Study On Timeliness Of PAHs Reference Materials And Solvent Effect Of Typical Organic Reference Materials

The application of organic reference materials(RM) is very important in the field of water resources investigation. It cannot guarantee the accuracy of the samples that people using the same ampoule of RM repeatedly and without thinking of the solvent effect of the apparatus have no clear understanding in timeliness and solvent effects of typical organic RM in many laboratories. The investigation of the timeliness in specific conditions is very meaningful for the selection and conservation of RM. The response value of the solute is different in the same concentration but various solvent. Solvent effect is still lack of systematic study on quantitative analysis of the chromatography. Improper selection of the solvent can lead to the abnormal of the chromatography response value and inaccuracy of samples.Take typical Semi-volatile organic RM"CATELOG#:PPH-10RPM,16 PAH-Mixture in Methanol"(USA) as study object, study on the timelines in the condition of -18℃stored, Agilent brown volumetric vial(2mL) kept. A gas chromatographic method with FID detector was applied for the determination of 16 components in different time. The condition of test was optimized and the graph showed a good linear relationship, RSD was between±5%. The research shows that the concentrations of each component were increased with the increasing of the storage time. The timeliness of the 16 PAHs was various between 35d(BghiP) and 115d(Chr). The analysis reason is the difference of boiling points between them and methanol. The larger the difference between the boiling points of every components and methanol, the larger the difference of the volatilization rate.Take RM: hexachlorobenzene, nitrobenzene, PCB28, fluazifop-butyl, fluazifop-p-butyl,γ-BHC as study objects of solvent effect in gas chromatography. Methanol, isooctane, hexane, cyclohexane, benzene, acetonitrile, petroleum ether were selected as typical solvents. The result indicates that the response value is different in various solvent. It differs little between weak polar solvents(isooctane, hexane, cyclohexane, petroleum ether)(<±5%), but differs large between strong polar solvents(methanol, acetonitrile) and weak polar solvents(16%~62%). When RM in weak polar substrate were diluted 50~100 times with strong polar solvents, the difference rely on the solvent. Generally, most of response value had little difference. It was showed that the response value is lower in methanol and acetonitrile. The reason is the difference polar of the solvents influence the response value of chromatography, the stronger the polar, the weaker the response. Take RM BaP as study object of solvent effect in liquid chromatography, take methanol and cyclohexane as solvent. The difference is smaller in response (4.76%). The research shows the solvent effect is weaker.