Design of a virtual sensor data array for the analysis of RDX, HMX and DMNB using metal-doped screen printed electrodes and chemometric analysis

The detection of explosive substances is a subject of high importance in several areas including environmental health, de-mining efforts (land and sea) and security and defence against terrorist activity. The use of electrochemical methods for the detection of these substances has increased in recent years but still is quite restricted to the most common explosives. The electrochemical detection of explosive nitroamines and taggant substances in solution using a virtual sensor array of metal-doped screen printed electrodes and differential pulse voltammetry was achieved. The multiple sets of voltammetric data from the different electrodic systems using Differential Pulse Voltammetry (DPV) were integrated using multivariate analysis (PCA, NIPALS and LDA) and matched with known substances present in explosives. These combinations created a mathematical array which separated the explosives, even if the electrochemical information is buried or mixed with the background noise. Two explosive substances: octogen (HMX- 1,3,5-Trinitroperhydro-1,3,5-triazine) and cyclonite (RDX- Hexahydro-1,3,5-trinitro-1,3,5-triazine) and a taggant agent 2,3-dimethyl-2,3-dinitrobutane (DMNB) were subjected to electrochemical analysis using a solid carbon- based screen printed electrode modified with silver, gold and platinum in aqueous solutions. Keywords

Chemometric study on the forensic discrimination of soil types using their infrared spectral characteristics

Soil has been utilized in criminal investigations for some time because of its prevalence and transferability. It is usually the physical characteristics that are studied, however the research carried out here aims to make use of the chemical profile of soil samples. The research we are presenting in this work used sieved (2mm) soil samples taken from the top soil layer (about 10cm) that were then analysed using mid infrared spectroscopy. The spectra obtained were pre-treated and then input into two chemometric classification tools: Nonlinear iterative partial least squares followed by linear discriminant analysis (NIPALS-LDA) and partial least squares discriminant analysis (PLS-DA). The models produced show that it is possible to discriminate between soil samples from different land use types and both approaches are comparable in performance. NIPALS-LDA performs much better than PLS-DA in classifying samples to locatio

The forensic analysis of soil by FTIR with multivariate analysis

Over the past few years more and more studies have been carried out in an attempt to utilize chemical profiles of soil using a wide variety of analytical methods. The value of soil as evidence rests with its prevalence at crime scenes and its transferability between the scene and the criminal. This can be of value for comparison if the scene of crime is known, but could also be so in the identification of a scene. The main basis for the comparison of sites to determine provenance is that soils vary from one place to another. The aim of this work is to find simple methods to identify soil provenance based on FTIR and multivariate analysi

Electrochemical reduction of carbamazepine in ethanol and water solutions using a glassy carbon electrode

The electrochemical reduction of carbamazepine in ethanol and water using a glassy carbon electrode has been studied. In all experimental conditions of scan rate and concentration of carbamazepine an irreversible cathodic wave was observed by cyclic voltammetry (CV). Electrochemical parameters and a plausible EqC mechanism have been reported from the electrochemical measurements and digital simulation. The values of thermodynamic E1/2 were correlated with solvent polarity parameters that it can be interesting for biological, pharmaceutical and forensic purposes. Limits of Detection (LOD) for DPV are 1.1 and 9.0 g/mL (4.65x10-6 and 3.81x10-5 M) in ethanol and water, respectively. The precision and recoveries obtained for tablets and plasma samples showed that the method could be successfully used for analysis

Temperature effect on the electrooxidation of gamma hdroxybutyric acid (GHB) on platinum catalyst through cyclic voltammetry, chronoamperometry, impedance spectroscopy and SERS spectroelectrochemistry

