Analytical applications of emulsions and microemulsions.

Dispersion systems like emulsions and microemulsions are able to solubilize both polar and non-polar substances due to the special arrangement of the oil and aqueous phases. The main advantages of using emulsions or microemulsions in analytical chemistry are that they do not require the previous destruction of the sample matrix or the use of organic solvents as diluents, and behave similarly to aqueous solutions, frequently allowing the use of aqueous standard solutions for calibration. However, it appears that there are many contradictory concepts and misunderstandings often related to terms definition when referring to such systems. The main aim of this review is to outline the differences between these two aggregates and to give an overview of the most recent advances on their analytical applications with emphasis on the potentiality of the on-line emulsification processes.

Pretreatment of oily samples for analysis by flow injection-spectrometric methods.

This review presents a critical discussion of selected reports dealing with the pretreatment methods of oily samples and the determination of their organic and inorganic constituents using flow systems and spectrometric methods. Special emphasis is given to the on-line couplings with detection systems based on UV-visible spectrophotometry and spectrofluorimetry, atomic absorption spectrometry either with flame or electrothermal atomization as well as inductively coupled plasma optical emission spectrometry or inductively coupled plasma-mass spectrometry. Simple dilution with organic solvents, digestion with concentrated acids under thermal heating, microwave or ultrasound radiation and emulsification procedures are mostly used. The empirical preparation of certain organized assemblies like micelles, emulsions and specially microemulsions added to the confusion of some of the terms, demand a brief description of their characteristics, the correct formulation and some of their applications to the manipulation and treatment of oily samples. The analytical capabilities of combining flow manifolds with spectrometric methods for the determination of specific parameters in oily samples apparently have not been sufficiently exploited yet.

Flow injection on-line dilution for zinc determination in human saliva with electrothermal atomic absorption spectrometry detection.

An automated method is described for the determination of zinc in human saliva by electrothermal atomic absorption spectrometry (ET AAS) after on-line dilution of samples with a significant reduction of sample consumption per analysis (<0.4 mL including the dead volume of the system). In order to fulfill this aim without changing the sample transport conduits during the experiments, a flow injection (FI) dilution system was constructed. Its principal parts are: one propulsion device (peristaltic pump, PP) for either samples, standards or washing solution all located in an autosampler tray and for the surfactant solution (Triton X-100) used as diluent, and a two-position time based solenoid injector (TBSI(1)) which allowed the introduction of 10 microL of either solution in the diluent stream. To avoid unnecessary waste of samples, the TBSI(1) also permitted the recirculation of the solutions to their respective autosampler cups. The downstream diluted solution fills a home made sampling arm assembly. The sequential deposition of 20 microL aliquots of samples or standards on the graphite tube platform was carried out by air displacement with a similar time based solenoid injector (TBSI(2)). The dilution procedure and the injection of solutions into the atomizer are computer controlled and synchronized with the operation of the temperature program. Samples or standards solutions were submitted to two drying steps (at 90 and 130 degrees C), followed by pyrolysis and atomization at 700 and 1700 degrees C, respectively. The aqueous calibration was linear up to 120.0 microgL(-1) for diluted standard solutions/samples and its slope was similar (p>0.05) to the standard addition curve, indicating lack of matrix effect. The precision tested by repeated analysis of real saliva samples was less than 3% and the detection limit (3sigma) was of 0.35 microgL(-1). To test the accuracy of the proposed procedure, recovery tests were performed, obtaining mean recovery of added zinc of 97.8+/-1.3%. Furthermore, Zn values estimated by the procedure developed in this work were compared with those obtained by a standard addition flame-AAS method applied to 20 randomly selected saliva samples. No significant differences (p>0.05) were obtained between the two methods. Zinc levels in saliva samples from 44 healthy volunteers, 15 male and 29 female, with ages between 20 and 51 years (mean 30.50+/-9.14 years) were in the range 22-98 microgL(-1) (mean of 55+/-17 microgL(-1)), similar to some and different from others reported in the literature. It was found that zinc values for male were statistically higher (p=0.006) than for female.

On-line electrochemical preconcentration and flame atomic absorption spectrometric determination of manganese in urine samples.

