Multivariate optimization for cloud point extraction and determination of lanthanides

Depoi, Fernanda dos Santos; Bentlin, Fabrina Regia Stumm; Ferrão, Marco Flôres; Pozebon, Dirce

doi:10.1039/c2ay25375e

Cited by 22 publications

(13 citation statements)

References 31 publications

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“…The workflow summary is showed in the Figure 2 (P01 to P07). They were carried out on six replicates per protocol in batches composed by blank samples spiked with all PYR analytes at maximum residue level (MRL) defined in NRCP 2013 [ 23 , 24 ]. Extraction efficiency was verified in terms of recovery ( RE ; percentage) by comparison between tissue standard ( TS ; samples spiked after extraction procedure, in a matrix-matched approach) and samples spiked with PYR pool before extraction (standard addition method).…”

Section: Methodsmentioning

confidence: 99%

“…Method development became more effective using multivariate optimization because more information is obtained about the interaction among the variables, sometimes undetected when univariate approach is used [ 19 , 23 , 24 , 25 ]. For analytical purposes, the Doehlert one has shown to be the most adequate kind of design and can be applied to response surfaces with a good estimation of the parameters of the quadratic mathematical model, allowing the study of independent variables, at different levels, and has been successfully used for optimization of extraction methods in food analysis [ 25 , 26 ].…”

Section: Introductionmentioning

confidence: 99%

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Multivariate Optimization for Extraction of Pyrethroids in Milk and Validation for GC-ECD and CG-MS/MS Analysis

Meneghini

Rübensam

Bica

et al. 2014

IJERPH

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A simple and inexpensive method based on solvent extraction followed by low temperature clean-up was applied for determination of seven pyrethroids residues in bovine raw milk using gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) and gas chromatography with electron-capture detector (GC-ECD). Sample extraction procedure was established through the evaluation of seven different extraction protocols, evaluated in terms of analyte recovery and cleanup efficiency. Sample preparation optimization was based on Doehlert design using fifteen runs with three different variables. Response surface methodologies and polynomial analysis were used to define the best extraction conditions. Method validation was carried out based on SANCO guide parameters and assessed by multivariate analysis. Method performance was considered satisfactory since mean recoveries were between 87% and 101% for three distinct concentrations. Accuracy and precision were lower than ±20%, and led to no significant differences (p < 0.05) between results obtained by GC-ECD and GC-MS/MS techniques. The method has been applied to routine analysis for determination of pyrethroid residues in bovine raw milk in the Brazilian National Residue Control Plan since 2013, in which a total of 50 samples were analyzed.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Multivariate Optimization for Extraction of Pyrethroids in Milk and Validation for GC-ECD and CG-MS/MS Analysis

Meneghini

Rübensam

Bica

et al. 2014

IJERPH

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“…Para a análise foram colocados 15 µL de biodiesel em um tubo de RMN e adicionado 550 µL de CDCl 3 . As amostras foram analisadas num espectrômetro Bruker AVANCE operando na freqüência de 400 MHz para 1 H e 100 MHz para 13 C, equipado com uma sonda de 5 mm com detecção direta. Os espectros foram obtidos selecionando-se alguns parâmetros na aquisição e no processamento para fornecer uma melhor resolução digital com base nos parâmetros.…”

Section: Caracterização Do Biodiesel Por Ressonância Magnética Nucleaunclassified

“…Este modelo reduz o número de experimentos a ser realizados e seu uso em conjunto com a metodologia de superfícies de resposta são muito utilizados para otimizar condições reacionais. 12,13 A literatura mostra, entre inúmeras aplicações, o uso de planejamentos experimentais como outra forma eficiente de avaliar e aprimorar métodos …”

Section: Introductionunclassified

Otimization of Transesterification Double Step Process (Tdsp) to the Production of Biodiesel Through Doehlert Experimental Design

