Fast and Greener Ultrasound-Assisted Acid Extraction for the Determination of Potentially Toxic Elements in Fluorescent Lamp Waste Using ICP OES.

BACKGROUND: Understanding the chemical composition of fluorescent lamp residue, particularly potentially toxic elements, is crucial for reducing environmental impacts and human health risks after disposal. However, the challenge lies in effectively analyzing these heterogeneous solid samples. Techniques involving quantitative dissolution become imperative, playing a fundamental role in quantifying trace elements. OBJECTIVE: The aim of this work is to develop and present a new, faster, and more efficient and environmentally friendly method using ultrasound-assisted acid extraction to quantify potentially toxic elements (Cu, Mn, Ni, Sr, and Zn) present in fluorescent lamp waste using the inductively coupled plasma-optical emission spectrometry technique. METHODS: An ultrasound-assisted acid extraction method for the quantification of potentially toxic elements in fluorescent lamp waste was developed and applied as a greener alternative to conventional digestion methods. For variable optimization, a full factorial design with two levels and two variables (time and temperature) was used to determine which factors significantly affected the observed response. RESULTS: The results obtained for the developed extraction method were compared with a reference method employing a heating acid digestion (with a mixture of HCl, HClO4, and HF) using statistical tools. The best results were obtained using an extraction time of 10 min and a temperature of 25°C. Inductively coupled plasma optical emission spectrometry was applied for element quantification. CONCLUSION: The proposed extraction method showed good results for Cu, Mn, Ni, Sr, and Zn. Furthermore, the proposed method based on ultrasound radiation presents additional criteria that align with the concepts of green analytical chemistry. HIGHLIGHTS: A greener alternative method for the determination of Cu, Mn, Ni, Sr, and Zn in fluorescent lamp waste was developed. Optimal conditions for ultrasound extraction of potentially toxic elements were achieved in 10 min at a temperature of 25°C. Environmentally friendly aspects of ultrasound align with the requirements of green analytical chemistry.

Is mercury in fluorescent lamps the only risk to human health? A study of environmental mobility of toxic metals and human health risk assessment.

Although fluorescent lamps (FL) are extensively used worldwide, recycling rates in some countries are still low. If disposed of inappropriately and broken, FL can cause soil contamination. Hg toxicity in FL is extensively discussed in the literature; however, few studies address the other toxic metals present in the phosphorous powder of FL (PPFL). This paper presents a characterization of the environmental mobility with sequential extraction scheme (SES) of Cd, Cu, Hg, Mn, Ni, Pb, and Zn in PPFL, and modeling the potential risks to human health, in case of direct disposal in soils. An after thermal treatment waste was used for safety reasons. The SES method included five fractions, and the quantification was performed by flame atomic absorption spectrometry (FAAS). Human health risk assessment (HHRA) was conducted using RISC4® software. The PPFL showed the following mobility sequence: Cu (85%) > Ni (81%) > Hg (80%) > Zn (77%) > Cd (75%) > Mn (6%) > Pb (2%), which suggests that Cu, Ni, Zn, and Cd, besides Hg, could be of environmental concern in terms of availability. HHRA showed the potential hazard of Cd, for both children and adults, in the hypothetical scenario of vegetable ingestion, considering vegetables grown in soils contaminated with FL waste. The thermal treatment does not completely remove Hg from the matrix, and the residual Hg still poses a risk to children. These results show that Hg and Cd can be hazardous to humans and reinforce the importance of the correct disposal and treatment of PPFL.

Gold mining tailing: Environmental availability of metals and human health risk assessment.

The gold ore from sulfide minerals is, in general, ore dressed by means of nine stages among which stand out flotation and cyanidation. The residues of these steps, containing potentially toxic elements, such as As, Cd, Cr, Mn, Zn and Pb disposed of tailings dams, which might be a source of environmental contamination if not suitably disposed and/or in cases of accidents and overflows. Sequential extraction schemes (SES) have been used to estimate the potential environmental availability of contaminants from environmental matrices and, lately, from residues. This research evaluates the environmental availability of As, Cr, Cd, Mn, Pb, and Zn, by using two different SES, Tessier and Marin (BCR) in cyanidation residues. The analytes were quantified by inductively coupled plasma with optical emission spectrometry (ICP OES). A human health risk assessment was performed considering a scenario of soil contamination by the tailing after failure dam, based on the potential environment availability of metals, resulted from distinct SES studied. The results showed that Mn and Pb are the most labile, and therefore the most dangerous and bioavailable for the surrounding environment (≥75%). Moreover, the scenario simulated demonstrated the risk for human health mostly due to As, Cd and Zn.

