Green analytical chemistry principles aim to minimize the negative impact of analytical procedure... more Green analytical chemistry principles aim to minimize the negative impact of analytical procedures in the environment, which can be considered both at close (to ensure the safety of the analysts) and global (to conserve our natural resources) levels. These principles suggest, among other guidelines, the reduction/minimization of the sample treatment and the use of renewable sources when possible. The first aspect is largely fulfilled by microextraction, which is considered to be among the greenest sample treatment techniques. The second consideration is attainable if natural products are used as raw materials for the preparation of new extraction phases. This strategy is in line with the change in our production system, which is being gradually moved from a linear model (take–make–dispose) to a circular one (including reusing and recycling as key terms). This article reviews the potential of natural products as sorbents in extraction and microextraction techniques from the synergic ...
The use of green extraction phases has gained much attention in different fields of study, includ... more The use of green extraction phases has gained much attention in different fields of study, including in sample preparation for the determination of organic compounds by chromatography techniques. Green extraction phases are considered as an alternative to conventional phases due to several advantages such as non-toxicity, biodegradability, low cost and ease of preparation. In addition, the use of greener extraction phases reinforces the environmentally-friendly features of microextraction techniques. Thus, this work presents a review about new materials that have been used in extraction phases applied to liquid and sorbent-based microextractions of organic compounds in different matrices.
In this study, a rapid and straightforward approach based on magnetic ionic liquids (MIL) as extr... more In this study, a rapid and straightforward approach based on magnetic ionic liquids (MIL) as extraction phases and dispersive liquid-liquid microextraction (DLLME) was developed to analyze the hormones estriol, 17-β-estradiol, 17-α-ethynylestradiol, and estrone in human urine samples. This is the first report of an application of manganese-based MILs compatible with HPLC to extract compounds of biological interest from urine samples. The hydrophobic MILs trihexyltetradecylphosphonium tetrachloromanganate (II) ([P][MnCl]) and aliquat tetrachloromanganate (II) ([Aliquat][MnCl]) were employed and the optimized extraction conditions were comprised of 5 mg of MIL ([P][MnCl]), 5 μL of methanol (MeOH) as disperser solvent, and an extraction time of 90 s at sample pH 6. The analytical parameters of merit were determined under optimized conditions and very satisfactory results were achieved, with LODs of 2 ng mL for all analytes, determination coefficients (R) ranging from 0.9949 for 17-β-es...
... b Department of Chemistry, Federal University of Santa Catarina, Trindade, Florianópolis, 880... more ... b Department of Chemistry, Federal University of Santa Catarina, Trindade, Florianópolis, 88040-900, Santa Catarina, Brazil. ... A high-pressure Merlin Microseal septumless injection kit (Merlin Instrument Co., Half Moon Bay, CA, USA) was obtained from Chromatographic ...
In this study a new method for chromium speciation in water using solid phase extraction coupled ... more In this study a new method for chromium speciation in water using solid phase extraction coupled to a flow injection system and flame atomic absorption spectrometry was developed. The adsorption behavior of Cr(III) and Cr(VI) on Nb2O5-SiO2 allowed the selective separation of Cr(III) from Cr(VI) in the pH range of 6-9. Thus, a method for Cr(III) preconcentration and extraction using Nb2O5-SiO2 was developed. Total chromium was determined after the reduction of Cr(VI) to Cr(III) using sodium sulfite in acidic medium. The operational variables of the preconcentration and reduction procedures were optimized through full factorial and Doehlert designs. The limit of detection for Cr(III) was 0.34microgL(-1) and the precision was below 4.6%. Results for recovery tests using different environmental samples were between 90 and 105%. Certified reference materials (NIST 1640 and NIST 1643e) were analyzed in order to check the accuracy of the proposed method, and the results were in agreement with the certified values.
This work presents a simple procedure using alkaline slurry and ultrasonic extraction for the det... more This work presents a simple procedure using alkaline slurry and ultrasonic extraction for the determination of selenium in soil samples by atomic absorption spectrometry with hydride generation and using graphite furnace (HG-GF AAS). The method allows the fractionation of the Se (IV) and Se (VI) species by the subtraction of Se (IV) from Total Se. The extraction has been performed with sodium hydroxide solution (0.5 mol L-1) while the supernatant of the extractions was used for the hydride generation and atomized using a GF coated with iridium as chemical modifier. The temperature program of the GF was optimized and the limits of detection and quantification for the developed method were 6 µg L-1 and 20 µg L-1, respectively, with linear range between 20 to 100 µg L-1 showing a linear coefficient of 0.999. The extraction efficiency was verified comparing the results obtained by the determination of total Se in the supernatant of the proposed method by high-resolution continuum source and graphite furnace atomic absorption spectrometry (HR-CS GF AAS), while the accuracy of the method was available using assisted-microwave digestion and direct solid sampling analysis by HR-CS GF AAS of the certified reference material of soil (MURST-ISS-A1 – Antartic marine sediment) and (BCR 142R – light sandy soil), as well as different soil samples from different regions of Brazil.