A sensitive and selective method was developed for the determination of traces of manganese in urine using on-line electrochemical preconcentration followed by flame atomic absorption spectrometry detection. A home made flow-through polypropylene cell (4.5cm longx0.8cm diameter filled with glass marbles) with an effective inner volume of 0.5ml containing a working and a counter electrode, both of glassy carbon and a Pt pseudo reference electrode was located in a flow injection manifold specially designed for the purpose of this work. The manganese was deposited from buffer solution of NH(3)/NH(4)Cl at pH 9.00 through an oxidizing process at a current of 400mA during 7min. A flow of HCl 0.1moll(-1) at 4mlmin(-1) through the cell, chemically dissolved the deposit. A small portion (15mul) of the concentrate was introduced in a continuously flowing system by means of a timing device and was then carried to the detector for the manganese quantification. All electrochemical and spectroscopic variables as well as possible interferences in both systems were systematically studied. The relative standard deviations for ten consecutive measurements of manganese solutions of 2.0 and 20mugl(-1) were of 2.3 and 1.5%, respectively, while for a sample processed five times was less then 5%. The accuracy of the developed procedure was evaluated by adding known amounts of manganese standard to urine samples and following the whole procedure. Recoveries within the range 97.2-102.8% were obtained. To further prove the accuracy, a Seronorm Trace Elements in Urine, Batch 403125 sample with a reported concentration of 13mugMnl(-1) was also analyzed. The experimental value obtained was of 12.7+/-0.1mugl(-1), which does not differ significantly from the reported amount (p<0.05). A preconcentration factor of 40, a linear range between 0.015 and 60mugl(-1) and a limit of detection of 15ngl(-1) permitted the determination of manganese in real urine samples from non-exposed subjects in the range 0.5-2.8mugl(-1).

Flow analysis-hydride generation-gas phase derivative molecular absorption spectrophotometric determination of antimony in oral homeopathic products ("AntimoniumTartaricum") formulated under alcoholic medium.

In this work, a flow analysis-hydride generation-gas phase derivative molecular absorption-(UV) spectrophotometric method has been developed for the direct determination of antimony in aqueous and hydro-alcoholic samples. Antimony (III) from undiluted samples is directly transformed into the gaseous stibine (SbH(3)) form by on-line reaction with sodium tetrahydroborate (NaBH(4)) in acidic medium (HCl). The gaseous phase generated is separated from the liquid phase using a commercial gas-liquid separator, and swept - with the help of a carrier gas (N(2)) stream - into a quartz gas cell (10cm pathlength); where the corresponding absorption spectrum is acquired in a continuous mode over the 190-300nm wavelength range, using a conventional spectrophotometer. A derivative strategy was selected in order to avoid the strong spectral interference of the ethanol vapor on the gaseous SbH(3) absorption spectrum. In this way, the peak height at 223nm of the second order derivative spectrum appears as a clear, clean and interference free analytical signal, which allows the direct determination of antimony. The recovery values obtained from homeopathic formulations (prepared in alcoholic medium) spiked with know amounts of antimony ranged between 97.5 and 103%. The method provides a dynamic range from 0.20 to 30mgSbl(-1). The precision (RDS), evaluated by replicate analysis (n=5) of samples and standard solution containing between 2.5 and 15mgSbl(-1) was in all cases lower than 1.2%. The proposed method was applied to the determination of antimony in commercial homeopathic products ("Antimonium Tartaricum") prepared in hydro-alcoholic medium; and showed to be simple, precise, and accurate.

On-line generation and hydrolysis of methyl borate for the spectrophotometric determination of boron in soil and plants with azomethine-H.

A continuous-flow system for boron determination in soils and plants with spectrophotometric detection using the azometihine-H-boron complex method was developed. In order to avoid the interferences of concomitants present in samples and to increase the sensitivity, the element was separated on-line from the matrix by methyl borate generation. For this purpose, a concentrated sulfuric acid sample solution was combined with methanol in 1:3 ratio which produce enough heating for the esterification reaction without external source. Subsequently, the methyl borate produced was stripped by the addition of a nitrogen flow and separated from the bulk solution in a gas-liquid separator to be then hydrolyzed in an ammonium-phosphate buffer solution (pH 6.8). Finally, the new bulk of phases were separated in a second gas-liquid separator and the liquid phase was combined with azomethine-H to form a boron complex for its detection at 420nm. The effects of a number of possible interferents, both anionic and cationic were evaluated. The most severe depressions were caused by fluoride and potassium for which a concentration of 100mugml(-1) caused a 5% depression on the signal. A linear response was obtained between the detection limit of 0.05mugml(-1) (3sigma of the blank) and 50mugml(-1) of boron. The precision (R.S.D.%) for 10 consecutive readings of the same solution (5.0mugml(-1) of boron) was 2.6%. Recoveries of boron added to the samples before the extraction process were 94, 97, and 101% for soil, fruit tissue, and leaf tissue, respectively. The developed system was applied to the determination of boron in soil, fruits tissue, and leaves tissue of coffee plantations from different towns of Mérida State, Venezuela.