Bundle para a prevenção de infecção de corrente sanguínea / Bundle for the prevention of bloodstream infection

Objetivo: verificar o conhecimento dos profissionais intensivistas sobre o bundle para a prevenção de infecção de corrente sanguínea relacionada ao cateter venoso central e sobre os cuidados no manejo deste dispositivo. Método: trata-se de um estudo quantitativo, de corte transversal, em um hospital público, com a participação de 82 profissionais da saúde da equipe intensivista. Utilizaram-se, para a análise dos dados, frequências absolutas e relativas, e se apresentam os resultados em tabelas. Resultados: relatou-se o conhecimento quanto ao bundle por 53,6% da amostra; 53,6% apontaram a veia subclávia como primeiro sítio de escolha para a inserção de cateteres centrais, enquanto que 25,6% responderam a veia jugular. Evidenciouse, em relação aos cuidados para a manutenção do cateter, que 51,6% dos profissionais de Enfermagem afirmaram realizar entre três e sete cuidados recomendados pelo bundle, enquanto 11,3% referiram adotar apenas até dois cuidados. Conclusão: adverte-se que, embora a maior parte dos entrevistados tenha mostrado um conhecimento satisfatório em relação ao bundle e aos cuidados no manejo dos cateteres, um percentual significativo demonstrou fragilidades ainda existentes.(AU)

Determination of low-molecular-weight amines and ammonium in saline waters by ion chromatography after their extraction by steam distillation.

A new method was developed for the determination of ammonium ion, monomethylamine and monoethylamine in saline waters by ion chromatography. Steam distillation was used to eliminate matrix interferences. Variables such as distillation time, concentration of sodium hydroxide solution and analyte mass were optimized by using a full two-level factorial (2(3) ) design. The influence of steam distillation on the analytical curves prepared in different matrices was also investigated. Limits of detection of 0.03, 0.05 and 0.05 mg/L were obtained for ammoniumion, monomethylamine and monoethylamine, respectively. Saline water samples from the Brazilian oil industry, containing sodium and potassium concentrations between 2.0-5.2% w/v and 96-928 mg/L, respectively, were analyzed. Satisfactory recoveries (90-105%) of the analytes were obtained for all spiked samples, and the precision was ≤ 7% (n = 3). The proposed method is adequate for analyzing saline waters containing sodium to ammoniumion, monomethylamine and monoethylamine concentration ratios up to 28 000:1 and potassium to ammonium, monomethylamine and monoethylamine concentration ratios up to 12 000:1.

Faster extraction of heavy metals from soils using vacuum and ultrasonic energy.

A fast vacuum- and ultrasound-assisted acid extraction of Co, Cu, Fe, Mn, Pb, and Zn from soils using a homemade system has been investigated. Preliminarily, a full factorial design with two levels and three variables (extracting agent, extraction temperature, and sonication time) was applied to optimize the extraction conditions (without vacuum) for some heavy metals (Cu, Mn, Pb, and Zn). The best results were obtained with a 3:1 HCI extraction solution, temperature of 80 degrees C, and time of 2 h. As this sonication time was too long, a vacuum pump was used to produce air bubbles in order to increase the contact between the sample and the extracting agent and to prevent the sample sedimentation. This improvement drastically reduced the sonication time to 2 min. Under these conditions, Co, Cu, Mn, and Zn were totally extracted (recoveries of 86-99%), while recoveries of 73-76 and 74% were obtained for Fe and Pb, respectively. The LOD values using flame atomic absorption spectrometry for determination of Co, Cu, Fe, Mn, Pb, and Zn were 3.2, 7.5, 37.5, 7.5, 22.5, and 3.8 micro glg, respectively. The RSDs were lower than 11% (n = 3).

Auditory processing in children and adolescents in situations of risk and vulnerability.

