Mineral and Trace Elements in Nutritious Flours: Total Contents, In Vitro Bioaccessibility and Contribution to Dietary Intake

The consumption of fruits, vegetables, and cereals in the form of flour has been an alternative for the intake of nutrients, currently seen in a society that seeks a healthier diet. Thus, the assessment of total contents and bioaccessibility is important to better understand the actual intake of nutrients or contaminants present in foods. The objective of this study was to determine the total content and estimate the bioaccessible fraction of Cu, Fe, and Zn in nutritious flours by inductively coupled plasma optical emission spectrometry (ICP OES) after microwave acid digestion. Bioaccessibility was assessed using the in vitro method, taking into account the entire gastrointestinal tract (Unified Bioaccessibility Method (UBM)). The following concentration ranges, in μg g^-1, were found: Ca (341-6275), K (2984-13,953), P (476-6110), Na (< 0.39-2995), Fe (1.4-167), Cu (< 0.01-59.6), and Zn (< 0.07-30.3). Principal component analysis (PCA) and hierarchical cluster analysis (HCA) showed a tendency towards the formation of three groups. The bioaccessible fractions for Cu, Fe, and Zn were considered low, ranging from 0.96 to 40% in the gastrointestinal phase and from 4.1 to 100% in the gastric phase.

Evaluation of the Mineral Content in Forage Palm (Opuntia ficus-indica Mill and Nopalea cochenillifera) Using Chemometric Tools

An acid digestion procedure of the forage palm (Opuntia ficus-indica Mill and Nopalea cochenilifera) employing a closed digestor block applied full 2⁴ factorial design was optimized. The optimal conditions were HNO₃ 5.0 mol L^-1, 2.0 mL of H₂O₂ 30% m m^-1, 120 min of digestion, and heating temperature of 180 °C. The certified reference materials of apple leaves (NIST 1515) and tomato leaves (Agro C1003a) were used to evaluate the accuracy of the analytical method. The concentrations of the macroelements were (in % m m^-1) Ca (1.32-3.71), K (0.88-5.29), Mg (0.70-1.78), and P (0.03-0.32). For the microelements, the concentrations (in μg g^-1) obtained were As (< 1.39), Cd (< 0.10), Cu (< 0.17-5.6), Fe (8.0-50.2), Na (< 1.85), Sr (41-348), and Zn (17.3-159). Essential elements such as Ca, Mg, and Zn made good contributions to daily intake, being an alternative to meet the nutritional needs of these macroelements and microelements in humans. Principal component analysis (PCA) and hierarchical cluster analysis (HCA) were used to evaluate the results, obtaining trends between the samples in relation to their mineral composition.

Selenium inorganic speciation in beers using MSFIA-HG-AFS system after multivariate optimization

In this work, the use of a multisyringe flow injection analysis coupled to hydride generation atomic fluorescence spectrometry (MSFIA-HG-AFS) for inorganic selenium chemical speciation was proposed. A Doehlert design was applied to optimize the experimental conditions for hydride generation (NaBH₄ and HCl concentrations). The limits of quantification (LoQ) obtained were 0.07 µg L^-1, for total inorganic Se, and 0.08 µg L^-1, for Se(IV). Accuracy and precision of the proposed analytical method were evaluated through analysis of standard reference material and addition and recovery tests. The optimized method was applied to analyses of eight samples of beer, produced in Spain, obtaining concentrations for Se(IV) (<0.08 - 0.46 ± 0.01 µg L^-1), total inorganic Se (0.47 ± 0.01 - 3.04 ± 0.62 µg L^-1) and Se(VI) (0.06 ± 0.01 - 3.00 ± 0.59 µg L^-1). The proposed analytical method was accurate, precise and sensitivity for determination of selenium species in beer samples.

Rare earth elements in drill cutting samples from off-shore oil and gas exploration activities in ultradeep waters

