Composites of ZnO nanoparticles and biomass based activated carbon: adsorption, photocatalytic and antibacterial capacities.

Composite material (AC-ZnO) was prepared by growing ZnO nanoparticles during the production of biomass based-activated carbon (AC) via the incorporation of zinc acetate in the process. Comprehensive analyses confirmed the presence of ZnO nanoparticles over the AC surface and described the particular nature of the composite adsorbent. Methylene blue (MB) equilibrium data fitted the Dubinin-Radushkevich model. The MB adsorption capacity was higher for the bare activated carbons (197.9-188.7 mg/g) than the activated carbons with ZnO nanoparticles (137.6-149.7 mg/g). The adsorption of the MB on the adsorbents is physical because the mean adsorption energy (E) is between 1.76 and 2.00 kJ/mol. Experiments that combine adsorption and photocatalysis were carried out with different loads of adsorbents and with and without UV-light exposure. Photocatalytic activity was identified mostly at the first stage of the adsorption process and, in the case of experiments with less load of the composite AC-ZnO, because the light obstruction effect of the activated carbon is more for higher loads. The ZnO grown over AC improves the adsorption of cations such as Pb, Al and Fe in aqueous phase (polluted river water) and provides antibacterial capacity against Escherichia coli and Salmonella typhimurium.

Adsorption of As(V), Cd(II) and Pb(II), in Multicomponent Aqueous Systems using Activated Carbons.

This paper studies the use of two activated carbon samples made of cocoa pod husk (CPH-AC) and one commercial activated carbon sample in the adsorption of As(V), Cd(II) and Pb(II) from multicomponent synthetic solutions and from the Puyango-Tumbes River water, a river located in northwest Peru. The characterization of the activated carbon samples was conducted. The CPH-AC samples exhibited a specific surface area (SBET) between 709 and 1117 m2/g and a pH point of zero charge (pHPZC) between 4.4 ± 0.2 and 5 ± 0.2, while the commercial material gave an SBET value of 775 m2/g and a pHPZC value of 7.6 ± 0.1. All the evaluated samples displayed the capacity to adsorb As(V), Cd(II) and Pb(II) from both aqueous systems. The adsorption efficiency for Pb was outstanding reaching the value of 89%. A pseudo-second order kinetic model was satisfactorily applied for most of the activated carbon samples.

Sewage surveillance reveals the presence of canine GVII norovirus and canine astrovirus in Uruguay.

Canine norovirus (NoV) and astrovirus (AstV) were studied in 20 domestic sewage samples collected in two cities in Uruguay. Four samples were characterized as canine AstV after phylogenetic analysis clustering with strains detected in Italy and Brazil in 2008 and 2012, respectively. One sample was characterized as canine NoV and clustered with a strain detected in Hong Kong and recently classified as GVII. This study shows the occurrence of a canine NoV GVII strain for the first time in the American continent and also warns about possible zoonotic infection, since canine strains were detected in domestic sewage.

Environmental assessment reveals the presence of MLB-1 human astrovirus in Uruguay.

AIMS: The aim of this study was to investigate the presence of the recently identified human astrovirus (HAstV) and to increase the knowledge of the molecular epidemiology of classical HAstV detected in Uruguay. METHODS AND RESULTS: Recently identified and classical HAstV genotypes were investigated by RT-PCR targeting the ORF1b and ORF2 genome regions in 20 samples obtained between September 2011 and April 2013 in two cities of the eastern region of Uruguay. Four of 20 samples (20%) were identified as MLB-1 genotype and it was found a new MLB-1 classification through the segregation of the worldwide reported MLB-1 strains in two genetic lineages proposed and named: MLB-1a and MLB-1b. Fourteen (70%) samples were positive for classical HAstV and 12 of them were successfully sequenced and genotyped as: HAstV-1 (n = 10), HAstV-2 and HAstV-5 (one sample each). CONCLUSION: These results constitute the first report in the Latin American region concerning the molecular detection and characterization of MLB-1 HAstV strains in environmental samples. SIGNIFICANCE AND IMPACT OF THE STUDY: This study highlights the benefits of an environmental surveillance to study emerging enteric viruses circulating in human societies.

Clinical and epidemiological features of patients with COVID-19 reinfection: a systematic review.