A simple strategy for determining ethanol in all types of alcoholic beverages based on its on-line liquid-liquid extraction with chloroform, using a flow injection system and Fourier transform infrared spectrometric detection in the mid-IR.

In this work, a simple strategy for the determination of ethanol in all types of alcoholic beverages using Fourier transform infrared spectrometric detection has been developed. The methodological proposal includes the quantitative on-line liquid-liquid extraction of ethanol with chloroform, through a sandwich type cell equipped with a PTFE membrane, using a two-channel manifold; and direct measurement of the analyte in the organic phase, by means of Fourier transform infrared spectrometry. The quantification was carried out measuring the ethanol absorbance at 877cm(-1)(,) corrected by means of a baseline established between 844 and 929cm(-1). The procedure, which does not require any sample pretreatment (except for the simple degassing of beer and gassy wine samples, and a simple dilution of spirits with water), was applied to determine ethanol in different alcoholic beverages such as beers, wines and spirits. The results obtained highly agree with those obtained by a derivative FTIR spectrometric procedure, and by head space-gas chromatography with FID detection. The proposed method is simple, fast, precise and accurate. Moreover, it can be easily adapted to any infrared spectrometer equipped with a standard transmission IR cell, and provides attractive analytical features, which are comparable to, or better than those offered by other published methods. In consequence, it represents a valid alternative for the determination of ethanol in alcoholic beverages, and could be suitable for the routine control analysis.

Flow analysis-vapor phase generation-Fourier transform infrared (FA-VPG-FTIR) spectrometric determination of nitrite.

In this work, the coupling between flow analysis (FA)-vapor phase generation (VPG) and Fourier transform infrared spectrometry (FTIR) has been proposed as a novel and alternative strategy for the determination of nitrite. The analyte was transformed into the gaseous nitric oxide (NO) by on-line reaction with potassium iodide (KI) or ascorbic acid in acidic medium. The gaseous NO generated was transported by means of a N(2) gas carrier stream inside the IR gas cell and the corresponding FTIR spectrum was acquired in a continuous mode. The absorbance at 1876cm(-1), corrected by a baseline established between 1879 and 1872cm(-1) at a nominal resolution of 2cm(-1), was selected as a measurement criterion. The effect of different spectroscopic and flow analysis experimental parameters, such as nominal resolution, number of scans, reducing agent and its concentration, acidic medium, reagents and sample flow rates, and the carrier gas flow rate on the analytical signal, and then in the figures of merit were initially evaluated by using a standard short path length (10cm) IR gas cell. The optimization of the system was carried out by the univariate method. The main aims of this study were: (i) to investigate the on-line generation of gaseous nitric oxide in a continuous flow system, and (ii) the use of Fourier transform infrared spectrometry as an alternative and selective detector for the determination of nitrite. The proposed method was initially tested and applied for the determination of nitrite in samples with very high concentration of nitrite, such as frankfurters.

Flow injection determination of bismuth in urine by successive retention of Bi(III) and tetrahydroborate(III) on an anion-exchange resin and hydride generation atomic absorption spectrometry.

Bismuth as BiCl(4)(-) and BH(4)(-) ware successively retained in a column (150mm x 4mm, length x i.d.) packed with Amberlite IRA-410 (strong anion-exchange resin). This was followed by passage of an injected slug of hydrochloric acid resulting in bismuthine generation (BiH(3)). BiH(3) was stripped from the eluent solution by the addition of a nitrogen flow and the bulk phases were separated in a gas-liquid separator. Finally, bismutine was atomized in a quartz tube for the subsequent detection of bismuth by atomic absorption spectrometry. Different halide complexes of bismuth (namely, BiBr(4)(-), BiI(4)(-) and BiCl(4)(-)) were tested for its pre-concentration, being the chloride complexes which produced the best results. Therefore, a concentration of 0.3moll(-1) of HCl was added to the samples and calibration solutions. A linear response was obtained between the detection limit (3sigma) of 0.225 and 80mugl(-1). The R.S.D.% (n = 10) for a solution containing 50mugl(-1) of Bi was 0.85%. The tolerance of the system to interferences was evaluated by investigating the effect of the following ions: Cu(2+), Co(2+), Ni(2+), Fe(3+), Cd(2+), Pb(2+), Hg(2+), Zn(2+), and Mg(2+). The most severe depression was caused by Hg(2+), which at 60mgl(-1) caused a 5% depression on the signal. For the other cations, concentrations between 1000 and 10,000mgl(-1) could be tolerated. The system was applied to the determination of Bi in urine of patients under therapy with bismuth subcitrate. The recovery of spikes of 5 and 50mugl(-1) of Bi added to the samples prior to digestion with HNO(3) and H(2)O(2) was in satisfactory ranges from 95.0 to 101.0%. The concentrations of bismuth found in six selected samples using this procedure were in good agreement with those obtained by an alternative technique (ETAAS). Finally, the concentration of Bi determined in urine before and after 3 days of treatment were 1.94 +/- 1.26 and 9.02 +/- 5.82mugl(-1), respectively.

