A bioaccessibility test with raw and cooked lamb meat samples was performed. The evaluated cooking devices were grill, microwave oven, air fryer, pressure cooker, and electric oven. Physicochemical parameters and the total mass fraction of Cu, Fe, K, Mg, P, and Zn were determined in raw and cooked samples by inductively coupled plasma optical emission spectrometry (ICP OES). The trueness was evaluated using certified reference materials, with recoveries from 87 to 101%. The pressure cooking presented the major changes, including the highest values of internal temperature, loss of inorganic elements after cooking, and the lowest values of moisture and analyte mass fractions. An in vitro gastrointestinal simulation was performed, and the method was validated by an addition and recovery test, in which the trueness varied from 87 to 115%. The bioaccessibility ranged between 28-56, 4-19, 68-76, 41-54, 48-57, and 1-21% for Cu, Fe, K, Mg, P, and Zn, respectively. The cooking methods promoted changes in the meat samples, thus affecting the bioaccessibility of the nutrients. Based on the recommended dietary intake (RDI) calculation, lamb meat can be considered a good Fe, P, and Zn source.

Multi-flow calibration (MFC) is based on monitoring the analytical signal from a single calibration standard solution at several different nebulization gas flow rates (Q), which normalizes plasma conditions and minimizes matrix effects. In the present study, MFC was evaluated, for the first time, applied to inductively coupled plasma optical emission spectrometry (ICP OES) and inductively coupled plasma mass spectrometry (ICP-MS) to analyze different and complex-matrix samples. Al, As, Cd, Cr, Cu, Mn, Pb, and Zn were determined by ICP OES, while As, Cd, Co, Cu, Hg, Mo, Mn, Ni, Se, Sb, Pb, and V were determined by ICP-MS. MFC results were compared with those obtained using external standard calibration (EC) for both techniques and in all cases, MFC showed equal or superior accuracy (recoveries between 80-120%) compared to EC, and lower relative standard deviation (RSDs ≤ 10%). Several tests were also performed using only two nebulization gas flows to build linear models for calibration (called two-flow calibration, TFC) and the accurate results (recoveries ranged from 80 to 110% for ICP OES and from 81 to 102% for ICP-MS) suggests that this strategy can be also applied, resulting in a method with high sample throughput.

This work describes the bioaccessibility in vitro simulated gastric digestion for levels of Zn, Ca, and P in milk and soybean extract samples. Total and dialyzed levels were determined by ICP OES. According to results of the dialyzed samples, it can be concluded that in 250 mL of milk (a glass) the body can be absorb about 1.2 ± 0.2 mg, 14.8 ± 1.2 mg, 4.5 ± 0.8 mg, 2.2 ± 0.4 mg and 4.9 ± 0.6 mg of Zn; 2079 ± 133 mg, 305 ± 4 mg, 2396 ± 16 mg, 2444 ± 54 mg, and 1527 ± 71 mg of Ca; and 2023 ± 275 mg, 811 ± 14 mg, 2688 ± 39 mg, 5089 ± 474 mg and 3467 ± 63 mg of P for raw sheep’s milk, soybean, raw cow’s milk, UHT goat’s milk, and UHT cow’s milk, respectively. These results correspond to approximately 45, 118, and 267% of diary human needed of Zn, Ca, and P, respectively. Accuracy was verified using CRM (NIST 8435) for total levels, and dialyzed samples were compared with FAAS, statistically evaluated by Student’s t-test. Results confirmed the methodology efficiency and allowed an estimate of the bioacessibility of nutrients.

The multi-energy calibration (MEC) was evaluated for the determination of Ca, Cu, Fe, K, Mg, Na, P, S, and Zn in meat samples by inductively coupled plasma optical spectrometry (ICP OES). This calibration method consists of using only two calibration standards and several atomic and ionic emission wavelengths with different sensitivities to determine the analyte concentration in the sample. Both calibration mixtures are prepared using the same amount of sample, which contributes to minimize matrix effects. The accuracy was evaluated using two certified reference materials, bovine liver (SRM 1577c) and bovine muscle (SRM 8414), with recoveries within 87-107% range. The method was applied for the determination of the analytes in meats of chicken, sheep loin, sheep carcass and bovine, and prove to be usable in samples with different characteristics.

