A single-run analytical method was developed to analyze the three herbicides azimsulfuron, bensul... more A single-run analytical method was developed to analyze the three herbicides azimsulfuron, bensulfuron-methyl, and mesotrione and its metabolite (4-methylsulfonyl-2-nitrobenzoic acid (MNBA)) in brown rice and rice straw using liquid chromatography-tandem mass spectrometry (LC/MS/MS). Samples extracted using various versions of Quick, Easy, Cheap, Effective, Rugged, and Safe "QuEChERS" (original unbuffered, acetate (AOAC), and citrate (EN) buffered) methods gave poor recoveries of all the tested analytes in both matrices. The extraction efficiency was improved when primary-secondary amine (PSA) sorbent was removed from the purification step, with the best recovery being achieved for EN-QuEChERS, which was subsequently used throughout the study. Overall, a determination coefficients (R(2))⩾0.995 was achieved at matrix-matched calibration curves at various concentration ranges. The recovery rates at three fortification levels (limit of quantification (LOQ), 1/2 maximum residu...
Lepimectin, as an emulsifiable concentrate, was sprayed on shallots at the recommended dose rate ... more Lepimectin, as an emulsifiable concentrate, was sprayed on shallots at the recommended dose rate (10 mL/20 L) to determine its residue levels, dissipation pattern, pre-harvest residue limits (PHRLs), and health risk. Samples were randomly collected over 10 days, extracted with acetonitrile, purified using an amino solid-phase extraction (NH2 -SPE) cartridge, and analyzed using a high-performance liquid chromatography-photodiode array detection (HPLC-PAD) method. Field incurred samples were confirmed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The linearity was excellent, with a determination coefficient (R(2) ) of ≥ 0.9991. The recoveries at two spiking levels (0.2 and 1.0 mg/kg) ranged from 84.49% to 87.64% with relative standard deviations (RSDs) of ≤ 7.04%. The developed method was applied to field samples grown in separate greenhouses, one located in Naju and one in Muan, in the Republic of Korea. The dissipation pattern was described by first-order kinetics with half-lives of 1.9 (Naju) and 1.7 days (Muan). The PHRL curves indicated that if the lepimectin residues are < 0.18 (Naju) and < 0.13 mg/kg (Muan) five days before harvest, the residue levels will be lower than the maximum residue limit (MRL = 0.05 mg/kg) upon harvesting. The risk assessment data indicated that lepimectin is safe for use in the cultivation of shallots, with no risk of detrimental effects to the consumer.
This study was conducted to characterize the residual level and perform a risk assessment of bupr... more This study was conducted to characterize the residual level and perform a risk assessment of buprofezin formulated as an emulsifiable concentrate (EC), wettable powder (WP), and suspension concentrate (SC) over various treatment schedules in plum, i.e., Prunus domestica. The samples were extracted with an AOAC quick, easy, cheap, effective, rugged, and safe "QuEChERS" method after major modifications. As intrinsic interferences were observed in blank plum samples following dispersive-solid phase extraction (d-SPE consisting of primary secondary amine (PSA) and C18 sorbents), amino cartridges were used for solid-phase extraction (SPE). Analysis was carried out using LC with diode array detection (DAD) and confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method showed excellent linearity with determination coefficient (R(2) = 1) and satisfactory recoveries (at two spiking level; 0.5 and 2.5 mg/kg) between 90.98-94.74% with relative standard deviat...
An analytical method to detect phorate and its metabolites, including phorate sulfone, phorate su... more An analytical method to detect phorate and its metabolites, including phorate sulfone, phorate sulfoxide, phoratoxon, phoratoxon sulfone, and phoratoxon sulfoxide, in porcine and chicken muscles and table eggs was developed and validated. Extraction was performed using a quick, easy, cheap, effective, rugged, and safe method and analysis was conducted using ultra-performance liquid chromatography-tandem mass spectrometry. Matrix-matched calibrations were linear over the tested concentrations, with a determination coefficient ≥ 0.995 for all tested analytes in the different matrices. The limits of detection and quantification were 0.001 and 0.004 mg/kg, respectively. The calculated recovery rates at three fortification levels were satisfactory, with values between 74.22 and 119.89% and relative standard deviations < 10%. The method was applied successfully to commercial samples collected from locations throughout the Korean Peninsula, and none of them showed any traces of the test...
