Bernardo Moreno Cordero

• Dr
• Professor (Full) at University of Salamanca

Nowadays there is a great interest in the development of fast and reliable methods for the determination of amino acids (AAs) in biological samples due to their biological importance. In the present work, a method based on the use of a guard column (gC) prior to tandem mass spectrometry (gC-MS/MS) is proposed for the determination of proteinogenic...

In this paper, we propose a fast and reliable method for the determination of polyamines and related compounds in urine samples using flow injection analysis directly coupled to a triple quadrupole mass spectrometer, with the inclusion of a guard column (XBridge® C18 guard column; 2.1 x 10 mm, 3.5 µm) as a low-resolution fractioning step prior to M...

Herein we propose, for the first time, a rapid method based on flow injection analysis, electrospray ionization-tandem mass spectrometry (FIA-ESI-MS/MS) and multivariate calibration for the determination of l-leucine, l-isoleucine and L-allo-isoleucine in saliva. As far as we know, multivariate calibration has never been applied to the data from th...

Here we show the determination of different polyamines (putrescine, cadaverine, spermidine) and related compounds (gamma-aminobutyric acid and L-ornithine) in saliva samples. These compounds are known to be biomarkers for several diseases. We have optimised an in situ derivatization process using ethyl chloroformate, an automated microextraction by...

A sensitive method for the quantification of polycyclic aromatic hydrocarbons (PAHs) in saliva samples is proposed. The method is based on the use of microextraction by packed sorbents (MEPS), injection with programmed temperature vaporizer (PTV), gas chromatography (GC) and mass spectrometry with a single quadrupole (MS). As far as we know, the ME...

The improvement of sensitivity in headspace (HS) sampling of not very volatile analytes constitutes a challenge that has usually been approached through coupling with additional techniques. Here we propose a new methodology for increasing sensitivity through a multistep approach. This proof of concept is based on direct coupling of a headspace samp...

Amino acids have been of great interest in clinical studies since variation in their concentration may provide information about different disorders. For the first time, a non-separative method based on single quadrupole mass spectrometry (qMS) for the simultaneous semiquantitative determination of sixteen amino acids in saliva samples has been dev...

In this paper, a high-throughput approach is proposed for the sensitive screening and the confirmatory analysis of polar compounds in saliva using a two-step approach based on a liquid chromatographic system coupled to a triple quadrupole mass spectrometer. A reversed-phase chromatographic column was used in both steps and changes in the compositio...

Polycyclic aromatic hydrocarbons (PAHs) have raised great concern all over the world due to their carcinogenicity and persistence in nature. Exposure to these analytes can be estimated by determining their concentration in biological matrices, allowing PAH levels in the corresponding samples to be extrapolated to those in the environment. In this a...

We present the development and validation of a sensitive method for the reliable determination of sixteen polycyclic aromatic hydrocarbons (PAHs) in saliva samples, which can be used as exposure markers. This method was based on a liquid-liquid extraction and programmed temperature vaporizer-gas chromatography-mass spectrometry analysis (LLE-PTV-GC...

In this review, an assessment of non-separative methods based on mass spectrometry used to analyse volatile organic compounds in the field of bioanalysis is performed. The use of non-separative methods based on mass spectrometry has been established as an attractive option for analysing compounds. These instrumental configurations are suitable for...

In this work, a method for the quantitative and qualitative analysis of 11 polycyclic aromatic hydrocarbons (PAHs) in urine samples is reported. The method is based on the coupling of a programmed temperature vaporizer (PTV) with a quadrupole mass spectrometer (qMS), via a deactivated fused silica tubing. Before the PTV-qMS analysis, the samples we...

The development of rapid analytical strategies plays a vital role for the research, discovery and confirmation of analytes that can be sensitive biomarkers. Within this line of work, a method based on headspace-gas chromatography-mass spectrometry has been developed and validated for the determination of possible biomarkers (dimethyl disulfide, tol...

