Assessment of total concentration and bioaccessible fraction of minerals in peaches from different cultivars by MIP OES

This paper describes studies for the determination of total concentration and bioaccessible fraction of minerals in peaches by MIP OES. The PCA analysis identified 3 distinct groups of elements concerning the total concentration, which was attributed to the origin of each cultivar. Among the macroelements, K presented higher values for total concentration, while B and Fe predominated among the microelements. Regarding the bioaccessible fraction, Mn presented the highest percentage (46-84%), followed by Zn and B (10-63% and 33-57%, respectively). Pearson's correlation coefficient revealed that reducing sugars and titratable acidity can influence the mineral bioaccessibility, highlighting the strong positive correlations between reducing sugars with Mn and total acidity with Fe. Peach cultivars have satisfactory nutritional value, but the total and bioaccessible concentrations of minerals obtained do not meet the recommended daily needs, requiring the consumption of other fruits and vegetables to complement the diet.

Evaluation of the Use of Diluted Formic Acid in Sample Preparation for Elemental Determination in Crustacean Samples by MIP OES

A simple procedure for determination of Al, Cr, K, Mg, Mn, and Zn using diluted organic acid in the preparation of shrimp (Macrobrachium amazonicum) and crab samples (Ucides cordatus) was proposed in this study. Determinations were performed using microwave-induced plasma optical emission spectrometer (MIP OES). The contents of elements were evaluated after solubilization of samples in 50% formic acid (v v^-1) and subsequent heating in bath with stirring and heating at 90 °C. The accuracy of the proposed procedure was assessed using certified fish protein reference material (DORM-4) and the recovery percentages ranged from 91 to 117%. Microwave-assisted acid decomposition was used for a comparison of results with the procedure proposed using diluted formic acid, and the values obtained for all analytes were statistically equal at 95% confidence level. Cr levels were below the limit of detection. Potassium (7917-19,644 mg kg^-1), Mg (1319-5376 mg kg^-1), and Zn (43-307 mg kg^-1) were the most abundant elements in the crustacean species studied can be considered good sources of these constituents for human diet. The proposed procedure using diluted formic acid was considered simple and suitable to determine Al, Cr, K, Mg, Mn, and Zn concentrations in crustaceans using MIP OES.

Assessment of chromium, lead and mercury in seawater and some fish species from the Gulf of Urabá, Colombian Caribbean: a baseline study

The coastline of the department of Antioquia, in Colombia, exhibits a wide variety of aquatic and land ecosystems rich in both diversity and abundance. However, it is exposed to a variety of human activities, including industry, tourism, and mining. Banana cultivation is the main activity carried out in this region, which offers large economic benefits. In addition, there are diverse fishery resources that are main basis of the economy and nutrition for the population. Over the years, the Gulf of Urabá has been affected by serious pollution problems due to elevated contents toxic compounds that deteriorate the aquatic ecosystem, even our laboratory has conducted previous studies in heavy metals in fish from this same area. The aim of this study was to evaluate the contents of chromium (Cr), lead (Pb), and mercury (Hg) in seawater and fish muscle in three fish species from the Gulf of Urabá that are commercialized and consumed by the population of the municipality of Turbo, using microwave-induced plasma optical emission spectrometry (MIP OES). The occurrence of toxic metals in seawater in this area has not been reported, and to the best of our knowledge, this is the first study. Cr and Pb concentrations in seawater from several sampling points were detected ranged from 0.025 to 0.369 mg/L and 0.012-0.165 mg/L, respectively, while Hg levels were below detection limit. Regarding fish samples, Pb and Hg levels range 0.64-1.91 mg/kg and 0.11-1.09 mg/kg, respectively. Sea catfish species exhibited the highest content of metals, followed by stone head catfish and anchovy, it which showed the lowest contamination by metals. In this study, levels that exceed the limits in Colombian regulations regarding metal contents in discharge points to surface water and fishery products for human consumption were found.