Continuous flow system for lead determination by faas in spirituous beverages with solid phase extraction and on-line copper removal.

A continuous flow system for the determination of lead in home made spirituous beverages was developed. The determination was based on the formation of a neutral chelate of the element with ammonium pyrrolidine dithiocarbamate, its adsorption onto a minicolumn packed with sodium faujasite type Y synthetic zeolite, followed by elution with methyl isobutyl ketone and determination by flame atomic absorption spectrometry. Ethanol and copper interfere strongly in the determination and therefore, must be separated prior to the analysis. Copper is removed by precipitation with rubeanic acid, while ethanol is eliminated by rotaevaporation. Sample solutions containing Pb(2+) in the concentration range from 5 to 120mugl(-1) at pH 2.5 could be analyzed, by using a preconcentration time of 3min. Preconcentration factors from 80 to 140 were achieved for a sample volume of 6ml and the detection limit varied from 1.4 to 3.5mugl(-1), depending on the matrix composition. The relative standard deviations for 60mugl(-1) Pb was 3.2% (n = 10) and the recovery of spikes (20, 40, 60 and 80mugl(-1)) added to the samples was estimated within 92-105% range, suggesting that lead can be quantitatively determined in such samples. Determining lead in several samples by an alternative technique further checked the accuracy. Finally, the concentrations of Pb(2+) determined in 28 samples of Venezuelan spirituous beverages were in 12.6-370.0mugl(-1) range, depending on the fermenting material based on different mixtures of agave, raw sugar cane and white sugar.

Distorción del mapa anzimático renal en ratas tratadas con menadiona (vitamina k3) / Distortion of the map enzyme renal in rats treaty with menadiona (vitamin k3)

La menadiona (2-metil-1,4-naftoquinona, vitamina k3) es una quinona, cuya toxicidad se atribuye al estrés oxidativo inducido por el ciclaje redox de esta droga en las células. Se ha señalado que el riñon es más sensible a la menadiona que otros órganos, incluyendo el corazón y el hígado. El propósito de este estudio es investigar, en ratas blancas, los efectos tóxicos de la menadiona sobre la actividad renal de las siguientes eszimas: deshidrogenasa láctica, maltasa ácida y alanina y aspartato aminotransferasas. La administración de menadiona a dosis elevadas determinó un grado variable de lesiones renales y un incremento significativo (p<0.05) en la actividad de todas las enzimas valoradas en comparación con los controles no tratados. El daño renal depende de las dosis administradas de vitamina K3, y puede ser debido a la liberación de las proteasas ácidas desde los lisosomas, después de la destrucción de sus membranas por el estrés oxidativo inducido por la quinona. Este daño, a su vez determina el incremento en la actividad de las otras enzimas estudiadas. En conclusión, la vitamina K3 a dosis elevadas, determina cambios importantes en las actividades enzimáticas renales

High-performance liquid chromatographic determination of cocaine and benzoylecgonine by direct injection of human blood plasma sample into an alkyl-diol-silica (ADS) precolumn.

A column-switching high-performance liquid chromatographic method with UV detection for the determination of cocaine (COC) and benzoylecgonine (BZE) in human blood plasma samples is described. The method uses an alkyl-diol-silica ADS-C18 extraction precolumn. A 50- micro L plasma sample was introduced to the ADS precolumn in order to separate the analytes from proteins and endogenous compounds. The fraction containing COC and BZE was back-flushed and transferred to an Alltech mixed-mode C(18)/cation-exchange analytical column for final separation. The validation of the method revealed quantitative recoveries from 95.0 to 99.0% for COC at three different concentrations (0.5, 1.0 and 2.0 micro g mL(-1)), and from 96.0 to 99.0% for BZE at the same concentration levels with coefficients of variation <4.00% (n=5). The detection limit (signal to noise ratio (S/N)>3) was 0.03 micro g mL(-1) for all the compounds with an injection volume of 50 micro L. However, it was possible to enhance the sensitivity further by injecting larger plasma volumes, up to 200 micro L, at the same optimal conditions. The overlap of sample preparation, analysis and reconditioning of the extraction column, increase the overall sample throughput to 5 samples h(-1). The developed method has been applied to human blood plasma samples from subjects suspected of cocaine abuse.

