The various microextraction techniques have been developed in order to reduce sample preparation ... more The various microextraction techniques have been developed in order to reduce sample preparation time, improve sensitivity and selectivity as well as to corroborate the recent advances in the development of highly sensitive and efficient analytical instrumentation. The current trend is aimed at the simplification and miniaturization of extraction steps, which has led to the combination of multi-step extraction and analytical analysis into single uninterrupted step. The method development involves the screening and subsequent optimization of both gas chromatography-mass spectrometry (GC-MS) and solid phase microextraction (SPME) parameters using multivariate experimental design, which has been shown to be efficient and effective with little experimental runs. The use of microextraction has been very effective in the analysis of contaminants in food, water and the environments to ensure they are safe and does not pose any health risk to human.
ABSTRACT Solid-phase microextraction (SPME) is a solvent-less sample preparation method which com... more ABSTRACT Solid-phase microextraction (SPME) is a solvent-less sample preparation method which combines sample preparation, isolation, concentration and enrichment into one step. SPME process involves two basic steps which are the partitioning of analytes between the polymeric fiber coating and the sample matrix, and desorption of the concentrated extracts into the analytical instrument, without any clean-up step. In this study, factors affecting the solid phase microextraction of pesticide residues (fenobucarb, diazinon, chlorothalonil and chlorpyrifos) were studied using a factorial design. The interactions and effects of temperature, time and salt addition on the efficiency of the extraction of the pesticides were evaluated using 2 3 factorial designs. A 10 g sample was weighed into 20 mL amber glass vial, fortified with the standard mixture at three concentration levels (10, 50 and 100 µg.L –1) and allowed to rest for 2 hrs. Optimum dilution was made with 10 mL of distilled water containing 10% NaCl and the mixture was shaken ultrasonically for 3 min. The analytes were then extracted with 100 µm PDMS fibers according to the factorial design matrix and desorbed into gas chromatography–mass spectrometry detector. The developed method was applied for the analysis of apple samples and the limit of detections was between 0.01 and 0.2 µg.L –1 , which were lower than the MRLs for apples.
A headspace single-drop microextraction (HS-SDME) procedure is optimized for the analysis of orga... more A headspace single-drop microextraction (HS-SDME) procedure is optimized for the analysis of organochlorine and organophosphorous pesticide residues in food matrices, namely cucumbers and strawberries by gas chromatography with an electron capture detector. The parameters affecting the HS-SDME performance, such as selection of the extraction solvent, solvent drop volume, extraction time, temperature, stirring rate, and ionic strength, were studied and optimized. Extraction was achieved by exposing 1.5 µL toluene drop to the headspace of a 5 mL aqueous solution in a 15-mL vial and stirred at 800 rpm. The analytical parameters, such as linearity, correlation coefficients, precision, limits of detection (LOD), limits of quantification (LOQ), and recovery, were compared with those obtained from headspace solid-phase microextraction (HS-SPME) and solid-phase extraction. The mean recoveries for all three methods were all above 70% and below 104%. HS-SPME was the best method with the lowest LOD and LOQ values. Overall, the proposed HS-SDME method is acceptable in the analysis of pesticide residues in food matrices.
The use of microextraction techniques for the analysis of pesticide residues in fruits, vegetable... more The use of microextraction techniques for the analysis of pesticide residues in fruits, vegetables and other contaminants have become very popular due to its environmental friendly nature. Modern trends in sample preparation and subsequent instrumental analysis are aimed towards reliable and accurate analysis of fruits and vegetables. It is focused on the simplifications, miniaturization and improvement and reduction in volume of sample and solvents used while maintaining high throughput performance. The microextraction techniques have been developed, in order to reduce sample preparation time, improve sensitivity and selectivity as well as to corroborate the recent advances in the development of highly sensitive and efficient analytical instrumentations. The combination of several novel microextraction techniques to gas chromatography (GC), liquid chromatography (LC) and capillary electrophoresis (CE) has helped in the analysis of pesticides residues in various food matrices with little or no interferences from the complex food matrices. This paper reviews the methodology, advantages and disadvantages of different microextraction techniques used in the analysis of pesticide residues from fruits and vegetables.
