A pirohidrólise foi utilizada no preparo de amostras de carbeto de silício (SiC) para posterior determinação de B usando espectrometria de emissão óptica com plasma indutivamente acoplado (ICP-OES) e espectrometria de massa com plasma indutivamente acoplado (ICP-MS). Parâmetros importantes como temperatura, fluxo de água e ar, tempo de reação e uso de V2O5 foram avaliados. Adicionalmente, foi avaliada a interferência de W sobre as linhas de emissão de B durante as determinações por ICP-OES. A exatidão foi avaliada usando material de referência certificado (CRM BAM S003) e valor de bias inferior a 1% foi encontrado entre os valores de referência e obtido experimentalmente. Limite de detecção (LOD) de 0,010 μg g−1 foi obtido usando pirohidrólise e determinação por ICP-MS. A pirohidrólise é um método de preparo de amostras simples que permitiu a utilização de água deionizada como solução absorvedora para a determinação de B em SiC.

Pyrohydrolysis was used for sample preparation of silicon carbide (SiC) and subsequent determination of B using inductively coupled plasma optical emission spectrometry (ICP-OES) and inductively coupled plasma mass spectrometry (ICP-MS). Important parameters for pyrohydrolysis method as temperature, air and water flow rates, reaction time and use of V2O5 were evaluated. In addition, a study of W spectral interference on B emission lines was evaluated for ICP-OES determination. Accuracy was evaluated using certified reference material (CRM BAM S003) and bias value lower than 1% between the certified and determined value was achieved. Limit of detection (LOD) of 0.010 μg g−1 was obtained using pyrohydrolysis and ICP-MS. Pyrohydrolysis is a very simple sample preparation method that allowed the use of deionized water as absorbing solution for B determination in SiC.

A method based on pyrohydrolysis was proposed for cement sample preparation and further chloride determination by spectrophotometry using flow injection analysis. Analytical parameters were evaluated and, under the selected conditions, the calibration curve was linear in the range of 0.2 to 10.0 µg mL-1 with r2 = 0.998. The limit of detection was5 µg g-1 of chloride and the relative standard deviation was less than 7%. The proposed pyrohydrolysis method is relatively simple and can be used for sample preparation for further spectrophotometric determination of low concentrations of chloride in cement.

A determinação de fluoreto por eletrodo íon seletivo (ISE) em nanotubos de carbono (CNTs) é proposta após a decomposição por piroidrólise. Até 1 g de amostra pode ser decomposta, obtendo-se assim baixos limites de detecção (1,5 μg g-1), boa precisão (RSD < 5%) e exatidão (concordância maior do que 95% com os valores dos materiais de referencia certificados (CRMs) e combustão iniciada por microondas (MIC)). O fluoreto é absorvido em água e a solução resultante pode ser analisada diretamente por ISE. A pirohidrólise é simples de ser executada e não requer instrumentação sofisticada, sendo bastante atrativa para controle de fluoreto em NTCs em análises de rotina.

Fluoride determination by ion selective electrode (ISE) in carbon nanotubes (CNTs) is proposed after pyrohydrolysis decomposition. Up to 1 g of CNTs could be decomposed improving the limit of detection (1.5 μg g-1), precision (RSD < 5%) and accuracy (agreement higher than 95% with values of certified reference materials (CRMs) and microwave-induced combustion (MIC)). Fluoride could be absorbed in water and the resulting solution can be analyzed by ISE. Pyrohydrolysis is easy to be performed and does not require any sophisticated instrumentation, which is attractive for routine fluoride control in CNTs.

Elementos traço e majoritários foram determinados em mexilhão dourado (Limnoperna fortunei) coletados no canal São Gonçalo (Rio Grande-RS, Brasil). Digestão assistida por microondas em sistema fechado foi utilizada para decomposição das amostras com subsequente determinação elementar por técnicas espectrométricas. Os resultados mostraram que o tecido de mexilhão contém Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, P, Pb, S, Sn, Sr, Ti, V e Zn, enquanto que na casca foram encontrados os mesmo elementos, exceto Ag e Hg, evidenciando seu potencial como biomarcador. Neste sentido, estes resultados podem ser utilizados para estabelecer um panorama inicial e contribuir para futuros estudos relacionados a contaminantes inorgânicos na área estudada.

Major and trace element content was determined in golden mussel (Limnoperna fortunei) collected in the São Gonçalo Channel (Rio Grande City, Brazil). A microwave-assisted digestion procedure in closed vessels was applied to mussel decomposition and subsequent determination of elements by spectrometric techniques. Results showed that the mussel tissue contains Ag, Al, As, B, Ba, Ca, Cd, Co, Cr, Cu, Fe, Hg, Li, Mg, Mn, Mo, P, Pb, S, Sn, Sr, Ti, V and Zn, while the same elements (except Ag and Hg) were quantified in its shell, demonstrating its potential as a biomarker. In this sense, these results can be used to establish an initial view and to contribute to further studies related to element contamination in the area under study.

A combustão iniciada com micro-ondas (MIC) foi aplicada para decomposição de amostras de tabaco de cigarro e subsequente determinação de bromo e cloro por espectrometria de emissão óptica com plasma indutivamente acoplado (ICP OES). Massas de amostra de até 500 mg foram decompostas em frascos fechados e pressurizados com 20 bar de oxigênio. A combustão foi completada em menos de 30 s e os analitos foram absorvidos em solução diluída de (NH4)2CO3. A exatidão foi avaliada usando materiais de referência certificados e mediante a determinação utilizando ICP-MS. A concordância foi melhor do que 98% usando 50 mmol L-1 de (NH4)2CO3 como solução absorvedora e 5 min de refluxo. A temperatura durante a combustão foi superior a 1400 ºC e o conteúdo de carbono residual nos digeridos após MIC foi menor que 1%. Até oito amostras podem ser decompostas simultaneamente. Limites de quantificação utilizando MIC e determinação por ICP OES foram de 12 e 6 µg g-1 para Br e Cl, respectivamente

The microwave-induced combustion (MIC) was applied for cigarette tobacco samples digestion and further determination of bromine and chlorine by inductively coupled plasma optical emission spectrometry (ICP OES). Samples masses up to 500 mg were combusted in closed vessels using 20 bar of oxygen. Combustion was complete in less than 30 s and analytes were absorbed in diluted (NH4)2CO3 solution. Accuracy was evaluated using certified reference materials with similar matrix composition and comparison with results obtained using ICP-MS. The agreement was better than 98% using 50 mmol L-1 (NH4)2CO3 as absorbing solution and 5 min of reflux. Temperature during combustion was higher than 1400 ºC and the residual carbon content in digest obtained after MIC was lower than 1%. Up to eight samples could be processed simultaneously and a single absorbing solution was suitable for both Br and Cl. Limit of quantification by MIC and further ICP OES determination was 12 and 6 µg g-1 for Br and Cl, respectively.

Traditionally, in the cigarettes industry, the determination of ammonium ion in the mainstream smoke is performed by ion chromatography. This work studies this determination and compares the results of this technique with the use of external and internal standard calibration. A reference cigarette sample presented measurement uncertainty of 2.0 μg/cigarette and 1.5 μg/cigarette, with external and internal standard, respectively. It is observed that the greatest source of uncertainty is the bias correction factor and that it is even more significant when using external standard, confirming thus the importance of internal standardization for this correction.