In this work, ten possible volatile biomarkers of lung cancer (acetone, 2-butanone, ethyl acetate, 2-pentanone, 4-methyl-2-pentanone, 2-hexanone, 3-heptanone, 2-heptanone, 3-octanone, and 2-nonanone) have been analyzed to evaluate their different concentration levels in urine samples from lung cancer patients (n = 12) and healthy controls (n = 12)....

Profile signals of urine samples corresponding to patients with lung cancer and controls were obtained using a non-separative methodology. The method is based on the coupling of a headspace sampler, a programed temperature vaporizer and a mass spectrometer (HS-PTV-MS). With only a centrifugation step as prior sample treatment, the samples were subj...

The process used to solve many analytical problems involves obtaining information on isolated compounds. Sample treatment is the costliest and most time-consuming part of the process and a frequent source of errors. However, sometimes it is not necessary to obtain information on individual compounds and profile signals are enough to make decisions....

A new method based on headspace programmed‐temperature vaporizer gas chromatography with mass spectrometry has been developed and validated for the determination of amino acids (alanine, sarcosine, ethylglycine, valine, leucine, and proline) in human urine samples. Derivatization with ethyl chloroformate was employed successfully to determine the a...

Sometimes it is not necessary to separate the individual compounds of a sample to resolve an analytical problem, it is enough to obtain a signal profile of the sample formed by all the components integrating it. Within this strategy, electronic noses based on the direct coupling of a headspace sampler with a mass spectrometer (HS-MS) have been prop...

A rapid method for the analysis of volatiles in saliva samples is proposed. The method is based on direct coupling of three components: a headspace sampler (HS), a programmable temperature vaporizer (PTV) and a quadrupole mass spectrometer (qMS). Several applications in the biomedical field have been proposed with electronic noses based on differen...

We propose a new method for the rapid determination of five volatile compounds described in the literature as possible biomarkers of lung cancer in urine samples. The method is based on the coupling of a headspace sampler, a programmed temperature vaporizer in solvent-vent injection mode, and a mass spectrometer (HS-PTV-MS). This configuration is k...

With a view to improving the sensitivity of direct coupling of a headspace sampler (HS) with a mass spectrometer (MS), here we propose the use of a programmed temperature vaporizer (PTV) in solvent-vent injection mode before the sample is introduced into the MS. This preconcentration scheme has been used for some time in many methods based on gas c...

The present research focuses on the evaluation of different ionic liquid stationary phases in gas chromatography. The different ionic liquid columns were evaluated in terms of peak resolution and peak symmetry for the separation of the chlorobenzenes. The determination of chlorobenzenes in soil samples by means of the optimal ionic liquid stationar...

EU legislation prohibits the use of certain azo dyes which, on reduction, form any of 22 aromatic amines listed in Regulation (EC) 1907/2006 at concentrations above the threshold limit of 30mgKg(-1). Two different extraction techniques for the determination of aromatic amines formed from azo dyes in textiles in combination with gas chromatography-m...

A modified version of the quick, easy, cheap, efficient, rugged, and safe method is proposed for the determination of chlorinated pollutants in soil samples. Measurements were collected using a programmed temperature vaporizer coupled to a gas chromatograph and a µ-electron capture detector. The optimization and validation of this extraction techni...

A fully automated method consisting of microextraction by packed sorbent (MEPS) coupled directly to programmed temperature vaporizer–gas chromatography–mass spectrometry (PTV–GC–MS) has been developed to determine the 12 chlorobenzene congeners (chlorobenzene; 1,2-, 1,3-, and 1,4-dichlorobenzene; 1,2,3-, 1,2,4-, and 1,3,5-trichlorobenzene; 1,2,3,4-...

A new method based on the coupling of microextraction by packed sorbents (MEPS) and gas chromatography with ionic liquid stationary phases for the determination of four haloanisoles in wine matrices is proposed. The analytes were concentrated in a C(18) barrel insert and needle (BIN), desorbed with a small volume of an organic solvent, and determin...

