离子选择电极阵列测定土壤中硝态氮

土壤硝态氮反映土壤短期氮素供应水平,实时了解土壤硝态氮的含量为精准农业和农业面源污染防控提供支撑,因此,在线实时检测土壤硝态氮方法突破就显得十分迫切。土壤硝态氮中的硝酸根离子在土壤中的高水溶性和流动性为全固态硝酸根离子选择电极高敏感检测土壤中硝态氮提供了条件,固态硝态氮离子选择电极的离子选择膜反应硝酸根离子在被测溶液中的浓度。采用全固态硝酸根离子选择电极ELIT NO₃^-,且与温度电极和pH电极融合组成电极阵列对土壤饱和溶液中的硝酸根离子进行检测。设计了高输入阻抗运算放大电路对电极信号进行采集,并通过微处理控制蠕动泵完成土壤硝态氮待测溶液连续流动测定及实时传输结果。实验结果表明,电极响应时间≤15 s,斜率-51.63 mV/decade,线性范围10^-5~10^-2.2 mol/L,最低检测限10^-5.23 mol/L。相对标准差在0.78%~4.5%,加标回收率均在90.0%~110%。与紫外可见分光光度法测试结果相比,相关系数(R²)为0.9952,为土壤硝态氮在现场检测奠定技术基础。     

离子选择电极阵列测定土壤中硝态氮

土壤硝态氮反映土壤短期氮素供应水平,实时了解土壤硝态氮的含量为精准农业和农业面源污染防控提供支撑,因此,在线实时检测土壤硝态氮方法突破就显得十分迫切。土壤硝态氮中的硝酸根离子在土壤中的高水溶性和流动性为全固态硝酸根离子选择电极高敏感检测土壤中硝态氮提供了条件,固态硝态氮离子选择电极的离子选择膜反应硝酸根离子在被测溶液中的浓度。采用全固态硝酸根离子选择电极ELIT NO~-_3,且与温度电极和pH电极融合组成电极阵列对土壤饱和溶液中的硝酸根离子进行检测。设计了高输入阻抗运算放大电路对电极信号进行采集,并通过微处理控制蠕动泵完成土壤硝态氮待测溶液连续流动测定及实时传输结果。实验结果表明,电极响应时间≤15 s,斜率-51.63 mV/decade,线性范围10~(-5)～10~(-2.2) mol/L,最低检测限10~(-5.23) mol/L。相对标准差在0.78%～4.5%,加标回收率均在90.0%～110%。与紫外可见分光光度法测试结果相比,相关系数(R~2)为0.995 2,为土壤硝态氮在现场检测奠定技术基础。     

离子选择性电极快速测定植物中氟

氟离子选择电极测定植物中氟有灰化法,氧瓶燃烧法、氢氧化钠熔融法和酸浸提法等。这些方法分析时间长、操作繁琐,且均需加入TISAB(总离子强度缓冲溶液)使pH=5～5.5,以防止低pH值时生成HF缔合物和高pH值时OH的干扰。为了达到快速分析的目的,我们在pH≈1时,不加TISAB,用标准加入法直接测定植物中氟,每次测定只需约30min。方法的精密度与准确度较好,分析结果与盐酸浸提法结果无     

保存、分析方法等因素对土壤中硝态氮测定的影响

为探明土壤中硝态氮测定的影响因素,采用黑土、潮土、红壤为材料,研究样品的保存方法、浸提剂种类、分析方法、实验用水及试剂纯度对土壤中硝态氮测定的影响。结果表明,测定土壤硝态氮时,土样在冷冻条件下保存优于冷藏条件。冷冻条件下保存可在45 d内完成测试,而冷藏保存则需在7 d内完成测试。采用0.01 mol/L CaCl2和2 mol/L KCl为浸提剂时,对土壤中硝态氮的测定结果无显著差异。紫外比色法的测定结果与林业标准法(LY/T1230-1999)相比无显著差异,但显著高于流动注射法,且紫外比色法与流动注射法之间有显著相关性。流动注射法的测定结果与林业标准法相比也无显著差异。实验用水的杂质可使土壤中硝态氮的测定结果显著偏高,对其进行加热煮沸、蒸馏及无氨化蒸馏后可显著降低水中杂质的含量。     

离子选择电极测定金的评述

综述了1976至1987年期间有关金离子选择电极的研究极道,引用文献39篇。     

离子选择电极测定环境样品中铅

1 引言 铅的测定多用原子吸收分光光度法和双疏腙比色法,这两种方法虽灵敏度高,但前者仪器昂贵,后者重现性差、操作繁琐、试剂不稳定、毒性大。我们用铅离子选择电极测定了几个环境样品中的铅,方法简便快速,结果与原子吸收分光光度法相符。     

离子选择电极分析法测定聚乙烯中氟

提出了一种新的离子选择性电极分析方法,即体积校正-等电位差-标准加入法,并用于聚乙烯中氟含量的测定。对样品干法灰化条件进行了考查。有机化合物标样回收率为98.0％,聚乙烯分析结果的相对标准偏差为1.6％。方法简便、准确。     