Recurrent positivity in a patient with COVID-19 may be due to various reasons, not necessarily reinfection. There is concern about the occurrence frequency of reinfection. Five databases and a preprint/preprint repository were searched. All case reports, case series, and observational studies were included. Bias was assessed for each study with the Newcastle-Ottawa Scale tool and reported according to the preferred reporting items for systematic reviews and meta-analyses (PRISMA-2020). After eligibility, 77 studies were included for qualitative synthesis (52 case reports, 21 case series, and four case-controls; 1131 patients included). Of these, 16 studies described a second contact with the SARS-CoV-2 positive case, five studies described healthcare profession-related infection, ten studies described that the source of reinfection was likely to be from the community, one study described travel-related infection, nine studies described vulnerability-related infection due to comorbidity. The mean number of days from discharge or negative test to reinfection ranged from 23.3 to 57.6 days across the different included studies. The risk of bias for all case report/series studies was moderate/high. For observational studies, the risk of bias was low. Reinfection of patients with COVID-19 occurs between the first and second month after the first infection, but beyond, and 90 days have been proposed as a point to begin to consider it. The main factor for reinfection is contact with COVID-19 positive cases.

Utility of preoperative polymerase chain reaction testing during SARS-CoV-2 pandemic: The challenge of evolving incidence.

INTRODUCTION: Due to its high transmissibility, measures aimed at reducing the spread of SARS CoV2 have become mandatory. Different organizations have recommended performing polymerase chain reaction tests (PCR) as part of the preoperative screening of surgical patients. We aimed to determine the performance of PCR testing to detect asymptomatic carriers. METHODS: Observational study carried out at a tertiary care center. We compared the results of preoperative real-time reverse-transcription-PCR test (RT-PCR) performed on a cohort of patients pending surgery with the results we would have expected assuming the epidemiological data released by government offices. RESULTS: We registered no positives in the 2,722 preoperative RT-PCR tests performed in our health care area between epidemiological Weeks 18 to 21, meaning a cumulative incidence trending to zero. Assuming public epidemiological data, the probabilistic projection of potential asymptomatic individuals ranged from 0.27 × 10e-4 (according to official data of new cases diagnosed by PCR) to 4.69 × 10e-4 if we assumed cases confirmed by IgG test in our province. Assuming a RT-PCR sensitivity of 95%, to obtain a positive result we should perform 38,461 and 2,028 tests respectively. CONCLUSIONS: In scenarios of very low prevalence and despite high sensitivity scores, indiscriminate preoperative RT-PCR screening is of a questionable effectiveness for detecting asymptomatic carriers. Our findings evidence the difficulty of establishing reliable predictive models for the episodic and rapidly evolving incidence of infections such as has characterized the SARS CoV2 pandemic.

Detection of uncommon rotavirus A strains P[8]G8 and P[4]G8 in the city of Rio de Janeiro, 2002.

Group A rotaviruses (RV-A) are the major cause of gastroenteritis in infants and young children around the world. Each year RV-A causes approximately 11 million episodes of severe diarrhea, with an estimated of 611,000 deaths. Epidemiologic surveys have identified P[8]G1, P[4]G2, P[8]G3, P[8]G4, and P[8]G9 as the most common global genotypes associated with diarrhea in children up to 5-year old. Surveillance studies and documentation of RV-A G and P genotypes is necessary for a comprehensive evaluation of the evolution of new strains, and assessing the capability of vaccines to provide heterotypic protection. It is known that reassortments are the driving force for genetic diversity through sudden changes in RV-A genome. In this study, we identified two unusual P/G combinations, P[8]G8 and P[4]G8, occurring in Rio de Janeiro during 2002. Results obtained in this study suggest that P[8]G8 RV-A strain originated from a reassortment event that occurred between RV-A P[4]G8 and P[8]G9 strains circulating in Rio de Janeiro in the same year. G8 strains identified in this study, as well as G8 strains detected in Recife by Montenegro et al. [Montenegro et al. (2007) J Med Virol 79: 335-340], showed a close genetic relationship with strains from Africa, where this genotype have become prevalent.

Late termination of pregnancy: a comparison of obstetricians' experience in eight European countries.

