离子色谱法检测生活饮水中硝酸盐和亚硝酸盐

利用抑制电导-离子色谱法测定"千沸水"、隔夜水、直饮水等生活饮用水中硝酸盐、亚硝酸盐。采用瑞士万通IC883型离子色谱仪同时测定硝酸盐和亚硝酸盐。硝酸盐的质量浓度为0.2～6.4 mg/L,R=0.99998,相对偏差0.789%,加标回收率为96.72%,仪器精密度为0.1%。亚硝酸盐的质量浓度为0.1～1.00 mg/L,R=0.9997,相对偏差1.904%,加标回收率为97.87%,仪器精密度0.7%。该方法具有灵敏度高、重复性好、准确度高、样品前处理操作简便的优点,适用于生活饮用水中亚硝酸盐和硝酸盐的检测。     

离子色谱法和分光光度法测定井水中硝酸盐氮和亚硝酸盐氮的对比

文中对比研究了离子色谱法和光度法测定农村井水中硝酸盐氮和亚硝酸盐氮。离子色谱法和光度法测定硝酸盐氮的检出限、精密度、加标回收率分别为0.014 mg/L、1.4%~4.9%、94%~106%和0.030 mg/L、1.6%~6.7%、98%~105%;离子色谱法和光度法测定亚硝酸盐氮的检出限、精密度、加标回收率分别为0.002 mg/L、1.4%~4.4%、90%~102%和0.004 mg/L、0.7%~3.6%、92%~104%。试验结果表明,离子色谱法的检出限低,而两种方法的精密度、准确度、t值检验无显著性差异,两种方法均满足日常监测要求。离子色谱法具有样品前处理过程简单,测定过程快速且可实现多种离子同时检测等优点,更利于对井水水质的检测分析。     

凯式定氮-离子色谱法测定香菇中二氧化硫

本方法采用凯式定氮法将香菇酸化蒸馏后,馏出液用1%过氧化氢溶液吸收,二氧化硫被过氧化氢溶液吸收并氧化生成硫酸根,吸收液过滤后用离子色谱法测定硫酸根浓度。该法前处理操作简单、快速,适合批量样品检测,实验结果表明:硫酸根离子浓度在2. 0～40. 0μg/m L范围内呈现良好的线性关系,相关系数r=0. 9993,检出限为0. 1mg/kg,定量限为0. 3mg/kg,RSD范围在3. 12%～6. 81%,加标回收率范围在82. 5%～92. 2%,可以准确测定香菇中二氧化硫的含量。     

离子色谱法测定牛肉中亚硝酸盐含量的不确定度评定

通过对酱卤肉制品牛肉中亚硝酸盐含量检测的不确定度评定,分析影响亚硝酸盐定量检测的相关因素。根据GB 5009.33-2016《食品中亚硝酸盐与硝酸盐的测定》中离子色谱法,按照JJF 1135-2005《化学分析测量不确定度评定》和JJF 1059.1-2012《测量不确定度评定与表示》中有关规定,建立测定亚硝酸盐不确定度数学模型,并对不确定度来源进行分析和评定。结果表明,当酱卤肉制品牛肉中亚硝酸盐含量为(32.3±4.0) mg/kg时,拓展不确定度为4.0 mg/kg (k=2)。不确定度主要来源为标准溶液配制。     

离子色谱法测定化妆品中的无机阴离子

采用离子色谱电导检测器对多种化妆品中的无机阴离子(F-,Cl-,NO2,Br-,NO-3,H2PO-4,SO2-4)进行测定,得到了上述7种阴离子的线性范围和相关系数,检出限分别为:0.004 mg/kg,0.007 mg/kg,0.021 mg/kg,0.032 mg/kg,0.003 mg/kg,0.781 mg/kg和0.075 mg/kg.结果表明:相关系数均达到0.9999以上,RSD均小于2%,样品加标回收率在96.3%～105.0%,样品中的共存离子对样品的测定无影响.     