The present study was carried out to develop an analytical method for the detection and quantific... more The present study was carried out to develop an analytical method for the detection and quantification of bistrifluron, a benzoylphenylurea compound, in pear using high-performance liquid chromatography with UV detection. Samples were extracted using conventional, AOAC, and EN quick, easy, cheap, effective, rugged, and safe "QuEChERS" methods. As expected, conventional and EN-QuEChERS methods gave higher recoveries than AOAC. In addition, interference around the analyte retention time was observed in the conventional method. Thus, the EN-QuEChERS method was selected and validated by studying various parameters, including linearity, limit of detection (LOD), limit of quantification (LOQ), recovery, and precision. Linearity was excellent, with a correlation coefficient (R(2) ) of 0.9998. Recovery rates at three spiking levels (0.05, 0.2, and 1 mg/kg) ranged from 73.76 to 98.66%. Intra- and inter-day precisions, expressed as relative standard deviations (RSDs), were <6%. T...
Perilla leaves contain many interfering substances; thus, it is difficult to protect the analytes... more Perilla leaves contain many interfering substances; thus, it is difficult to protect the analytes during identification and integration. Furthermore, increasing the amount of sample to lower the detection limit worsens the situation. To overcome this problem, we established a new method using a combination of solid-phase extraction (SPE) and dispersive solid-phase (d-SPE) extraction to analyze pyraclostrobin in perilla leaves by liquid chromatography with ultraviolet absorbance detection. The target compound was quantitated by external calibration with a good determination coefficient (R(2) = 0.997). The method was validated (in triplicate) with three fortification levels, and 79.06- 89.10% of the target compound was recovered with a relative standard deviation < 4. The limits of detection and quantification were 0.0033 and 0.01 mg/kg, respectively. The method was successfully applied to field samples collected from two different areas at Gwangju and Muan. The decline in the res...
In this study, a simple, rapid, and sensitive method was developed for the extraction of ethephon... more In this study, a simple, rapid, and sensitive method was developed for the extraction of ethephon from homogenized tomatoes that does not require a cleanup procedure. In a syringe filter, three distinct layers - aqueous, acetonitrile, and n-hexane - are clearly separated after storage at -80 °C for 5-10 min. A Dionex IonPac column was used to separate the analyte before detection using negative-ion mode liquid chromatography with tandem mass spectrometry (LC/MS/MS). The matrix effect of the tested analyte was negligibly small and the matched calibration showed a good linearity over a concentration range of 0.01-1.0 mg/kg with a correlation coefficient (R(2) ) of 0.9998. The recovery at three fortification levels (0.1, 0.5 and 1.0 mg/kg) was between 82.9 and 108.6% with relative standard deviations (RSDs) <5.0%. The limit of quantification (0.03 mg/kg) was lower than the maximum residue limit (3 mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. From a field tr...
The aim of this study was to establish an analytical method to detect fluquinconazole and tetraco... more The aim of this study was to establish an analytical method to detect fluquinconazole and tetraconazole in soil using supercritical fluid extraction (SFE) and gas chromatography (GC). The optimal extraction conditions for SFE were: temperature, 60 °C; pressure, 280 kg/cm(2) ; extraction time, 50 min; and a 10% modifier ratio. The linearity of the calibration curves was good and yielded a determination coefficient (R(2) ) ≥ 0.995. The soil samples were fortified with known quantities of the analytes at three different concentrations (0.01, 0.02 and 0.1 µg/g for fluquinconazole; 0.05, 0.1 and 0.5 µg/g for tetraconazole), and the recoveries ranged between 83.7 and 94.1%. The intra- and inter-day relative standard deviations were 1.3-10.6 and 2.2-11.9% for fluquinconazole and tetraconazole, respectively. The limit of detection and limit of quantitation were 0.002 and 0.01 µg/g for fluquinconazole and 0.01 and 0.05 for tetraconazole, respectively. The method was successfully applied to t...