OBJECTIVE: To compare the experience and attitude of obstetricians in Europe towards late termination of pregnancy and the factors affecting their responses. DESIGN: Cluster sampling cross-sectional survey. All neonatal intensive care unit (NICU)-associated maternity units were recruited (census sampling) in Luxembourg, the Netherlands and Sweden. In France, Germany, Italy, Spain and the UK, units were selected at random. In every recruited unit, all obstetricians with at least 6 months' experience were invited to participate. SETTING: NICU-associated maternity units in eight European countries. POPULATION: Obstetricians with at least 6 months' clinical experience. METHODS: An anonymous, self-administered questionnaire was used. Multinomial logistic analysis was used to identify factors predicting the obstetricians' views about modifying the law governing late termination in their country. MAIN OUTCOME MEASURE: Obstetricians' experience of late termination of pregnancy and views about national policies. RESULTS: One hundred and five units and 1530 obstetricians participated (response rates 70 and 77% respectively). The most common indications for late termination were congenital anomalies and women's physical health. Feticide was not common except in France, Luxembourg and the UK. Active euthanasia of a liveborn was practiced in France and the Netherlands. Obstetricians in Germany were more likely to feel that late termination should be more severely restricted, the opposite was true in Spain and the Netherlands. In Italy, there was dissatisfaction with current status, but opinion was divided, reflecting views on both sides of the debate. CONCLUSIONS: This research outlines current practice in a difficult and sensitive area and suggests the need for more discussion and support for all those who were involved.

Neuroprotective effect of carvedilol and melatonin on 3-nitropropionic acid-induced neurotoxicity in neuroblastoma.

In neurodegenerative diseases, progressive oxidative stress is a major event that precedes neuronal death. Oxidative stress is characterized by an imbalance between oxidants and antioxidants. This imbalance induced oxidative molecular and cell damage, reducing cellular viability. 3-Nitropropionic acid (3NP) causes oxidative stress and other molecular and cellular changes similar to those observed in neurons of patients with Huntington's disease. Since carvedilol and melatonin act as free-radical scavengers, this study examined the effect of carvedilol (10(-5) M) and melatonin (10(-5) M) on oxidative and cell damage induced by 3NP in N1E-115 neuroblastoma cells. Carvedilol and melatonin prevented the increases in lipid peroxidation and total LDH activity, as well as the depletion of reduced glutathione (GSH) and the reduction of antioxidative enzymes activities in N1E-115 cells incubated with 100 mM 3NP. All these carvedilol and melatonin effects were more intense when the drugs were added before rather than after inducing the damage by 3NP. These results also provided evidence supporting the hypothesis that carvedilol and melatonin can be useful for treating neurodegenerative diseases, such as Huntington's disease.

Differences in binding kinetics, bond strength and adduct formation between Pt-based drugs and S- or N-donor groups: A comparative study using mass spectrometry techniques.

Pt-S and Pt-N interactions resulting from the coordination of cisplatin, oxaliplatin and carboplatin to two synthetic peptides that differ from each other in one amino acid (Met or His) have been thoroughly studied in this work. The degree of Pt-binding was determined by inductively coupled plasma mass spectrometry after the separation of the Pt-complexes from the unreacted drugs by size exclusion chromatography. Cisplatin and oxaliplatin showed high affinity for the peptides from the first hours of incubation, although the peptides required longer incubation times to obtain the same platination degrees with cisplatin than with oxaliplatin. Once the reactions reached their maximum binding degrees, the complexes with oxaliplatin began to dissociate, revealing binding reversibility, while a pseudo steady-state was observed for cisplatin until the last day of incubation. Conversely, the equilibrium was not reached for carboplatin and the His-peptide after 30 days, showing a binding degree of 16%, versus 78% for the Met-peptide. The S-donor group also presented an important influence on the reactivity and the adduct formation. The reaction rate for the Met-peptide was faster than the hydrolysis of oxaliplatin and carboplatin, and all the drugs, except oxaliplatin, were able to coordinate up to 3 different donor groups, which were identified by nanospray mass spectrometry. Since structural characterization of metal-complexes often represents an analytical challenge during electrophoretic separations, the strength of Pt-Met and Pt-His bonds was also evaluated under these conditions. The nature of the electrophoretic agents and the incubation times used were the parameters that most affected the stability. Higher Pt losses were found for the Met-peptide (35-90%) than for the His-peptide (16-48%), indicating that Pt-Met bonds were kinetically preferred while Pt-His interactions were thermodynamically favored.

Accumulation, fractionation, and analysis of platinum in toxicologically affected tissues after cisplatin, oxaliplatin, and carboplatin administration.