We report a sensitive method for the determination of 15 aromatic amines in environmental water samples. They have been included in the list of priority pollutants in surface water by the European Union. The method is based on analyte enrichment using microextraction by packed sorbent (MEPS) and later analysis using programmed temperature vaporizer...

We report a methodology for the rapid determination of biomarkers in saliva. The method is based on direct coupling of a headspace sampler with a mass spectrometer. The saliva samples are subjected to the headspace generation process, and the volatiles generated are introduced directly into the mass spectrometer, thereby obtaining a fingerprint of...

The present work describes the development and validation of a method for the determination of five non-steroidal anti-inflammatory drugs (NSAIDs: clofibric acid, ibuprofen, naproxen, diclofenac and ketoprofen) in water samples. The fully automated method includes in situ aqueous derivatization followed by analyte enrichment by microextraction by p...

A new analytical method for the determination of trace levels of five non-steroidal anti-inflammatory drugs (NSAIDs: clofibric acid, ibuprofen, naproxen, diclofenac and ketoprofen) in water samples is described. The analytical procedure involves in situ aqueous derivatization with N-(3-dimethylaminopropyl)-N'-ethylcarbodiimide hydrochloride (EDC) a...

A method based on simplified QuEChERS (Quick, Easy, Cheap, Effective, Rugged and Safe) extraction followed by large-injection volume-fast gas chromatography and mass spectrometry detection has been developed for the determination of trihalomethanes (chloroform, bromodichloromethane, dibromochloromethane and bromoform) and BTEX (benzene, toluene, et...

A method using headspace generation and in situ derivatization with water soluble EDC (1-[3-(dimethylamino)propyl]-3-ethylcarbodiimide) and TFEA (2,2,2-trifluoroethylamine) has been optimized for the determination of ibuprofen (2-(p-isobutylphenyl)propionic acid), one of the most common non-steroid anti-inflammatory drug (NSAIDs) residues in surfac...

A sensitive method is presented to determine antioxidants (2-, 3-, and 4-tert-butylphenol, 2,6-di-tert-butylphenol, 3-tert-butyl-4-hydroxyanisol, 2,6-di-tert-butyl-4-methylphenol, 1-naphthol, and diphenylamine) in new and used lubricant oil samples. Research was carried out on a GC device equipped with a headspace sampler, a programmed temperature...

A method based on QuEChERS extraction is proposed for the determination of trihalomethanes (chloroform, bromodichloromethane, dibromocloromethane and bromoform) in soil samples. The new version of QuEChERS adapted to soil samples consists of liquid extraction with ethyl acetate, the addition of water to moisten the samples, salting-out partitioning...

In the present work, a strategy for the qualitative and quantitative analysis of 24 volatile compounds listed as suspected allergens in cosmetics by the European Union is reported. The list includes benzyl alcohol, limonene, linalool, methyl 2-octynoate, beta-citronellol, geraniol, citral (two isomers), 7-hydroxycitronellal, anisyl alcohol, cinnama...

A simplified version of the QuEChERS method for the extraction of chlorinated pollutant compounds from soil samples is proposed. The procedure involves simple liquid extraction of the soil sample with ethyl acetate, followed by the addition of anhydrous MgSO(4). Gas chromatography/electron capture detection (ECD) is then used to analyse the extract...

A methodology based on the coupling of a headspace autosampler with a GC and a MS detector operating in SIM mode has been developed for the determination of volatile organic compounds (THMs and BTEX) in soils. The GC device used is equipped with a programmable temperature vaporizer (PTV) packed with Tenax-TA to introduce the samples (the injection...

The aim of the present work is to propose a method for the determination of ibuprofen, as a typical representative of pharmaceutical compounds, in aqueous samples. To do so, an in situ derivatization reaction in aqueous medium was employed in the vial of a headspace sampler (HS), after which instrumental measurements were made with gas chromatograp...