CONTEXT AND OBJECTIVE: Children and adolescents who live in situations of social vulnerability present a series of health problems. Nonetheless, affirmations that sensory and cognitive abnormalities are present are a matter of controversy. The aim of this study was to investigate aspects to auditory processing, through applying the brainstem auditory evoked potential (BAEP) and behavioral auditory processing tests to children living on the streets, and comparison with a control group. DESIGN AND SETTING: Cross-sectional study in the Laboratory of Auditory Processing, School of Medicine, Universidade de São Paulo. METHODS: The auditory processing tests were applied to a group of 27 individuals, subdivided into 11 children (7 to 10 years old) and 16 adolescents (11 to 16 years old), of both sexes, in situations of social vulnerability, compared with an age-matched control group of 10 children and 11 adolescents without complaints. The BAEP test was also applied to investigate the integrity of the auditory pathway. RESULTS: For both children and adolescents, there were significant differences between the study and control groups in most of the tests applied, with significantly worse performance in the study group, except in the pediatric speech intelligibility test. Only one child had an abnormal result in the BAEP test. CONCLUSIONS: The results showed that the study group (children and adolescents) presented poor performance in the behavioral auditory processing tests, despite their unaltered auditory brainstem pathways, as shown by their normal results in the BAEP test.

Impact of the analytical blank in the uncertainty evaluation of the copper content in waters by flame atomic absorption spectrometry.

Chemical analysts use analytical blanks in their analyses, but seldom is this source of uncertainty evaluated. Generally, there is great confusion. Although the numerical value of the blank, in some situations, can be negligible, its source of uncertainty cannot be. This article discusses the uncertainty contribution of the analytical blank using a numerical example of the copper content in waters by flame atomic absorption spectrometry. The results indicate that the uncertainties of the analytical blank can contribute up to 50% when the blank sample is considered in this analysis, confirming its high impact. This effect can be primarily observed where the analyte concentration approaches the lower range of the analytical curve. Even so, the blank is not always computed. Therefore, the relevance of the analytical blank can be confirmed by uncertainty evaluation.

Matrix-elimination with steam distillation for determination of short-chain fatty acids in hypersaline waters from pre-salt layer by ion-exclusion chromatography.

A method for determination of formic, acetic, propionic and butyric acids in hypersaline waters by ion-exclusion chromatography (IEC), using steam distillation to eliminate matrix-interference, was developed. The steam distillation variables such as type of solution to collect the distillate, distillation time and volume of the 50% v/v H2SO4 solution were optimized. The effect of the addition of NaCl different concentrations to the calibration standards on the carboxylic acid recovery was also investigated. Detection limits of 0.2, 0.5, 0.3 and 1.5 mg L⁻¹ were obtained for formic, acetic, propionic and butyric acids, respectively. Produced waters from petroleum reservoirs in the Brazilian pre-salt layer containing about 19% m/v of NaCl were analyzed. Good recoveries (99-108%) were obtained for all acids in spiked produced water samples.

Investigação de marcadores periféricos alternativos da hiperatividade simpática central em modelo experimental de hipertensão arterial / Investigation of alternative peripheral markers of central sympathetic hyperactivity in experimental hypertension

Atualmente, a hipertensão arterial constitui uma doença cardiovascular de altíssima prevalência. A hiperatividade do sistema nervoso simpático é considerada como uma importante característica fisiopatológica da hipertensão arterial. Portanto, sua modulação farmacológica pode ser considerada como um alvo terapêutico estratégico. No entanto, a avaliação da atividade simpática sistêmica em pacientes é ainda bastante controversa. O objetivo principal do presente estudo foi avaliar a existência de uma possível relação entre a expressão da enzima tirosina hidroxilase(TH) em leucócitos periféricos e a concentração plasmática de catecolaminas. Os experimentos foram realizados em ratos Wistar Kyoto (WKY-VEI) e ratos espontaneamente hipertensos (SHR). Os animais foram tratados por gavagem com losartan (SHR-LOS, 10 mg/kg/dia), clonidina (SHR-CLO, 0,1 mg/kg/dia) ou veículo (SHR-VEI) durante 28 dias. A pressão arterial sistólica (PAS) e a leucometria foram avaliadas antes e após o tratamento. Ao final do tratamento, os animais foram eutanasiados e foi feita a coleta de sangue, bulbo raquidiano e glândulas supra-renais para análises posteriores. A expressão da TH foi avaliada através da técnica de western blotting. A PAS estava elevada nos ratos SHR-VEI antes e após o tratamento com veículo, em comparação com o grupo WKY-VEI. Já nos grupos SHR-LOS e SHR-CLO, o tratamento farmacológico foi capaz de reduzir a PAS para níveis semelhantes àqueles encontrados em animais normotensos. Não foram observadas diferenças significativas na leucometria entre os diferentes grupos experimentais. As concentrações de adrenalina plasmática estavam aumentadas no grupo SHR-VEI, mas não foram reduzidas de maneira significativa por nenhum dos tratamentos farmacológicos. Já a noradrenalina, também elevada no grupo SHR-VEI, foi marcadamente reduzida pelos tratamentos utilizados. A expressão da TH se encontrava elevada nos animais do grupo SHR-VEI em todos os tecidos estudados, tendo sido também reduzida significativamente após o tratamento SHR-CLO em todos os tecidos. No grupo SHR-LOS não houve redução significativa da expressão de TH em nenhum tecido. Nossos achados sugerem que os leucócitos periféricos são diretamente influenciados pela hiperatividade simpática sistêmica presente neste modelo experimental. Tais resultados podem abrir novos caminhos para o desenvolvimento de um novo método de análise da hiperatividade simpática em pacientes, o que seria de grande valia não só para o tratamento da hipertensão arterial como também para outras condições patológicas que apresentam esta hiperatividade como característica.

