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Purpose:Tounderstandtheprincipleofpetroleumdetermination.Tomasteroneofthesamplepretreatmentmethods,liquid-liquidextraction.TogetfamiliarwiththeoperationofUVandfluorescencespectrometers.2.10DeterminationofPetroleumWhatispetroleum?Hydrocarbonsofvariousmolecularweightsandotherorganiccompoundsfromcrudeoilandpetroleumproducts(Gasoline,kerosene,diesel,lubricant).DetectionMethods•Weighingmethod•Infraredspectroscopy•Gaschromatography•Ultravioletspectroscopy•FluorescencespectroscopyUVabsorptionspectrumofpetroleumSRMCyclohexaneasreferenceAlkenes(higherthan210nm)Aromatic(about254nm)Choose225nmAllthecompoundsabsorbing220-225nmlightswillbecountedaspetroleum–overestimatedExcitationandemissionspectraofpetroleumSRMexcitationwavelength280nmemissionwavelength345nmOnlythecompoundsabsorbingandemittingcertainlights(280/345nm)canbecountedaspetroleum–underestimatedExtractionLiquid-liquidextraction(LLE)Solidphaseextraction(SPE)Solidphasemicroextraction(SPME)Liquidphasemicroextraction(LPME)①振摇水样瓶后,用量筒量取100.0mL水样,倒入分液漏斗中。加入2mL1+1硫酸和2g氯化钠。②在小漏斗中塞入一团脱脂棉,加入适量无水硫酸钠。③用5mL环己烷清洗量筒,移入分液漏斗1。振荡萃取3min,静置分层。将下层的水相收集至分液漏斗2中,将上层环己烷倒入装有无水硫酸钠的小漏斗,流出漏斗的环己烷收集于25mL比色管中。④再取5mL环己烷,清洗分液漏斗1,并将环己烷转移至分液漏斗2,重复萃取一次,弃去水相,将上层环己烷倒入装有无水硫酸钠的小漏斗,即将两次的萃取液合并。⑤用适量环己烷淋洗装有无水硫酸钠的小漏斗,流出的环己烷与萃取液合并。用环己烷将萃取液定容到10mL。加入适量无水硫酸钠。此溶液将用于紫外分光光度法和荧光法的测定。配制工作曲线溶液:工作曲线及样品测定:1,仪器预热2,波长:紫外225nm,荧光激发280/290nm,发射345nm3,比色皿:石英,只用1个,溶液装满2/3,加盖子。4,每1组测定1条紫外工作曲线,每个同学1个样品。5,每6组测定1条荧光工作曲线,每个同学1个样品。Attention!!取样的量筒需要用环己烷清洗,清洗后的环己烷倒入分液漏斗1,用于第一次萃取。分液漏斗1需用环己烷清洗,清洗后的环己烷倒入分液漏斗2,用于第二次萃取。用环己烷淋洗装有无水硫酸钠的小漏斗。萃取液定容后,加无水硫酸钠脱水。小漏斗中的脱脂棉不宜过多。只有10mL试样,要用于两种仪器分析方法的测定!绘制工作曲线,不强求过原点(以环己烷为参比,工作曲线加入0.00mL标准油的溶液为样品)。萃取液回收!今天应该洗头洗澡!AdditionalQuestionsShouldthesolutionsofthecalibrationcurvebeextractedasthesamples?Andwhy?Discussthepossibledeviationanderrorofthisexperiment.
本文标题:矿物油的测定课堂PPT1
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