基于ISE的土壤硝态氮多参数检测仪研究

电极法检测土壤硝态氮时，共存氯离子是影响检测精度的重要因素。针对当前检测仪为单一离子离线检测的问题，设计了基于嵌入式开发的ISE土壤硝态氮多参数检测仪。仪器嵌入BP神经网络模型，实现土壤硝态氮的在线实时检测。针对BP算法收敛速度慢、易陷入局部极小值的缺点，采用5种方法进行改进；采用两个校正方法校准检测仪检测结果；采用稳定判断程序提高电势采集的稳定性。开展标准溶液检测试验，验证检测仪检测精度；开展土壤硝态氮检测试验，并将检测结果与传统的一元线性模型结果和光学法检测结果进行对比，验证检测仪排除氯离子干扰的效果及检测土壤硝态氮的准确性。结果表明，检测仪对离子的检测结果与离子计检测结果误差不超过1.0mV，满足精度要求；检测仪对土壤硝态氮含量的检测结果与光学法检测结果的平均相对误差为8.83%，低于一元线性模型与光学法检测结果的平均相对误差12.17%，拟合系数R2均大于0.97。基于ISE的土壤硝态氮多参数检测仪可有效减小氯离子干扰，准确性高，可用于土壤硝态氮的在线检测。     

利用高氯酸作为氟离子选择性电极法的新介质测定食品中的微量氟

对HCLO4作为新介质在氟离子选择性电极法中测定食品中的微量氟做了探索和研究。在0.35 MOL/L HCLO4介质中,氟离子浓度在1.0×10-2~1.0×10-6MOL/L范围内呈良好的线性关系,线性相关系数R=0.999 7。利用本法测定了牛奶、卷心菜中氟离子的含量,其结果与现有其他文献方法相当,但本法试验操作大为简化。测定的相对标准偏差在1.54%~2.30%之间。在该介质中测定微量氟操作简便、快速,具有较高的精密度和准确度。所以,HCLO4溶液可作为氟离子选择性电极的测定介质。     

土壤全氟含量测定方法的比较

应用氟离子选择电极测定土壤的全氟的含量,对标准曲线测定法、TISAB标准加入法和高氯酸标准加入法进行了比较. 结果表明,TISAB标准加入法的回收率最高,加标回收率在86.9%～102.3%之间,平均回收率达96.8%. 高氯酸标准加入法次之, 平均回收率为93.8%, 标准曲线测定方法平均回收率最低, 只有88.4%. 实测结果表明, 3种方法所得数据之间无显著差异, TISAB标准加入法和高氯酸标准加入法的测量结果较为接近, 但相比较而言, 后者试剂更为简单, 价廉, 更具实用性.     

铜席夫碱配合物中性载体水杨酸根离子电极的研究

报道了以Cu(Ⅱ)配合物为中性载体的PVC膜电极对水杨酸根(Sal-)具有优良的电位响应性能和选择性并呈现出反Hofmeister选择性行为,其选择性从大到小次序为Sal-,ClO4-,SCN-,I-,NO2-,Cl-,F-,Br-,H2PO4-.在pH=4.0的磷酸盐缓冲体系中,电极电位呈现近能斯特响应,线性响应范围为3.0×10-6～1.0×10-1 mol/L Sal-,斜率为-58.7 mV/dec(20℃),检测下限为1.5×10-6 mol/L.采用交流阻抗技术研究了电极的响应机理,结果表明,配合物中心金属原子的结构以及载体本身的结构与电极的响应行为之间有非常密切的构效关系.电极可用于药品分析.     