Auditory processing in children and adolescents in situations of risk and vulnerability / Processamento auditivo em crianças e adolescentes em situação de risco e vulnerabilidade

CONTEXT AND OBJECTIVE: Children and adolescents who live in situations of social vulnerability present a series of health problems. Nonetheless, affirmations that sensory and cognitive abnormalities are present are a matter of controversy. The aim of this study was to investigate aspects to auditory processing, through applying the brainstem auditory evoked potential (BAEP) and behavioral auditory processing tests to children living on the streets, and comparison with a control group. DESIGN AND SETTING: Cross-sectional study in the Laboratory of Auditory Processing, School of Medicine, Universidade de São Paulo. METHODS: The auditory processing tests were applied to a group of 27 individuals, subdivided into 11 children (7 to 10 years old) and 16 adolescents (11 to 16 years old), of both sexes, in situations of social vulnerability, compared with an age-matched control group of 10 children and 11 adolescents without complaints. The BAEP test was also applied to investigate the integrity of the auditory pathway. RESULTS: For both children and adolescents, there were significant differences between the study and control groups in most of the tests applied, with significantly worse performance in the study group, except in the pediatric speech intelligibility test. Only one child had an abnormal result in the BAEP test. CONCLUSIONS: The results showed that the study group (children and adolescents) presented poor performance in the behavioral auditory processing tests, despite their unaltered auditory brainstem pathways, as shown by their normal results in the BAEP test.

CONTEXTO E OBJETIVO: Crianças e adolescentes que vivem em situação de vulnerabilidade social apresentam uma série de problemas de saúde. Apesar disso, ainda é controversa a afirmação sobre a existência de alterações cognitivas e/ou sensoriais. O objetivo deste estudo foi investigar aspectos relacionados ao processamento auditivo, através da aplicação de testes de potencial evocado auditivo de tronco encefálico (PEATE) e avaliação comportamental do processamento auditivo em crianças em situação de rua, comparando a um grupo controle. TIPO DE ESTUDO E LOCAL: Estudo transversal no Laboratório de Processamento Auditivo, Faculdade de Medicina da Universidade de São Paulo. MÉTODOS: Os testes de processamento auditivo foram aplicados em um grupo de 27 indivíduos, subdivididos em grupos de 11 crianças (7 a 10 anos) e 16 adolescentes (11 a 16 anos) de ambos os sexos, em situação de vulnerabilidade social, e comparado a um grupo controle, formado por 21 crianças, subdivididas em grupos de 10 crianças e 11 adolescentes, pareados por idade, sem queixas. Também se aplicou os PEATE para investigação da integridade da via auditiva. RESULTADOS: Para ambas as faixas etárias, foram encontradas diferenças significantes entre grupos estudo e controle para a maioria dos testes aplicados, sendo que o grupo estudo apresentou desempenho estatisticamente pior do que o controle para todos os testes, exceto para o teste pediatric speech intelligibility. Apenas uma criança apresentou resultado alterado para os PEATE. CONCLUSÕES: Os resultados demonstraram pior desempenho do grupo estudo (crianças e adolescentes) para os testes comportamentais de processamento auditivo, apesar de estes apresentarem integridade da via auditiva em nível de tronco encefálico, demonstrada pela normalidade nos resultados do PEATE.