The concentration of arsenic in tissues of tilapia was evaluated and an estimation of the risks associated with the consumption of this fish was done, taking into account the guidelines established by FAO/WHO. The inductively coupled plasma mass spectrometry (ICP-MS) technique in kinetic energy discrimination (KED) mode was employed and certified reference materials were analyzed with recoveries of 101, 110, and 80% from NIST 1640a (trace elements in water), NIST 1566b (oyster tissue), and DORM-3 (fish protein). In the consumable portion (the muscle fish tissue), the average concentration found was 0.030 ± 0.008 µg g-1, which is below the arsenic maximum level established by international regulatory agencies. The average concentration found in the viscera (stomach, gills, and liver) was 0.485 ± 0.225 µg g-1, concluding that the viscera had greater capacity for the bioaccumulation of arsenic. From this study was possible to monitor the arsenic element in different tilapia specimens evidencing its accumulation throughout the body of the fish.

Determination of Se by inductively coupled plasma mass spectrometry (ICP-MS) can be difficult due to spectral interferences; however, these interferences can be eliminated by using collision-reaction interface (CRI) technology. A simple and fast procedure for determination of total Se concentration in bovine semen by ICP-MS after sample solubilization with diluted formic acid is here proposed. Formic acid caused an increase of up to 50% in selenium net signals and the maximum gain was obtained at 10% v v-1 formic acid solution. The optimized nebulizer gas flow rates were 1.05 and 0.95 L min-1, and radio frequency applied power were 1.3 and 1.4 kW without and with CRI, respectively. Microwave-assisted acid digestion was also implemented in the preparation of semen sample for comparison of results. No statistical differences between these sample preparation strategies at 95% confidence level (t-test) were observed for 76Se+, 77Se+, 78Se+ and 82Se+ without using CRI and 82Se+ with CRI.

Inorganic elements present in pharmaceutical products were determined by inductively coupled plasma-mass spectrometer (ICP-MS), employing microwave acid digestion as a sample preparation method. The most abundant isotopes, 75As+, 65Cu+, 52Cr+, 58Ni+, 208Pb+, and 51V+, were determined in acyclovir ointment and its constituents. Elemental impurities in the pharmaceutical samples were determined using an inductively coupled plasma-universal cell technology-mass spectrometer (ICP-UCT-MS) operated in kinetic energy discrimination (KED) and standard mode. The accuracy of the method was assessed by means of addition and recovery experiments. Except for Cr, spiked recoveries of the elements added to the samples before microwave acid digestion (MW-AD) step were between 95.1 and 126%, and after MW-AD step ranged from 85.6 to 132%. Limits of detection (LOD) obtained by proposed method is in agreement to those required by the U.S. Pharmacopeia Convention (USP), showing that the ICP-MS technique is well suited for quantification of these elements. The LOD's (ng L-1) for 51V+, 52Cr+, 58Ni+, 65Cu+, 75As+ and 208Pb+ in 1% v v-1 HNO3 medium were: 2.2, 81.3, 91.9, 6.9, 0.2 and 3.1, respectively. The concentration of the analytes in these samples presented a wide range, varying from 2.3 ± 0.8 µg kg-1 for As to 3446 ± 47 µg kg-1 for Cr.

In the present work, an inductively coupled plasma-tandem mass spectrometer (ICP-MS/MS) operating in single quadrupole and mass shift modes were evaluated for As determination in mineral fertilizers and agricultural gypsum with high contents of rare earth elements. For MS/MS mode, oxygen was the gas introduced into the octopole reaction system (ORS3). Samples were prepared by microwave-assisted digestion with diluted nitric acid solution. The accuracy was checked by analysis of a fertilizer certified reference material (NIST SRM 695) and by addition and recovery experiments. When operating in single quadrupole mode, recoveries ranged from 59 to 151%; while values obtained by MS/MS mode varied from 81 to 105% when 0.30 mL min-1 O2 was introduced into the ORS3. Limits of detection for As+ in single quadrupole and AsO+ in MS/MS mass shift mode were 6 and 9 ng L-1, respectively.

