Suwansa-ard Siriwan, Kanatharana Proespichaya, Asawatreratanakul Punnee, Limsakul Chusak, Wongkittisuksa Booncharoen, Thavarungkul Panote
Biophysics Research Unit: Biosensors and Biocurrents, Prince of Songkla University, Hat Yai, Songkhla 90112, Thailand.
Biosens Bioelectron. 2005 Sep 15;21(3):445-54. doi: 10.1016/j.bios.2004.11.005. Epub 2004 Dec 21.
Two flow-injection biosensor systems using semi disposable enzyme reactor have been developed to determine carbamate pesticides in water samples. Acetylcholinesterase was immobilized on silica gel by covalent binding. pH and conductivity electrodes were used to detect the ionic change of the sample solution due to hydrolysis of acetylcholine. Carbamate pesticides inhibited acetylcholinesterase and the decrease in the enzyme activity was used to determine these pesticides. Parameters influencing the performance of the systems were optimized to be used in the inhibition procedure. Carbofuran and carbaryl were used to test these systems. Detection limits for the potentiometric and conductimetric systems were both at 10% inhibition corresponding to 0.02 and 0.3 ppm of carbofuran and carbaryl, respectively. Both systems also provided the same linear ranges, 0.02-8.0 ppm for carbofuran, and 0.3-10 ppm for carbaryl. The analysis of pesticides was done a few times before the reactor was disposed. Percentages of inhibition obtained from different reactors were reproducible, therefore, no recalibration was necessary when changing the reactor. The biosensors were used to analyze carbaryl in water samples from six wells in a vegetable growing area. Both systems could detect the presence of carbaryl in the samples and provided good recoveries of the added carbaryl, i.e., 80-106% for the potentiometric system and 75-105% for the conductimetric system. The presence of carbaryl in water samples analyzed by the biosensors was confirmed by gas chromatography-mass spectrometric system. These biosensors do not require any sample preconcentration and are suitable for detecting pesticides in real water samples.
已开发出两种使用半一次性酶反应器的流动注射生物传感器系统，用于测定水样中的氨基甲酸酯类农药。通过共价结合将乙酰胆碱酯酶固定在硅胶上。使用pH电极和电导率电极检测由于乙酰胆碱水解导致的样品溶液离子变化。氨基甲酸酯类农药抑制乙酰胆碱酯酶，利用酶活性的降低来测定这些农药。对影响系统性能的参数进行了优化，以便用于抑制过程。使用呋喃丹和西维因对这些系统进行测试。电位测定系统和电导测定系统的检测限均为10%抑制率，分别对应0.02 ppm的呋喃丹和0.3 ppm的西维因。两个系统还提供相同的线性范围，呋喃丹为0.02 - 8.0 ppm，西维因为0.3 - 10 ppm。在处置反应器之前对农药进行了几次分析。从不同反应器获得的抑制百分比具有可重复性，因此，更换反应器时无需重新校准。使用这些生物传感器分析了蔬菜种植区六口水井水样中的西维因。两个系统都能检测到样品中西维因的存在，并对添加的西维因具有良好的回收率，即电位测定系统为80 - 106%，电导测定系统为75 - 105%。通过气相色谱 - 质谱系统证实了生物传感器分析的水样中西维因的存在。这些生物传感器不需要任何样品预浓缩，适用于检测实际水样中的农药。