A sensitive method for the fast analysis of filbertone in spiked olive oil samples is presented. The applicability of a headspace (HS) autosampler in combination with a gas chromatograph (GC) equipped with a programmable temperature vaporizer (PTV) and a mass spectrometric (MS) detector is explored. A modular accelerated column heater (MACHTM) was...

In the present work we propose the combined use of a derivatization reaction within the vial of a headspace sampler with a programmed temperature vaporizer (PTV) inlet in the solvent vent mode as a new methodology for obtaining an increase in sensitivity in headspace-gas chromatography (HS-GC) for the analysis of sparingly volatile compounds. As te...

This article reviews the most recent literature addressing the analytical methods applied for trihalomethanes (THMs) determination in water samples. This analysis is usually performed with gas chromatography (GC) combined with a preconcentration step. The detectors most widely used in this type of analyses are mass spectrometers (MS) and electron c...

A sensitive method is presented for the fast analysis of three aromatic and six polycyclic aromatic hydrocarbons (biphenyl, 3-methylbiphenyl, 4-methylbiphenyl, fluorene, phenanthrene, fluoranthene, pyrene, 1,2-benz(a)anthracene and chrysene) in gasoline samples. The applicability of a GC device equipped with a programmable temperature vaporizer (PT...

A new method based on the use of a headspace autosampler in combination with a GC equipped with a programmable temperature vaporizer (PTV) and an MS detector has been developed for the screening and quantitative determination of trihalomethanes (THMs) in different aqueous matrices. The use of headspace generation to introduce the sample has the adv...

In the present work we report the results obtained with a methodology based on direct coupling of a headspace generator to a mass spectrometer for the identification of different types of petroleum crudes in polluted soils. With no prior treatment, the samples are subjected to the headspace generation process and the volatiles generated are introdu...

A sensitive method is presented for the fast analysis of seven fuel oxygenates (methanol, ethanol, tert-butyl alcohol (TBA), methyl tert-butyl ether (MTBE), ethyl tert-butyl ether (ETBE), tert-amyl methyl ether (TAME) and diisopropyl ether (DIPE)) and benzene, toluene, ethylbenzene and p-xylene (BTEX) in water samples. The applicability of a headsp...

A high-speed determination of naphthalene and total methylnaphthalenes using a non-separative method based on direct injection into the mass spectrometer was performed. The results obtained for total methylnaphthalenes were very similar to those provided with fast gas chromatography-mass spectrometry (GC-MS). However, the non-separative method affo...

A sensitive method is presented for the fast screening and determination of residual class 1 solvents (1,1-dichloroethene, 1,2-dichloroethane, 1,1,1-trichloroethane, carbon tetrachloride and benzene) in pharmaceutical products. The applicability of a headspace (HS) autosampler in combination with GC equipped with a programmed temperature vaporizer...

The coupling of a headspace sampler to a fast gas chromatography system with mass spectrometry detection is proposed as a method for the identification of the sources of contamination in soils due to the presence of hydrocarbons derived from petroleum. The samples are subjected to the headspace generation process, with no prior treatment, and the v...

A high-speed determination of benzene in gasoline samples using a non-separative method based on direct injection into the mass spectrometer is proposed. The results obtained are very similar to those provided with fast GC-MS. The calibration set was made up of gasoline samples in which the benzene was determined chromatographically and samples of...

In the present work a strategy for the qualitative and quantitative analysis of residual solvents in pharmaceutical products is reported. First, a low-resolution chromatogram is generated for the identification of the solvents present in the samples by means of headspace generation-fast gas chromatography−mass spectrometry (HS-fast GC/MS). From the...

We review the state of the art and current trends in the development of strategies for qualitative and quantitative analysis with electronic noses based on mass spectrometry (MS), with special reference to applications in the environmental field.The “mass sensor” provides a fingerprint of the sample that is analyzed without prior chromatographic se...

One of the main limitations to the use of direct coupling of headspace mass spectrometry (HS-MS) for the quantitative determination of analytes in a sample is related to factors affecting the signal intensity. The importance of strategies aimed at compensating this problem is considerable in the case of classification, and is indeed critical as reg...

