热焓法测定亚硝酸根的研究

本文以对氨基苯磺酸与亚硝酸在酸性条件下重氮化的放热反应为基础，通过测定孤立体系中的温度变化，建立起亚硝酸根的热焓分析方法，该方法在０．０３５－０．２３０ｍｇ／ｍｌ范围内可准确测定ＮＯ＾－２的含量，相对标准偏差小于１．３６％，平均相对误差小于０．７２％，最低检限为０．０３５ｍｇ／ｍｌ。     

二甲苯蓝FF分光光度法测定微量亚硝酸根

研究了在稀盐酸介质中微量亚硝酸根与二甲苯蓝ＦＦ发生的亚硝化反应，建立了测定微亚硝酸极的新方法，方法的线性范围为０．２×１０＾－６～１５×１０＾－６ｇ／２５ｍｌＮＯ＾－２其Ｓａｎｄｅｌｌ灵敏度为９．１５×１０＾－１０ｇ／ｃｍ＾２，方法已用于水微量亚硝酸根的测定，并对反应机理进行了初步探讨。     

溴酸钾氧化酸性品红催化光度法测定亚硝酸根

研究了在强酸介质中亚硝酸根催化溴钾氧化酸性品红的褪色反应及其动力学条件，建立了高灵敏测定痕量亚硝酸根的新催化光度法。方法灵敏度为３．７×１０＾－１１ｇ／ｃｍ＾２亚硝酸态氮，线性范围为０．０６－０．４２μｇ／１０ｍＬ，用于测定唾液及硝钾中亚硝酸根。     

溴酸钾氧化中性红催化光度法测定NO-2的研究

研究了盐酸介质中,痕量亚硝酸根催化溴酸钾氧化中性红褪色反应及其动力学条件,建立了催化动力学光度法测定痕量亚硝酸根的新方法,ＮＯ＾－２的测定线性范围为１－７μｇ／２５ｍｌ,检出限为１．５＊１０＾－８ｇ．ｍｌ＾－１。用于化学试剂及唾液中痕量ＮＯ＾－２的测定,结果满意。     

基于亚硝化反应吖啶红极谱法测定亚硝酸根

研究了在稀盐酸介质中吖啶红与亚硝酸根发生亚硝化反应,建立了极谱法测定亚硝酸根的新方法。反应产物的２．５次微分波的峰谷电位为－０．４９Ｖ,亚硝酸根浓度在０．０２－０．６μｇ．ｍｌ＾－１范围内与峰高呈线性关系,检出限为６．２＊１０＾－３μｇ．ｍｌ＾－１。相对标准偏差为１．８４％,用于测定环境水样中亚硝酸根,结果满意。     

催化光度法测定肉制品中亚硝酸盐

基于亚硝酸根在稀磷酸溶液中催化文思蓝－氰钾氧化还原反应,建立了微量ＮＯ＾－２的催化光度法。在最大吸收波长６１０ｎｍ处,ＮＯ＾－２在０－３．０μｇ／２５ｍｌ范围内呈线性关系,检出下限为３．５１＊１０＾－９ｇ．ｍｌ＾－１。方法用于肉制品中ＮＯ＾－２的测定。结果满意,且与国家标准方法结果相符。     

光化学反应在流动注射分析中的应用研究：Ⅴ.硝酸根—鲁米诺光化学…

基于紫外光照射下硝酸根能够转化生成过氧化亚硝酸酯及过氧化亚硝酸酯氧化鲁米诺而产生化学发发光，建立了流动注射光化学反应测定痕量硝酸根的新方法，测定硝酸根的线性范围是５×１０＾－８－１×１０＾－４ｍｏｌ／Ｌ，进样频率为６０－８０次／ｈ。     

动力学催化光度法测定痕量亚硝酸根

磷酸和棉红在１００℃下反应生成天蓝色物质（λｍａｘ＝６７５ｎｍ）,该物质在痕量亚硝酸根的催化下被ＫＢｒＯ３氧化褪色,研究了反应的条件,测定了动力学参数,建立了测定痕量亚硝酸根的方法,方法检出限是４＊１０＾－１０ｇ／ｍＬ,测定范围是０．４０－２０．００μｇ／Ｌ,用于水体中痕量亚硝酸根的测定,结果满意。     

溴酸钾氧化亮绿SF催化光度法测定痕量亚硝酸根

本文基于亚硝酸根对溴酸钾氧化亮绿ＳＦ而使其褪色所起的催化作用，建立了高灵敏度催化吸光光度法测定痕量亚硝酸根的新方法，测定范围为０．０５－２０ｎｇ／ｍｌ，用于不同水样中亚硝酸根的测定，获得了满意结果。     

