离子色谱法检测熟肉制品中亚硝酸盐含量的影响因素分析

目的:探讨离子色谱法检测熟肉制品中亚硝酸盐含量的影响因素。方法:样品提取净化后,用离子色谱法测定,对峰面积进行定量。结果:样品提取条件为40℃超声提取30 min,色谱检测条件是4.5 mmol/L Na2CO3+0.8 mmol/L Na HCO3缓冲液,流速为1.2 m L/min,进样体积为50μL,相关系数0.9932,线性范围0.1~20 mg/L,检出限0.02 mg/L,回收率在97%~99%之间,相对标准偏差RSD小于5%。结论:所测结果准确可靠,灵敏度高,重现性好,适用于熟肉制品中亚硝酸盐含量的检测。     

离子色谱法测定包装饮用水中的亚硝酸盐

对包装饮用水中亚硝酸盐含量的测定方法进行研究,优化色谱条件,建立了梯度淋洗-离子色谱法测定包装饮用水中亚硝酸盐的方法。选用ThermoAS11-HC色谱柱,以6～70mmol/LKOH淋洗液梯度淋洗,抑制型电导检测器检测。结果表明:亚硝酸盐在0.00～2.00mg/L有良好的线性关系,相关系数(r)为0.9999;方法检出限为0.75μg/L;3个不同水平(0.15、0.30、0.60mg/L)的加标平均回收率为95.94%～97.61%,RSD值为0.87%～1.01%。该方法具有操作简便、分析快速、灵敏度高、重现性佳等优点,适用于包装饮用水中亚硝酸盐含量的检测。     

衍生化/表面增强拉曼光谱快速检测乳制品中 亚硝酸盐

目的基于衍生化-表面增强拉曼光谱技术,开展奶粉中亚硝酸盐快速定量分析方法的研究,建立一种简单、快速、灵敏的奶粉中亚硝酸盐的检测方法。方法采用重氮化-偶合反应,以金纳米粒子为增强试剂,将弱拉曼活性的亚硝酸根衍生成具有强拉曼活性的偶氮染料,通过对偶氮染料的测定实现对奶粉中亚硝酸盐的间接检测,优化了衍生化、前处理及检测条件。结果在优化条件下,方法的线性范围为0.030~1.0 mg/L、RSD小于14.8%、检出限为0.014 mg/L。方法用于奶粉样品分析的回收率为99.6%~128.9%、RSD为4.6%~15.8%。结论该方法简单快速、准确可靠,适用于乳制品中亚硝酸盐的分析检测。     

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。     

离子色谱-电导检测法快速测定乳与乳制品中 硫氰酸根含量的研究

目的建立一种离子色谱-电导检测法快速测定乳与乳制品中硫氰酸根含量的方法。方法样品经水和甲醇震荡提取、离心后上清液用滤膜过滤后,AS16分离柱分离,由35 mmol/L氢氧化钾溶液等度洗脱,用电导检测器检测,外标法定量。结果方法的线性范围为0.02~20μg/m L,R=0.9990,检出限为0.1 mg/kg,相对标准偏差为0.89%~3.31%,回收率范围为96%~105%。结论该离子色谱法快速、准确、精密度高,适用于乳与乳制品中硫氰酸根的批量检测。     

高效液相色谱法测定乳与乳制品中 L-羟脯氨酸的含量

目的建立高效液相色谱法测定乳与乳制品中L-羟脯氨酸的含量。方法样品水解衍生后采用C18色谱柱,以乙腈和10 mmol/L乙酸钠(p H=5.0)为流动相,梯度洗脱,流速为1.0 m L/min,柱温35℃,荧光检测器进行检测。结果 L-羟脯氨酸检出限为0.5 mg/kg,线性范围为1.0~100.0μg/m L,加标回收率在95.3%~102.7%之间,相对标准偏差在1.46%~7.56%之间。结论该方法操作简便、准确、快速,提高了样品检出灵敏度,适用于测定乳与乳制品中L-羟脯氨酸的含量。     

高效毛细管电泳法快速测定乳制品中三聚氰胺

建立高效毛细管电泳快速测定乳制品中三聚氰胺含量的方法。样品用100mmol/L 醋酸提取,以150mmol/L磷酸二氢钠为分离缓冲液,以未涂敷石英毛细管(20cm(有效长度)× 50μm)为分离柱,于235nm 波长处检测,采用峰面积外标法定量。实验研究缓冲溶液的浓度、分离溶液pH 值及样品前处理条件对三聚氰胺准确定量的影响。方法检出限为0.06mg/L,定量限为0.2mg/L,线性范围为0.2～200mg/L,线性相关系数r=0.9998。1.0、10mg/L 添加水平的平均加标回收率分别为93.0% 及84.3%。该方法简单快速,6min 之内即可完成一次样品分析(预清洗2min,分离4min)且试剂消耗少、环境友好及检测准确,适合于各类乳制品中三聚氰胺的常规测定。     

