16 research outputs found
Optimization of chromatographic conditions for determination of aflatoxin B1, B2, G1 and G2 by using liquid chromatography-mass Spectrometry
No full textA QUANTITATIVE STRUCTURE-PROPERTY RELATIONSHIP (QSPR) EVALUATION OF CRITICAL VOLUME OF UNSATURATED HYDROCARBON ALKENES AND ALKYNES USING SIMPLE CONNECTIVITY INDICES
No full textA quantitative structure-property relationships (QSPR) was used in this study to relate the critical volume (Vc) of unsaturated hydrocarbons alkenes and alkynes compounds to their molecular structures. A QSPR study of Vc was performed on the basis of simple connectivity indices (SCI’s). The obtained QSPR model is predictive and requires only one SCI descriptor in the calculation with statistical parameters including standard coefficient correlation (R2)=0.997, cross-validated correlation coefficients (Q2)=0.976, and average absolute error (AAE)=0.12. Application of the best QSPR model to a testing set of 30 alkenes and alkynes demonstrates good predictability without the needs in any experimental physicochemical properties data
VERIFICATION OF GC-μ
No full textGas Chromatography equipped with a Micro Electron Capture Detector (GC-&m
Validation and Uncertainty Evaluation of an LC-DAD Method for Simultaneous Quantification of Benzoic Acid, Methylparaben, and N-Butylparaben in Soy Sauce
Get PDFChemical food preservation is the common strategy used by human to preserve the natural properties and to increase the shelf life of food. Although preservatives are useful to keep the food fresh and to stop the bacterial growth, there are certain preservatives that are harmful if taken in more than the prescribed limits. Some of the typical used—benzoic acid, methylparaben, and n-butylparaben—were employed in this work with the aim of establishing a simultaneous liquid chromatography (LC) method for detecting each in soy sauce matrices. Liquid and C18 solid phase extraction were performed in this procedure prior to LC using Diode Array Detector analysis. In gradient elution of a format buffer (pH 4.4) and acidified acetonitrile, the target components were successfully separated. Calibration curve ranged from 0.61–140 mg/kg linearly while the limit of quantification for benzoic acid, methylparaben, and n-butylparaben were 0.41, 0.10, and 0.11 mg/kg, respectively. The intermediate precision and recovery were in the range between 0.15-1.89% and 100.5-103.3%, respectively. The expanded uncertainty (k=2) in sample measurement was estimated at 3.4-6.5%. The offered method was conformed to the validation acceptance criteria and can be applied as a routine method in the laboratory at ppm level
Evaluation of Uncertainty in the Determination of Pesticide Residues in Tea using GC-ECD
No full textKey indicator of quality in test results is the uncertainty value, which could be evaluated using several common approach. Uncertainty evaluation in a-endosulfan and bifenthrin in Oolong tea, and cypermethrin in green tea using bottom-up approach showed that uncertainty component arising from GC-ECD instrument calibration, method performance i.e. repeatability and recovery were the main contributors to total uncertainty. Uncertainty component arising from weighing, dilution factor, stock standard solution, calibration solution, and moisture correction had no significant effect to total uncertainty, hence they could be neglected. Relative standard uncertainty obtained for all of pesticides residue were 18.23, 10.44, dan 14.98% for a-endosulfan, bifenthrin, and cypermethrin, respectively. Comparison with 2/3 CV Horwitz of 17.33, 10.62, and 12.44% respectively for all pesticide residues indicated that the evaluation of uncertainties were realisti
Analytical Method Development for the Determination of Α-Endosulfan and Bifenthrin Pesticide Residues in Tea