A method for determination of arsenic in mineral fertilizers by continuous flow hydride generation atomic absorption spectrometry (CF-HG-AAS) was developed by using diluted acid and digester block with perfluoroalkoxy (PFA) tubes to sample preparation. An additional sample preparation procedure using microwave-assisted digestion was evaluated and compared with the proposed procedure. A full factorial design was applied to investigate the effect of the variables and the best conditions found were 7 mol L−1 HNO3 + 30% (m/m) H2O2 as reagents, 4 h of digestion and concentration of reagents diluted 1:1. The effect of concomitants on the analytical signal of arsenic was investigated and no one significant interference was observed, with recoveries ranged from 97 to 103%. The accuracy of proposed method was evaluated by certified reference material (NIST SRM 695) and recovery of 95% was obtained. The arsenic concentration (8.9 ± 0.2 mg kg−1) found in the fertilizer is below of maximum concentration established by Brazilian legislation.

The applicability of the recently proposed procedure based on gradual sample addition to microwave-assisted pre-heated concentrated acid is limited by the sample viscosity. In this work, lubricating oil samples with high viscosity were encapsulated and manually added to the microwave-assisted pre-heated concentrated digestion mixture. The procedure was applied for determination of Al, Ca, Cr, Cu, Fe, Mg, Ni, P, Pb, Si, Sn, Sr, V, W, and Zn in lubricating oil by inductively coupled plasma optical emission spectrometry (ICP OES). Determined and certified values for Ca, Mg, P, and Zn in lubricating oil were in agreement at a 95% confidence level.

The use of factorial design was evaluated for optimization of focused-microwave-assisted digestion of bean samples. Calcium, Fe, Mg, Mn and Zn percentual recoveries were determined in digestates after focused-microwave-assisted digestion according to factorial design procedures. A cavity microwave digestion was carried out to certify the elemental compositions obtained. The accuracy was checked using a standard reference material, the NIST SRM 8433 - Corn Bran. Results are in agreement with certified values at the 95% confidence limit when the Student t-test was used. Volumes of nitric and sulfuric acid, temperature, and the interplay between HNO3 and H2SO4 initial volumes were significant variables according to P-values in the analysis of variance (ANOVA).

A eficiência dos procedimentos de digestão em fornos de microondas pode ser afetada por parâmetros experimentais críticos, como massa de amostra, volume da mistura ácida, potência de radiação aplicada e o tempo da digestão. Neste trabalho foi proposta a utilização de um planejamento fatorial completo para a otimização da digestão de amostras de óleo lubrificante em forno de microondas, com recipientes fechados. O teor de carbono residual e a acidez final das soluções foram determinados em todos os digeridos provenientes do forno de microondas, como resposta ao planejamento fatorial. Cálcio, Cu, Mg, P, S e Zn foram determinados nos digeridos ácidos e a exatidão foi checada utilizando-se um material de referência certificado, NIST SRM 1848-Lubricating Oil Additive Package. Os resultados encontrados para as amostras e para o material de referência certificado estão em concordância a um nível de confiança de 95%. Tempo de digestão, potência de radiação aplicada, massa de amostra e as interações entre essas variáveis foram significativas (P < 5%), aplicando-se a análise de variância (ANOVA).

This work proposes the use of factorial design for optimization of microwave-assisted digestion of lubricating oil. The accuracy of digestion procedures is affected by critical experimental parameters, such as sample amount, concentrated acid volumes, microwave radiation applied power, and digestion time. The effects of these key variables on the microwave-assisted digestion efficiency were investigated. The residual carbon content and the acidity were determined in all digestates after microwave-assisted digestion as response of the factorial design. Calcium, Cu, Mg, P, S, and Zn were determined in oil digestates obtained by using two systems: a cavity- and a focused-oven. The accuracy was checked using one standard reference material, NIST SRM 1848 - Lubricating Oil Additive Package. All determined and certified values are in agreement at a 95% confidence level. The digestion time, microwave applied power, sample mass, and the interaction between these variables were significant according to P-values when the analysis of variance (ANOVA) was used.

