研究构建了一种新型、高灵敏性和高选择性的电化学传感器,结合差分脉冲溶出伏安法快速检测茶叶样品中的痕量铅。采用超传导性粘结剂离子液体1-丁基-3-甲基咪唑六氟磷酸盐（[BMIM]PF6）和功能化的多壁碳纳米管（MWCNTs）修饰丝网印刷碳电极,提高了电极表面的导电性和信号转换。在含0.006mol/L I–, pH4.5的NaAc-HAc缓冲液中,Pb2+在–1.1V沉积电位下吸附于MWCNTs-IL-SPCE膜上,当正电压扫过时,铅氧化溶出,在–0.30V下出现一个很好的溶出峰,低浓度的I¯明显增强了铅的溶出峰电流。溶出峰高值与Pb2+浓度在2~600μg/L范围内呈线性关系,相关系数为0.99926,检测限为0.63μg/L。试验结果与ICP-MS测定值进行t检验,无显著性差异。该方法灵敏、稳定,可用于茶叶中痕量铅简单、经济的检测。
A new, high sensitivity and selectivity electrochemical sensor for determination of trace lead in tea by differential pulse stripping voltammetry was investigated. For modification of the screen-printed carbon electrode, 1-butyl-3-methylimidazolium hexafluorophosphate was applied as a super conductive binder and multi-walled carbon nanotubes were used after being functionalized. They improved the conductivity and signal transduction of electrode surface. In pH4.5 NaAc-HAc buffer containing 0.006mol/L I¯, Pb2+ adsorbed onto the surface of MWCNTs-IL film coated SPCE at the deposition potential of –1.1V. During the positive potential sweep, lead was oxidized, and a good stripping peak appeared at –0.30V. Low concentration of I¯ significantly enhanced the stripping peak current of lead. The liner relationship between stripping peak value and concentration of Pb2+ was in the range of 2~600μg/L with the R value of 0.99926 and detection limit of 0.63μg/L. No significant difference existed after the detection results were compared with ICP-MS method using t test. The high sensitivity and stability of this method demonstrated the application for a simple and economical determination of trace lead in tea.
[1] Chung FL, Schwartz J, Herzog CR, et al. Tea and cancer prevention: studies in animals and humans[J]. The Journal of Nutrition, 2003(133): 3268S-3274S.
[2] Hirano R, Momiyama Y, Takahashi R, et al. Comparison of green tea intake in Japanese patients with and without angiographic coronary artery disease[J]. The American Journal of Cardiology, 2002(90): 1150-1153.
[3] Yang CS, Chung JY, Yang GY, et al. Tea and tea polyphenols in cancer prevention[J]. The Journal of Nutrition, 2000(130): 472S-478S.
[4] Jin CW, Zheng SJ, He YF, et al. Lead contamination in tea garden soils and factors affecting its bioavailability[J]. Chemosphere, 2005(59): 1151-1159.
[5] Jin CW, He YF, Zhang K, et al. Lead contamination in tea leaves and non-edaphic factors affecting it[J]. Chemosphere, 2005(61): 726-732.
[6] 石元值, 马立峰, 韩文炎, 等. 浙江省茶园中铅元素含量现状研究[J]. 茶叶科学, 2003, 23(2): 163-166.
[7] Han WY, Zhao FJ, Shi YZ, et al. Scale and causes of lead contamination in Chinese tea[J]. Environmental Pollution, 2006(139): 125-132.
[8] Gunasingham H, Dalangin RR.Anodic stripping voltammetry of lead using a copper-mercury film electrode[J]. Analytica Chimica Acta, 1991(246): 309-313.
[9] Zen JM, Huang SY.Square-wave voltammetric determination of lead(Ⅱ) with a Nafion/2,2-bipyridyl mercury film electrode[J]. Analytica Chimica Acta, 1994(296): 77-86.
[10] Carapuca HM, Monterroso SCC, Rocha LS, et al. Simultaneous determination of copper and lead in seawater using optimised thin-mercury film electrodes in situ plated in thiocyanate media[J]. Talanta, 2004(64): 566-569.
[11] Ghiaci M, Rezaei B, Kalbasi RJ.High selective SiO2-Al2O3 mixed-oxide modified carbon paste electrode for anodic stripping voltammetric determination of Pb[J]. Talanta, 2007(73): 37-45.
[12] Somerset V, Iwuoha E, Hernandez L.Stripping voltammetric measurement of trace metal ions at screen-printed carbon and carbon paste electrodes[J]. Procedia Chemistry, 2009(1): 1279-1282.
[13] Senthilkumar S, Saraswathi R.Electrochemical sensing of cadmium and lead ions at zeolite-modified electrodes: optimization and field measurements[J]. Sensors and Actuators B, 2009(141): 65-75.
[14] El Mhammedi MA, Achak M, Chtaini A.Ca10(PO4)6, 2009(161): 55-61.
[15] Rao GP, Lu C, Su F.Sorption of divalent metal ions from aqueous solution by carbon nanotubes: A review[J]. Separation and Purification Technology, 2007(58): 224-231.
[16] Rozniecka E, Shul G, Sirieix-Plenet J, et al. Electroactive ceramic carbon electrode modified with ionic liquid[J]. Electrochemistry Communications, 2005(7): 299-304.
[17] Khani H, Rofouei MK, Arab P, et al. Multi-walled carbon nanotubes-ionic liquid-carbon paste electrode as a super selectivity sensor: Application to potentiometric monitoring of mercury ion[J]. Journal of Hazardous Materials, 2010(183): 402-409.
[18] Wu K, Hu S, Fei J, et al. Mercury-free simultaneous determination of cadmium and lead at a glassy carbon electrode modified with multi-wall carbon nanotubes[J]. Analytica Chimica Acta, 2003(489): 215-221.
[19] 梁逸曾, 俞汝勤. 化学计量学[M]. 北京: 高等教育出版社, 2003: 116-185.
[20] 张虹. 加标回收率的测定和结果判断[J]. 石油与天然气化工, 2000, 29(1): 50-52.
浙公网安备 33019902000101号 