催化光度法测定痕量亚硝酸根的研究：溴酸钾—维多利亚蓝B …

基于在稀磷酸介质中，亚硝酸根在溴酸钾氧化维多利亚蓝Ｂ反应具有催化作用，建立了测定痕量亚硝酸根的新催化光度法，方法的检出限为２．５×１０＾－９ｇ．ｍｌ＾－１，线性范围为７．４～１４８ｎｇ．ｍｌ＾－１，回收率为９６％～１０３％，用于地面水及地下水的测定，结果满意。     

A simple simultaneous flow injection method based on phosphomolybdenum chemistry for nitrate and nitrite determinations in water and fish samples

A direct spectrophotometric flow injection method for the simultaneous determination of nitrite and nitrate has been developed. The method is based on the oxidation of a phosphomolybdenum blue complex by the addition of nitrite and the decrease in absorbance of the blue complex is monitored at 820 nm. The injected sample is split into two segments. One of the streams was directly reacted with the above reagent and detected as nitrite. The other stream was passed through a copperised cadmium reductor column where reduction of nitrate to nitrite occurs, and the sample was then mixed with the reagent and passed through the cell of the spectrophotometer to be detected as nitrite plus nitrate. The conditions for the flow injection manifold parameters were optimised by experimental design and the concentration of nitrite and nitrate was determined in the linear range from 0.05 to 1.15 mug ml(-1) nitrite and 0.06 to 1.6 mug ml(-1) nitrate with a detection limit of 0.01 mug ml(-1) for nitrite and 0.025 mug ml(-1) for nitrate. The method is suitable for the simultaneous determination of nitrite and nitrate in fish and water samples with a sampling rate of 25+/-2 sample per hour.     

Effect of surfactants on the determination of nitrite and nitrate in water samples

Summary The effect of four surfactants on the determination of nitrite and nitrate has been examined. The method which has been tested for nitrite is based on the formation of an azodye. The results show that cationic and non-ionic surfactants do not interfere with the determination of nitrite while anionic surfactants cause significant interferences, which could be eliminated by treating the water samples with a cationic surfactant.Two methods have been tested for the determination of nitrate in the presence of surfactants. One method is based on the nitration of salicyclic acid, while the other is based on the reduction of nitrate to nitrite. Results for the first method show that the non-ionic surfactant Triton-X causes significant interferences. Cationic and anionic surfactants do not interfere, when their concentration is relatively low. For higher concentrations an increasing interference is observed. Results for the second method show effects similar to those obtained for nitrite.

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Wirkung oberflächenaktiver Substanzen auf die Bestimmung von Nitrit und Nitrat in Wasserproben

     

药物中亚硝酸根的流动注射催化光度法分析

以亚硝酸根催化溴酸钾在磷酸介质中氧化维多利亚天蓝Ｂ褪色为指示反应，建立了反相流动注射催化光度法测定痕量亚硝酸根的新方法。本法操作简单、快速，灵敏度高，测定亚酸根的线性范围为２￣８０μｇ／Ｌ，直接用于含硝酸内服药和针剂中亚硝酸根的测定，与α－萘胺比色法对照结果一致。     

Fluorimetric Determination of Nitrate

Abstract

A sensitive fluorimetric method has been developed for the determination of nitrate based on the reduction of nitrate to nitrite with hydrazine sulfate and the subsequent determination of the nitrite formed with 2, 3-diaminonaphthalene. Solvent effect on fluorescence intensity, optimum reaction conditions, and sensitivity of the method are discussed.     

Error sources in simultaneous nitrate/nitrite determinations using copperised cadmium as nitrate reducing agent

The accuracy of the nitrate determination by the standard method, based on the reduction of nitrate to nitrite on copperised cadmium, has been found to be highly dependent on an overreduction of nitrite, if present in the sample. Using FIA, based on a two sample-loops injector and one detector, the influence of the pH value of the carrier and the contact time of the sample plug with the reducing agent on the further reduction of nitrite, have been studied in detail and optimised to a contact time of 20 s and a pH value of 9.5.     

Flow-injection analysis of nitrate by reduction to nitrite and gas-phase molecular absorption spectrometry

Two flow-injection manifolds have been investigated for the determination of nitrate. These manifolds are based on the reduction of nitrate to nitrite and determination of nitrite by gas-phase molecular absorption spectrophotometry. Nitrate sample solution (300 microL) which is injected to the flow line, is reduced to nitrite by reaction with hydrazine or passage through the on-line copperized cadmium (Cd-Cu) reduction column. The nitrite produced reacts with a stream of hydrochloric acid and the evolved gases are purged into the stream of O2 carrier gas. The gaseous phase is separated from the liquid phase using a gas-liquid separator and then swept into a flow-through cell which has been positioned in the cell compartment of an UV-visible spectrophotometer. The absorbance of the gaseous phase is measured at 204.7 nm. A linear relationship was obtained between the intensity of absorption signals and concentration of nitrate when Cd-Cu reduction method was used, but a logarithmic relationship was obtained when the hydrazine reduction method was used. By use of the Cd-Cu reduction method, up to 330 microg of nitrate was determined. The limit of detection was 2.97 microg nitrate and the relative standard deviations for the determination of 12.0, 30.0 and 150 microg nitrate were 3.32, 3.87 and 3.6%, respectively. Maximum sampling rate was approximately 30 samples per hour. The Cd-Cu reduction method was applied to the determination of nitrate and the simultaneous determination of nitrate and nitrite in meat products, vegetables, urine, and a water sample.     