Ten-year follow-up of a case series of primary epithelial neoplasms of the lacrimal gland: clinical features, surgical treatment and histopathological findings.

PURPOSE: To describe and analyze the features of a cases series of patients with primary epithelial neoplasms of the lacrimal gland, its surgical treatment, and histopathological findings. METHODS: Retrospective evaluation of files from patients with primary epithelial neoplasms of the lacrimal gland in the period from 1997 to 2007. All patients with primary epithelial tumors of the lacrimal gland were included in this study. Data on gender, age, clinical features, surgical treatment, histopathological findings and follow-up were collected. The slides with histological sections of the tumors were reviewed by the same pathologist. RESULTS: During the study period, there were 12 patients, 5 (41.7%) with benign tumors, all pleomorphic adenomas (benign mixed tumor) and 7 (58.3%) with malignant neoplasms, thus distributed: four cases of adenoid cystic carcinoma, two of mucoepidermoid carcinoma and one carcinoma expleomorphic adenoma. Globally, patients mean age was 54.1 years-old (ranging from 14 to 70 years-old), with mean age of 52.4 years-old (ranging from 14 to 65 years-old) for benign neoplasms, and 55.3 years-old for malignant neoplasms (ranging from 26 to 70 years-old). Clinical follow-up information, ranging from 2 to 10 years-old, was available for all patients. Three patients developed distant metastasis and died of disease. CONCLUSIONS: The most frequent primary epithelial neoplasms of the lacrimal gland were pleomorphic adenoma and adenoid cystic carcinoma during the study period. Malignant tumors were more frequent than benign tumors. The histopathological diagnosis and the disease initial stage can play a significant role in patient's survival.

Ten-year follow-up of a case series of primary epithelial neoplasms of the lacrimal gland: clinical features, surgical treatment and histopathological findings / Dez anos de acompanhamento de uma série de casos de neoplasias epiteliais primárias da glândula lacrimal: características clínicas, tratamento cirúrgico e achados histopatológicos

PURPOSE: To describe and analyze the features of a cases series of patients with primary epithelial neoplasms of the lacrimal gland, its surgical treatment, and histopathological findings. METHODS: Retrospective evaluation of files from patients with primary epithelial neoplasms of the lacrimal gland in the period from 1997 to 2007. All patients with primary epithelial tumors of the lacrimal gland were included in this study. Data on gender, age, clinical features, surgical treatment, histopathological findings and follow-up were collected. The slides with histological sections of the tumors were reviewed by the same pathologist. RESULTS: During the study period, there were 12 patients, 5 (41.7 percent) with benign tumors, all pleomorphic adenomas (benign mixed tumor) and 7 (58.3 percent) with malignant neoplasms, thus distributed: four cases of adenoid cystic carcinoma, two of mucoepidermoid carcinoma and one carcinoma expleomorphic adenoma. Globally, patients mean age was 54.1 years-old (ranging from 14 to 70 years-old), with mean age of 52.4 years-old (ranging from 14 to 65 years-old) for benign neoplasms, and 55.3years-old for malignant neoplasms (ranging from 26 to 70 years-old). Clinical follow-up information, ranging from 2 to 10 years-old, was available for all patients. Three patients developed distant metastasis and died of disease. CONCLUSIONS: The most frequent primary epithelial neoplasms of the lacrimal gland were pleomorphic adenoma and adenoid cystic carcinoma during the study period. Malignant tumors were more frequent than benign tumors. The histopathological diagnosis and the disease initial stage can play a significant role in patient's survival.

