流动注射法快速测定乳粉中的亚硝酸盐及硝酸盐

采用在线透析和在线镉柱还原-流动注射法测定乳粉中的硝酸盐和亚硝酸盐。方法基于测定亚硝酸盐与磺胺、N-(1-萘基)乙二胺二盐酸盐形成偶氮染料的吸光度,硝酸盐经过在线镉柱还原为亚硝酸盐,得到硝酸盐与亚硝酸盐含量的总和。该方法的RSD值仅为4.06%,亚硝酸盐检出限为0.011 mg/kg,硝酸盐的检出限为0.129 mg/kg,亚硝酸盐在0.75~2.00 mg/kg范围内的加标回收率在98%~106%之间,硝酸盐在9.24~61.60 mg/kg范围内的加标回收率在98%~105%之间,样品测定速度为30样/h。此方法极为简单快捷,对实际乳粉的亚硝酸钠、硝酸钠含量的测定结果令人满意。     

流动注射法测定乳粉中的亚硝酸盐及硝酸盐

在参照GB 5009.33—2010"食品安全国家标准食品中亚硝酸盐和硝酸盐的测定"基础上,选择流动注射仪测定乳粉中亚硝酸盐及硝酸盐含量。确定了亚硝酸盐检出限为0.05 mg/L,加标回收率95.3%~97.0%,硝酸盐加标回收率92.1%~98.9%,精密度良好,测定结果可靠。     

间断化学分析仪法测定奶粉中硝酸盐含量

文章建立了一种快速、批量测定奶粉中硝酸盐含量的检测方法。方法首先对奶粉样品进行沉淀蛋白质、除去脂肪处理,然后采用间断化学分析仪自动进样还原硝酸盐为亚硝酸盐,自动加显色剂进行显色比色测定。文章同时分析了方法的线性、准确性、精密度、加标回收率等参数,结果表明硝酸盐在0~2μg/m L的范围内该方法线性良好,回归方程:y=0.2252x-0.0009,相关系数r=0.9999,相对标准偏差RSD5%,加标回收率在89.0%~99.6%。方法简便快速、灵敏度高、准确性、重复性好。     

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。     

离子色谱法测定虾酱中的亚硝酸盐和硝酸盐

建立了虾酱中亚硝酸盐和硝酸盐的离子色谱分析方法。样品经乙酸沉淀蛋白,经固相萃取小柱净化后,采用Metrosep A Supp 4-250阴离子分析柱分离,电导检测器检测,外标法定量。亚硝酸盐、硝酸盐在相应浓度范围内均呈现良好的线性关系,相关系数(r)均大于0.999。虾酱样品中亚硝酸盐、硝酸盐的定量限分别为0.31 mg/kg、0.14mg/kg,实际样品加标回收率为93.3%~102.5%,相对标准偏差RSD(n=6)为1.51%~5.70%。该方法操作简便快速,结果准确,精密度高,能够满足检测工作的实际要求。     

离子色谱法检测果脯中的亚硫酸盐

建立离子色谱(IC)测定地瓜果脯中的亚硫酸盐(以SO2计)含量的分析方法,确定样品的前处理方法和超声波萃取条件,样品经处理后IC测定.结果表明:亚硫酸盐在0.5 mg/L～7 meCL浓度范围内有良好的线性,其相关系数r=0.9998,精密度RSD=1.31%(n=12),样品加标回收率在96.50%～101.42%的范围内.与国标方法比较,操作简便,结果准确可靠.     

气相色谱法测定食醋中邻苯二甲酸二丁酯及其不确定度评定

建立食醋中邻苯二甲酸二丁酯（DBP）的气相色谱测定方法,并进行方法学验证,同时对所建方法进行不确定度评定。结果表明,DBP在0.19～4.75 mg/L质量浓度范围内线性关系良好（R2=0.999 9）,检出限为0.01 mg/L,精密度试验相对标准偏差（RSD）为0.96%,加标回收率在90.14%～96.41%之间,RSD为2.53%。样品中DBP平均检测结果为（0.111±0.005） mg/L,表明所测样品中DBP的迁移量均未超出相关规定的限量（0.3 mg/kg）。该方法的不确定度主要来源于标准曲线的拟合,其次为前处理回收率。     