Journal of the Korean Society for Applied Biological Chemistry, 2014
ABSTRACT The present study estimated the residue levels of abamectin (B1a) in green tea leaves an... more ABSTRACT The present study estimated the residue levels of abamectin (B1a) in green tea leaves and tea infusion. Samples were hydrated with water prior to extraction by using the quick, easy, cheap, effective, rugged, safe method and was analyzed with liquid chromatography-tandem mass spectrometry in positive ion mode. The matrix-matched calibration was linear over the concentration range of 0.01–2mg/kg with determination coefficients (R 2 ) &gt;0.995. Recovery rates at two spiking levels (0.1 and 0.5 mg/kg) ranged between 80.5–99.7% with a relative standard deviation &lt;11%. The compound was stable at 20°C for 174 days with a recovery estimate of 109.9%. Although the maximum residue limit was not established by the Ministry of Food and Drug Safety, Republic of Korea, the limit of quantitation was very low at 0.01 mg/kg. The method was successfully applied to field incurred samples and detected residue of 0.02 mg/kg in green tea samples sprayed twice (7-3 days). Abamectin was not transferred to tea infusion.
A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) acetate-buffered sample prep... more A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) acetate-buffered sample preparation method was developed to improve extraction recovery of flonicamid and its two metabolites (4-trifluoromethylnicotinic acid and N-(4-trifluoromethylnicotinoyl)glycine) in paprika followed by analysis using tandem mass spectrometry. Acidified acetonitrile (containing 5% acetic acid) was used as an extraction solvent and partitioning was carried out using sodium chloride. The extract was then cleaned up using C18. The linearity over a concentration range of 0.005-1 μg/mL was good with a determination coefficient (R(2))&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;0.9997. Recovery at three different fortification levels was 82.2-101.7% with a relative standard deviation &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;10 for all analytes. The limit of quantitation of 0.01 mg/kg was quite lower than the maximum residue level set by the Korea Food and Drug Administration (2mg/kg). The method was successfully applied to determine flonicamid and its metabolites from field incurred samples. The undulating residue pattern observed for the parent analyte together with its metabolites could explain the movement behavior of systemic pesticides into plants over time.
A single-run analytical method was developed to analyze the three herbicides azimsulfuron, bensul... more A single-run analytical method was developed to analyze the three herbicides azimsulfuron, bensulfuron-methyl, and mesotrione and its metabolite (4-methylsulfonyl-2-nitrobenzoic acid (MNBA)) in brown rice and rice straw using liquid chromatography-tandem mass spectrometry (LC/MS/MS). Samples extracted using various versions of Quick, Easy, Cheap, Effective, Rugged, and Safe "QuEChERS" (original unbuffered, acetate (AOAC), and citrate (EN) buffered) methods gave poor recoveries of all the tested analytes in both matrices. The extraction efficiency was improved when primary-secondary amine (PSA) sorbent was removed from the purification step, with the best recovery being achieved for EN-QuEChERS, which was subsequently used throughout the study. Overall, a determination coefficients (R(2))⩾0.995 was achieved at matrix-matched calibration curves at various concentration ranges. The recovery rates at three fortification levels (limit of quantification (LOQ), 1/2 maximum residu...
Lepimectin, as an emulsifiable concentrate, was sprayed on shallots at the recommended dose rate ... more Lepimectin, as an emulsifiable concentrate, was sprayed on shallots at the recommended dose rate (10 mL/20 L) to determine its residue levels, dissipation pattern, pre-harvest residue limits (PHRLs), and health risk. Samples were randomly collected over 10 days, extracted with acetonitrile, purified using an amino solid-phase extraction (NH2 -SPE) cartridge, and analyzed using a high-performance liquid chromatography-photodiode array detection (HPLC-PAD) method. Field incurred samples were confirmed using ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The linearity was excellent, with a determination coefficient (R(2) ) of ≥ 0.9991. The recoveries at two spiking levels (0.2 and 1.0 mg/kg) ranged from 84.49% to 87.64% with relative standard deviations (RSDs) of ≤ 7.04%. The developed method was applied to field samples grown in separate greenhouses, one located in Naju and one in Muan, in the Republic of Korea. The dissipation pattern was described by first-order kinetics with half-lives of 1.9 (Naju) and 1.7 days (Muan). The PHRL curves indicated that if the lepimectin residues are &lt; 0.18 (Naju) and &lt; 0.13 mg/kg (Muan) five days before harvest, the residue levels will be lower than the maximum residue limit (MRL = 0.05 mg/kg) upon harvesting. The risk assessment data indicated that lepimectin is safe for use in the cultivation of shallots, with no risk of detrimental effects to the consumer.