A calixarene-based ion-selective electrode for thallium(I) detection

Three new calixarene Tl⁺ ionophores have been utilized in Tl⁺ ion-selective electrodes (ISEs) yielding Nernstian response in the concentration range of 10⁻²–10⁻⁶ M TlNO₃ with a non-optimized filling solution in a conventional liquid contact ISE configuration. The complex formation constants (log β_IL) for two of the calixarene derivatives with thallium(I) (i.e. 6.44 and 5.85) were measured using the sandwich membrane technique, with the other ionophore immeasurable due to eventual precipitation of the ionophore during these long-term experiments. Furthermore, the unbiased selectivity coefficients for these ionophores displayed excellent selectivity against Zn²⁺, Ca²⁺, Ba²⁺, Cu²⁺, Cd²⁺ and Al³⁺ with moderate selectivity against Pb²⁺, Li⁺, Na⁺, H⁺, K⁺, NH₄⁺ and Cs⁺, noting that silver was the only significant interferent with these calixarene-based ionophores. When optimizing the filling solution in a liquid contact ISE, it was possible to achieve a lower limit of detection of approximately 8 nM according to the IUPAC definition. Last, the new ionophores were also evaluated in four solid-contact (SC) designs leading to Nernstian response, with the best response noted with a SC electrode utilizing a gold substrate, a poly(3-octylthiophene) (POT) ion-to-electron transducer and a poly(methyl methacrylate)–poly(decyl methacrylate) (PMMA–PDMA) co-polymer membrane. This electrode exhibited a slope of 58.4 mV decade⁻¹ and a lower detection limit of 30.2 nM. Due to the presence of an undesirable water layer and/or leaching of redox mediator from the graphite redox buffered SC, a coated wire electrode on gold and graphite redox buffered SC yielded grossly inferior detection limits against the polypyrrole/PVC SC and POT/PMMA–PDMA SC ISEs that did not display signs of a water layer or leaching of SC ingredients into the membrane.     

新型全固态丁卡因选择电极的研究

改进了以脲醛树脂为框架以KCl为活性物质的全固态Ag/AgCl参比电极。以改进后的Ag/AgCl电极为基体,以丁卡因 四苯硼酸根离子缔合物为活性物质,研制了一种新型全固态丁卡因选择性电极,并对此电极的性质进行了研究。该电极的适用范围为pH3.0～6.5,线性范围为5×10-5～5×10-2mol/L,检测下限为2.2×10-5mol/L。该电极能用于盐酸丁卡因的含量测定。     

Thin layer coulometric determination of nitrate in fresh waters

A nitrate ion-selective electrode (ISE) employing a permeable tubular membrane impregnated with a conventional ISE cocktail has been used successfully in the coulometric analysis of nitrate in fresh waters. The liquid ISE membrane comprising a nitrate ionophore [tridodecylmethylammonium nitrate (TDMAN)], lipophilic electrolyte [tetradodecyl-ammoniumtetrakis(4-chlorophenyl)borate (ETH 500)] and plasticizer [bis(3-ethyl-hexyl)sebacate (DOS)] was supported on a porous polypropylene tube. Coulometric analysis with the tubular membrane ISE showed that nitrate could be detected in the range 10–100 μM with a precision of 2.3% relative standard deviation (RSD), limit of detection of 1.1 μM and relative accuracy of 4.4% compared to a certified reference material (CRM) Lake sample.     

Determination of phosphate in hydroponic nutrient solutions using flow injection potentiometry and a cobalt-wire phosphate ion-selective electrode

The direct flow injection potentiometric (FIP) analysis of phosphate in hydroponic nutrient solution has been carried out using a cobalt-wire ion-selective electrode (ISE). Synthetic hydroponic nutrient solution, commercial hydroponic nutrient solution and working hydroponic farm nutrient solution were analysed for phosphate using the FIP technique. It is shown that FIP results compare favourably to standard methods of analysis such as spectrophotometry and indirect photometric ion-pair chromatography. Reproducible FIP response curves with a slope of −(47.57±0.03) mV per decade and intercept of −(169.7±0.1) mV were obtained for four separate calibrations in the concentration range 5.0×10⁻⁴–1.0×10⁻² M H₂PO₄⁻. Anion corrections for interferences by Cl⁻, NO₃⁻ and SO₄²⁻ were applied to all samples using the selectivity coefficients determined independently using a fixed interference method. Nevertheless, it was found that anion corrections were not necessary, as the deviations fell within the bounds of experimental error for the cobalt-wire ISE technique (i.e.±2–5% R.S.D.). The proposed FIP method enables the direct determination of phosphate in hydroponic nutrient solutions.     

镉柱还原光度法测定海水中的硝酸盐氮

将纯镉柱还原法与流动注射技术和分光光度法相结合,建立了一种快速测定海水样品中硝酸盐氮含量的方法。用粒径为2～5 mm的镉粒填装有效柱长为10 cm的镉柱,在停留时间为480s,温度为20～35℃,pH2.5～3.0条件下,还原效率可稳定在95％以上,且测定结果不受海水中主要共存离子的影响。方法对硝酸盐氮的测定范围为0～...     

Carbon nanotube composite PVC coated stainless steel disc electrode for detection of Ga(III)

This study demonstrates the application of the composite of multi-walled carbon nanotube polyvinylchloride (MWCNT-PVC) based on Bismarck Brown R for gallium sensor. MWCNT has a role to enhance the hydrophobicity of the membrane, which leads to a more stable potential signal. In addition by applying polypyrrol on the surface of this sensor a reduction in the drift of potential occurred and equilibrium potential was achieved faster. Compared to previous studies, using a stainless steel disc instead of a wire electrode causes to obtain an easily and more homogeneous coated electrode. The sensor shows a good Nernstian slope of 19.70?±?0.37?mV?decade^?1 in a wide linear range concentration of 1.0?×?10^?7 to 1.0?×?10^?2?M of Ga(NO₃)₃. The detection limit of this electrode was 7.7?×?10^?8?M of Ga(NO₃)₃. This proposed sensor is applicable in a wide pH range of 2 to 8. It has a short response time of about 8?s and has a good selectivity over twenty four various metal ions. The practical analytical utility of this electrode is demonstrated by measurement of Ga(III) in rock and different water samples.