The various microextraction techniques have been developed in order to reduce sample preparation ... more The various microextraction techniques have been developed in order to reduce sample preparation time, improve sensitivity and selectivity as well as to corroborate the recent advances in the development of highly sensitive and efficient analytical instrumentation. The current trend is aimed at the simplification and miniaturization of extraction steps, which has led to the combination of multi-step extraction and analytical analysis into single uninterrupted step. The method development involves the screening and subsequent optimization of both gas chromatography-mass spectrometry (GC-MS) and solid phase microextraction (SPME) parameters using multivariate experimental design, which has been shown to be efficient and effective with little experimental runs. The use of microextraction has been very effective in the analysis of contaminants in food, water and the environments to ensure they are safe and does not pose any health risk to human.
ABSTRACT Solid-phase microextraction (SPME) is a solvent-less sample preparation method which com... more ABSTRACT Solid-phase microextraction (SPME) is a solvent-less sample preparation method which combines sample preparation, isolation, concentration and enrichment into one step. SPME process involves two basic steps which are the partitioning of analytes between the polymeric fiber coating and the sample matrix, and desorption of the concentrated extracts into the analytical instrument, without any clean-up step. In this study, factors affecting the solid phase microextraction of pesticide residues (fenobucarb, diazinon, chlorothalonil and chlorpyrifos) were studied using a factorial design. The interactions and effects of temperature, time and salt addition on the efficiency of the extraction of the pesticides were evaluated using 2 3 factorial designs. A 10 g sample was weighed into 20 mL amber glass vial, fortified with the standard mixture at three concentration levels (10, 50 and 100 µg.L –1) and allowed to rest for 2 hrs. Optimum dilution was made with 10 mL of distilled water containing 10% NaCl and the mixture was shaken ultrasonically for 3 min. The analytes were then extracted with 100 µm PDMS fibers according to the factorial design matrix and desorbed into gas chromatography–mass spectrometry detector. The developed method was applied for the analysis of apple samples and the limit of detections was between 0.01 and 0.2 µg.L –1 , which were lower than the MRLs for apples.
A headspace single-drop microextraction (HS-SDME) procedure is optimized for the analysis of orga... more A headspace single-drop microextraction (HS-SDME) procedure is optimized for the analysis of organochlorine and organophosphorous pesticide residues in food matrices, namely cucumbers and strawberries by gas chromatography with an electron capture detector. The parameters affecting the HS-SDME performance, such as selection of the extraction solvent, solvent drop volume, extraction time, temperature, stirring rate, and ionic strength, were studied and optimized. Extraction was achieved by exposing 1.5 µL toluene drop to the headspace of a 5 mL aqueous solution in a 15-mL vial and stirred at 800 rpm. The analytical parameters, such as linearity, correlation coefficients, precision, limits of detection (LOD), limits of quantification (LOQ), and recovery, were compared with those obtained from headspace solid-phase microextraction (HS-SPME) and solid-phase extraction. The mean recoveries for all three methods were all above 70% and below 104%. HS-SPME was the best method with the lowest LOD and LOQ values. Overall, the proposed HS-SDME method is acceptable in the analysis of pesticide residues in food matrices.
The use of microextraction techniques for the analysis of pesticide residues in fruits, vegetable... more The use of microextraction techniques for the analysis of pesticide residues in fruits, vegetables and other contaminants have become very popular due to its environmental friendly nature. Modern trends in sample preparation and subsequent instrumental analysis are aimed towards reliable and accurate analysis of fruits and vegetables. It is focused on the simplifications, miniaturization and improvement and reduction in volume of sample and solvents used while maintaining high throughput performance. The microextraction techniques have been developed, in order to reduce sample preparation time, improve sensitivity and selectivity as well as to corroborate the recent advances in the development of highly sensitive and efficient analytical instrumentations. The combination of several novel microextraction techniques to gas chromatography (GC), liquid chromatography (LC) and capillary electrophoresis (CE) has helped in the analysis of pesticides residues in various food matrices with little or no interferences from the complex food matrices. This paper reviews the methodology, advantages and disadvantages of different microextraction techniques used in the analysis of pesticide residues from fruits and vegetables.
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