ABSTRACT
Objective: To establish an electrochemical method for the determination of phenol. Methods: An electrochemical workstation with three electrodes system was used with glassy carbon electrode as working electrode, Ag/AgCl as reference electrode and Pt as counter electrode. Cyclic voltammetry and differential pulse voltammetry were used for the determination of phenol. Results:Under the condition of 4% Na2SO4as the supporting electrolyte, phenol showed an obvious oxidation peak on the glassy carbon elec-trode. The peak current increased linearly with the concentration of phenol within the range of 0. 8 μg·ml-1-10. 2 μg·ml-1( r=0. 997 5). The lower limit of detection was 0. 20 μg·ml-1. The average recovery was 101. 2% (RSD=2. 2% , n=6). Conclusion:The method is simple and accurate, and can be used for the determination of phenol.
ABSTRACT
Objective:To establish a GC-MS method for determing 19 organochlorine pesticide residues in sargassum fusiforme. Methods:Nineteen organochlorine pesticide residues were simultaneously determined by GC-MS, and the established method was vali-dated. The HP-5 gas chromatography column (30 m × 0. 25 mm,0. 25 μm) was used. The column temperature was programming in-creased with initial temperature of 70℃, maintaining for 1min, then raising to 180℃ with a rate of 15℃·min-1 ,and then raised to 280℃ with a rate of 4℃·min-1 to keep 7min. The inlet temperature was 240℃. The MS detector was used with EI source at 230℃, and analysis mode was multiple reaction monitoring. Results:Sargassum fusiforme was analyzed. The separation degree of the standard and samples met the requirements. The recoveries of the organochlorine pesticides were 72%-127% except for hexachlorobenzene, and the relative standard deviation also met the requirements. The experimental results showed that the 19 organochlorine pesticides were not detected out in sargassum fusiforme. Conclusion: The method provides the technical parameters for the determination of organo-chlorine pesticide residues in sargassum fusiforme.
ABSTRACT
Objective: To compare the inclusion rate of menthol with β-cyclodextrin (β-CD) from different sources.Methods: β-Cyclodextrin-menthol inclusion complexes were prepared by a grinding method.The inclusion compound was verified by thin layer chromatography (TLC), powder X-ray diffraction (PXRD) and gas chromatography (GC).The optimized conditions of PXRD were as follows: the graphite monochromator was Cu Kα, the voltage was 40 kV, the current was 40 mA, the 2θ scanning range was from 3° to 35°, the scanning step was 0.02° and the scanning rate was 5°·min-1.The optimized conditions of GC were as follows: an Agilent DB-wax capillary column, the column temperature was 120°, the inlet temperature was 250°, the detector temperature was 250° and the split ratio was 10∶1.Results: The results of TLC and PXRD proved the formation of inclusion complexes.The inclusion rate of menthol with β-CD from home and abroad was 25% and 47.9%, respectively.Conclusion: The method is simple, accurate and rapid, which can be used to determine the inclusion rate of β-CD from different sources.The results show that the inclusion effect of imported β-CD is better than that of domestic β-CD.
ABSTRACT
Objective:To establish a GC method for the determination of metacresol. Methods:The separation was performed on an Agilent DB-225 MS column (30 m × 0. 25 mm,0. 25 μm). The initial column temperature was set at 90℃,maintained 10 min, raised to120℃ with a rate of 2℃·min-1 ,and then raised to 150℃ with a rate of 10℃·min-1 and maintained for 5 min. The inlet temperature was 200℃. The detector was a flame ionization detector (FID) and the temperature was 250℃. The flow rate was 1. 8 ml ·min-1 split ratio was 1∶30 and the carrier gas was nitrogen. Results:The linear range was 0. 6-1. 8 mg·ml-1 . The average recovery was 96. 0% (RSD=2. 6%,n=9). The content of 3 batches of the samples was 99. 3%, 98. 7% and 98. 4%, respectively. Conclu-sion:The established quantitative analysis method is applicable in the quality control of metacresol.