Banca de DEFESA: SAMIR HIPOLITO DOS SANTOS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : SAMIR HIPOLITO DOS SANTOS
DATE: 22/08/2022
TIME: 08:30
LOCAL: Plataforma RNP às 08:30h
TITLE:

Inorganic constituents present in samples of urban soil, fertilizers and food: development of methodologies, use of chemometric tools and evaluation of guide values

KEY WORDS:

Urban Soil; Food Additives; Inorganic Constituents; Sample Preparation; Chemometric Tools; Soil Pollution Indices; ICP OES.

PAGES: 202
BIG AREA: Ciências Exatas e da Terra
AREA: Química
SUBÁREA: Química Analítica
SPECIALTY: Análise de Traços e Química Ambiental
SUMMARY:

In this work, three methods of sample preparation were developed using closed digester block and ultrasound-assisted digestion methods, being one procedure for urban soil samples, and two procedures for food essence. Chemical analyzes were performed using inductively coupled plasma optical emission spectrometry (ICP OES). The soil sample preparation procedure was optimized using fractional factorial design and Doehlert design. The accuracy of the analytical method was confirmed by chemical analysis of six certified reference materials: , light sandy soil (BCR 142), moroccan phosphate rock  (BCR 032), phosphate rock (Florida, NIST SRM 120c), phosphate rock, (Western, NIST SRM 694), trace elements in multi-nutrient fertilizer (NIST SRM 695) and Montana I Soil highly elevated trace element concentrations (NIST SRM 2710a), obtaining agreement values between 80 and 119%. Precision was expressed as relative standard deviation (%RSD), being better than 10%, (n=3). The proposed methodology was applied to 43 samples of urban soils collected from the municipality of Aracaju, Sergipe, Brasil, in two depth fractions (fraction S (0-20 cm) and F (20-40 cm)). In these samples, the concentrations of 22 inorganic constituents (Al, As, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sb, Sr, U , V and Zn) were determine by ICP OES. According to the soil quality reference values (valores de referência de qualidade para solos - VRQs), only the 2S and 2F samples showed lower concentrations of inorganic constituents than the VRQs, and in samples 13F, 15S and 18F values were found higher than the prevention value. (VP, 2.00 mg kg^-1, Sb). The granulometric analysis showed that the chemical elements are distributed among the very fine sand, silt and clay particles. The enrichment factor (EF) indicated that only samples 11S, 12S and 12F showed severe enrichment by anthropic influences for Zn concentrations. The geoaccumulation index (I_geo) characterized sample 11S as moderately polluted and samples 12S and 12F as moderately to heavily polluted. Principal component analysis (PCA) indicated that in samples from areas where vehicular traffic was more intense, the concentrations of chemical elements were higher. The methodology proposed for soil samples was also applied to mineral fertilizer samples for determination of the same 22 inorganic constituents by ICP OES. The concentrations of chemical elements varied between 0.16 mg kg^-1 (Cd) and 427 g kg^-1 (P). Fertilizer samples Fert.12, 14, 15, 16 and 18 showed the highest concentrations in most of the chemical elements determined. The following samples showed concentrations above the maximum limit allowed by current Brazilian legislation: Fert.12, Fert.14, Fert.15, Fert.16 and Fert.18 for As, Fert.12, Fert.14 and Fert.15 for Cd and Fert.12 for Cr and Pb. The PCA indicated that the samples with the highest concentrations of the chemical elements are of the superphosphated type. Two procedures for preparing the food essence samples were optimized. The first one, involving a fractional factorial design that allowed a digestion assisted by an ultrasonic bath, with the chosen factors such as: HNO₃ concentration, ultrasonic bath time, heating temperature, for a volume of 2.0 mL of sample. Another preparation method using a closed digester block was also optimized, through fractional factorial design containing the following factors: HNO₃ concentration, digestion time, heating temperature for a volume of 2.0 mL of sample. The accuracy of the ultrasound-assisted digestion method was evaluated by comparing it with the digestion block method, varying between 90% (Mn) and 117% (Fe). The accuracy of the two methods was also evaluated through the analyte addition and recovery test, ranging from 84% (Al) to 104% (Ca) for ultrasound-assisted digestion, and for digestion in a closed digester block, ranging from 80% ( Mg) and 119% (Sr). Precision for both sample preparation methods was expressed as a relative standard deviation, being better than 10%, (n=3). The methodology using ultrasound-assisted digestion was applied to samples of food essence, energy drink, powdered gelatin and powdered soft drink, for determination of Al, As, Ba, Ca, Cd, Co, Cr, Cu, Fe, K, Mg, Mn, Mo, Na, Ni, P, Pb, S, Sr, Ti, V and Zn by ICP OES. The elements Na (158 mg L^-1) and S (594 mg L^-1) presented the highest average concentrations in the food essence samples. The presence of Al was found only in samples of energy drink A (2.52 mg L^-1) and powdered soft drink (7.50 µg g^-1). The sample of energy drink A was the only sample that showed a concentration of Ba (0.119 µg g^-1). Only the powdered refreshment sample showed a concentration of Ti

BANKING MEMBERS:
Presidente - 1698441 - RENNAN GEOVANNY OLIVEIRA ARAUJO
Interno - 3204824 - JOAO BATISTA PEREIRA JUNIOR
Externa à Instituição - ELISANGELA DE ANDRADE PASSOS - UFS
Externo à Instituição - MADSON DE GODOI PEREIRA
Externo à Instituição - MARCO TADEU GRASSI
Externa à Instituição - SARAH ADRIANA ROCHA SOARES
Externo à Instituição - SILVÂNIO SILVÉRIO LOPES DA COSTA - UFS
Externo à Instituição - CARLOS ALEXANDRE BORGES GARCIA - UFS
Externa à Instituição - TATIANE DE ANDRADE MARANHÃO
Externa à Instituição - ADNÍVIA SANTOS COSTA MONTEIRO