离子色谱法同时测定海产品中的硝酸盐、亚硝酸盐和多聚磷酸盐

建立超声辅助提取离子色谱法测定海产品中硝酸盐、亚硝酸盐和多聚磷酸盐（包括正磷酸盐、焦磷酸盐、三聚磷酸盐和三偏磷酸盐）含量的方法,对样品中硝酸盐、亚硝酸盐和多聚磷酸盐的稳定性进行研究,并采用该法对典型海产品中的硝酸盐、亚硝酸盐和多聚磷酸盐含量进行测定。结果表明：采用亲水性阴离子交换分离柱,KOH溶液为淋洗液作梯度淋洗,硝酸盐、亚硝酸盐和多聚磷酸盐的线性相关系数在0.998 1～0.999 8之间,回收率为79.2%～93.6%,相对标准偏差小于8.2%。经处理后的样品中,焦磷酸盐、三聚磷酸盐和三偏磷酸盐的总量在14 h内保持稳定。利用该法对东海地区典型海产品中的硝酸盐、亚硝酸盐和多聚磷酸盐进行了测定,结果显示不同品种的海产品中硝酸盐、亚硝酸盐和多聚磷酸盐含量分布有较大差异,除其中一份虾制品中多聚磷酸盐含量超过5 g/kg外,其余均符合国家限量标准。     

离子色谱法测定婴幼儿米粉中硝酸盐和亚硝酸盐

建立婴幼儿米粉中硝酸盐和亚硝酸盐的在线超滤-离子色谱测定方法。样品经超声提取,3%乙酸沉淀蛋白质后,低温离心,取上清液依次过C_(18)小柱,Ag柱、Na柱,经在线超滤装置自动净化样品,由电导检测器检测样品中的硝酸盐和亚硝酸盐含量。硝酸盐(以NO_3~-计)和亚硝酸盐(以NO_2~-计)分别在0.10 mg/L~2.0 mg/L和0.010 mg/L~0.20 mg/L的范围内线性良好,相关系数R~2均大于0.999 9。方法的硝酸盐(以NO3-计)检出限为0.2 mg/kg,亚硝酸盐(以NO_2~-计)检出限为0.1 mg/kg,硝酸盐回收率为89.8%~96.1%,亚硝酸盐回收率为89.5%~96.0%。此法所获得结果准确可靠,重复性良好,实现对婴幼儿米粉中硝酸盐和亚硝酸盐的准确定量分析。     

小白菜硝酸盐含量与NO3－/NH4+及氮代谢关键酶的相关性

采用液体培养实验研究了不同NO3－与NH4＋浓度比（分别为50∶50、75∶25和100∶0）对10 个品种小白菜（Brassica chinensis L.）的硝酸盐含量、光合系统参数及氮代谢关键酶活性的影响。结果表明,随着硝铵比的增加,小白菜总干质量逐渐增加（除品种天津小白菜和大头清江白菜的总干质量随硝铵比的增加先降低后升高,品种香港春秀甜白菜（236）和正旺达88的总干质量先升高后降低外）,与c（NO3－）∶c（NH4＋）为50∶50比较,增幅分别为12.66%～76.88%（c（NO3－）∶c（NH4＋）为75∶25）和17.98%～95.07%（c（NO3－）∶c（NH4＋）为100∶0）;小白菜叶和根中的硝酸盐含量增加,而叶柄硝酸盐含量则表现出先增加后下降的趋势,小白菜硝酸盐的含量叶柄（3 882.62～5 448.81 mg/kg）＞叶（2 004.86～4 146.50 mg/kg）＞根（505.39～2 188.68 mg/kg）。小白菜叶片中硝酸盐含量与硝酸还原酶活性成显著负相关,而与亚硝酸还原酶和谷氨酰胺合成酶活性成显著正相关。小白菜叶片中硝酸盐的含量随着净光合速率（Pn）和胞间二氧化碳浓度（Ci）的增加而下降,随蒸腾速率（Tr）的增强而增加。     