Antitumoral Pt-containing drugs present side effects like nephrotoxicity and ototoxicity. Several systematic experiments have been carried out with Wistar rats treated with cisplatin, carboplatin, and oxaliplatin to study Pt-drugs accumulation and elimination, and Pt-biomolecule distribution in the cells and cytosols of ear, kidney, and liver. Inductively coupled plasma-mass spectrometry (ICP-MS) analysis shows a cisplatin accumulation capability between oxaliplatin (the highest) and carboplatin (the lowest). The maximum concentration of Pt in all the organs studied was achieved around the first week after cisplatin treatment. During the first 30 days, the elimination was very fast, decreasing in the subsequent 60 days in all the organs. Analysis of cytosols by liquid chromatography (LC)-ICP-MS showed an analogous behavior. In most samples, the distribution of the three drugs in the cellular and cytosolic fractions was similar for all the tissues. For kidney and ear, approximately 60% and 30%, respectively, of the metal accumulated was present in the cytosol, the cytosolic fractions smaller than 50 KDa being especially important. Cisplatin-biomolecule interaction strength under denaturing conditions was evaluated by LC-ICP-MS and showed a quite strong bond.

Cisplatin-induced hearing loss does not correlate with intracellular platinum concentration.

CONCLUSION: Inductively coupled plasma mass spectrometry (ICP-MS) can be applied to organic tissues obtained from experimental animals. Hearing loss does not correlate with the platinum (Pt) concentration found in the inner ear. Drug structure and affinity to inner ear proteins could explain ototoxicity caused by cisplatin. OBJECTIVES: To analyse Pt affinity for brain and ear tissues (of similar embryologic origin) in the Wistar rat and clearance gradient after a single dose, and to correlate these findings with hearing changes. MATERIALS AND METHODS: Thirty-two Wistar rats were intraperitoneally injected with cisplatin at a dose of 5 mg/kg. Animals were sacrificed after obtaining auditory brain responses (ABRs) at 3, 7, 30 and 90 days (nine, seven, seven and nine animals, respectively). Brain and both temporal bones were extracted from each animal and analysed by ICP-MS to determine the absolute concentrations of the metal. Eight non-treated animals were employed as a control group. RESULTS: The ABR thresholds were significantly elevated in animals from all groups after cisplatin treatment. A maximum accumulation of Pt for inner ear and brain was revealed around the first week: 3.175 (57%) and 0.342 (72%), respectively. Pt significantly accumulated in greater quantities in ear than in brain (p<0.01) and was cleared at a higher rate in brain than in ear (p<0.01) following cochlea/brain ratio analysis. No statistically significant correlation was found between amounts of Pt and hearing loss in the study animals.

An approach for quantification of platinum distribution in tissues by LA-ICP-MS imaging using isotope dilution analysis.

Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been revealed as a convenient technique for trace elemental imaging in tissue sections, providing elemental 2D distribution at a quantitative level. For quantification purposes, in the last years several approaches have been proposed in the literature such as the use of CRMs or matrix matched standards. The use of Isotope Dilution (ID) for quantification by LA-ICP-MS has been also described, being mainly useful for bulk analysis but not feasible for spatial measurements so far. In this work, a quantification method based on ID analysis was developed by printing isotope-enriched inks onto kidney slices from rats treated with antitumoral Pt-based drugs using a commercial ink-jet device, in order to perform an elemental quantification in different areas from bio-images. For the ID experiments 194Pt enriched platinum was used. The methodology was validated by deposition of natural Pt standard droplets with a known amount of Pt onto the surface of a control tissue, where could be quantified even 50pg of Pt, with recoveries higher than 90%. The amount of Pt present in the whole kidney slices was quantified for cisplatin, carboplatin and oxaliplatin-treated rats. The results obtained were in accordance with those previously reported. The amount of Pt distributed between the medullar and cortical areas was also quantified, observing different behavior for the three drugs.

Simultaneous characterisation of silver nanoparticles and determination of dissolved silver in chicken meat subjected to in vitro human gastrointestinal digestion using single particle inductively coupled plasma mass spectrometry.

