increase the cost of analysis and the risk of sample contamination, producing important waste amounts.Solvent bar micro-extraction (SBME) allows the pre-concentration...
A series of glucose bioelectrodes were prepared by glucose oxidase (GOx) immobilization into laponite hydrogel films containing DNA bioinspired polycations made of vinylbenzyl thymine (VBT) and vinylbenzyl triethylammonium chloride (VBA) with general formulae [(VBT)m(VBA)n]≈25n+ with m=0, 1 and n=2, 4, 8, deposited onto glassy carbon electrode. The bioelectrodes were characterized by chronoamperometry,...
During the last decade, hollow fiber liquid phase micro-extraction (HF-LPME) has become an attractive alternative in sample treatment for the analysis of trace metals in seawater. If compared with other similar methodologies, its main advantages are associated to a higher stability of the organic solution contained into the pores of the fiber, which acts as a lipophilic membrane during the extraction...
Silver is recognized as an important pollutant of natural waters. This element is a selective tracer of anthropogenic pollution related to sewage. Studying its bio-availability requires the application of specific separation of the free ion. A liquid membrane is proposed for separating Ag + from estuarine water samples.A bulk liquid membrane (BLM) has been selected. Free silver is transported...
Antimony(V) is volatilized by reaction with potassium bromide in concentrated sulfuric acid media. After volatilization, the gases can be transported to an inductively coupled plasma spectrometer for atomic emission of antimony and its analytical determination. The influent factors, concentrated sulfuric acid volume, concentration and volume of the potassium bromide aqueous solution and carrier gas...
A rapid spectrophotometric method for sulphate determination in a discontinuous mode is described. The method is based on sulphate reduction to hydrogen sulphide followed by its volatilization and absorption in an alkaline solution. The reduction is obtained when a sulphate sample is heated to 287 °C for 15 min, with a mixture of Fe°/KI and phosphoric acid. The resulting gas is swept by nitrogen...
The use of an internal standard is proposed in this work for first derivative spectrophotometric determination of azinphos in formulations. Generally, the spectrophotometric procedure is simpler and less expensive than chromatographic techniques recommended for the analysis of pesticides. However, while determining the pesticide in commercial formulations the, many-fold dilution required for such...
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