Neste trabalho foi investigada a aplicação da síntese mecanoquímica para promover reações na amostra e sintetizar novos compostos visando aumentar as intensidades de emissão de elementos presentes em suspensões de argilas e materiais refratários quando introduzidas em espectrômetro de emissão óptica com plasma acoplado indutivamente com configuração axial. A hipótese formulada é que é possível gerar compostos mais voláteis durante a moagem e esses novos compostos causam aumento da intensidade dos sinais de emissão para os analitos em suspensões introduzidas no plasma. A ação de dois modificadores, LiBO2 e Na2CO3, adicionados durante a etapa de moagem foi investigada. As argilas e materiais refratários foram moídos juntamente com os modificadores químicos durante 2 h usando um moinho de bolas de alto impacto com recipiente e bolas de carbeto de tungstênio. As suspensões foram preparadas dispersando as argilas e os materiais refratários modificados em solução 10% v v-1 HNO3 e, posteriormente, sonicadas em banho de ultra-som para melhorar a homogeneização. Os compostos produzidos durante a etapa de moagem foram caracterizados por difração de raios X e análise termogravimétrica. Ambas as técnicas indicaram a formação de novos compostos nas argilas e materiais refratários por síntese mecanoquímica. Os efeitos da modificação química foram avaliados pelas mudanças nas intensidades de emissão dos analitos Al, Ca, Fe, K, Mg, P, Si e Ti. Ambos modificadores causaram aumento na sensibilidade para todos os analitos de até 665% (Na2CO3) e 583% (LiBO2) quando comparados às intensidades dos sinais de emissão obtidos para os analitos nas suspensões preparadas com as amostras sem modificação química.

The developed work investigated the application of mechanochemical synthesis for promoting reactions in the samples and for synthesizing new compounds for increment of emission intensities of analytes in clays and refractory materials slurries in inductively coupled plasma optical emission spectrometry with axial viewing. The hypothesis is that it is possible to generate more volatile compounds during the grinding step and these new compounds will increase the intensities of emission signals for slurries introduced in the plasma. The action of two chemical modifiers, LiBO2 and Na2CO3, added during the grinding step was evaluated. The clays and refractory materials mixed with the chemical modifier were ground for 2 h using a high impact ball mill with a tungsten carbide grinding container and balls. Slurries were prepared by dispersing the modified clays and refractory materials in 10% v v-1 HNO3 solution and by shaking them in an ultrasonic bath to ensure good dispersion. The compounds produced during the grinding step were characterised by X-ray diffraction and thermogravimetric analysis. Both techniques indicated the formation of new compounds in clays and refractory materials by mechanochemical synthesis. Chemical modification effects were evaluated by changes of the emission intensities of Al, Ca, Fe, K, Mg, P, Si, and Ti. Both modifiers caused increments of sensitivities for all analytes in up to 665% (Na2CO3) and 583% (LiBO2) compared to the emission signals for analytes present in slurries prepared using samples ground without adding modifiers.

Neste trabalho foi investigada a aplicação da síntese mecanoquímica para promover reações na amostra e sintetizar novos compostos visando aumentar as intensidades de emissão de elementos presentes em suspensões de argilas e materiais refratários quando introduzidas em espectrômetro de emissão óptica com plasma acoplado indutivamente com configuração axial. А hipótese formulada é que é possível gerar compostos mais voláteis durante a moagem e esses novos compostos causam aumento da intensidade dos sinais de emissão para os analitos em suspensões introduzidas no plasma. А ação de dois modificadores, LiBO2 e Na2CO3, adicionados durante a etapa de moagem foi investigada. As argilas e materiais refratários foram moídos juntamente com os modificadores químicos durante 2 h usando um moinho de bolas de alto impacto com recipiente e bolas de carbeto de tungstênio. As suspensões foram preparadas dispersando as argilas e os materiais refratários modificados em solução 10% v v-1 HNO3 e, posteriormente, sonicadas em banho de ultra-som para melhorar a homogeneização. Os compostos produzidos durante a etapa de moagem foram caracterizados por difração de raios X e análise termogravimétrica. Ambas as técnicas indicaram a formação de novos compostos nas argilas e materiais refratários por síntese mecanoquímica. Os efeitos da modificação química foram avaliados pelas mudanças nas intensidades de emissão dos analitos Al, Ca, Fe, K, Mg, P, Si e Ti. Ambos modificadores causaram aumento na sensibilidade para todos os analitos de até 665% (Na2CO3) e 583% (LiBO2) quando comparados às intensidades dos sinais de emissão obtidos para os analitos nas suspensões preparadas com as amostras sem modificação química.