In this study, a chicken meat containing AgNPs (candidate reference material Nanolyse 14) has been used as a model matrix to study the fate and behaviour of AgNPs upon oral ingestion following an in vitro model that included saliva, gastric and intestinal digestions. The behaviour of a 40nm AgNPs standard solution during the three digestion steps was also evaluated. Sample preparation conditions were optimised to prevent AgNPs oxidation and/or aggregation and to ensure the representativeness of the reported results. Total silver released from the test sample and the evaluated AgNP standard was determined by inductively coupled plasma mass spectrometry (ICPMS). The presence of both AgNPs and dissolved silver in the extracts was confirmed by single particle (SP)-ICPMS analysis. AgNPs were sized and the particle number concentration determined in the three digestion juices. Experimental results demonstrated differentiated behaviours for AgNP from the standard solution and the meat sample highlighting the relevance of using physiological conditions for accurate risk assessment. In the most realistic scenario assayed (i.e., spiked chicken meat analysis), only 13% of the AgNPs present in the reference material would reach the intestine wall. Meanwhile, other bioaccessible dissolved forms of silver would account for as much as 44% of the silver initially spiked to the meat paste.

Diagnostic concordance of DSM-IV and DSM-5 Posttraumatic Stress Disorder (PTSD) in a clinical sample.

BACKGROUND: The present study aims to analyze diagnostic concordance between the DSM-IV and the DSM-5 for posttraumatic stress disorder (PTSD) diagnostic criteria and their different groups of symptoms. Furthermore, analyses are conducted to establish the features of participants with no concordant diagnoses. METHOD: The study assessed 166 people over 18 who had experienced at least one traumatic event. PTSD diagnosis was established using the Global Scale for Posttraumatic Stress (EGEP), a self-report measure to assess PTSD. RESULTS: The presence of cognitive avoidance was a determinant in the PTSD DSM-5 diagnosis (86% positive predictive value). The analysis of the non-concordant individuals revealed that individuals who were diagnosed according to the DSM-IV criteria but not the DSM-5 criteria were primarily indirect victims. Conversely, individuals who were diagnosed with the DSM-5 criteria and not with the DSM-IV criteria presented cognitive avoidance and alterations in cognition not included in the DSM-IV criteria. CONCLUSIONS: A within-subjects concordance analysis showed high agreement for PTSD diagnosis between the two classifications. Differences between the diagnoses are due to the new definition of C (avoidance) and D (negative alterations in cognitions and mood) in the DSM-5.

Silver speciation and characterization of nanoparticles released from plastic food containers by single particle ICPMS.

Silver migration from a commercial baby feeding bottle and a food box containing AgNPs, as confirmed by SEM-EDX analysis, was evaluated using food simulant solutions [i.e., water, 3% (v/v) acetic acid, and 10% and 90% (v/v) ethanol]. Silver release was investigated at temperatures in the 20-70°C range using contact times of up to 10 days. Migration of silver from the food box was in all cases 2 to 3 orders of magnitude higher than that observed for the baby bottle, although the total silver content in the original box material was half of that found in the baby bottle. As expected, for both food containers, silver migration depended on both the nature of the tested solution and the applied conditions. The highest release was observed for 3% acetic acid at 70°C for 2h, corresponding to 62ngdm(2) and 1887ngdm(-2) of silver for the baby bottle and the food box, respectively. Single particle-inductively coupled plasma mass spectrometry (SP-ICPMS) was used to characterise and quantify AgNPs in the food simulants extracts. Sample preparation was optimized to preserve AgNPs integrity. The experimental parameters affecting AgNPs detection, sizing and quantification by SP-ICPMS were also optimised. Analyses of water and acidic extracts revealed the presence of both dissolved silver and AgNPs. Small AgNPs (in the 18-30nm range) and particle number concentrations within the 4-1510 10(6)L(-1) range were detected, corresponding to only 0.1-8.6% of the total silver released from these materials. The only exception was AgNPs migrated into water at 40°C and 70°C from the food box, which accounted for as much as 34% and 69% of the total silver content, respectively.

Environmental Assessment of Classical Human Astrovirus in Uruguay.