This study describes a combination between hollow fiber membrane and dispersive liquid-liquid mic... more This study describes a combination between hollow fiber membrane and dispersive liquid-liquid microextraction for determination of aflatoxins in soybean juice by HPLC. The main advantage of this approach is the use of non-chlorinated solvent and small amounts of organic solvents. The optimum extraction conditions were 1-octanol as immobilized solvent; toluene and acetone at 1:5 ratio as extraction and disperser solvents (100μL), NaCl at 2% of the sample volume and extraction time of 60min. The optimal condition for the liquid desorption was 150μL acetonitrile:water (50:50 v/v) and desorption time of 20min. The linear range varied from 0.03 to 21μgL(-1), with R(2) coefficients ranging from 0.9940 to 0.9995. The limits of detection and quantification ranged from 0.01μgL(-1) to 0.03μgL(-1) and from 0.03μgL(-1) to 0.1μgL(-1), respectively. Recovery tests ranged from 72% to 117% and accuracy between 12% and 18%.
A method for determination of lead and cadmium in aqueous samples using solvent microextraction a... more A method for determination of lead and cadmium in aqueous samples using solvent microextraction and dithizone as complexing agent with FAAS was developed. Solvent microextraction parameters were optimized. The effect of foreign ions on the extraction yields was studied. The extraction was carried out until the aqueous to organic phase ratio achieved a 250 fold preconcentration of metals. For preconcentration times of 4 min the 3σ detection limits, relative standard deviations (n=7) and linear calibration ranges were 1.6 μg L -1, 5.8% and 10.0 - 80.0 μg L -1 for lead and 11.1 ng L -1, 5.9% and 0.3 - 3.0 μg L -1 for cadmium, respectively. The solvent microextraction procedure presented here was applied to the determination of lead and cadmium in natural waters.
Green analytical chemistry principles aim to minimize the negative impact of analytical procedure... more Green analytical chemistry principles aim to minimize the negative impact of analytical procedures in the environment, which can be considered both at close (to ensure the safety of the analysts) and global (to conserve our natural resources) levels. These principles suggest, among other guidelines, the reduction/minimization of the sample treatment and the use of renewable sources when possible. The first aspect is largely fulfilled by microextraction, which is considered to be among the greenest sample treatment techniques. The second consideration is attainable if natural products are used as raw materials for the preparation of new extraction phases. This strategy is in line with the change in our production system, which is being gradually moved from a linear model (take–make–dispose) to a circular one (including reusing and recycling as key terms). This article reviews the potential of natural products as sorbents in extraction and microextraction techniques from the synergic ...
The use of green extraction phases has gained much attention in different fields of study, includ... more The use of green extraction phases has gained much attention in different fields of study, including in sample preparation for the determination of organic compounds by chromatography techniques. Green extraction phases are considered as an alternative to conventional phases due to several advantages such as non-toxicity, biodegradability, low cost and ease of preparation. In addition, the use of greener extraction phases reinforces the environmentally-friendly features of microextraction techniques. Thus, this work presents a review about new materials that have been used in extraction phases applied to liquid and sorbent-based microextractions of organic compounds in different matrices.
In this study, a rapid and straightforward approach based on magnetic ionic liquids (MIL) as extr... more In this study, a rapid and straightforward approach based on magnetic ionic liquids (MIL) as extraction phases and dispersive liquid-liquid microextraction (DLLME) was developed to analyze the hormones estriol, 17-β-estradiol, 17-α-ethynylestradiol, and estrone in human urine samples. This is the first report of an application of manganese-based MILs compatible with HPLC to extract compounds of biological interest from urine samples. The hydrophobic MILs trihexyltetradecylphosphonium tetrachloromanganate (II) ([P][MnCl]) and aliquat tetrachloromanganate (II) ([Aliquat][MnCl]) were employed and the optimized extraction conditions were comprised of 5 mg of MIL ([P][MnCl]), 5 μL of methanol (MeOH) as disperser solvent, and an extraction time of 90 s at sample pH 6. The analytical parameters of merit were determined under optimized conditions and very satisfactory results were achieved, with LODs of 2 ng mL for all analytes, determination coefficients (R) ranging from 0.9949 for 17-β-es...