Get PDFThe development of analytical method for the determination of α-endosulfan and bifenthrin residues in tea has been done. The complex matrices and also the pigment were the challenge in doing quantification of the pesticide residues in tea matrices. In order to get appropriate analysis method for the determination of pesticide residues in tea, the modification was done in the analytical method for the determination of organochlorine multiresidue in non fat matrices: seasoning and spicy that is published by Directorate General of Food Crops, Directorate of Food Plant Protection. The modification was done particularly in clean-up step to remove the interferences from the extract of tea matrices such as the pigment that usually interfere the measurement with Gas Chromatography (GC). The result showed that the MDL value for both analytes were 0.5 ng/g that were much lower than MRLs. The percent recovery obtained from the method was 78.58 and 90.19% for α-endosulfan and bifenthrin, respectively. The precision of the analysis method for both analytes were good since the % RSD values were below than the Horwitz’s value that was 19.18% at spiking level concentration of 300 ng/g
Development of Candidate Reference Materials of Endosulfan Sulfate and Bifenthrin in Black Tea
Get PDFThe candidate reference materials of endosulfan sulfate and bifenthrin in black tea have been developed according to the requirements of ISO Guide 34 and 35. Preparation of candidate material includes grinding and sieving of the black tea leaves, spiking the black tea powder by both analytes, homogenization, and bottling. Homogeneity and short-term stability test were performed using a GC-µECD instrument. Meanwhile, the characterization was carried out by a collaborative study using both of GC-µECD and GC-MS instruments. The uncertainty budget was evaluated from sample inhomogeneity, short-term instability and variability in the characterization procedure. In a dry mass fraction, endosulfan sulfate was assigned to be 491 µg kg-1 with a relative expanded uncertainty of ± 33.2%, and bifenthrin was assigned to be 937 µg kg-1 with a relative expanded uncertainty of ± 18.5%. The candidate reference materials are aimed to support the need of matrix CRM especially for the measurement of pesticide residue for quality assurance work done by laboratories in Indonesia
Screening of the presence organophosphates and organochlorines pesticide residues in vegetables and fruits using gas chromatography-mass spectrometry
No full textAnalytical Method Development for the Determination of Α-Endosulfan and Bifenthrin Pesticide Residues in Tea
Get PDFThe development of analytical method for the determination of α-endosulfan and bifenthrin residues in tea has been done. The complex matrices and also the pigment were the challenge in doing quantification of the pesticide residues in tea matrices. In order to get appropriate analysis method for the determination of pesticide residues in tea, the modification was done in the analytical method for the determination of organochlorine multiresidue in non fat matrices: seasoning and spicy that is published by Directorate General of Food Crops, Directorate of Food Plant Protection. The modification was done particularly in clean-up step to remove the interferences from the extract of tea matrices such as the pigment that usually interfere the measurement with Gas Chromatography (GC). The result showed that the MDL value for both analytes were 0.5 ng/g that were much lower than MRLs. The percent recovery obtained from the method was 78.58 and 90.19% for α-endosulfan and bifenthrin, respectively. The precision of the analysis method for both analytes were good since the % RSD values were below than the Horwitz’s value that was 19.18% at spiking level concentration of 300 ng/g.</jats:p
Analytical Method Development for Bisphenol a in Tuna by Using High Performance Liquid Chromatography-UV
No full textAbstractBisphenol A (BPA) detection in food has gained research interest in recent years. This attention is based on BPA characteristic, easy to migrate and potentially hazard for human, and their usage in many packaging products polluting food and environment. In this research, a reverse phase high liquid chromatography coupled with UV detector (HPLC-UV) was developed for determination BPA in tuna. The analytical method was validated based on the following criteria: linearity, precision, repeatability, limit detection, and recovery. Excellent linear correlation with R2 = 0.9992 was observed over the range of 2 to 250mg/kg. The detection limit was calculated to be 0.8mg/kg, while the limit of quantification (LOQ) value of the validated method was measured to be 1.5mg/kg. Intra-day and intermediate precision (RSD, %) were 3.42 and 3.50, respectively. Good recoveries of 89.84% with RSD% = 5.41 were obtained at level concentration 32mg/kg. The proposed method was found to be suitable and precised for the determination of BPA in tuna by using HPLC-UV