离子色谱法测定氧化胺中的亚硝酸盐和硝酸盐

建立了测定氧化胺中亚硝酸盐和硝酸盐的离子色谱分析方法。样品使用IC-C18反相吸附柱和0.45μm的微孔水系滤膜处理后,经4.0 mmol/L Na2CO3和1.2 mmol/L Na HCO3混合淋洗液载入高性能阴离子专用色谱分析柱,并通过抑制型电导检测器检测。结果表明:NO2-和NO3-在质量浓度0.1~10.0 mg/L内线性关系良好,相关系数R20.999 9;检出限分别为0.035和0.028 mg/L;相对标准偏差(RSD,n=7)为0.46%~2.24%;回收率为94.3%~102.5%。该方法具有简便、快速、准确、高效的特点,灵敏度高,安全实用,满足工业分析的要求。     

固相萃取-离子色谱法测定土壤中三种有效阴离子

探讨离子色谱法测定土壤中PO43-、Br-、NO2-等有效阴离子的可行性以及相关的前处理方法。采用固相萃取技术处理土壤样品,应用离子色谱法测定土壤中的三种有效阴离子。多次重复测定标准物质PO43-、Br-、NO2-三种有效阴离子,验证方法可行性,测得峰面积的相对平均标准偏差分别为2.02%,0.67%,1.40%。测得土壤中PO43-、Br-、NO2-三种有效阴离子的检出限分别为0.1,1.0,1.0 mg/kg,平均回收率分别为97.82%,96.35%,97.82%。通过一定前处理方法,减少土壤中杂质对测定的干扰和对色谱柱的污染,优化了三种阴离子的色谱分离和测定条件,准确测定了土壤中三种阴离子含量。固相萃取-离子色谱法测定土壤中三种有效阴离子方法简便、快速、灵敏度高。     

离子色谱法测定奶粉中亚硝酸盐含量的优化

严格依据GB 5009.33-2016~([1])《食品安全国家标准食品中亚硝酸盐与硝酸盐测定》第一法离子色谱法测定奶粉中亚硝酸盐含量,回收率和准确率较低,通过研究比较不同的前处理方法,建立了采用C_(18)柱进行净化前处理,用紫外检测器检测奶粉中亚硝酸盐含量的离子色谱法。回归方程为y=1.7253x-0.0037,相关系数r=0.9997,RSD=4.65%,其加标回收率为91.7%～97.5%,提高了奶粉中亚硝酸盐的准确性。     

气相色谱法测定涂料和胶粘剂中游离甲醛含量

采用水性涂料、胶粘剂称样稀释至一定稀释倍数,吸取定量的样品溶液,加入一定体积pH=6的乙酰丙酮溶液加热显色后冷却至室温,采用乙酸乙酯萃取后稀释至规定刻度,气相色谱法检测,以3-亚甲基-2,4-戊二酮出峰时间定性、峰面积定量计算甲醛含量。研究结果表明:使用此方法测定涂料的检出限为0.6 mg/kg,胶粘剂的检出限为6 mg/kg;同一操作重复性≤1%,不同人及实验室的再现性为≤9%,可信度为99%;12个不同种类的样品加标检测后,加标回收率为93.6%～103.6%,认定本方法的准确性较高。     

非抑制型离子色谱法同时测定食盐中微量阴离子

建立了食盐中微量F-、NO2-、SO24-的非抑制型离子色谱检测方法。自制银离子交换树脂,将食盐溶液与银离子交换树脂混合,充分搅拌10～15 min后过滤,以3.0 mmol/L邻苯二甲酸氢钾为淋洗液,非抑制型离子色谱法电导检测器同时测定食盐中微量F-、NO2-、SO24-。F-、NO2-、SO24-的标准曲线范围分别为0～400、0～500、0～700μg/mL,相关系数0.9998以上,其检出限分别为0.028、0.029、8.27 ng/mL,相对标准偏差均小于5.0%,样品加标回收率为90%～103%。该方法灵敏度高,精密度好,线性范围宽,回收率高,适用于食盐中微量阴离子的检测。     

环保型蔬菜专用叶面肥配方研究及试验

介绍环保型蔬菜专用叶面肥配方设计的研究方法,提出了20个配方进行大田小区试验,优选出的配方经在蔬菜上施用后,产量增加,蔬菜中亚硝酸盐含量低于0.001mg/kg;根茎类蔬菜中硝酸盐含量低于198mg/kg,叶菜类蔬菜中硝酸盐含量低于50mg/kg,达到了无公害蔬菜的要求。     