A high-speed quantitative analysis of methyl tert-butyl ether (MTBE) using three different methods with mass spectrometry detection has been performed. The first method is based on fast chromatography and required an analysis time of 5.23 min per sample, although a certain period (6 min) was necessary for the initial measurement conditions to be re...

The direct coupling of a headspace sampler with a mass spectrometer is proposed as a screening tool for the rapid detection of soil pollution by hydrocarbons from petroleum and derivatives. The samples are subjected to the headspace generation process, with no prior treatment, and the volatiles generated are introduced directly into the mass spectr...

It is reported that calibration transfer is able to compensate the variations in sensitivity in direct coupling of a headspace sampler to a mass spectrometer when used for quantification purposes using multivariate calibration techniques. This strategy of signal stability compensation allows the use of models constructed from large calibration stan...

In the present work, we report a methodology for the rapid detection of soil pollution by hydrocarbons that is based on direct coupling of a headspace sampler with a mass spectrometer. With no prior treatment, the samples are subjected to the headspace generation process and the volatiles generated are introduced directly into the mass spectrometer...

In the present work we propose the use of headspace-mass spectrometry (HS-MS) for the characterisation of monovarietal olive oils, an issue of interest when the origin of an oil has to be determined. The HS-MS procedure involves the direct introduction of the sample into a vial, headspace generation and automatic injection of the volatiles into a m...

An “electronic nose” has been used for the detection of adulterations of virgin olive oil. The system, comprising 12 metal oxide semiconductor sensors, was used to generate a pattern of the volatile compounds present in the samples. Prior to different supervised pattern recognition treatments, feature selection techniques were employed to choose a...

In the present work, we propose the use of direct coupling of a headspace sampler to a mass spectrometer for the detection of adulterants in olive oil. Samples of olive oils were mixed with different proportions of sunflower oil and olive-pomace oil, respectively, and patterns of the volatile compounds in the original and mixed samples were generat...

In the present work, we propose the use of direct coupling of a headspace sampler to a mass spectrometer for the detection of adulterants in olive oil. Samples of olive oils were mixed with different proportions of sunflower oil and olive-pomace oil, respectively, and patterns of the volatile compounds in the original and mixed samples were generat...

Different supervised pattern recognition treatments were applied to the signals generated by an electronic nose for the classification of vegetable oils. The system, comprising six metal oxide semiconductor sensors, was used to generate a pattern of the volatile compounds present in the samples. Feature selection techniques were employed to choose...

A membrane separation module has been coupled on-line to a high-resolution liquid chromatographic system. A microcomputer controls the set of operations required in the overall automatic process. Two types of membranes, homogeneous (silicone) and microporous with air-filled pores, have been investigated and the results obtained for five chloropheno...

An overview of the analytical applications of membrane-based systems for sample enrichment in chromatography and capillary electrophoresis is presented. A brief introduction to the different types of membranes and the main forces related to the transport through them is also given.

The use of preconcentration steps based on phase separation by the cloud point technique offers a convenient alternative to more conventional extraction systems. It has been used successfully for the preconcentration of species of widely differing character and nature, such as metal ions, proteins and other biomaterials, or organic compounds of str...

An overview about the electronic olfactometry is presented. The principles, sensor technologies and chemometric treatment of signals are briefly discussed. Applications of commercial instruments currently available in food technology, environmental analysis, the follow-up of biological processes and the future developments are reviewed.

The potential of the cloud point methodology for the preconcentration of relatively polar compounds was studied using the non-ionic surfactant Triton X-114 and five EPA chlorophenols as test analytes. Analyte determination was performed using reversed-phase gradient LC with electrochemical and spectrophotometric detection. The amount of surfactant...