Determination of some cationic species in temporary teeth.

Some cationic species (Ca, Mg, Sr, Cu, Zn and Pb) have been determined in temporary teeth (n = 67) sampled from a children population living in Mérida, Venezuela, with a mean age of 87.76 +/- 34.50 months within a range from 29 to 151 months. Each powdered tooth sample was analyzed for calcium, magnesium, strontium and zinc and for copper and lead by atomic absorption spectrometry with flame and electrothermal atomization, respectively. Relations between variables (elements concentration, age, sex, tooth type and caries status) were established using the Pearson correlation matrix and analysis of variance. The mean global concentrations were of 39.25 +/- 5.36; 1.08 +/- 0.81; 89.27 +/- 13.26 and 2.85 +/- 1.14 micrograms/g for Sr, Cu, Zn and Pb and of 208.45 +/- 33.18 and 8.51 +/- 2.05 mg/g for Ca and Mg, respectively. There were no changes in the teeth mineral content with respect to the children age and sex. With respect to the tooth type, there were significant differences only for strontium which varied in the order molars > canines > incisors. Although healthy teeth had higher mineral concentrations than carious teeth, there were not significant differences, proving that both, carious and healthy teeth could be used as indicators of mineral uptake. Magnesium and copper are the elements least related with the others. Significant positive correlations were found between Sr-Zn, Sr-Cu, Sr-Pb, and the only negative correlations were between Ca-Zn and Ca-Pb for the different types of teeth. While the positive association might indicate competition for anionic groups or similar affinity for the same sites in the crystalline structure, the negative correlations showed possible substitutions among the elements.

Flow analysis-hydride generation-Fourier transform infrared spectrometry. A new analytical technique for the simultaneous determination of antimony, arsenic and tin.

The combination of flow analysis (FA), hydride generation (HG) and Fourier transform infrared (FTIR) spectrometry is proposed as a novel and powerful analytical technique for the individual and simultaneous determination of antimony, arsenic and tin in aqueous samples. The analytes were transformed into the volatile hydride form by on-line reaction with sodium tetrahydroborate in acidic medium. The gaseous analyte hydrides [M(n)H(m), (g)] generated, were transported by means of a carrier gas stream inside the IR gas cell and the corresponding FTIR spectrum was acquired in a continuous mode. The 1893, 1904 and 2115 cm(-1) bands of the SbH3, SnH4, and AsH3 were selected for the determination of antimony, tin and arsenic, respectively. The limit of detection (3sigma) obtained by using a short-path (10 cm) IR gas cell were 0.25, 0.30 and 1.2 mg l(-1) for the determination of antimony, tin and arsenic, respectively; while the precision (relative standard deviation, RSD, n 5) found from a standard solution containing 50 mg l(-1) of each element was, in all cases, less than 0.3%. However, the use of a long-path (7.25 m) IR gas cell improved the figures of merit (sensitivity, limits of detection and quantification) nearly 60-fold. The effect of the main experimental and instrumental variables, such as acidic media, sodium tetraborohydrate concentration, nitrogen flow rate, nominal resolution and the scan accumulation on the analytical signals of the antimony, tin and arsenic hydrides, were studied. Further, the potential of the proposed technique for the simultaneous determination of these elements was tested, analyzing synthetic samples containing different amounts of Sb, Sn and As.

Observation on a human intentional poisoning case by the organophosphorus inserticide fenthion / Observaciones sobre un caso humano de envenenamiento intencional por el insecticida órgano fosforado fention

A case of acute poisoning by oral ingestion of fenthion is reportd. Plasma cholinesterase activity and fenthion whole blood concentration were throughly evaluated during the therapeutic intervention that consisted in administration of atropine, toxogonine and fresh plasma. Correlation studies between clinical signs, cholinesterase activity and fenthion levels revealed that pChE activity was not as helpful as the patient's clinical status in determining when the atropine infusion could be stopped. Morever pChE was also useless in signaling sudden relapses. It is concluded, based on this case, that supportive care combined with antidotal therapy remains the cornerstone of treatment specially in severe acute poisoning cases