This study was conducted to characterize the residual level and perform a risk assessment of bupr... more This study was conducted to characterize the residual level and perform a risk assessment of buprofezin formulated as an emulsifiable concentrate (EC), wettable powder (WP), and suspension concentrate (SC) over various treatment schedules in plum, i.e., Prunus domestica. The samples were extracted with an AOAC quick, easy, cheap, effective, rugged, and safe "QuEChERS" method after major modifications. As intrinsic interferences were observed in blank plum samples following dispersive-solid phase extraction (d-SPE consisting of primary secondary amine (PSA) and C18 sorbents), amino cartridges were used for solid-phase extraction (SPE). Analysis was carried out using LC with diode array detection (DAD) and confirmed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). The method showed excellent linearity with determination coefficient (R(2) = 1) and satisfactory recoveries (at two spiking level; 0.5 and 2.5 mg/kg) between 90.98-94.74% with relative standard deviat...
An analytical method to detect phorate and its metabolites, including phorate sulfone, phorate su... more An analytical method to detect phorate and its metabolites, including phorate sulfone, phorate sulfoxide, phoratoxon, phoratoxon sulfone, and phoratoxon sulfoxide, in porcine and chicken muscles and table eggs was developed and validated. Extraction was performed using a quick, easy, cheap, effective, rugged, and safe method and analysis was conducted using ultra-performance liquid chromatography-tandem mass spectrometry. Matrix-matched calibrations were linear over the tested concentrations, with a determination coefficient ≥ 0.995 for all tested analytes in the different matrices. The limits of detection and quantification were 0.001 and 0.004 mg/kg, respectively. The calculated recovery rates at three fortification levels were satisfactory, with values between 74.22 and 119.89% and relative standard deviations < 10%. The method was applied successfully to commercial samples collected from locations throughout the Korean Peninsula, and none of them showed any traces of the test...
The present study was carried out to develop an analytical method for the detection and quantific... more The present study was carried out to develop an analytical method for the detection and quantification of bistrifluron, a benzoylphenylurea compound, in pear using high-performance liquid chromatography with UV detection. Samples were extracted using conventional, AOAC, and EN quick, easy, cheap, effective, rugged, and safe "QuEChERS" methods. As expected, conventional and EN-QuEChERS methods gave higher recoveries than AOAC. In addition, interference around the analyte retention time was observed in the conventional method. Thus, the EN-QuEChERS method was selected and validated by studying various parameters, including linearity, limit of detection (LOD), limit of quantification (LOQ), recovery, and precision. Linearity was excellent, with a correlation coefficient (R(2) ) of 0.9998. Recovery rates at three spiking levels (0.05, 0.2, and 1 mg/kg) ranged from 73.76 to 98.66%. Intra- and inter-day precisions, expressed as relative standard deviations (RSDs), were <6%. T...
Perilla leaves contain many interfering substances; thus, it is difficult to protect the analytes... more Perilla leaves contain many interfering substances; thus, it is difficult to protect the analytes during identification and integration. Furthermore, increasing the amount of sample to lower the detection limit worsens the situation. To overcome this problem, we established a new method using a combination of solid-phase extraction (SPE) and dispersive solid-phase (d-SPE) extraction to analyze pyraclostrobin in perilla leaves by liquid chromatography with ultraviolet absorbance detection. The target compound was quantitated by external calibration with a good determination coefficient (R(2) = 0.997). The method was validated (in triplicate) with three fortification levels, and 79.06- 89.10% of the target compound was recovered with a relative standard deviation < 4. The limits of detection and quantification were 0.0033 and 0.01 mg/kg, respectively. The method was successfully applied to field samples collected from two different areas at Gwangju and Muan. The decline in the res...