The potential of the cloud point methodology for the preconcentration of relatively polar compounds was studied using the non-ionic surfactant Triton X-114 and five EPA chlorophenols as test analytes. Analyte determination was performed using reversed-phase gradient LC with electrochemical and spectrophotometric detection. The amount of surfactant...

An overview about the analytical applications of membrane-based systems is presented. The different types of membranes (microporous, homogenous, ion-exchange and asymmetric) and the main forces related to the transport through them (differences in concentration, pressure or electrical potential) are briefly discussed.

Determination of phenols in crude oils and derived fuels requires a sample pretreatment step, usually performed by liquid–liquid extraction or preparative chromatography. In this work, sample preparation is accomplished using a silicone membrane separation unit coupled on-line to a high performance liquid chromatograph with amperometric and ultravi...

Determination of phenols in crude oils and derived fuels requires a sample pretreatment step, usually performed by Liquid-liquid extraction or preparative chromatography. In this work, sample preparation is accomplished using a silicone membrane separation unit coupled on-line to a high performance liquid chromatograph with amperometric and ultravi...

The purpose of this work was to attempt to classify edible vegetable oils by chemometric treatment of the data obtained from an array of gas sensors. A commercial Electronic Nose (FOX 2000) comprising six metal oxide semiconductor sensors was used to generate a pattern of the volatile compounds present in the samples. Linear discriminant analysis (...

On-line coupling of devices for nonchromatographic separation to chromatographic analysis systems affords a substantial improvement in sample processing and facilitates the automation of the procedure, considerably decreasing the error of the analytical methods used. In this work, a silicone membrane device has been coupled to a high-performance li...

A simple and versatile method for the preconcentration of trace amounts of nickel and zinc is proposed. The method, which does not require the use of organic solvents, is based on the phase separation phenomenon undergone by aqueous solutions of non-ionic surfactants and can be used as a prior step to the determination of these elements by flame at...

On-line coupling of devices for non-chromatographic separation to chromatographic analysis systems affords a substantial improvement in the handling of organic samples whose physicochemical characteristics hinder their treatment. Here we report for the first time a simple and rapid automatic method for the determination of phenols in crude oil usin...

The present work studies the analytical possibilities of the electroluminescent detection of hydrogen peroxide generated in an enzymatic reaction. Glucose oxidation through the enzyme glucose oxidase (GOD) was used as the study system. The hydrogen peroxide generated reacts in situ with the radical obtained by electrochemical oxidation of luminol (...

Cloud point methodology has been successfully used for the preconcentration of trace amounts of cadmium as a prior step to its determination by flame atomic absorption spectrometry. A procedure based on the formation of a complex with 1-(2-pyridylazo)-2-naphthol (PAN) is used for the preconcentration of cadmium in a surfactant-rich phase of Triton...

The electrochemical detection of analytes subjected to cloud point preconcentration opens new perspectives to this methodology, whose major limitation lies in the high absorbance background due to the surfactant. In the present work, dual electrochemical detection (reductive-oxidative mode) was used for the liquid chromatographic analysis of organo...

The use of aqueous or aqueous methanolic ionene (cationic polyelectrolytes consisting of dimethylammonium charge centers interconnected by alternating alkyl chain segments containing x and y methylene groups) solutions as mobile phases in thin layer chromatography (TLC) is described. The ortho, meta and para isomers of chlorobenzoic acid and phenyl...

The retention mechanism of zwitterion solutes in micellar liquid chromatography is discussed. Five cephalosporins, cephazolin, cephalexin, cephalothin, cephaloridine and cephradine, and two precursor acids of these antibiotics, 7-aminocephalosporanic acid and 7-aminodesacetoxycephalosporanic acid, were studied using aqueous sodium dodecyl sulfate a...

The synthesis and relevant properties of some cationic polyelectrolytes of the [x,y]-ionene type (i.e., molecules consisting of dimethylammonium charge centers interconnected by alternating alkyl chain segments containing x and y methylene groups) are described. Such hydrophobic ionenes can form intramolecular aggregates and function as micelle-mim...