On-Line Preconcentration and Simultaneous Determination of Cu and Mn in Water Samples Using a Minicolumn Packed with Sisal Fiber by MIP OES

An on-line preconcentration system for the simultaneous determination of Copper (Cu) and manganese (Mn) in water samples was developed and coupled to a microwave-induced plasma optical emission spectrometer (MIP OES). The flow injection system was designed with a minicolumn packed with sisal fiber (Agave sisalana). A multivariate experimental design was performed to evaluate the influence of pH, preconcentration time, and eluent concentration. Optimal conditions for sample preparation were pH 5.5, preconcentration time was 90 s, and HCl 0.5 mol L^-1 was the eluent. The main figures of merit were detection limits 3.7 and 9.0 µg L^-1 for Cu and Mn, respectively. Precision was expressed as a relative standard deviation better than 10%. Accuracy was evaluated via spiked recovery assays with recoveries between 75-125%. The enrichment factor was 30 for both analytes. These results were adequate for water samples analysis for monitoring purposes. The preconcentration system was coupled and synchronized with the MIP OES nebulizer to allow simultaneous determination of Cu and Mn as a novel sample introduction strategy. The sampling rate was 20 samples/h. Sisal fiber resulted an economical biosorbent for trace element preconcentration without extra derivatization steps and with an awfully time of use without replacement complying with the principles of green analytical methods.

Multi-element determination in chocolate bars by microwave-induced plasma optical emission spectrometry

Macro- and microelement determination in chocolate bars by microwave-induced plasma optical emission spectrometry (MIP OES) was evaluated after microwave-assisted sample digestion. Optimization of the sample digestion was carried out, and the recommended conditions were obtained at a temperature of 190 °C, with a digestion time of 40 min and in a mixture constituted by 2.3 mL of nitric acid, 1.0 mL of hydrogen peroxide and 4.7 mL of water. The method was applied in the analysis of chocolate bars, and the concentration ranges of the elements determined were (in mg kg^-1): Ca (653-3096); Cr (<0.6-2.8); Cu (<0.16-19.5); Fe (<1.6-227); Mg (147-2775); K (3554-8573); Mn (<0.03-25.2); Na (45.6-1095); Ni (3.2-10.2); P (1111-22594) and Zn (4.8-33.3). The association of the proposed microwave-assisted acid digestion with the MIP OES technique was adequate for multi-element determination in chocolate bars for routine analysis.

Cold finger with semi closed reflux system for sample preparation aiming at Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Ni, V and Zn determination in Drinking Water Treatment Sludge by MIP OES

This study presents method development and optimization, based on statistical approaches, of an alternative sample preparation methodology for Drinking Water Treatment Sludge, through decomposition in semi closed system with cold finger, aiming at the determination of Al, Ca, Cr, Cu, Fe, K, Mg, Mn, Ni, V and Zn by microwave induced plasma optical emission spectrometry. This system was employed to decompose three different Drinking Water Treatment Sludge samples, from three different treatment plants. The compromise conditions were 250 mg of dried sample, 5 mL of HNO₃, 1 mL of H₂SO₄ and heating at 225 °C for 150 min. After the digestion, 1% of cesium and lanthanum chloride buffer solution was added to all samples and standard solutions. The accuracy of the proposed sample preparation method was evaluated by analyzing a sediment certified reference material (CRM NIST 1646a) as well as the spike recovery technique. The recoveries ranged from 83% to 119% for all elements, and the found concentrations for the CRM agreed with the respective certified values, at 95% confidence level. The correlation coefficients for all investigated elements were higher than 0.999. The method LOQ values were adequate and complied with the Drinking Water Treatment Sludge regulation avaliable, ranging from 0.3 (V) and 32 (Zn) μg L^-1, or 0.1 (V) to 13 (Zn) mg kg^-1. The digestion procedure in acidic medium showed suitable to measure the analytes in the investigated matrix by microwave induced plasma optical emission spectrometry.

Microwave-Assisted Digestion Procedures Using Diluted Oxidant Mixture for Elemental Analysis of Crustaceans by MIP OES

The aim of this study was to evaluate three digestion procedures using a diluted oxidant mixture of nitric acid, hydrogen peroxide, and water for determination of Cu, Fe, K, Mg, Mn, and Zn in shrimp and crab samples from Northern Brazil by microwave-induced plasma optical emission spectrometry. The efficiency of the digestion procedure was evaluated by comparing the residual carbon content, residual acidity, and elemental concentrations obtained in the samples. Digestion procedure 2 (4 mL HNO₃ + 4 mL H₂O₂ + 4 mL H₂O) was chosen due the adequate residual carbon content (5.85%) and low residual acidity (2.94 mol L^-1). The recoveries obtained using the certified reference material (DORM-4) varied from 90 to 105%. High contents of K and Mg were found in the studied crustaceans. Also, it can give an excellent contribution to the recommended daily intake of Cu and Zn, indicating that these foods can be considered a good source of these minerals for the human diet.