在线渗析-离子色谱联用同时测定熟肉制品中的亚硝酸盐和硝酸盐

采用在线渗析技术与离子色谱法联用测定熟肉制品中的亚硝酸盐和硝酸盐。样品经纯水振荡、超声提取后,离心所得的上清液过Ag 柱经在线渗析后进入分离柱,采用Metrosep A Supp 4 阴离子交换柱,以1.8mmol/LNa2CO3 溶液与1.7mmol/L NaHCO3 溶液作为淋洗液,用化学抑制型电导检测器检测。方法中NO2 和 NO3 的检出限为0.004mg/L 和0.005mg/L,样品加标回收率在88%～105% 之间。该法快速、灵敏、准确,高效自动化,可同时测定熟肉制品中的亚硝酸盐和硝酸盐含量。     

奶粉中亚硝酸盐和硝酸盐成分分析基体标准物质的应用

建立了奶粉中亚硝酸盐和硝酸盐含量准确测定的方法,以奶粉中亚硝酸盐和硝酸盐成分分析基体标准物质作为质控品进行方法学的考察与评价。奶粉样品经低温-酸沉淀/固相萃取净化,采用离子色谱-电导检测分析。结果表明,亚硝酸盐(以NO_2-计)和硝酸盐(以NO_3~-计)分别在0.010μg/m L~0.500μg/m L和0.100μg/m L~5.00μg/m L的范围内线性良好,相关系数(r)均大于0.99,在奶粉中的最低定量限分别为0.400/4.00 mg/kg(NO_2~-/NO_3~-);亚硝酸盐和硝酸盐测定方法中的基质效应分别为95.6%/99.6%(NO_2~-/NO_3~-);基于基质效应的加标回收率分别为90.3%/87.1%(NO_2~-/NO_3~-);以奶粉基体标准物质进行方法学考察,方法的准确性分别为90.5%/89.9%(NO_2~-/NO3-),精密度(RSD)分别为2.1%/0.7%(NO_2~-/NO_3~-)。奶粉中亚硝酸盐和硝酸盐成分分析基体标准物质作为质控品,可以用于分析测试方法的评价、实验室结果的比对,以及相关行业奶粉中亚硝酸盐和硝酸盐含量监测量值传递体系的建立,为奶粉的质量控制和安全评价提供保障。     

烤烟硝酸盐、亚硝酸盐含量与若干品质指标的典型相关分析

采用典型相关分析方法研究了湖南烤烟叶片硝酸盐和亚硝酸盐含量与若干品质指标间的关系.结果表明:不同等级烟叶硝酸盐、亚硝酸盐含量与烟碱、总氮的第一典型相关系数均达到1%极显著水平,其所包含的相关信息占两组变量间总相关信息的75.41%～86.92%,且这一相关关系主要由硝酸盐与烟碱、总氮间的相关所引起;不同等级烟叶硝酸盐、亚硝酸盐含量与石油醚提物、总糖、还原糖的第一典型相关系数也均达到1%极显著水平,其所包含的相关信息占两组变量间总相关信息的77.16%～92.04%,且这一相关关系主要由硝酸盐与还原糖、总糖间的相关所引起.不同等级烟叶硝酸盐、亚硝酸盐含量与烟叶11种营养元素间的典型相关系数则均未达到5%的显著水平.     