In chromatographic analysis of polycyclic aromatic hydrocarbons (PAH), three important aspects must be taken into account: losses by sorption onto the containers, association with dissolved organic material, and the need for high preconcentration factors. In this work, fluorescence detection was used for Liquid chromatographic analysis of polycycli...

In chromatographic analysis of polycyclic aromatic hydrocarbons (PAH), three important aspects must be taken into account: losses by sorption onto the containers, association with dissolved organic material, and the need for high preconcentration factors. In this work, fluorescence detection was used by liquid chromatographic analysis of polycyclic...

A flow injection method for the determination of sulfite using gas diffusion and micellar catalysis has been developed. The analyte was detected by reaction with 5,5′-dithiobis(2-nitrobenzoic acid)(DTNB) in the presence of cationic micelles of cetyltrimethylammonium bromide (CTAB). Use of a prior separation process affords an improvement in selecti...

The analytical potential shown by the cloud point phenomenon for the separation and preconcentration of different analytes as an alternative method to other separation techniques is studied. We offer and discuss several examples that can be applied in flow injection analysis and high performance liquid chromatography with both optical (UV and fluor...

A simultaneous kinetic resolution of binary mixtures of cyanide, sulfide, and sulfite by reaction with 5,5́-dithiobis(2-nitrobenzoic acid) (DTNB) in aqueous cetyltrimethylammonium bromide (CTAB) micelles was developed. The use of micelles increased the rate constants of the three reactions involved to a different extent and this differential behavi...

Cloud point extraction has been used for the preconcentration of uranium, prior to its determination by flow injection. The non-ionic surfactant employed was Triton X-114 and the reagent chosen to form a hydrophobic chelate of uranium was 1-(2-pyridylazo)-2-naphthol. The optimum conditions for the preconcentration and determination of uranium have...

One of the major disadvantages of cloud point preconcentration prior to HPLC analysis is the high absorbance background due to the surfactant that, in many cases, despite the optimum performance of the separation step, makes this methodology useless when optical detection is used. In this paper electrochemical detection is proposed for the first ti...

The preconcentration of thorium and uranium on Dowex 50-X8 was studied as a method for the preconcentration of these cations prior to their determination by flow injection with spectrophotometric detection using Arsenazo III in 3.6 M HCl stabilized with Triton X-100 as chromogenic reagent. The preconcentration device is a minicolumn included in the...

The optimum conditions for the determination of Gd using the Gd–1-(2-pyridylazo)-2-naphthol (PAN) system in micelles of Triton X-100 have been studied. Under the conditions chosen, the molar absorptivity was 4.8 × 104 dm3 mol–1 cm–1. It is possible to determine Gd at levels of between 0.9 and 8.8 µg ml–1 by injection into a stream, buffered at pH 9...

The optimum conditions for the determination of Gd using the Gd-1-(2-pyridylazo)-2-naphthol (PAN) system in micelles of Triton X-100 have been studied. Under the conditions chosen, the molar absorptivity was 4.8 × 104 dm3 mo-1 cm-1. It is possible to determine Gd at levels of between 0.9 and 8.8 μg ml-1 by injection into a stream, buffered at pH 9....

Species that are slightly soluble in water (reagents, analytes or reaction products can be used in hydrodynamic analytical systems by means of a judicious choice of an appropriate organized medium allowing one to operate in homogeneous media with the attendant advantages. In addition, these systems allow one to improve existing analytical methods a...

Premiere utilisation d'une valve a six orifices pour realiser des multidosages par une simple injection. Application au dosage simultane du thorium et de l'uranium avec l'arsenazo-III par spectrophotometrie et au dosage amperometrique des nitrates et nitrites

The determination of uranium by a flow system with reagent injection is based on the reaction of U(IV) with Arsenazo III in 3.6 M HCl; U(IV) is generated by reduction of uranyl ion in a lead reductor minicolumn installed in the sample channel of the manifold. The interference effect caused by several ions is studied. The calibration graph is linear...