液相色谱法快速测定乳制品中三聚氰胺含量

建立高效液相色谱法快速测定乳制品中三聚氰胺的分析方法.采用三氯乙酸溶液-乙腈提取乳制品中的三聚氰胺,用强阳离子交换色谱柱(SCX,250 min×4.6 mm,5μm),在流动相配比为0.05 mol/L磷酸二氢钾缓冲液(pH=310)-乙腈(65+35,体积比)条件下分离,紫外检测器210mm波长检测.结果表明:采用外标法定量,该方法在0.10mg/L～10.0 mg/L浓度范围内有良好的线性关系,加标回收率均在91%以上,相关系数R2为0.9999,相对标准偏差不大于1.2%,方法最低检出限为0.01 mg/L.通过实验室间能力验证证明,该方法具有快速、准确、灵敏度高,样品前处理简便易行等优点,可满足实验室日常快速检测乳制品中三聚氰胺的工作需求.     

腌制食品中亚硝酸盐的电化学检测

目的:制备基于磷钨杂多酸盐(Na3PW12O40)的多层膜电化学传感器,实现其对腌制食品中亚硝酸盐含量的快速检测.方法:用层接层法(Layer-by-Layer)将Na3PW12O40和PAH交替沉积于以(PEI/PSS/PAH)为底层的ITO电极上,制得多层膜亚硝酸盐传感器,分析该传感器的电化学性质,并利用其在溶液中对亚硝酸根的安培传感,测定腌制食品中亚硝酸盐含量.结果:制备的传感器在亚硝酸盐浓度1.67×10-8～3.23×10-6mol/L范围呈现良好的线性关系,I(μA)=0.125+0.630c(μmol/L),R=0.9992(n=10),响应电流达到95%时所需时间小于3s.结论:用电化学方法检测操作简便,灵敏度高,检出限低,结果准确,可用于腌制食品中亚硝酸盐含量的检测.     

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。     

高效毛细管电泳法测定奶制品中三聚氰胺含量

目的：建立奶制品中三聚氰胺的含量测定方法。方法：采用高效毛细管电泳法测定,以30mmol/L 磷酸盐缓冲液(pH5.0)为电泳介质,未涂层石英毛细管(75μm× 78cm,有效长度70cm)为分离通道,紫外检测波长240nm,分离电压10kV。结果：三聚氰胺在10.0～50.0μg/mL 范围内线性关系良好,r=0.9992。平均加标回收率为97.04%,平均RSD 为1.24%(n=3)。结论：该方法快速简便、灵敏度高、重现性好,可用于奶制品中三聚氰胺含量的测定。     

Technical note: Optimization of lactose quantification based on coupled enzymatic reactions

A colorimetric microplate-adapted lactose assay was developed to quantify lactose in dairy products. The assay was based on the coupled enzymatic reaction of β-galactosidase-glucose oxidase-horseradish peroxidase using Amplex red as detection probe. The assay showed good linearity in the range of 0.1 to 0.5 mmol of lactose/L, with a limit of detection of 0.0433 mmol/L and a limit of quantification of 0.1313 mmol/L. The lactose assay at optimized conditions (5 U of β-galactosidase/mL, 5 U of glucose oxidase/mL, 1 U of horseradish peroxidase/mL, and 100 μmol of Amplex red/L for 1 h at 37°C in the dark) showed good correlation with a commercial lactose enzymatic kit with intraassay variation below 10% and interassay variations below 7.6%. The developed lactose microplate assay can be adopted as routine analysis for lactose determination in dairy products due to its relatively low cost compared with a commercial kit, relatively short reaction time, and high sensitivity and reproducibility.     

核磁共振磷谱法测定乳制品中的酪蛋白含量

基于插值法建立乳制品中酪蛋白的核磁共振磷谱定量检测方法.结果表明,该方法的检出限为0.38 g/L(信噪比(RSN)=3),定量限为1.25 g/L(RSN=10);在5.00～35.00 g/L质量浓度范围内线性良好,相关系数R2大于0.999;加标回收率在91.94％～105.10％范围区间;日内精密度在0.65％...     

催化荧光法测定蔬菜中痕量亚硝酸根的研究

该研究建立了催化荧光分析法测定蔬菜中痕量NO2-的方法。NO2-可以催化中性红的荧光褪色反应,且其含量与褪色反应速率成正比。通过单因素试验以及均匀试验优化了实验条件,确定了最佳的试剂因素组合。实验结果表明:在激发波长λex=537 nm和发射波长λem=595 nm,试剂因素组合中性红900μL,溴酸钾1 850μL,硫酸1 050μL时,方法NO2-测定的工作曲线为y=1.58x+0.46,相关系数r=0.999 5,线性范围为0.02~0.11 mmol/L,检出限0.001 2 mmol/L,变异系数为6.5%,平均回收率为100.2%,此法适合于根茎类蔬菜中微量NO2-含量的测定。     

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.     