重庆市菜园土壤与蔬菜硝酸盐和亚硝酸盐含量及相关性研究

研究重庆4 个农贸市场市售3大类19 种蔬菜73 个样品中硝酸盐含量及重庆市13 个主要蔬菜基地土壤和蔬菜的硝酸盐、亚硝酸盐含量及相关性。结果表明,重庆市售蔬菜不同种类及同种蔬菜不同部位的硝酸盐含量差异显著。大小顺序为叶菜类（X =1 619.73 mg/kg）＞茄果类（X =1 327.67 mg/kg）＞葱蒜类（X =
1 078.39 mg/kg）;莴苣叶（X=1 567.91 mg/kg）＞莴苣茎（X=1 871.62 mg/kg）。叶菜类全部超过了一级标准,污染指数高达9.09,污染程度最为严重;茄果类和葱蒜类超过一级标准的样本占81.3%和87.5%,污染指数分别高达8.85和6.56。重庆市13 个主要蔬菜基地不同蔬菜以及同种蔬菜不同部位的硝酸盐含量差异也显著,大小顺序为萝卜叶（X=745.97 mg/kg）＞莴苣茎（X=730.88 mg/kg）＞莴苣叶（X=693.32 mg/kg）＞白菜（X=617.63 mg/kg）＞萝卜根（X=575.74 mg/kg）。土壤中NO3－-N含量差异也显著,大小顺序为种植莴苣的土壤（X=75.24 mg/kg）＞种植白菜的土壤（X=47.05 mg/kg）＞种植萝卜的土壤（X=33.42 mg/kg）。蔬菜可食部分的硝酸盐与土壤中的NO3－-N含量呈极显著正相关关系,线性方程y=407.872＋4.796x。供试重庆市13 个主要蔬菜基地土壤及蔬菜可食部分的NO2－-N含量均较低且差异不显著,蔬菜中的亚硝酸盐含量和土壤中的NO2－-N含量也无显著相关性。     

接种与调酸发酵对白菜中亚硝酸盐含量的影响

为探寻腌制菜中亚硝酸盐含量超标的抑制手段,研究了接种和调酸发酵工艺对腌制白菜中亚硝酸盐含量的降低作用.以新鲜白菜为供试材料,采用接种初始浓度为2x 106CFU/mL的乳酸菌或用0.2mol/L乳酸缓冲液调节发酵初始pH为3.5、4.0、4.5、5.0的发酵工艺,评价二者对其亚硝酸盐含量的降低效果.结果表明,当采用接种发酵工艺时,发酵白菜中硝酸盐含量显著下降,亚硝酸盐含量不超过1mg/kg.调节初始发酵液pH＜4.5时,可以抑制发酵过程中亚硝酸盐的产生,使其低于3mg/kg.接种与调酸发酵工艺都能使发酵白菜中亚硝酸盐含量低于国家安全标准,比自然发酵工艺对人体健康更为有利.     

ICS-1500离子色谱测定乳粉中的氯、硝酸盐与亚硝酸盐

建立用离子色谱法测定乳粉中氯、硝酸盐与亚硝酸盐含量的方法。该方法采用3%乙酸沉淀乳粉样品中的蛋白质和脂肪等有机物,再通过OnGuard II RP柱预处理后,利用阴离子分析柱分离、检测,以保留时间定性,峰面积外标法定量。试验结果表明:该方法氯在1.0～50.0mg/L,硝酸盐在0.2～10.0mg/L,亚硝酸盐0.02～1.0mg/L,相关系数均大于0.999,回收率大于94%;R SD分别为0.83～1.98%、0.93%～2.13%、0.91%～2.00%,最低检出浓度分别为0.02mg/L、0.05mg/L、0.01mg/L。本方法具有快速、准确、灵敏度高,精密度好等优点,适合于牛奶及其制品中氯、亚硝酸盐、硝酸盐含量的测定。     

离子色谱法测定肉制品中的硝酸盐和亚硝酸盐

目的:建立离子色谱法快速定量肉制品中的硝酸盐和亚硝酸盐的含量。方法:样品以醋酸沉淀蛋白,样品液直接通过固相萃取小柱进入离子色谱仪分析,测定硝酸盐和亚硝酸盐含量。结果:在0.5～50 mg/L范围内硝酸盐线性关系良好,相关系数为0.9999,样品在0.05、0.10、0.15 mg 3个添加水平的平均回收率为98.8%(RSD为0.74%),检出限0.008 mg/L。在0.1～20 mg/L范围内亚硝酸盐线性关系良好,相关系数为0.9998,样品在0.05、0.10、0.15 mg 3个添加水平的平均回收率为96.6%(RSD为0.25%),检出限0.006 mg/L。结论:方法简单,易于操作,适用于检测机构对肉制品中大批量样品的检测工作。     