In this study, a simple, rapid, and sensitive method was developed for the extraction of ethephon... more In this study, a simple, rapid, and sensitive method was developed for the extraction of ethephon from homogenized tomatoes that does not require a cleanup procedure. In a syringe filter, three distinct layers - aqueous, acetonitrile, and n-hexane - are clearly separated after storage at -80 °C for 5-10 min. A Dionex IonPac column was used to separate the analyte before detection using negative-ion mode liquid chromatography with tandem mass spectrometry (LC/MS/MS). The matrix effect of the tested analyte was negligibly small and the matched calibration showed a good linearity over a concentration range of 0.01-1.0 mg/kg with a correlation coefficient (R(2) ) of 0.9998. The recovery at three fortification levels (0.1, 0.5 and 1.0 mg/kg) was between 82.9 and 108.6% with relative standard deviations (RSDs) <5.0%. The limit of quantification (0.03 mg/kg) was lower than the maximum residue limit (3 mg/kg) set by the Ministry of Food and Drug Safety, Republic of Korea. From a field tr...
The aim of this study was to establish an analytical method to detect fluquinconazole and tetraco... more The aim of this study was to establish an analytical method to detect fluquinconazole and tetraconazole in soil using supercritical fluid extraction (SFE) and gas chromatography (GC). The optimal extraction conditions for SFE were: temperature, 60 °C; pressure, 280 kg/cm(2) ; extraction time, 50 min; and a 10% modifier ratio. The linearity of the calibration curves was good and yielded a determination coefficient (R(2) ) ≥ 0.995. The soil samples were fortified with known quantities of the analytes at three different concentrations (0.01, 0.02 and 0.1 µg/g for fluquinconazole; 0.05, 0.1 and 0.5 µg/g for tetraconazole), and the recoveries ranged between 83.7 and 94.1%. The intra- and inter-day relative standard deviations were 1.3-10.6 and 2.2-11.9% for fluquinconazole and tetraconazole, respectively. The limit of detection and limit of quantitation were 0.002 and 0.01 µg/g for fluquinconazole and 0.01 and 0.05 for tetraconazole, respectively. The method was successfully applied to t...
Journal of the Korean Society for Applied Biological Chemistry, 2014
ABSTRACT The present study estimated the residue levels of abamectin (B1a) in green tea leaves an... more ABSTRACT The present study estimated the residue levels of abamectin (B1a) in green tea leaves and tea infusion. Samples were hydrated with water prior to extraction by using the quick, easy, cheap, effective, rugged, safe method and was analyzed with liquid chromatography-tandem mass spectrometry in positive ion mode. The matrix-matched calibration was linear over the concentration range of 0.01–2mg/kg with determination coefficients (R 2 ) &gt;0.995. Recovery rates at two spiking levels (0.1 and 0.5 mg/kg) ranged between 80.5–99.7% with a relative standard deviation &lt;11%. The compound was stable at 20°C for 174 days with a recovery estimate of 109.9%. Although the maximum residue limit was not established by the Ministry of Food and Drug Safety, Republic of Korea, the limit of quantitation was very low at 0.01 mg/kg. The method was successfully applied to field incurred samples and detected residue of 0.02 mg/kg in green tea samples sprayed twice (7-3 days). Abamectin was not transferred to tea infusion.
A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) acetate-buffered sample prep... more A modified quick, easy, cheap, effective, rugged and safe (QuEChERS) acetate-buffered sample preparation method was developed to improve extraction recovery of flonicamid and its two metabolites (4-trifluoromethylnicotinic acid and N-(4-trifluoromethylnicotinoyl)glycine) in paprika followed by analysis using tandem mass spectrometry. Acidified acetonitrile (containing 5% acetic acid) was used as an extraction solvent and partitioning was carried out using sodium chloride. The extract was then cleaned up using C18. The linearity over a concentration range of 0.005-1 μg/mL was good with a determination coefficient (R(2))&amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt;0.9997. Recovery at three different fortification levels was 82.2-101.7% with a relative standard deviation &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt;10 for all analytes. The limit of quantitation of 0.01 mg/kg was quite lower than the maximum residue level set by the Korea Food and Drug Administration (2mg/kg). The method was successfully applied to determine flonicamid and its metabolites from field incurred samples. The undulating residue pattern observed for the parent analyte together with its metabolites could explain the movement behavior of systemic pesticides into plants over time.
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