抑制电导-离子色谱法同时测定肉制品中亚硝酸盐和硝酸盐

建立了一种灵敏、快速的同时测定肉制品中亚硝酸盐和硝酸盐的抑制电导-离子色谱分析方法。样品经超声提取后,以DIONEX IonPac AS19(4mm×250mm)色谱柱分离,用DIONEX EG40淋洗液发生器自动淋洗,采用梯度洗脱方式,以抑制电导检测器进行检测。实验表明,硝酸盐和亚硝酸盐的方法检出限(3S/N)为0.6mg/kg和0.8mg/kg,在0.1～50ug/ml范围内呈良好线性关系,回收率为98.4%和96.5%,重复性(RSD)为2.8%和3.2%。本方法灵敏度高,重复性好,可用于肉制品中的亚硝酸盐和硝酸盐的检测。     

Simultaneous Determination of Nitrite and Nitrate in Milk Samples by Ion Chromatography Method and Estimation of Dietary Intake

The presence of nitrate and nitrite in foods may be considered hazardous after ingestion in the gastrointestinal tract due to their reaction with naturally occurred secondary amines to form potentially carcinogenic nitrosamines. Due to this fact, a new method was developed in this study for the simultaneous determination of nitrite and nitrate in milk samples using by ion chromatography. Proposed mobile phase composed of sodium hydrogen carbonate and sodium carbonate (1.0 and 3.2 mmol/L) with a flow rate of 0.7 ml/min. The average recoveries for nitrate and nitrite were higher than 86 and 88%, respectively. The limit of detection for nitrate and nitrite were 0.24 and 0.09 mg/L, respectively. The results of 102 real milk samples showed nitrate was found in all of the samples (100%) with a mean of 34 ± 11 mg/L, while nitrite was found in none of the samples. The mean intake of nitrate in all age groups was lower than World Health Organization guideline. The present assessment concludes that the maximum contaminant level was equal to 82.8 mg/L nitrate. This method was fast, sensitive and accurate and is capable of being an alternative method in food control laboratories for investigation of nitrite and nitrate content. This is the first study of the determination and survey of nitrite and nitrate and exposure assessment of the Iranian population to nitrite and nitrate level in milk, which was widely used in infants and adolescents as one of the basic food components.     

HPCE法同时检测果蔬及肉制品中硝酸盐和亚硝酸盐含量

为了能够同时、快速检测果蔬及肉制品中的硝酸盐和亚硝酸盐,利用高效毛细管电泳对其进行检测,重点研究检测条件的筛选和干扰离子的排除。使用内径50?μm、总长40?cm、有效长度30?cm的毛细管柱,在214?nm条件下,采用毛细管区带电泳-直接紫外法,研究分离缓冲液的pH值、浓度、电渗流改性剂十六烷基三甲基溴化铵的添加量、排除Cl－干扰方式以及分离电压对分离效果的影响,同时进行方法学检验,以确定其回收率、线性、检出限和精密度。结果表明：对于含盐量500?mmol/L以下的样品在6?min内NO3－和NO2－能够达到很好分离,该方法的加标回收率在81.82%～100.91%之间,线性范围较宽,相关系数均在0.99以上,检出限分别为0.69?μg/mL和0.50?μg/mL,精密度均不高于3.2%,具有简便、快速、准确、环保等优点,也为生产中快速监控硝酸盐和亚硝酸盐残留量提供了科学依据。     

毛细管电泳-电化学发光法测定荷叶中荷叶碱与莲子心中莲心碱含量

建立毛细管电泳-电化学发光法同时测定荷叶中荷叶碱与莲子心中莲心碱含量的方法。对三联吡啶钉(Ru(bpy)_3~(2+))溶液浓度、检测电位、磷酸盐缓冲液浓度和pH值、进样时间和分离电压等实验条件进行考察和优化。结果表明,在检测电位为1.20 V,运行缓冲液为10 mmol/L磷酸盐缓冲液(pH 5.74),5 mmol/L Ru(bpy)_3~(2+)溶液,检测池内磷酸盐缓冲液浓度为60 mmol/L(pH 8.30),进样电压为8 kV,进样时间为10 s,分离电压为13 kV,荷叶碱检出限为7.7×10~(-7)mol/L(R_(SN)-3),莲心碱检出限为7.8×10~(-7)mol/L(R_(SN)-3)。对浓度为6.8×10~(-5)mol/L荷叶碱和3.1×10~(-5)mol/L莲心碱的标准品溶液进行5次平行测定表明:荷叶碱峰面积的相对标准偏差(relative standard deviation,RSD)为3.76%,迁移时间RSD为0.83%;莲心碱峰面积RSD为4.28%,迁移时间RSD为1.37%。该方法可用于测定荷叶中的荷叶碱与莲子心中莲心碱含量。