F. J. Barragán de la Rosa

Assessment of metals in sediments in a tributary of Guadalquivir River (Spain). Heavy metal partitioning and relation between the water and sediment system.

A physical-chemical characterisation of the sedimentsof the Guadaira River in Southwest Spain has beencarried out, determining twenty-three parameters persample. Non-treated urban sewage and industrialwastewaters from olive oil and table olives affectthis river. The factor analysis of the data showshigh organic matter contents with metallicpollution. Consequently, points downstreamstand out because of very high organic and metallicpollution (Zn, Pb, Cr, Cu and Cd, in order ofabundance, showing concentrations in sediments rangingfrom 50–7500 times those of waters). Heavy metals partitioning studies can be a goodapproach to show the real activity of these metals in theaquatic environment. We applied Tessiers analytical sequential extraction scheme to sediments.Sediments would be in general mildly hazardous because wefound low levels of easily interchangeable metals in the first fraction. Nevertheless, that is not thecase in the rivers last stretch, precisely wheresediments are most abundant, the heavy metal levelslargest and dredgings are made periodically. Here,their disposal is of concern; since the actual use ofthese sediments as organic amendment for agriculturalsoils is unacceptable.Interaction between waters and sediments in theriverbed by means of correlation, factor and clusteranalysis on waters and sediments data, wasinvestigated. With this approach we concluded that inthe final stretch there is a problem of contaminationof both, sediments and waters. However, in the middlecourse only sediments are actually polluted. Thiscorresponds to the previous research, when thesituation of waters in this zone was even worse.A physical-chemical characterisation of the sedimentsof the Guadaira River in Southwest Spain has beencarried out, determining twenty-three parameters persample. Non-treated urban sewage and industrialwastewaters from olive oil and table olives affectthis river. The factor analysis of the data showshigh organic matter contents with metallicpollution. Consequently, points downstreamstand out because of very high organic and metallicpollution (Zn, Pb, Cr, Cu and Cd, in order ofabundance, showing concentrations in sediments rangingfrom 50–7500 times those of waters). Heavy metals partitioning studies can be a goodapproach to show the real activity of these metals in theaquatic environment. We applied Tessiers analytical sequential extraction scheme to sediments.Sediments would be in general mildly hazardous because wefound low levels of easily interchangeable metals in the first fraction. Nevertheless, that is not thecase in the rivers last stretch, precisely wheresediments are most abundant, the heavy metal levelslargest and dredgings are made periodically. Here,their disposal is of concern; since the actual use ofthese sediments as organic amendment for agriculturalsoils is unacceptable.Interaction between waters and sediments in theriverbed by means of correlation, factor and clusteranalysis on waters and sediments data, wasinvestigated. With this approach we concluded that inthe final stretch there is a problem of contaminationof both, sediments and waters. However, in the middlecourse only sediments are actually polluted. Thiscorresponds to the previous research, when thesituation of waters in this zone was even worse.

Derivatives of carbohydrazide, thiocarbohydrazide and diaminoguanidine as photometric analytical reagents-I 1,3-bis[(2-pyridyl)methyleneamino]thiourea and 1,3-bis[(2-pyridyl)methyleneamino]guanidine.

1,3-Bis[(2-pyridyl)methyleneamino]thiourea (PMAT) and 1,3-bis[(2-pyridyl)methyleneamino]-guanidine (PMAG) have been prepared. They have been examined and characterized by infrared and ultraviolet spectroscopy. A spectrophotometric method has been used for determination of the protonation constants of the reagents. Finally, a spectrophotometric survey has been made of the reactions of various cations with PMAT and PMAG.

Simultaneous Determination of Cefepime and the Quinolones Garenoxacin, Moxifloxacin and Levofloxacin in Human Urine by HPLC-UV

Abstract.A liquid chromatographic method with a C18 column and acetonitrile/0.1 M phosphoric acid/ sodium hydroxide buffer (pH 3.0)/0.01 M n-octylamine (pH 3.0) as mobile phase in gradient mode has been developed and optimised for the simultaneous determination of the cephalosporin cefepime and the quinolones garenoxacin, levofloxacin and moxifloxacin. Identification and quantification was carried out with a diode-array UV detector, with working wavelengths of 256 nm for cefepime, 292 nm for levofloxacin, 294 nm for moxifloxacin and 282 nm for garenoxacin. The mobile flow-rate and sample volume injected were 1 mL min−1 and 20 µL, respectively. The retention times and detection limits for each antibiotic were 4.9 min and 1.9 µg mL−1 for cefepime, 7.5 min and 2.2 µg mL−1 for levofloxacin, 8.9 min and 2.7 µg mL−1 for moxifloxacin and 10.7 min and 1.8 µg mL−1 for garenoxacin, respectively. The method was applied to the determination of the four molecules in spiked samples of human urine.

Hydrochemical study of an aquifer system in an agricultural area in South West Spain

Abstract A hydrochemical study of an aquifer located in a wide agricultural region in the Guadalquivir river basin has been carried out. Samples of 51 points in the aquifer network have been taken, and 30 parameters, indicating its physical-chemical quality, have been determined for each sample. Classifications of the samples according to their hydrochemical facies have been established and the quality of waters for both agricultural and industrial uses has been tested. Its characteristics for processing to make them drinkable have also been assessed. Isocontent maps of some parameters have allowed to show the alarming pollution state of waters caused mainly by nitrates, and to a lesser extent by organic compounds and metals. Statistical Quality Indexes of both global and partial type has also been established.