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。     

在线镉柱还原-流动注射光度法测定食品中硝酸盐/亚硝酸盐氮

采用在线镉柱还原流动注射分析法测定食品中的硝酸盐氮和亚硝酸盐氮。其中硝酸盐氮方法的线性范围为20.0～2000.0μg/L,相关系数r≥0.999,检出限为1.1μg/L,相对标准偏差为0.97%,样品测定频率为22样/h,实际水样的加标回收率为94%～106%。亚硝酸盐氮方法的线性范围为2.0～200.0μg/L,相关系数r≥0.999,检出限为0.4μg/L,相对标准偏差分别为0.35%,样品测定频率为27样/h,实际水样的加标回收率为91%～109%。此方法简单快捷,对于食品样品的测定结果令人满意。     

基于溴甲酚绿酸性染料比色的玛咖酒中总生物碱的检测方法构建

建立玛咖酒中总生物碱含量的测定方法。采用分光光度法,以苦参碱为对照品,0.5%盐酸溶解,正丁醇-三氯甲烷提取,以溴甲酚绿为显色剂,在416 nm波长下进行测定。结果表明,苦参碱检测浓度在0～0.18 mg范围内与吸光度呈良好线性关系(R~2=0.9954),正确度偏差范围在-8%～6%之间,方法精密度RSD=3.3%,加标浓度为5 mg/L和10 mg/L时回收率在90%～96%之间,回收率稳定在同一水平。     

氢化物原子荧光光谱法测定酱油中微量铅的方法研究

建立了一种快速、高效的QuEChERS-高效液相色谱-质谱联用法（QuEChERS-HPLC-MS/MS）测定谷类杂粮制品中脱氧雪腐镰刀菌烯醇（DON）、3-乙酰脱氧雪腐镰刀菌烯醇（3-ADON）、15-乙酰脱氧雪腐镰刀菌烯醇（15-ADON）和玉米赤霉烯酮（ZON）共4种真菌毒素。样品前处理采用乙腈-水溶剂提取，经Florisil+C18+无水硫酸镁净化后检测。以0.10%甲酸-乙腈作为流动相，在质谱检测器的多反应监测模式下进行分析。结果表明，4种真菌毒素在各自的线性范围内线性关系良好，相关系数R2均大于0.999，回收率在85.1%～102.0%，相对标准偏差（RSD）为2.11%～6.22%。该方法具有前处理简单、净化效果好、灵敏度高和检测速度快的优点，适用于谷类杂粮制品中DON、3-ADON、15-ADON 和ZON的分析和定量检测。     

高效液相色谱法测定酱油中组胺的含量

目的建立丹磺酰氯柱前衍生-高效液相色谱法测定酱油中组胺含量的方法。方法样品酱油以1,7-二氨基庚烷作为内标,用正丁醇:三氯甲烷(1:1,V:V)萃取净化,经丹磺酰氯衍生,乙醚萃取后氮气吹干,用乙腈定容,高效液相色谱仪测定,内标法定量。结果组胺含量在1~100 mg/L线性关系良好,线性相关系数r=0.9999,检出限为0.5 mg/kg。在精密度实验中,其相对标准偏差为2.59%~6.48%,在1.0、10.0、50.0 mg/kg的添加水平下,加标回收率为88.0%~104.2%。结论该方法线性关系好、检出限低、稳定性好、回收率高、测定结果准确,适合酱油中组胺的测定。     

Direct determination of free tryptophan contents in soy sauces and its application as an index of soy sauce adulteration

A simple and rapid HPLC method using UV detector for determination of tryptophan (Trp) contents in pure fermented soy sauces, acid-HVP, and commercial soy sauces was developed. The method requires only simple sample pretreatment. The limit of detection (LOD) is estimated at 1 mg/L (signal-to-noise ratio of 3), and the recovery yields ranged from 92% to 108%. The analysis showed that Trp in all of the analysed acid-HVP samples was not detected and there was obvious detection of Trp (ranged from 136.4 to 261.8 mg/L) in all of the analysed fermented soy sauce samples. The observations suggest that Trp is a practical index of pure fermented soy sauce. The absence of Trp contents or lower level of Trp contents than that in pure fermented soy sauces suggests the soy sauces are not pure fermented soy sauces or presence of soy sauce adulteration. Simultaneous determination of levulinic acid (LV) in samples may be a good help in making assessment of soy sauce adulteration with acid-HVP.     

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。     

Development and Validation of a Method for Determination of Residual Nitrite/Nitrate in Foodstuffs and Water After Zinc Reduction

An environmentally friendly and cost-effective spectrophotometric method to analyze nitrate and/or nitrite was developed. The method is based on reduction of nitrate with zinc powder (instead of the cadmium or enzymes used in the standard methods approved by ISO/CEN). The initial nitrite concentration and total nitrite after reduction are determined by the very sensitive and widely used diazotization-coupling Griess reaction. A single-laboratory validation was applied in five different matrices (vegetable, meat product, baby food, dairy product, and surface water). The results show that the new method fulfills the international criteria for precision and recovery. The limit of detection for several matrices, calculated using fortified samples, ranged from 3 to 5 mg/kg for both nitrite and nitrate. Furthermore, the results obtained were in good agreement with those obtained using the CEN method (HPLC) and the ISO method (Cd reduction).     