A study of the electro-oxidation of gamma hydroxybutyric acid (GHB) on platinum electrode in acidic media has been investigated by cyclic voltammetry, chronoamperometry and electrochemical impedance spectroscopy in the temperature range between 5 and 30ºC. The variation of the j-E curves allows the determination of activation energy in a wide interval of potentials where three characteristic oxidation peaks appear. The j-t curves were registered at the more positive potentials corresponding with the A and B peaks. Stationary current intensity measurements allowed the determination of the activation energy in pure kinetic region conditions. Electrochemical impedance spectroscopy made also possible the study of the electrochemical behavior in the same potential region. Temperature dependence of the charge-transfer resistance (Rct) and the rate constant associated with the surface coverage by an adsorbed intermediate (-1=Ro/L) during the GHB electro-oxidation process were evaluated and discussed. In all cases, the values of activation energy, below 30 kJ/mol, suggest that a complex mechanism takes place for the GHB electro-oxidation free of strong interactions with the platinum surface. In situ Surface Enhanced Raman Scattering (SERS) spectroelectrochemistry spectra corresponding to coadsorbed species, including intermediates of reaction, have been analyzed at several potentials

Computational Design of a Molecularly Imprinted Polymer for the Biomonitoring of the Organophosphorous Metabolite Chlorferron

: Coumaphos is an organophosphorus compound used as insecticide and frequently used by beekeepers for the management of parasitic mites. The most important metabolite, chlorferron (CFN), has been identified in biological samples and foodstuff. The need to quickly identify the presence of typical metabolites, as an indication of interaction with coumaphos has driven the need to produce a highly sensitive electrochemical method for chlorferron analysis, based on molecularly imprinting polymers (MIP) technology. It showed irreversible behaviour with mixed diffusion/adsorption�controlled reactions at the electrode surface. A monoelectronic mechanism of reaction for oxidation has also been suggested. The linear range observed was from 0.158 to 75 µM. Median precision in terms of %RSD around 3% was also observed. For DPV, the limit of detection (LOD) and the limit of quantitation (LOQ) for the CFN-MIP were 0.158 µM and 0.48 µM, respectively. The obtained median % recovery was around 98%. The results were also validated to reference values obtained using GC-MS. Urine and human synthetic plasma spiked with CFN were used to demonstrate the usability of the method in biological samples, showing the potential for biomonitoring. The developed imprinted sensor showed maximum signal change less than 16.8% when related metabolites or pesticide were added to the mix, suggesting high selectivity of the MIP sensor toward CFN molecules. The results from in vitro metabolism of CMP analysed also demonstrates the potential for detection and quantification of CFN in environmental samples. The newly developed CFN-MIP sensor offers similar LoDs than chromatographic methods with shorter analysis time

A molecular imprinted polymer sensor for biomonitoring of fenamiphos pesticide metabolite fenamiphos sulfoxide.

A new electrochemical method for the identification and quantification of Fenamiphos pesticide’s major metabolite in biological samples –Fenamiphos Sulphoxide (FNX) was developed. Computational calculations, Density Functional Theory (DFT) and semi-empirical models (PM3) were performed to determine the best monomer, pyrrole, and a ratio of 1:5 (template: monomer) was chosen for the fabrication of the FNX-MIP sensor obtained by electropolymerization. The FNX�MIP sensor responded well to increasing FNX concentrations (range of 1-30 µM). Limit of detection and quantification (LOD=0.183 µM, LOQ=0.601 µM), respectively, selectivity, and repeatability were also investigated for the developed method. The obtained percentage of recovery showed good agreement compared to reference values obtained from GC-MS, which was used as a reference method. The FXN-MIP sensor proved selective in the presence of potential interferents. The developed sensor was successfully applied for the determination of FNX in spiked plasma and urine matrixes with acceptable recovery rates. The proposed method also proved successful in detecting FNX prepared from the in vitro metabolism of FNP using liver microsomes to metabolize it

PLANEACIÓN DIDÁCTICA GENERAL DE LA ASIGNATURA DE PROGRAMACIÓN Y CÓMPUTO

GUÍA DIDÁCTICA / PLANEACIÓN DIDÁCTICA (NMS

COMPUTACION APLICADA

GUIA DIDACTICA / PLANEACION DIDACTICA (NMS

SISTEMAS DE INFORMACION

GUIA DIDACTICA / PLANEACION DIDACTICA (NMS