The aim of this study was to determine the molecular epidemiology of classical human astrovirus (HAstV) strains in sewage samples from four Uruguayan cities: Bella Unión, Salto, Paysandú, and Fray Bentos, located in the Northwestern region of the country. Overall, 96 sewage samples were collected biweekly between March 2011 and February 2012 and were subject to ultracentrifugation methodology in order to concentrate the viruses. RT-PCR directed to the ORF2 genome region was performed followed by sequencing and phylogenetic analysis. Forty-three (45 %) out of 96 analyzed samples were positive for HAstV (Mamastrovirus 1) and 31 of them were successfully sequenced being 21 (49 %) of them classified as HAstV-1 genotype (1a lineage) and 10 (23 %) as HAstV-2 genotype (eight strains belonging to the 2d lineage and two strains to the 2c lineage). The 1a lineage circulated throughout the year, while the 2d lineage only in the coldest months (June to October). Strikingly, the 2c lineage was detected only in Salto city during March 2011. In this city it was observed the highest frequency of HAstV and the greatest genetic diversity, probably due to its role as high touristic spot with an important influx of visitants from others regions of Uruguay and also from other countries. This study constitutes the first report in Uruguay that describes the phylogenetic diversity and genotype distribution of HAstV strains circulating in the Northwestern region evidencing a high frequency and also the presence of several different lineages.

Central origins of cranial nerve parasympathetic neurons in the rat.

The location of central neurons that contribute preganglionic parasympathetic axons to cranial nerves VII, IX, and X in rats has been identified using horseradish peroxidase (HRP) tracing methods. Collectively, these neurons form an uninterrupted dorsal column that extends over the entire length of the medulla. The cephalic end of this column turns ventrally with neurons scattered in the parvicellular reticular formation between the rostral pole of the nucleus of the solitary tract (NST) and the facial motor nucleus. Applying HRP crystals to the cut cervical vagus labels neurons in the classically defined dorsal motor nucleus. Rostrally, this distribution continues along the medial edge of NST, ending just caudal to neurons exiting in the lingual-tonsilar branch of IX. At the rostral pole of the NST and ventral to it, neurons occur that serve the lingual-tonsilar and tympanic branches of IX, as well as the chorda tympani and greater superficial petrosal (GSP) branches of VII. Central neurons of the chorda tympani and tympanic nerves spread ventrally from NST into a sparse but largely coextensive distribution in the reticular formation lateral to the ascending radiations of the facial motor nucleus. Immediately ventral to this distribution, a dense accumulation of GSP efferent neurons appears rostrolateral to the facial motor nucleus. Although they vary considerably in number and packing density, the neurons of the dorsal efferent column and those extending from it into the reticular formation have similar morphological characteristics. The somata are medium-sized, fusiform, or multipolar, but with usually no more than five or six major processes.

4-Alkyl-1,4-dihydropyridines derivatives as specific PAF-acether antagonists.

A new series of 4-alkyl-1,4-dihydropyridines (1,4-DHP) were synthesized and evaluated for their ability to inhibit washed rabbit platelet aggregation induced by PAF-acether (1-O-hexadecyl/octadecyl-2-O-acetyl-sn-glycero-3-phosphorylcholine) and to reverse PAF-induced hypotension in anesthetized rats. Additionally, compounds were evaluated for their ability to inhibit the binding of radiolabeled PAF to its receptor on rabbit platelets. Among these compounds, 6I and 6L were the most potent and specific antagonists. At concentrations up to 100 microM, neither compound 6I nor compound 6L caused platelet aggregation nor did they inhibit platelet aggregation induced by collagen or adenosine diphosphate. Compound 6L did not show in vitro calcium channel blocker activity measured on vascular smooth muscle preparations of rabbit aorta and on [3H]nitrendipine binding assays. The compound did not show any cardiovascular effects in anesthetized rat at iv doses up to 1000 micrograms/kg, and the Ki value was 568.62 nmol. These results indicate that compound 6L is a potent and specific PAF antagonist with 1,4-dihydropyridine structure but devoid of a significant cardiovascular activity related to calcium-antagonist properties.

Trace enrichment and measurement of platinum by flow injection inductively coupled plasma mass spectrometry.

A flow injection system incorporating an alumina microcolumn has been coupled to inductively coupled plasma mass spectrometry (ICP-MS) for on-line preconcentration and determination of platinum (IV) in natural waters. Depending on the nature of the sample, a nominal preconcentration factor of up to 600 can be achieved by eluting with 50microl of 2 mol/l NH(4)OH. The limit of detection after a 5 min preconcentration time was 4 ngl(-1), with a relative standard deviation of 4% (100 ngl(-1) working solution). The proposed method was assessed for the determination of platinum (IV) in natural waters, motor car exhaust and some common analytical reagents.