共振光散射光谱法测定亚硝酸根的研究

基于在盐酸介质中,亚硝酸根与氨基苯磺酸发生重氮化反应,氨基苯磺酸共振光散射强度随亚硝酸根的加入量增加而明显降低的现象,建立了新的共振光散射法测定亚硝酸根的方法。该方法对亚硝酸根检测的线性范围为0.01～0.70？g/mL,检出限为7.2ng/mL（3σ）。该方法应用于自来水中亚硝酸根离子的测定,回收率为93.1%～105.7%。     

Impact of Exogenous Silicate Amendments on Nitrogen Metabolism in Wheat Seedlings Subjected to Arsenate Stress

We intended to investigate the response of arsenate on nitrogen metabolism in wheat seedlings and aimed to assess the efficacy of silicon amendments in modulating the metabolic disturbances caused by arsenate stress. The nitrogen metabolism of wheat cultivated in different levels of arsenate with or without silicate in a medium supplemented with modified Hoagland’s solution for 21 days was studied. Experimental design was completely randomized with different arsenate concentrations (0, 25, 50 and 100 μM) with or without 5 mM silicate. Arsenate treatment decreased growth along with decline in nitrate (NO3−) uptake and accumulation. Activities of nitrate reductase (NR), nitrite reductase (NiR), glutamine synthetase (GS) as well as glutamate synthase (GOGAT) were lowered in the test seedlings. Decline in nitrite (NO2−) and amino acid contents were also evident along with an enhancement in the accumulation of toxic ammonia. Silicate supplementation under arsenate stress however, improved growth, repaired the arsenate-induced effects leading to an enhancement in nitrate (NO3−) uptake and consequently improved nitrite (NO2−) and amino acid contents as well. The total and soluble nitrogen contents were enhanced along with enhancements in activities of enzymes associated with nitrate metabolism while ammonia accumulation was lowered. Results therefore, imply the involvement of exogenous silicon amendments in relieving the metabolic alterations in nitrogen metabolism caused by arsenate stress that enabled wheat seedlings to adapt under arsenate excess and eventually promoted plant growth.     

锡砷冶金物料中硝酸盐的直接电极电位法研究

采用离子选择性电极分析技术,在硫酸铝-硫酸银-硼酸-氨基磺酸离子强度剂体系中对锡酸钠、砷酸液等两种物料中的硝酸盐进行检测。用稀酸碱沉淀分离不大于0.80g锡酸根或25mg铁、锑、钙,200mg砷不产生干扰,硝酸盐浓度在3.23×10-5mol/L～1.61×10-2mol/L内电极响应符合能斯特方程式（斜率≥90%）,检测下限可达1.61×10-5mol/L,相对标准偏差（m=6,n=5～11）为1.44%～9.64%,加标回收率为86.0%～123.4%。     

几种蔬菜中亚硝酸盐含量的测定

用盐酸萘乙二胺比色法分别测定10种蔬菜中亚硝酸盐的含量,结果表明,在λ=538nm处,该络合物具有最大吸光度,在0～1μg·mL-1范围内,亚硝酸盐含量x(μg)与吸光度A之间具有良好的线性关系,其线性方程为y=0.0282x+0.0015,相关系数r=0.9997.从测定的芫荽等10种蔬菜当中,亚硝酸含量最高的为茄子...     

异养硝化菌的分离及脱氮特性研究

从活性污泥中分离得到异养硝化菌株Y1,该菌的最优硝化条件：C／N为9．6,温度为30％,初始pH为9．0,摇床转速为250r／min。在此条件下,初始浓度为152．88mg／L的氨氮经8h降解后浓度降低到4．02mg／L,硝化过程中未发现中间产物亚硝酸氮和硝酸氮积累。菌株Y．不仅具有异养硝化作用,还能以硝酸氮作为唯一氮源进行好氧反硝化作用,40h内对初始浓度为196mg／L的NO3--N降解率为99．05％。     