The developed work investigated the application of mechanochemical synthesis for promoting reactions in the samples and for synthesizing new compounds for increment of emission intensities of analytes in clays and refractory materials slurries in inductively coupled plasma optical emission spectrometry with axial viewing. The hypothesis is that it is possible to generate more volatile compounds during the grinding step and these new compounds will increase the intensities of emission signals for slurries introduced in the plasma. The action of two chemical modifiers, LiBO2 and Na2CO3, added during the grinding step was evaluated. The clays and refractory materials mixed with the chemical modifier were ground for 2 h using a high impact ball mill with a tungsten carbide grinding container and balls. Slurries were prepared by dispersing the modified clays and refractory materials in 10% v v-1 HNO3 solution and by shaking them in an ultrasonic bath to ensure good dispersion. The compounds produced during the grinding step were characterised by X-ray diffraction and thermogravimetric analysis. Both techniques indicated the formation of new compounds in clays and refractory materials by mechanochemical synthesis. Chemical modification effects were evaluated by changes of the emission intensities of Al, Ca, Fe, K, Mg, P, Si, and Ti. Both modifiers caused increments of sensitivities for all analytes in up to 665% (Na2CO3) and 583% (LiBO2) compared to the emission signals for analytes present in slurries prepared using samples ground without adding modifiers.

É proposto um procedimento para a determinação direta de vanádio em amostras de urina por espectrometria de absorção atômica com atomização eletrotérmica em forno de grafite usando injeção à quente e pré-concentração dentro do tubo de grafite. Três aliquotas de 60 µL foram injetados seqüencialmente dentro do atomizador pré-aquecido a uma temperatura de 110 ºC. As etapas de secagem e pirólise foram repetidas após cada injeção. Às amostras de urina foram adicionados o modificador químico fluoreto de bário (100 mg L-1) e o surfactante Triton X-100 (0,3% v v-1). A vazão da amostra durante a injeção dentro do tubo pré-aquecido foi de 0,5 µL s-1. Os limites de detecção e de quantificação sem pré-concentração foram, respectivamente, 0,54 e 1,82 mg L-1, e com pré-concentração 0,11 e 0,37 µg L-1. O teste de adição e recuperação foi empregado em amostras de urina para avaliar a exatidão do procedimento proposto. Os valores de recuperação obtidos variaram de 96,0 a 103,0% para as adições de 0,8 a 3,5 µg L-1 V. O procedimento proposto possibilita a determinação de vanádio sem nenhum pré-tratamento e com mínima diluição da amostra.

In this work it was developed a procedure for the determination of vanadium in urine samples by electrothermal atomic absorption spectrometry using successive injections for preconcentration into a preheated graphite tube. Three 60 µL volumes were sequentially injected into the atomizer preheated to a temperature of 110 ºC. Drying and pyrolysis steps were carried out after each injection. A chemical modifier, barium difluoride (100 mg L-1), and a surfactant, Triton X-100 (0.3% v v-1), were added to the urine sample. When injecting into a hot graphite tube, the sample flow-rate was 0.5 µL s-1. The limits of detection and quantification were 0.54 and 1.82 without preconcentration, and 0.11 and 0.37 µg L-1 with preconcentration, respectively. The accuracy of the procedure was evaluated by an addition-recovery experiment employing urine samples. Recoveries varied from 96.0 to 103% for additions ranging from 0.8 to 3.5 µg L-1 V. The developed procedure allows the determination of vanadium in urine without any sample pretreatment and with minimal dilution of the sample.