... b Department of Chemistry, Federal University of Santa Catarina, Trindade, Florianópolis, 880... more ... b Department of Chemistry, Federal University of Santa Catarina, Trindade, Florianópolis, 88040-900, Santa Catarina, Brazil. ... A high-pressure Merlin Microseal septumless injection kit (Merlin Instrument Co., Half Moon Bay, CA, USA) was obtained from Chromatographic ...
In this study a new method for chromium speciation in water using solid phase extraction coupled ... more In this study a new method for chromium speciation in water using solid phase extraction coupled to a flow injection system and flame atomic absorption spectrometry was developed. The adsorption behavior of Cr(III) and Cr(VI) on Nb2O5-SiO2 allowed the selective separation of Cr(III) from Cr(VI) in the pH range of 6-9. Thus, a method for Cr(III) preconcentration and extraction using Nb2O5-SiO2 was developed. Total chromium was determined after the reduction of Cr(VI) to Cr(III) using sodium sulfite in acidic medium. The operational variables of the preconcentration and reduction procedures were optimized through full factorial and Doehlert designs. The limit of detection for Cr(III) was 0.34microgL(-1) and the precision was below 4.6%. Results for recovery tests using different environmental samples were between 90 and 105%. Certified reference materials (NIST 1640 and NIST 1643e) were analyzed in order to check the accuracy of the proposed method, and the results were in agreement with the certified values.
This work presents a simple procedure using alkaline slurry and ultrasonic extraction for the det... more This work presents a simple procedure using alkaline slurry and ultrasonic extraction for the determination of selenium in soil samples by atomic absorption spectrometry with hydride generation and using graphite furnace (HG-GF AAS). The method allows the fractionation of the Se (IV) and Se (VI) species by the subtraction of Se (IV) from Total Se. The extraction has been performed with sodium hydroxide solution (0.5 mol L-1) while the supernatant of the extractions was used for the hydride generation and atomized using a GF coated with iridium as chemical modifier. The temperature program of the GF was optimized and the limits of detection and quantification for the developed method were 6 µg L-1 and 20 µg L-1, respectively, with linear range between 20 to 100 µg L-1 showing a linear coefficient of 0.999. The extraction efficiency was verified comparing the results obtained by the determination of total Se in the supernatant of the proposed method by high-resolution continuum source and graphite furnace atomic absorption spectrometry (HR-CS GF AAS), while the accuracy of the method was available using assisted-microwave digestion and direct solid sampling analysis by HR-CS GF AAS of the certified reference material of soil (MURST-ISS-A1 – Antartic marine sediment) and (BCR 142R – light sandy soil), as well as different soil samples from different regions of Brazil.
This study describes a combination between hollow fiber membrane and dispersive liquid-liquid mic... more This study describes a combination between hollow fiber membrane and dispersive liquid-liquid microextraction for determination of aflatoxins in soybean juice by HPLC. The main advantage of this approach is the use of non-chlorinated solvent and small amounts of organic solvents. The optimum extraction conditions were 1-octanol as immobilized solvent; toluene and acetone at 1:5 ratio as extraction and disperser solvents (100μL), NaCl at 2% of the sample volume and extraction time of 60min. The optimal condition for the liquid desorption was 150μL acetonitrile:water (50:50 v/v) and desorption time of 20min. The linear range varied from 0.03 to 21μgL(-1), with R(2) coefficients ranging from 0.9940 to 0.9995. The limits of detection and quantification ranged from 0.01μgL(-1) to 0.03μgL(-1) and from 0.03μgL(-1) to 0.1μgL(-1), respectively. Recovery tests ranged from 72% to 117% and accuracy between 12% and 18%.
A method for determination of lead and cadmium in aqueous samples using solvent microextraction a... more A method for determination of lead and cadmium in aqueous samples using solvent microextraction and dithizone as complexing agent with FAAS was developed. Solvent microextraction parameters were optimized. The effect of foreign ions on the extraction yields was studied. The extraction was carried out until the aqueous to organic phase ratio achieved a 250 fold preconcentration of metals. For preconcentration times of 4 min the 3σ detection limits, relative standard deviations (n=7) and linear calibration ranges were 1.6 μg L -1, 5.8% and 10.0 - 80.0 μg L -1 for lead and 11.1 ng L -1, 5.9% and 0.3 - 3.0 μg L -1 for cadmium, respectively. The solvent microextraction procedure presented here was applied to the determination of lead and cadmium in natural waters.
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