基于量子点增敏化学发光同时测定尿液中的亚硝酸盐和硝酸盐

采用铜镉柱还原硝酸盐,与CdTe量子点增敏过氧亚硝酸-碳酸钠体系的化学发光信号相结合,开发了快速在线同时分析亚硝酸盐和硝酸盐的新方法.对流动注射、化学发光等实验参数条件进行优化,在Na2CO3的浓度为0.2 M、H2O2的浓度为0.03 M、Na2EDTA的浓度为1×10-3 M、CdTe量子点粒径为2.84 nm的条件下,过氧亚硝酸-碳酸钠体系可以获得最优的化学发光信号.该方法检测亚硝酸盐的线性范围为0.3~75μM,检测限可达0.12μM,其相对标准偏差为1.9%;硝酸盐的线性范围为1.0~100μM,检测限可达0.26μM,其相对标准偏差为1.5%.此方法无需衍生和分离,可以实现同时、准确、快速和高选择性地检测人体尿液中亚硝酸盐和硝酸盐的含量,回收率分别为94%~105%和96.6%~110.4%.     

Liquid chromatographic determination of residual nitrite/nitrate in foods: NMKL collaborative study

Nitrite and nitrate are used as additives in the food industry to provide color and taste and to control undesirable gas and flavor production by anaerobic bacteria by virtue of their antimicrobial properties. The analytical method that has been widely used to determine nitrite and nitrate involves the use of toxic cadmium. In response to a request from the Nordic Committee on Food Analysis, a study was performed to obtain an alternative chromatographic method to determine residual nitrite and nitrate in meat products. The study was done in 3 stages: (1) comparative evaluation of the performance of 3 liquid chromatographic methods, (2) internal validation of the selected ion chromatographic method, and (3) a collaborative study in which 17 laboratories from European countries participated. Furthermore, the applicability of the method to matrixes other than meat and meat products was demonstrated. The results of the collaborative study show that the European Prestandard prENV 12014-4 is well suited for the determination of nitrite and nitrate in different foods (e.g., meat products, vegetables, baby food, and cheese). The limits of detection for nitrite and nitrate ions are 1 and 10 mg/kg, respectively. Recoveries of residual nitrite/nitrate ranged from 96 to 108%. Repeatability and reproducibility were satisfactory.     

Simultaneous determination of nitrite and nitrate in human plasma by on-capillary preconcentration with field-amplified sample stacking

A simple method for the determination of nitrite and nitrate in human plasma has been developed using CZE with minimal sample preparation. Field‐amplified sample stacking (FASS) was used to achieve submicromolar detection by dilution of the plasma sample with deionized water. In CZE, the separation of nitrite and nitrate was achieved within 10 min without adding EOF modifier. The optimal condition was achieved with 50 mM phosphate buffer at pH 9.3. The ninefold diluted plasma samples were injected hydrodynamically for 40 s into a 60 cm×75 μm id uncoated fused‐silica capillary. The separation voltage was 20 kV (negative potential) and UV detection was performed at 214 nm. The linearity curves for nitrite and nitrate were obtained by the standard addition method. The estimated LODs for nitrite and nitrate in ninefold diluted plasma sample were 0.05 and 0.07 μM, respectively. The LODs for nitrite and nitrate in original plasma samples were 0.45 and 0.63 μM. The intra‐ and inter‐day precisions for both analytes were <2.6% and the recovery ranged between 92.3 and 113.3%. It was found that nitrite was more stable than nitrate in the plasma after the sample preparation. This proposed method was applied to a number of human plasma samples and the measured nitrite and nitrate concentrations in human plasma were consistent with the literature ranges.     

An automatic absorptiometric method for the determination of nitrate

A method has been developed for the determination of nitrate with the Technicon Autoanalyser in the range 2–10 p.p.m. The method depends on the reduction of nitrate to nitrite by hydrazine in alkaline solution, with copper as a catalyst. The nitrite produced diazotises sulphanilamide and the product is coupled with N-(1-naphthyl) ethylenediamine, to give a red dye, the absorbance of which is measured at 550 mμ. A relative standard deviation of 3–4% is obtained.