OBJETIVO: Descrever e analisar as características de uma série de casos de portadores de neoplasias epiteliais primárias da glândula lacrimal, o tratamento cirúrgico, assim como os achados histopatológicos. MÉTODOS: Avaliação retrospectiva dos arquivos de pacientes com neoplasias epiteliais primárias da glândula lacrimal, no período de 1997 até 2007. Todos os pacientes com tumores epiteliais primários da glândula lacrimal foram incluídos neste estudo. Foram analisados os dados sobre sexo, idade, características clínicas, tratamento cirúrgico, achados histopatológicos e seguimento dos pacientes. As lâminas com secções histológicas dos tumores foram revisadas pelo mesmo patologista. RESULTADOS: No período do estudo, foram encontrados 12 pacientes, sendo 5 (41,7 por cento) portadores de tumores benignos, todos adenomas pleomórficos (tumor benigno misto), e 7 (58,3 por cento) com neoplasias malignas, assim distribuídos: quatro casos de carcinoma adenóide cístico, dois de carcinoma mucoepidermóide e um de carcinoma ex-adenoma pleomórfico. Analisando-se de modo global, a idade média dos portadores foi de 54,1 anos (variando de 14 a 70 anos); com média de idade de 52,4 anos (variando de 14 a 65 anos) para neoplasias benignas, e 55,3 para neoplasias malignas (variando de 26 a 70 anos). Informações do seguimento, variando de 2 a 10 anos, estavam disponíveis para todos os pacientes. Três pacientes desenvolveram metástases distantes e morreram devido à doença. CONCLUSÕES: A maioria das neoplasias epiteliais primárias da glândula lacrimal foi o adenoma pleomórfico e o carcinoma adenóide cístico no período de estudo. Os tumores malignos foram mais frequentes que os benignos. O diagnóstico histopatológico e o estadiamento inicial da doença podem desempenhar uma papel significante na sobrevida do paciente.

Determination of metals in coal fly ashes using ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry.

A method for determination of Co, Cr, Cu, Fe, Mn, Ni, Ti, V and Zn in coal fly ash samples using ultrasound-assisted digestion followed by inductively coupled plasma optical emission spectrometry (ICP-OES) is proposed. The digestion procedure consisted in the sonication of the previously dried sample with hydrofluoric acid and aqua regia at 80 degrees C for 30 min, elimination of fluorides by heating until dryness for about 1h and dissolution of the residue with nitric acid solution. A classical digestion method, used as comparative method, consisted in the addition of HCl, HNO(3) and HF to 1 g of sample, and heating on a hot plate until dryness for about 6h. The proposed method presents several advantages: it requires lower amounts of sample and reagents, and it is faster. It is also advantageous when compared to the published methods, which also use ultrasound-assisted digestion procedure: lower detection limits for Co, Cu, Ni, V and Zn, and it does not require shaking during the digestion. The detection limits (microg g(-1)) for Co, Cr, Cu, Fe, Mn, Ni, Ti, V and Zn were 0.06, 0.37, 1.0, 25, 0.93, 0.45, 4.0, 1.7 and 4.3, respectively. The results were in good agreement with those obtained by the classical method and reference values. The exception was Cr, which presented low recoveries in classical and proposed methods (83 and 87%, respectively). Also, the concentration for Cu obtained by the proposed method was significantly different from the reference value, in spite of the good recovery (91+/-1%).

A simplified version of the total Kjeldahl nitrogen method using an ammonia extraction ultrasound-assisted purge-and-trap system and ion chromatography for analyses of geological samples.

The total Kjeldahl nitrogen (TKN) method was simplified by using a manifold connected to a purge-and-trap system immersed into an ultrasonic (US) bath for simultaneous ammonia (NH(3)) extraction from many previously digested samples. Then, ammonia was collected in an acidic solution, converted to ammonium (NH(4)(+)), and finally determined by ion chromatography method. Some variables were optimized, such as ultrasonic irradiation power and frequency, ultrasound-assisted NH(3) extraction time, NH(4)(+) mass and sulfuric acid concentration added to the NH(3) collector flask. Recovery tests revealed no changes in the pH values and no conversion of NH(4)(+) into other nitrogen species during the irradiation of NH(4)Cl solutions with 25 or 40 kHz ultrasonic waves for up to 20 min. Sediment and oil free sandstone samples and soil certified reference materials (NCS DC 73319, NCS DC 73321 and NCS DC 73326) with different total nitrogen concentrations were analysed. The proposed method is faster, simpler and more sensitive than the classical Kjeldahl steam distillation method. The time for NH(3) extraction by the US-assisted purge-and-trap system (20 min) was half of that by the Kjeldahl steam distillation (40 min) for 10 previously digested samples. The detection limit was 9 microg g(-1)N, while for the Kjeldahl classical/indophenol method was 58 microg g(-1)N. Precision was always better than 13%. In the proposed method, carcinogenic reagents are not used, contrarily to the indophenol method. Furthermore, the proposed method can be adapted for fixed-NH(4)(+) determination.