大白菜贮藏过程中硝酸盐和亚硝酸盐含量变化分析

在不同贮藏温度（0、10、20 ℃）、贮藏方式（未包装、0.04 mm PE保鲜袋包装）条件下贮藏大白菜（Brassica rapa pekinensis）16 d后,采用高效液相色谱法测定大白菜中硝酸盐和亚硝酸盐含量的变化。结果表明,在不同贮藏温度和贮藏方式条件下,硝酸盐和亚硝酸盐的含量随着贮藏时间的延长均呈现先增加、后降
低、再上升的趋势,其中硝酸盐的含量在整个贮藏期间,均在低于432 mg/kg的安全食用范围内;亚硝酸盐含量在20 ℃贮藏条件下贮藏7 d即超过了4 mg/kg的安全摄入量,而其他贮藏条件均在安全食用范围内。大白菜中硝酸盐与亚硝酸盐的含量在贮藏过程中随贮藏温度的降低而显著减少,到贮藏末期（16 d时）20 ℃和10 ℃贮藏大白菜中硝酸盐含量分别是0 ℃贮藏的1.2 倍和1.1 倍,亚硝酸盐含量分别是0 ℃贮藏的1.4 倍和1.2 倍。PE保鲜袋包装有助于减少大白菜在中、低温（10、0 ℃）贮藏中硝酸盐与亚硝酸盐的含量,但在高温（20 ℃）贮藏中其含量增加。因此,建议贮藏大白菜时最好采用PE保鲜袋包装和0～10 ℃的贮藏温度,以保证其硝酸盐和亚硝酸盐含量不超标。     

Nitrate and nitrite in vegetables on the Danish market: content and intake

The contents of nitrate and nitrite in lettuce, leek, potato, beetroot, Chinese cabbage and white cabbage on the Danish market were determined for 3 years in the period 1993-1997 as part of the Danish food monitoring programme. These vegetables are supposed to provide the major contribution to the intake of nitrate from the diet. Results for nitrate and nitrite in fresh and frozen spinach are also shown. The highest content of nitrate was found in lettuce followed by beetroot, Chinese cabbage, fresh spinach, leek, frozen spinach, white cabbage and potatoes. For all the products a great variation in the content of nitrate was found. For lettuce a characteristic variation throughout the year is clearly seen with the highest content in the winter period the lowest content in the summer period. Generally, the content of nitrite was low but in spinach high contents were found, probably due to improper storage conditions during transportation. The intake of nitrate and nitrite from these vegetables is calculated on the basis of two different consumption surveys. For both surveys the average intake of nitrate from the vegetables included in the monitoring programme is estimated to be approximately 40mg day^-1, whereas for nitrite the average intake is approximately 0.09mg day^-1. The total intake of nitrate and nitrite is estimated to be respectively 61mg day^-1 and 0.5mg day^-1.     

Nitrate and nitrite in vegetables from north China: content and intake

The contents of nitrate and nitrite in potato, cabbage, Chinese cabbage, scallion (shallot), celery, cucumber, tomato, eggplant and wax gourd taken from the north China market from 1998 to 1999 were determined. These vegetables provide the major contribution to the nitrate intake from the diet. The highest content of nitrate was found in celery followed by Chinese cabbage, cabbage, scallion, wax gourd and eggplant. For all the products, a great variation in the content of nitrate was found. Generally, the nitrite content was low. The average intake of nitrate and nitrite from these vegetables was estimated as approximately 422.8 and 0.68 mg day -1 , respectively.     

Nitrate and nitrite levels in commonly consumed vegetables in Hong Kong

Levels of nitrate and nitrite in 73 different vegetables, a total of 708 individual samples grouped into leafy, legumes, root and tuber, and fruiting vegetables, which are traded mainly in Hong Kong, were measured. Where available, five samples of each vegetable type were purchased from different commercial outlets during the winter of 2008 and summer of 2009. Levels of nitrate and nitrite were determined by ion chromatography and flow injection analysis, respectively. Nitrate and nitrite levels of all samples ranged <4–6300 and <0.8–9.0 mg?kg^?1, respectively. Nitrate concentrations for the different groups, in descending order, were leafy?>?root and tuber?>?fruiting and legume vegetables. More than 80% of vegetables had mean nitrate concentrations less than 2000?mg?kg^?1, but mean nitrate concentrations of three types of leafy vegetables, namely Chinese spinach, Shanghai cabbage and Chinese white cabbage, were >3500?mg?kg^?1. On the other hand, nitrite concentrations were generally low –?<1?mg?kg^?1 on average. Nitrate in vegetables (i.e. Chinese flowering cabbage, Chinese spinach and celery) can be reduced significantly (12–31%) after blanching for 1–3?min, but not after soaking.     