Actividad de diversas enzimas relacionadas con el metabolismo glúcido en cataratas seniles / The activity of various enzymes related with the metabolism carbohydrates in senile cataracts

En la presente investigación se desarrolló un estudio clínico, del tipo "caso-control", sin hipótesis previa, observándose la distribución de las alteraciones de ciertas enzimas vinculadas al metabolismo intermediario de los glúcidos, como son: la glucógeno fosforilasa, la glucosa-6-fosfatasa, la amilasa, la deshidrogenasa láctica y la fosfohexosaisomerasa en cristalinos con cataratas seniles en comparación con lo que se detecta en cristalinos humanos normales, no opacificados. Las actividades enzimáticas de los cristalinos normales fueron muy parecidas a las detectadas en diferentes especies animales, con excepción de la actividad amilolítica. En las cataratas seniles, los resultados obtenidos muestran una marcada disminución en todas las actividades enzimáticas valoradas. Se establecieron las correlaciones correspondientes y se concluye que los hallazgos obtenidos pudieran deberse a una disminución en la estabilidad y/o en la actividad de estas enzimas, por diversos factores, lo cual produce un grave deterioro del metabolismo glucídico en las cataratas seniles, con interferencia en los mecanismos de producción de energía. Los resultados confirman lo establecido previamente en diversas especies, con respecto a la edad y al cristalino

Efecto de la hipervitaminosis D sobre la actividad de algunas enzimas en higado de ratas / Effect of hypervitaminosis D on the activity of some enzymes in the liver of rats

Se determinó el efecto de ocho dosis de 10,000, 20,000 y 30,000 UI de vitamina D2, administradas día de por medio a tres grupos de ratas, sobre la actividad de algunas enzimas a nivel hepático. En términos generales, el mapa enzimático de los animales tratados con dicha vitamina se caracterizó por un descenso de la actividad enzimática de la G-6-Pasa, la glucógeno fosforilasa y de la arginasa. Asimismo, se observó un aumento de la actividad enzimática de la maltasa ácido y de las transaminasas glutámico-oxaloacética y glutámico-pirúvica. Además, hubo también variaciones, dependiendo de la dosis de vitamina D administrada, en la actividad de la acetilcolinesterasa y de la amilasa

Modificaciones del metabolismo proteico en la hipervitaminosis A aguda, en ratas / Changes of the protein metabolism in acute hypervitaminosis A, in rats

Se presentó el efecto de 100.000 U.I. (700.000 U.I. en total) de vitamina A, administradas diariamente, durante siete días sobre diversos marcadores séricos y hepáticos relacionados con el metabolismo proteico, en ratas. Los resultados obtenidos indican que la hipervitaminosis A aguda determina una disminución significativa de las proteínas totales, del ARN, de los aminoácidos y de la ureogénesis a nivel hepático y, de la albúmina, de las alfa-globulinas y de los niveles de la urea y de los aminoácidos en suero. Por otra parte, se encontró un aumento significativo en la concentración del ADN hepático y en las globulinas gama y ß séricas. Se discuten los resultados obtenidos y se concluye que la hipervitaminosis A aguda determina profundas alteraciones en el metabolismo proteico

Hipercincemia en pacientes con síndrome de Chediak-Higashi / Hyperzincemia in patients with Chediak-Higashi syndrome

Se practicó la determinación de cinc en plasma de dos pacientes de 2 y 4 años de edad con síndrome de Chediak-Higashi en fase acelerada. Se usó un espectrofotómetro de absorción atómica para las medidas de absorbancia y la muestras fueron recolectadas en tubos de ensayo inmersos de ácido nítrico al 15% durante 24 horas y lavados con agua destilada desionizada. La concentración de cinc en plasma de ambos pacientes (354 microng/dl y 132 microng/dl) fue significativamente mayor que en niños sanos de igual edad (91 + ou - 20 microng/dl). Las causas de niveles altos de cinc en plasma son desconocidas, pero reconociendo que el cinc juega un papel importante en el crecimiento y en muchas funciones biológicas, incluyendo inmunocompetencia (disminución de la quimiotaxis, de la fagocitosis de bacterias por leucocitos polimorfonucleares, así como disminución de la respuesta de los linfocitos a la estimulación con fitohemaglutinina en pacientes con niveles altos de cinc), sugiere que estos niveles de cinc pudieran ser parcialmente responsables de las alteraciones de algunas funciones de los leucocitos en pacientes con Chediak-Higashi