Rare earth elements (REEs) are essential in high technology industries and have great economic value. The monitoring of REEs concentrations in rocks from oil well drill cuttings is critical to avoid environmental contamination and evaluate new sources of these elements. However, information is scarce about the REEs concentrations in drill cuttings. In this work, the concentration of REEs in drill cuttings from oil and gas exploration wells in ultradeep coastal water of Brazilian were investigated at different depths. The drill cutting samples were submitted to microwave-assisted acid digestion prior to the determination of concentration by ICP-MS, using Rh as internal standard for calibration. The limits of quantification (LoQ) ranged from 3.3 μg kg^-1 for Ho to 198 μg kg^-1 for Sm. The accuracy was evaluated by analyzing certified reference materials for rocks. The obtained REEs concentrations agreed with the certified values, reaching 83%-105% agreement. The drill cutting depth profile analysis indicates Ce, La, Nd, Sm, and Eu concentrations up to mg kg^-1. The REEs concentrations obtained in drill cutting depth profile was analyzed by principal component analysis (PCA), and hierarchical cluster analysis (HCA) identified tendency and similarity between drill cutting samples. Three groups were formed according to the composition of the REEs. In addition, the concentration of these chemicals elements varied at different depths. The analysis of drill cuttings revealed REEs concentrations up to the mg per kg-range (ppm), potentially making this disposable material an alternative source for REEs extraction, and adding value to this material.

Speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry

In this work, a methodology for chemical speciation analysis of inorganic As and Sb in urban dust using slurry sampling and detection by fast sequential hydride generation atomic absorption spectrometry is proposed. Doehlert design and desirability function were used to find the optimum conditions for hydride generation (1.0 mol L^-1 HCl and 0.9% m v^-1 NaBH₄). The accuracy of the analytical method was evaluated by analysis of reference material fly ash (BCR 176R), addition and recovery tests for inorganic As species, and comparison of independent methods for Sb determination in urban dust samples. The determination of the total concentrations of As and Sb and their inorganic species presented good accuracy, between 80 ± 1 and 101 ± 6%. Precision was expressed as the relative standard deviation and was better than 4.7% (n = 3). The limit-of-quantification values were 0.23 and 1.03 mg kg^-1 for As and Sb, respectively. The methodology was applied to eight samples of dust collected in an urban area of Salvador and Jaguaquara cities, Bahia, Northeast, Brazil, with an aerodynamic size lower than 38 μm. Concentrations of pentavalent inorganic species (iAs⁵⁺ and iSb⁵⁺) in relation to trivalent species (iAs³⁺ and iSb³⁺) were found in urban dust collected in the city of Salvador, which are regarded as more toxic for both elements. The enrichment factor and geoaccumulation index (I_geo) values showed that for some samples, the concentrations of iAs and iSb presented strong enrichment and, and regarding environment, strong to moderately polluted by iAs and iSb, with an indication of anthropogenic contributions. The occurrence of these inorganic constituents in the urban area of Salvador can be related with intense industrial activities and vehicular traffic.

Sequential determination and chemical speciation analysis of inorganic As and Sb in airborne particulate matter collected in outdoor and indoor environments using slurry sampling and detection by HG AAS

In this work, fast sequential determination and chemical speciation analysis of inorganic arsenic and antimony in airborne particulate matter collected in outdoor and indoor environments using slurry sampling and detection by hydride generation atomic absorption spectrometry (HG-AAS) is proposed. A Doehlert design was applied to optimise the hydride generation conditions of As and Sb for fast sequential determination in the same aliquot of particulate matter samples after preparation of the slurry. The limits of quantification (LoQ) obtained for As and Sb were 0.3 and 0.9 ng m^-3, respectively. The accuracy of the analytical method was confirmed by analysis of the certified reference material of urban particulate matter (SRM NIST 1648a), presenting concordance with certified values of 92.7±7.7% for As and 91.2±9.5% for Sb. Precision was expressed as relative standard deviation (% RSD, n=3), with our results presenting values better than 3.4% and 4.2% for total inorganic As and Sb, respectively. For all analysed samples, total As concentrations and its inorganic species were below the LoQ of the analytical method (<0.3 ng m^-3). However, the averages of total inorganic Sb concentrations in airborne particulate matter, collected as total suspended outdoor particles (TSP_outdoor), inhalable particulate matter (PM₁₀), and total suspended indoor particles (TSP_indoor), were 3.1±0.5, 2.4±0.6, and 2.6±0.4 ng m^-3, respectively. Trivalent Sb (Sb³⁺) was the predominant inorganic species in all samples investigated, with mean percentages of 76%, 72%, and 73% in TSP_outdoor, PM₁₀, and TSP_indoor, respectively. The presence of Sb and its predominant inorganic form (Sb³⁺) can be attributed to vehicular traffic close to the sampled urban areas. Therefore, fast sequential determination of As and Sb and their inorganic species in particulate matter samples prepared as slurry by FS-HG-AAS is an efficient, accurate, and precise method and can be successfully applied to routine analysis.