大豆分离蛋白中的亚硝酸盐超声辅助提取分析方法的研究

大豆分离蛋白在肉制品、乳制品和面制品等食品中都具有广泛的应用,是一类重要的食品配料,因此其安全问题十分重要。而亚硝酸盐含量是食品安全控制的重要内容,作为配料的大豆分离蛋白是否含有亚硝酸盐以及亚硝酸盐的含量水平应该得到重视。实验发现,使用国标法中的分光光度法测定大豆分离蛋白中亚硝酸盐的含量,回收率较低,不到80%,这样会造成测定的不准确,不利于亚硝酸盐的含量监控。因此本研究利用超声波400W辅助提取,省去了样品于沸水浴中加热15min的步骤,对大豆分离蛋白中亚硝酸盐含量进行测定。实验结果表明,改进后的大豆分离蛋白亚硝酸盐超声波辅助提取方法回收率高(97.2%)、精密度好(相对标准偏差为2.5%),适合大豆分离蛋白中亚硝酸盐的测定。     

Determination of HMF in Vinegar and Soy Sauce Using Two-Step Ultrasonic Assisted Liquid–Liquid Micro-Extraction Coupled with Capillary Electrophoresis-Ultraviolet Detection

A new, rapid, and inexpensive method using two-step ultrasonic assisted liquid–liquid micro-extraction (UALLME) coupled with capillary electrophoresis-ultraviolet (CE-UV) was developed for 5-hydroxymethylfurfural (HMF) analysis in high ion strength samples (like vinegar and soy sauce). The factors affecting the extraction efficiency were optimized such as the extraction volume, the ultrasonic time, and the power density of ultrasonic. Under the optimum conditions, the limit of detection (LOD) and the limit of quantification (LOQ) for HMF were 0.03 and 0.10 mg/L, respectively. The relative standard deviations (RSD %) for HMF were ranging from 0.53 to 3.17%, and the recoveries of HMF were ranging from 91.24 to 109.39%. The results turned out that two-step UALLME-CE-UV was applicable to analyze HMF in vinegar and soy sauce. Eleven brands of vinegar and soy sauce were tested by two-step UALLME-CE-UV, and the results showed that the method had a potential application in analysis of foodstuffs. The two step UALLME method was effective to improve the selectivity and sensitivity of CE-UV method for HMF analysis in vinegar and soy sauce.     

A Novel Method for the Determination of the Ethanol Content in Soy Sauce by Full Evaporation Headspace Gas Chromatography

A full evaporation headspace gas chromatographic (HSGC) method is described for rapid determination of ethanol in soy sauce. The results demonstrated that a near-complete mass transfer of ethanol in the soy sauce sample to the vapor phase (headspace) was achieved within 2 min at 105 °C when a very small (≤40 μL) sample was added to a 20-mL headspace sample vial. The ethanol in the vapor phase was then determined by HSGC using a flame ionization detector. The results showed that the method has an excellent measurement precision (relative standard deviation <0.41 %) and accuracy (recovery?=?99.85?±?1.85 %) for ethanol quantification in soy sauce samples. The method requires no sample pretreatment, so it is a simple, rapid, and sensitive method for the accurate quantification of ethanol content in soy sauce and suitable for applications in food industry.     

高效液相色谱内标法测定酱油中糖精钠和苯甲酸钠

以山梨酸钾为内标物,采用高效液相色谱法测定酱油中的糖精钠和苯甲酸钠的含量。样品经体积分数为50%的乙醇溶液提取后,采用Nova-Pak C18色谱柱(3.9 mm×15 mm×5 μm)分离,以甲醇-0.02 mol/L乙酸铵（5∶95,V/V）为流动相进行洗脱,流速1 mL/min,紫外检测波长230 nm。结果表明,在0.1～1.4 mg/kg的添加范围,糖精钠、苯甲酸钠的加标回收率分别为99.5%～102.3%,95.1%～102.1%,相对标准偏差(RSD)分别为0.69%和0.82%。所测酱油中糖精钠和苯甲酸钠的含量分别为3.27 mg/kg和0.133 mg/kg。采用该方法回收率高、准确性好,可用于酱油中糖精钠和苯甲酸钠含量分析。