电感耦合等离子体发射光谱法测定E10乙醇汽油中的钠和锌

Determination of Sodium and Zinc in Ethanol Gasoline for Motor Vehicles(E10)by ICP-OES

车用乙醇汽油是一种新型、清洁的汽车燃料,在燃烧过程中,微量的重金属杂质对汽车的行驶和养护有着至关重要的影响,一些燃烧产物可能会污染环境,威胁人们的身体健康,因此有必要对其中的微量元素进行控制。以异辛烷稀释汽油样品,电感耦合等离子体发射光谱(ICP-OES)法测定车用E10乙醇汽油中钠、锌含量的方法,选择钠和锌的分析谱线分别为:589.592和213.857 nm,实验优化了雾化气流量和蠕动泵速率对信背比的影响,应用了半导体制冷雾化系统(雾化室温度设置为-10℃)降低了进样过程中溶液的挥发性,保证了等离子体的稳定性,同时,实验研究了稀释比、内标元素以及稀释剂的类型对测定结果的影响,结果表明:(1)在-10℃低温下选择航空煤油为稀释剂,钠和锌的回收率均在120%以上,Y内标比值均在1.20以上,异辛烷为稀释剂时回收率和内标比值均满足要求,可能是航空煤油在低温下的密度和黏度较大导致,得出低温条件下异辛烷比航空煤油更适合作为乙醇汽油的稀释剂;(2)当选择Co做为内标元素时,有些样品的内标元素比值在120%以上,Y为内标元素时,样品的内标元素比值均满足要求,可能是由于Co的稳定性较差或样品里含有Co,得出Y比Co元素更适合做为乙醇汽油的内标元素;(3)本方法的钠和锌元素的检出限分别为0.013和0.005 mg·kg^(-1),加标回收率为85.1%~106.0%,相对标准偏差(RSD,n=7)为1.0%~4.8%;(4)通过与微波消解-ICP-OES法进行比较,本方法的测定结果与加标理论值较接近,弥补了微波消解法元素易损失的缺点。此法具有快速、灵敏、准确的优点,可应用于乙醇汽油中钠和锌元素的监测。

Ethanol gasoline for motor vehicles(E10)is a new and clean automobile fuel.In the combustion process,trace heavy metal impurities have a crucial impact on the driving and maintenance of the car.Some combustion products may pollute the environment and threaten people’s health.Therefore,it is necessary to control the trace elements.The method with the direct dilution of isooctane was used to realize the quantitative determination of sodium and zinc in ethanol gasoline,The spectral lines of sodium and zinc were respectively 589.592 and 213.857 nm,the effects of atomization gas flow rate and peristaltic pump speed on the signal to back ratio were optimized.The semiconductor refrigeration atomization system(the temperature of the atomization chamber was set to -10℃)was applied to reduce the volatility of ethanol gasoline.At the same time,the effects of dilution ratio,standard internal elements and diluent types were studied.The results show that:(1)When kerosene was used as the diluent,the recoveries of sodium and zinc were above 120%,and the ratio of Y internal standard was above 1.20,When isooctane was used as the diluent,the recovery rate and standard internal ratio meet the requirements,which may be caused by the high density and viscosity of kerosene at low temperature,it was concluded that isooctane is more suitable as diluent;(2)When Co was selected as the standard internal element,the standard internal ratio of some samples was more than 120%,and when Y was the internal standard,the standard internal ratio meets the requirements,it may be due to the poor stability of Co or the presence of Co in the sample,Y was suitable.(3)The detection limits of sodium and zinc are 0.013 and 0.005 mg·kg^(-1) respectively.The method showed lower detection limits,and the recoveries ranged from 85.1%~106.0%.The relative standard deviation(RSD)was between 1.0% and 4.8%.(4)Compared with the microwave digestion method,the result of this method is close to the theoretical value,which makes up the disadvantage of the microwave digestion method.The results show that the method was rapid,sensitive and accurate,and it was suitable for the determination of sodium and zinc in ethanol gasoline.