Optimization of a Sequential Extraction Scheme for Speciation of Metals in Fine Urban Particles

A sequential extraction procedure fractioned in four steps was optimized with the purpose of improving a previous scheme for determining the chemical forms of metals in fine airborne particles. The optimization was tested on synthetic samples and then confirmed on real samples of fine particles, optimizing the type of reagent, its concentration, pH, temperature and extraction time. Synthetic samples were prepared in the laboratory with compounds of reagent grade. The analytical method applied consisted of extracting the metals from each sample in a rotator with each type of reagent under different conditions of the parameters and then centrifuging before measuring by ICP-AES. The improved and previous scheme was checked on real samples and the differences were significant in the percentages of the soluble chemical forms in the improved scheme (5.2% in front to 22.0% for Pb, 27.0% in front to 50.0% for Cd and 32.4% in front to 9.0% for Ni) from 55.6, 0.23 and 1.48 ng m− 3 of total metal concentrations respectively.

Spectrophotometric determination of gallium in alloys and fly-ash with pyridoxal derivatives of thiocarbohydrazide and carbohydrazide

The symmetric derivatives of pyridoxal with thiocarbohydrazide and carbohydrazide, and the asymmetric derivatives of pyridoxal and salicylaldehyde with the same hydrazides have been synthesized and their analytical potential for spectrophotometric and kinetic fluorimetric determination of metal ions was studied. Gallium(III) and PyMAU(1,3-bis{[4-(2-methyl-3-hydroxy-5-hydroxymethyl)pyridyl]methyleneaminourea at pH = 4.2 form a complex with a single absorption maximum at 425 nm, which can be extracted into cyclohexanone in the presence of a controlled amount of sodium perchlorate. The extract has maximum absorbance at 435 nm. Both systems can be used for determining gallium. The optimal range of gallium concentration for measurement in a 1-cm cell is 0.5-1.25 gmg/ml for the procedure in homogeneous medium ((425) = 3.76 x 10(4).mole(-1).cm(-1)) and 0.25-1.25 mug/ml for the extraction procedure ((435) = 5.30 x 10(4) 1.mole(-1).cm(-1). The latter procedure has been applied to the determination of gallium in alloys and fly-ash.

Spectrophotometric determination of mercury with 5-(6-methyl-2-pyridyl)methylene-2-thiohydantoin

Abstract A method is described for the direct spectrophotometric determination of mercury(II) with 5-(6-methyl-2-pyridyl)methylene-2-thiohydantoin. The influence of the different experimental parameters on the formation of the complex were studied and optimum conditions for the determination of mercury were established. The precision of the procedure, expressed in terms of relative standard deviation, was 0.2%. Two different complexes (1:2 and 1:1 cation-reagent stoichiometries) have been detected. The method has been tested on copper amalgam for dental use.

Polarographic determination of picolinaldehyde in the presence of some related compounds

Abstract A d.c. polarographic method is described for the determination of picolinaldehyde (1.5 × 10 −5 –2.9 × 10 −4 M), based on the in situ formation of its Girard-P derivative in aqueous solution. A mechanism of reduction ( E 1/2 = −0.71 V at pH 3.5) is proposed. The applicability of this method is checked in synthetic samples containing pyridine, picoline and pyridine carboxylic acids.

Spectroscopic study of 5-(2-methyl-3-hydroxy-5-hydroxymethyl-4-pyridylmethylidene)-1-(salicylidene)-carbohydrazone

Abstract 5-(2-methyl-3-hydroxy-5-hydroxymethyl-4-pyridylmethylidene)-1(salicylidine)-carbohydrazone (PXSC) has been synthesized and charactherized by infrared, NMR and UV Spectroscopy. A spectrophotometric method has been used for the determination of the protonation constants of the reagent. Finally a analytical evaluation of The PXSC is described.

Spectrophotometric determination of copper in beverages, feeding-stuffs, drugs and alloys with 1,3-bis[di(2-pyridyl)methyleneamino]urea

1,3-Bis[di(2-pyridyl)methyleneamino]urea has been examined as a selective Spectrophotometric reagent for copper. It gives a yellow complex with copper in acid medium (pH 1), with an absorption maximum at 400 nm, and molar absorptivity 1.49×1041·mole−1· cm−1. Copper can be quantitatively determined with it in the presence of a large number of ions. The reagent has been applied to the determination of copper in beverages, feeding-stuffs, drugs and alloys.Summary1,3-Bis[di(2-pyridyl)methyleneamino]urea has been examined as a selective Spectrophotometric reagent for copper. It gives a yellow complex with copper in acid medium (pH 1), with an absorption maximum at 400 nm, and molar absorptivity 1.49×1041·mole−1· cm−1. Copper can be quantitatively determined with it in the presence of a large number of ions. The reagent has been applied to the determination of copper in beverages, feeding-stuffs, drugs and alloys.Zusammenfassung1,3-Bis[di(2-pyridyl)methylenamino]harnstoff wurde auf seine Eignung als selektives spektrophotometrisches Reagens für Kupfer geprüft. Es gibt in saurer Lösung mit Kupfer eine gelbe Komplexverbindung mit einem Absorptionsmaximum bei 400 nm und einer molaren Absorbanz von 1,49×10−41·mol−1·cm−1. Kupfer läßt sich damit in Gegenwart vielerlei anderer Ionen quantitativ bestimmen. Das Reagens wurde für die Kupferbestimmung in Getränken, Futtermitteln, Drogen und Legierungen verwendet.