Ruschel¹,

Ferrão²,

Santos³

et al. 2016

Química Nova

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. In this work, Doehlert experimental design was used to optimize the Transesterification Double Step Process (TDSP) method of methyl soybean oil biodiesel production which starts with a basic catalysis followed by an acidic catalysis. The conversion values were calculated from NMR spectra. Response surface was used to show the results of the interactions between the variables. This experimental design evaluated variables like catalyst and alcohol amount for the basic catalysis and time and temperature for the acidic catalysis. According to results obtained after Doehlert design application the alcohol amount was the main factor that influenced on the basic catalysis but for the acidic catalysis both time and temperature are important and their effects are opposite. It resulted on excellent conversions for both steps obtaining for the basic catalysis about 100% when was used like optimal conditions catalyst amount equal to 0.40 g and volume of methanol equal to 60 mL and for the acidic catalysis about 99% when was used like optimal conditions temperature of 65 °C and 90 minutes for reaction time.Keywords: transesterification double step process; biodiesel; NMR; Doehlert design. INTRODUÇÃOA produção de biodiesel, já bem consolidada no Brasil e no mundo, há mais de uma década, é um assunto que continua a atrair interesse de vários setores, especialmente da indústria de biocombustíveis e dos pesquisadores em geral, uma vez que sempre há o objetivo de aumentar a qualidade e aprimorar o processo de produção deste combustível ainda muito valorizado. 1Este tema é um setor importante para a economia nacional que ainda necessita tanto do desenvolvimento de novas tecnologias quanto soluções para questões econômicas e sociais.2 Neste sentido, atualmente, há necessidade de pesquisas para diversas finalidades: diversificar fontes de matéria-prima, incluindo renováveis 3 ou óleos residuais, 4 diminuir custos de produção, criar novas metodologias de produção, 5 melhorar características físico-químicas, 6 qualidade e consequente rendimento e emissões do motor, 7 entre outros. O processo de transesterificação em duas etapas (TDSPTransesterification Double Step Process) utilizado neste estudo foi inicialmente desenvolvido por Samios et al. para produzir biodiesel metílico a partir de alguns óleos clássicos no Brasil como girassol e linhaça, por ser um método simples e rápido de síntese, que facilita o procedimento de separação dos produtos e resulta em ótima eficiência de conversão.8 Ao longo dos anos também vem sendo aprimorada desde a sua criação, resultando na aplicação para produção de biodiesel etílico também, 9 além de possibilitar o uso de outras fontes de matéria-prima, como banha, sebo e a reutilização de óleo de fritura por exemplo. 10Neste estudo é proposta a inserção do planejamento experimental Doehlert, 11 que foi desenvolvido por David H. Doehlert em 1972, como um instrumento para otimizar as condições de síntese do biodiesel produzido pelo método TDSP. Modelos multivariados, como é o caso do planejamento Doehlert,...

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“…Although there is the possibility of interferences caused by the mineral fertilizer matrix, it can be overcome by appropriate dilution of the sample solution and/or matrix matching calibration, in addition to adjustments of instrumental parameters that can be carried out following multivariate approaches. 20 In this sense, Doehlert matrices 21 have been used for optimization of sample preparation methods [22][23][24] and instrumental parameterts 19,25 for subsequent element determination by means of ICP OES.…”

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confidence: 99%

Method Development and Total Uncertainty Estimation for Boron, Sulfur and Phosphorus Determination in Mineral Fertilizer Using ICP OES

Oliveira¹,

Rampazzo²,

Ferrão³

et al. 2016

Journal of the Brazilian Chemical Society

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This study deals with B, S, and P determination in mineral fertilizer and S in commercial sulfur-formulation using inductively coupled plasma optical emission spectrometry. According to multivariate optimization using a Doehlert matrix, the analytes extraction in fertlizer can be conducted in open flask and heating on hot plate or in closed flask in microwave oven. However, when S is present in its elemental form in the fertilizer, the sample must be decomposed in closed flask in microwave oven for accurate S quantification. The uncertainties of the method were estimated according to the bottom-up approach, which were 7.1, 4.3, and 7.8% for B, S and P, respectively. The main sources of uncertainty identified were the intermediate precision, accuracy, regression of the calibration curve and errors originated from volumetric flasks and pipettes. Satisfactory results were obtained in the analysis of certified reference materials and sample from inter-laboratory programs as well as S recovery in a commercial elemental sulfur sample.

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Multivariate optimization for cloud point extraction and determination of lanthanides

Cited by 22 publications

References 31 publications

Multivariate Optimization for Extraction of Pyrethroids in Milk and Validation for GC-ECD and CG-MS/MS Analysis

Multivariate Optimization for Extraction of Pyrethroids in Milk and Validation for GC-ECD and CG-MS/MS Analysis

Otimization of Transesterification Double Step Process (Tdsp) to the Production of Biodiesel Through Doehlert Experimental Design

Method Development and Total Uncertainty Estimation for Boron, Sulfur and Phosphorus Determination in Mineral Fertilizer Using ICP OES

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