非参数估计用于离子选择电极多组分的测定

The calibration technique of nonparametric estimation combined with least squares is introduced, which can be used to quantify mixtures of analytes when the theoretical calibration model of a system is unknown or departs from the true behavior of the syst     

生长素促进拟南芥AtNRT1.1基因表达增强硝酸盐吸收

为研究生长素信号对植物硝酸盐营养吸收的调控作用,采用扫描离子选择电极技术 (SIET) 和实时荧光定量 PCR 技术(qRT-PCR),测定拟南芥野生型Col-0、生长素过表达突变体yuc1-D以及生长素通路缺失突变体axr1-12 3种株系初始根中硝酸根离子(NO-3)吸收速率以及硝酸盐转运蛋白基因AtNRT1.1表达量的差异,并进一步检测Col-0株系以及硝酸盐转运蛋白突变体nrt1.1株系在正常条件(CK)或施加外源IAA及生长素极性运输抑制剂2,3,5 三碘苯甲酸(TIBA)处理下的NO-3流速和AtNRT1.1基因表达量的差异。结果表明:yuc1 D株系的NO-3吸收速率以及AtNRT1.1基因表达量相比野生型均有大幅增加,而axr1-12株系的 NO-3吸收速率以及AtNRT1.1基因表达量相比野生型显著降低;在Col-0株系中施加外源IAA对NO-3吸收速率以及AtNRT1.1基因表达量有明显促进作用,而施加TIBA的效果反之,说明生长素对硝酸盐吸收有增强效应。nrt1.1株系在CK、IAA、TIBA处理下NO-3吸收速率差异较野生型不明显,揭示了AtNRT1.1基因在生长素促进硝酸盐吸收途径中所起的重要作用。      

Ion-Selective Electrode Offers Accurate,Inexpensive Method for Analyzing Soil Solution Nitrate in Remote Regions

Nitrogen (N) applied as fertilizer is subject to runoff and leaching. Nitrate (NO₃^?-N) concentrations in soil solution reflect the impacts of farm management on N cycling. Some of the most remote regions in the world are undergoing rapid land-use change, yet there are major barriers to conducting research in these locations. Fortunately, new tools such as ion-selective electrodes (ISEs) provide low-cost and simple methods for conducting chemical analysis in the field. Researchers compared soil solution NO₃^?-N concentrations measured using an ISE with concentrations measured on a colorimeter (cadmium reduction) and found good agreement (r² = 0.96, P < 0.0001) between the two methods. The ISE is also 66 times less expensive than in-country laboratory analysis or shipping and analyzing the samples in the United States. Thus, the ISE is an excellent tool for rapid analysis of N in soil solution, providing critical information on N dynamics in remote regions.     

Determination of arylsulphatase and phosphatase enzyme activities in soil using screen-printed electrodes modified with multi-walled carbon nanotubes

Sustainability of agricultural systems has become an important issue all over the world. The activity of enzymes is potentially an important quality bioindicator in soils. The aim of the present study was to develop a simple and convenient assay to determine the activity of arylsulphatase (AS), acid (ACP) and alkaline phosphatase (ALP) in agricultural soil. The activities of these enzymes were detected using a non-electroactive substrate, which produces an electroactive product. To this end, p-aminophenyl phosphate (pAPP) was used as a substrate which is converted to p-aminophenol (pAP) after enzymatic dephosphorylation; and 4-nitrocatechol sulphate (4-NCS) was used as a substrate for AS activity based on its catalytic effect on the hydrolysis of 4-NCS into 4-nitrocatechol (4-NC). The products of both enzymatic reactions were quantified on carbon-based screen-printed electrodes (SPCEs) modified with carbon nanotubes (CNTs), using Osteryoung square-wave voltammetry (OSWV). The determination of the reaction products allowed more sensitive determination of ALP, ACP and AS activities in soil than that obtained with a spectrophotometric method. This assay also diminishes the generation of waste, which is desirable in green analytical chemistry. The optimization of the analytical procedure in terms of the nature of electrode type, applied potential, pH of solution, and precision of measurements is reported.     

氧弹燃烧-氟离子选择电极法测定蔬菜中的氟

本试验建立了一种测定蔬菜中氟含量的新方法。蔬菜经氧弹燃烧处理后在一定浓度的高氯酸和柠檬酸钠的介质中利用氟离子选择性电极法测定其微量氟。菠菜、卷心菜、油菜、生菜、香麦、白菜中氟的测定结果表明,氟离子浓度为1.0×10-2~1.0×10-6mol/L范围内呈现良好线性关系,线性相关系数r为0.999 3,相对标准偏差(RSD)为0.93%~1.91%(n=6),不同添加水平中回收率均在96.4%~105.7%之间。