Nitrates and nitrites in homemade and industrial cheeses commercialized in the Southern region of Minas Gerais, Brazil

The evaluation of nitrate and nitrite in homemade and industrialized cheeses commercialized in the southern region of Minas Gerais State, was the aim of this work. In Brazil, the use of these additives is permitted at maximum levels of 50 mg/kg. The basis of the previously validated method is the quantitative reduction of nitrate to nitrite through cadmium column and spectrophotometric determination after nitrite diazotation with sulphanilic acid/alpha-naphtol reagent. From all samples analyzed, 38 (88.37%) showed neither a nitrate nor nitrite detectable content; 5 samples (11.63%) presented nitrate, 4 of them being above the tolerated level and only one (2.33%) showed detectable nitrite, however below the permissible limit. The majority of samples did not show nitrate or nitrite at detectable levels. However, though probably safe from a toxicological point of view, the results can implicate an increased risk of bacteriological contamination.     

煤系高岭土制备Fe-MCM-41介孔分子筛及其氨选择性催化还原NOx

以煤系高岭土、十六烷基三甲基溴化铵（CTAB）、硝酸铁等为原料,通过水热法合成不同Fe含量的六方介孔分子筛Fe-MCM-41。通过傅里叶变换红外光谱、N2吸附脱附、高分辨透射电子显微镜对催化剂进行表征,并以氨为还原剂研究其选择性催化还原NO活性以及反应条件（包括Fe掺量、反应温度、空速、氨氮比和O2浓度等）对催化性能的影响。结果表明,Fe成功进入MCM-41介孔材料的骨架内,Fe-MCM-41介孔分子筛BET比表面积为980.2～596.8 m2/g,孔容积为0.95～0.60 cm3/g,平均孔径在3.90～3.45 nm。随着铁掺杂量的增加,介孔结构的有序度下降。当n(Fe)/n(Si)=0.05、空速为5000 h?1,Fe-MCM-41催化剂在350 ℃反应时NO转化率最高,可达90.7%;且当氨氮比为1.1和O2含量为2.5%时,催化剂能保持较高的活性。     

曲利本兰分光光度法测定微量亚硝酸根

盐酸介质中,曲利本兰与NO2-反应后发生颜色变化,最大褪色波长位于600 nm,此波长处体系吸光度的降低与溶液中NO2-的浓度成正比,在0.04~1.2 mg/L NO2-范围内符合比耳定律,线性关系良好。方法具有较高的灵敏度,检测限为0.018 mg/L。共存物质的影响研究表明方法选择性好。用于环境水中微量NO2-的测定,结果满意。     

Determination of Mineral Oil-Saturated Hydrocarbons (MOSH) in Vegetable Oils by Large Scale Off-Line SPE Combined with GC-FID

A method based on an off-line large-scale solid phase extraction (SPE) approach combined with conventional gas chromatographic-flame ionization detection (GC-FID) was developed to determine the mineral oil-saturated hydrocarbons (MOSH) in vegetable oils. A large-scale SPE column loaded with 10 g of activated silica gel impregnated with 1% silver nitrate which was used to retain lipids and olefins in vegetable oils and the MOSH in the oil samples was eluted with hexane. Then 2 μL concentrated solution was splitlessly injected into a common GC-FID instrument. The quantification limit reached 2.5 mg/kg when the MOSH fraction was concentrated to 0.1 mL. The accuracy of this procedure, as assessed by measuring the recoveries from spiked oil samples, was higher than 80%. This procedure was applied to analyze the MOSH in 38 commercial vegetable oils from Chinese market, which was the first survey of mineral oil contaminant in Chinese edible oils. The oil samples contaminated with different levels of MOSH, among which, 15 samples contained no mineral oils and 3 samples were contaminated with more than 50 mg/kg of MOSH. The highest contamination level was found in one of rice oils, in which the concentration of MOSH was up to 713.36 mg/kg. Of the 9 types of oils analyzed, camellia oil contained MOSH ranging between 6.76 and 78.49 mg/kg, averaging 46.72 mg/kg, indicating a higher contamination level than other types of oils. The results suggested that it is necessary to routinely detect mineral oil contamination in vegetable oils for food safety.