Assessment of cadmium and lead in commercial coconut water and industrialized coconut milk employing HR-CS GF AAS

In this work, an analytical method for the determination of Cd and Pb in natural coconut water samples, industrialized coconut water samples and coconut milk using high-resolution continuum source graphite furnace atomic absorption spectrometry (HR-CS GF AAS), after minimum treatment of the sample was developed. The analytical method was applied to 46 samples collected in Salvador, Bahia (Brazil). The ranges of concentrations obtained were: 0.42-18.72 μg L^-1 Cd and <0.70-36.32 μg L^-1 Pb for natural coconut water samples (n = 14); <0.06-1.49 μg L^-1 Cd and 6.57-29.02 μg L^-1 Pb for industrialized water coconut samples (n = 16); and <0.10-5.93 ng g^-1 Cd and <0.85-22.41 ng g^-1 Pb for coconut milk samples (n = 16). For all samples, Cd and Pb concentrations were below the maximum tolerated values recommended by Brazilian Health Surveillance Agency (Agência Nacional de Vigilância Sanitária, ANVISA).

Comparison of Spectrophotometric Methods for the Determination of Copper in Sugar Cane Spirit

Three spectrophotometric methods were developed for the determination of copper (Cu) in sugar cane spirit using the chromogenic reagents neocuproine, cuprizone, and bathocuproine. Experimental conditions, such as reagent concentration, reducer concentration, pH, buffer concentration, the order of addition of reagents, and the stability of the complexes, were optimized. The work range was established from 1.0 to 10.0 µg/mL, with correlation coefficients of >0.999 for all three optimized methods. The methods were evaluated regarding accuracy by addition and recovery tests at five concentration levels, and the obtained recoveries ranged from 91 to 105% (n = 3). Precision was expressed as RSD (relative standard deviation), with values ranging from 0.01 to 0.17% (n = 10). The method using the chromogenic reagent cuprizone presented the greatest molar absorptivity, followed by bathocuproine and neocuproine. The methods were applied for the determination of Cu in sugar cane spirit, and the results were compared with a reference method by flame atomic absorption spectrometry (FAAS). Calibration curve solutions for FAAS analysis were prepared in a 40% (v/v) alcohol medium in a range of concentrations from 0.5 up to 5 µg/mL. Measurements for Cu determination were carried out at a wavelength of 324.7 nm. The concentrations obtained for Cu in sugar cane spirit samples from Brazil were between 1.99 and 12.63 µg/mL, and about 75% of the samples presented Cu concentrations above the limit established by Brazilian legislation (5.0 µg/mL or 5.0 mg/L).

Determination of nutrients in sugarcane juice using slurry sampling and detection by ICP OES

The fractional factorial and Doehlert designs for optimization of a slurry sampling procedure to determine of nutrients in sugarcane juice by inductively coupled plasma optical emission spectrometry (ICP OES) were applied. External calibration curves were used for direct analysis of the slurry. This procedure allowed determination of Ca, Cu, Fe, K and Mg with limits of detection (LoD) obtained of 2.0, 0.04, 0.2, 1.0 and 1.5 mg L^-1, respectively. The precision was expressed as relative standard deviation (%RSD), being better than 1.4% (n = 3). Accuracy was confirmed by comparison with sample digestion method. The results for analysis of fourteen sugarcane juices samples demonstrated that the nutrients Ca, Cu, Fe, K and Mg have average contents of 108, 0.506, 6.40, 470 and 114 mg L^-1, respectively. The proposed analytical method is a good alternative for simultaneous determination of nutrients in sugarcane juice using introduction of slurries and detection by ICP OES.

Determination of Zn in Dry Feeds for Cats and Dogs by Energy-Dispersive X-Ray Fluorescence Spectrometry

This work describes an analytical method for Zn determination in dry feeds for cats and dogs by energy-dispersive X-ray fluorescence (EDXRF). Samples of dry feed were powdered and prepared in the form of pellets for direct analysis by EDXRF. The LOQ (10σ) was 0.4 mg/kg. The samples were also analyzed by inductively coupled plasma-optical emission spectrometry (ICP-OES) as an independent comparative method. Application of a paired t-test showed no significant differences between Zn concentrations obtained by EDXRF and ICP-OES (at a 95% confidence level). Analysis of variance was also applied to the results and revealed no significant differences between the two techniques (at a 95% confidence level). The precision, expressed as the RSD (n = 3), was RSD < 4.55%. This analytical method provides a simple, rapid, accurate, and precise determination of Zn in dry feeds for cats and dogs by EDXRF as direct, solid-sample analysis.