离子色谱法测定香肠中的亚硝酸盐和硝酸盐

建立了离子色谱-电导检测法测定香肠中亚硝酸盐和硝酸盐的分析方法。样品经过亚铁氰化钾溶液和乙酸锌溶液沉淀蛋白质后,离心取其上清液依次过C18柱、Ag柱和Na柱净化后,以氢氧化钾为淋洗液,经DIONEX IonPacTM AS11-HC(4 mm×250 mm)阴离子柱分离,采用DIONEX AERS 500(4mm)阴离子抑制器和电导检测器检测,优化色谱条件后检测样品中亚硝酸盐和硝酸盐的含量。结果表明:亚硝酸盐浓度在0.1~2mg/L、硝酸盐浓度在0.2~8mg/L范围内线性关系良好,相关系数R2均大于0.9998。该方法亚硝酸盐的检出限为0.1mg/kg,硝酸盐的检出限为0.2mg/kg。亚硝酸盐的回收率在96.8%~99.9%,硝酸盐的回收率在98.8%~99.3%。亚硝酸盐的相对标准偏差RSD在0.79%~1.2%,硝酸盐的相对标准偏差RSD在0.26%~2.2%。离子色谱法测定亚硝酸盐和硝酸盐具有方法简便、重现性好、灵敏度高、检测数据准确可靠的特点。     

Nitrate and nitrite in vegetables from areas affected by war-time operations in Croatia

To evaluate nitrate and nitrite contents in cabbage and potatoes, the most consumed vegetables in Croatia, and to examine if war-time operations in Croatia affected nitrate and nitrite levels in vegetables, potatoes and cabbage cultivated in the war region (East Slavonia) and out of war regions were analyzed. Data showed that nitrate contents were higher in the samples from the war region (32% and 24% in potatoes and cabbage, respectively) but differences were not statistically significant. The nitrate levels found in potato samples (196 mg NaNO₃/kg fresh weight (FW) and cabbage samples (911 mg NaNO₃/kg FW) were comparable with levels reported for other countries. The nitrite contents in potatoes (321 μg NaNO₂/kg FW) and cabbage (173 μg NaNO₂/kg FW) were lower than the contents reported for most other countries. Further examinations of nitrate and nitrite concentrations in vegetables in Croatia as well as examinations of the influence of war-time operations on accumulation of these toxic contaminants are necessary.     

Corn leaf nitrate reductase--a nontoxic alternative to cadmium for photometric nitrate determinations in water samples by air-segmented continuous-flow analysis

Development, characterization, and operational details of an enzymatic, air-segmented continuous-flow analytical method for colorimetric determination of nitrate + nitrite in natural-water samples is described. This method is similar to U.S. Environmental Protection Agency method 353.2 and U.S. Geological Survey method 1-2545-90 except that nitrate is reduced to nitrite by soluble nitrate reductase (NaR, EC 1.6.6.1) purified from corn leaves rather than a packed-bed cadmium reactor. A three-channel, air-segmented continuous-flow analyzer-configured for simultaneous determination of nitrite (0.020-1.000 mg-N/L) and nitrate + nitrite (0.05-5.00 mg-N/L) by the nitrate reductase and cadmium reduction methods-was used to characterize analytical performance of the enzymatic reduction method. At a sampling rate of 90 h(-1), sample interaction was less than 1% for all three methods. Method detection limits were 0.001 mg of NO2- -N/L for nitrite, 0.003 mg of NO3-+ NO2- -N/L for nitrate + nitrite by the cadmium-reduction method, and 0.006 mg of NO3- + NO2- -N/L for nitrate + nitrite bythe enzymatic-reduction method. Reduction of nitrate to nitrite by both methods was greater than 95% complete overthe entire calibration range. The difference between the means of nitrate + nitrite concentrations in 124 natural-water samples determined simultaneously bythe two methods was not significantly different from zero at the p = 0.05 level.     

干酪乳杆菌11MZ-5-1发酵酸菜化学成分及细菌多样性分析

以分离自酸菜发酵液的干酪乳杆菌（Lactobacillus casei）11MZ-5-1为发酵剂,构建酸菜发酵微生物生态系统研究模型,利用高效液相色谱和气相色谱-质谱联用技术,分析L. casei 11MZ-5-1发酵酸菜中风味物质及菌群分布情况。结果表明L. casei 11MZ-5-1发酵酸菜总酸含量较高,亚硝酸盐含量较低,甘油、甘露醇、2,3-丁二醇、VC等有益代谢产物产量分别为（0.36±0.03）、（13.82±0.42）、（0.22±0.02）g/L和（445±13.23）mg/kg,挥发性风味物质的相对含量为（91.13±4.29）%,均高于自然发酵酸菜（P＜0.05）,安全性、营养价值更高,风味物质含量丰富、感官品质更优。此外,L. casei 11MZ-5-1发酵酸菜微生物多样性低于自然发酵酸菜（P＜0.05）,且在整个发酵过程中,L. casei始终保持优势地位。研究结果不仅展现了L. casei 11MZ-5-1在酸菜发酵工业生产中的应用前景,还有助于酸菜生产工艺监控和质量标准的建立。     

离子色谱法测定FAPAS比对肉粉样品中亚硝酸盐、硝酸盐含量

为建立离子色谱法测定肉粉样品中亚硝酸盐和硝酸盐含量的方法,将样品经超声和水浴提取后,经阳离子 交换树脂柱净化,以氢氧化钾为淋洗液,经Dionex IonPacTMAS19阴离子柱分离,采用AERS 500（4 mm）阴离子抑 制器、电导检测器进行检测,标准曲线定量。结果表明：亚硝酸根离子在质量浓度0.10～4.00 mg/L、硝酸根离子在 质量浓度0.50～20.00 mg/L范围内线性关系良好,相关系数均为0.999 9;样品中亚硝酸盐和硝酸盐的平均回收率分 别为99.53%（n=9）和99.29%（n=9）,相对标准偏差分别为0.60%和0.25%。本次比对结果为“满意”,表明本方 法科学、可靠,适用于基质复杂的熟肉制品中亚硝酸盐和硝酸盐的测定。     

The oral nitrate and nitrite intake in The Netherlands: evaluation of the results obtained by HPIC analysis of duplicate 24-hour diet samples collected in 1994.

In spring and autumn of 1994 duplicates of 24-h diets were collected from 123 respondents. One of the goals of this study was to determine the amount of nitrite and nitrate in the duplicates of 24-h diets to establish the oral daily intake of these analytes. For this purpose an HPIC/UV method for the determination of nitrate and nitrite in duplicate diets was developed and validated. The sample preparation procedure was derived from the in-house method used for the determination of nitrate and nitrite in human blood plasma. The sample is diluted with water, deproteinized with Carrez reagent, followed by chromatographic clean-up on an SPE C18-column. Both the nitrate and the nitrite results are quantitative. The recovery for nitrite was on average 104% (n = 21, spiking levels: 0.84-95 mg/kg) and for nitrate on average 103% (N = 21, spiking levels: 1.8-404 mg/kg). Samples of duplicates of 24-h diets were analysed according to the method developed. The median intake of nitrite calculated from the samples collected in spring 1994 was 0.6 mg/person day (range < 0.1-6.1 mg/person/day). For the samples collected in autumn 1994 these figures were < 0.2 mg/person/day (range < 0.1-16 mg/person/day). The mean intake of nitrate was 73 mg/person/day (range 7-322 mg/person/day) in spring 1994 and 87 mg/person/day (range 1-310 mg/person/day) in autumn 1994. The overall mean intake of nitrate in 1994 was 80 mg/person/day. The daily intake for nitrate was higher than that found in the duplicate diet study carried out in 1984/1985, when an average daily intake of 52 mg/person was measured. The intake of nitrite was also higher than found in the duplicate diets collected in 1984/1985. The findings of the study are discussed in the context of the ADI for nitrate and nitrite as well as the outcome of other recent European intake studies.