有机酸对离子色谱法测定氟离子的影响

比较了不同体系下离子色谱法测定考核样中氟离子的准确度。在碳酸盐–碳酸氢盐体系下分析氟标准样品,进行甲酸根、乙酸根加标试验,讨论了甲酸根、乙酸根对氟定量准确性的影响。考核样品色谱峰处理前氟测定结果为0.273 mg/L,与统计均值0.240 mg/L相比偏高,色谱峰处理后结果为0.243 mg/L,在统计Z值偏差范围内。同时在氢氧根体系下分析考核样品,有效改善了氟离子与乙酸、甲酸的分离度。在氢氧根体系下分析环境水样中低浓度氟离子快速、方便。     

高效液相色谱法同时测定食品中的8种添加剂

建立高效液相色谱法同时测定食品中的安赛蜜、苯甲酸、山梨酸、苋菜红、脱氢乙酸、胭脂红、日落黄、诱惑红8种添加剂。样品采用Agilent zorbax sb–C_(18)色谱柱梯度洗脱,紫外检测器检测,外标法定量分析。结果表明,8种添加剂的质量浓度在0.5~20μg/m L范围内与其色谱峰面积线性关系良好,相关系数均大于0.999,方法检出限为0.06~0.18 mg/kg。样品的加标回收率为91.3%~101.1%,测定结果的相对偏差为0.47%~1.35%(n=6)。该方法操作简单,灵敏度高,结果准确可靠,适用于食品添加剂的常规分析。     

气相色谱法检测月饼中的脱氢乙酸

应用硫酸锌试剂沉淀月饼样品中的蛋白,乙醚提取样品中的脱氢乙酸,建立了Rtx-5弱极性毛细管柱-气相色谱分离检测月饼中的脱氢乙酸的方法。经方法验证,方法的检出限为0.24μg/mL,定量下限为0.32μg/mL,在0.0～0.5 mg/mL浓度范围内脱氢乙酸的浓度与色谱峰面积呈良好线性关系,相关系数r2=0.999 5,加标回收率在87.9%～94.4%之间,测定结果的相对标准偏差为2.5%(n=12)。该方法样品处理简单,适合月饼中脱氢乙酸的定量分析检测。     

超高效液相色谱法同时测定食品中5种添加剂

采用超高效液相色谱法同时测定食品中的安赛蜜、山梨酸、苯甲酸、脱氢乙酸和糖精钠的含量。不同食物样品经过前处理后,分析物经ACQUITY UPLC BEH C18色谱柱分离,以甲醇-含0.02mol·L~(-1)乙酸铵的乙酸溶液(pH 5.17)为流动相进行梯度洗脱,采用二极管阵列检测器,检测波长为230nm。结果表明:5种食品添加剂在4min内可以完全分离,线性范围均为0.10~50.0mg·L~(-1),检出限在1.0~3.4μg·L~(-1)之间。加标回收率在90.1%~106%之间,测定值的相对标准偏差(n=7)在1.7%~4.9%之间。     

离子色谱法测定乳品中硫氰酸钠含量

采用离子色谱法测定乳品中硫氰酸钠的含量。样品用5 mL乙腈沉淀蛋白质,上清液过C18柱净化,所得的产物采用离子色谱法测定,外标法定量。结果表明,通过流动相以及前处理方法的改进,硫氰酸钠质量浓度在0.10~4.00 mg/L范围内与色谱峰面积呈良好的线性,相关系数r2=1,方法的检出限为0.01 mg/L。在牛奶样品中加入硫氰酸钠标准溶液进行回收试验,测得回收率为95.0%~101.0%,测定结果的相对标准准偏差为1.8%~2.8%(n=7)。该方法操作简便,能有效避免假阳性的发生,测定结果准确,适合于乳品中硫氰酸钠的检测。     

热裂解气相色谱法测定动物源性食品中敌百虫残留量

通过对热裂解气相色谱及气-质联用技术测定动物源性食品中敌百虫的探讨,建立了气相色谱进样口裂解产物的检测方法,并确定了气相色谱的主要分析条件(进样口280℃,DB-225毛细管色谱柱及FPD检测器)。样品前处理结合动物源性食品的特点,采用V(乙腈)∶V(水)=9∶1提取,乙酸锌水解除酯,并利用三氯化碳相转移的方式,建立了一套前处理方法。检测方法的回收率在80.7%~96.5%之间,RSD<5.5%,线性相关系数为0.9991,检出限为0.02mg/kg。该方法是按照我国关于兽药残留分析方法要求建立的,适合进出口及日常动物源性食品中敌百虫残留量的检测。     

高效液相色谱法检测塑料食品接触材料中的双氰胺

建立了使用高效液相色谱法检测塑料食品接触材料中双氰胺的分析方法.采用4％乙酸提取样品、色谱柱分离、紫外检测器检测、外标法定量测定双氰胺残留.双氰胺在质量浓度为0.1 ～5.0 mg/L范围内线性良好,相关系数为0.9996.双氰胺的最低仪器检出限为5μg/L,方法的定量下限为0.40mg/kg,样品加标的回收率在94.4％ ～ 98.0％之间,相对标准偏差小于1.0％.该方法具有样品处理简单方便、灵敏度高、分析时间短等优点,可以满足塑料食品接触材料中双氰胺残留的测定,并为进出口塑料餐具中双氰胺残留量的检验提供依据.     

凝胶色谱净化-气相色谱法测定酱油中7种防腐剂

建立了凝胶色谱净化-气相色谱法测定酱油中山梨酸、苯甲酸、脱氢乙酸、对羟基苯甲酸甲酯、对羟基苯甲酸乙酯、对羟基苯甲酸丙酯、对羟基苯甲酸丁酯共7种防腐剂的方法.样品经过乙醚提取,凝胶渗透色谱净化,毛细管柱(Rxi-17,30 m×0.25 mm×0.25μm)分离后,FID检测器检测.7种化合物在10.0～400.0 mg...     

高效液相色谱法同时测定功能饮料中烟酰胺、咖啡因、维生素B_6、柠檬黄、胭脂红和苯甲酸的含量

建立了一种同时快速检测功能饮料中烟酰胺、咖啡因、维生素B_6、柠檬黄、胭脂红和苯甲酸6种食品添加剂的高效液相色谱方法。6种食品添加剂的检出限分别为烟酰胺0.1 mg/L,咖啡因0.1 mg/L,维生素B6 0.2 mg/L,柠檬黄0.2 mg/L,胭脂红0.1 mg/L,苯甲酸0.1 mg/L,测定结果的相对标准偏差不大于4.57%(n=6),加标回收率在95.80%~113.68%之间。该方法满足GB/T 5009.197–2003,GB/T 23495–2009和SN/T 2105–2008对于上述6种食品添加剂检出限的要求。     

超高效液相色谱法测定聚乙烯类食品接触材料中8种添加剂

食品接触材料中添加剂残留量的测定为食品接触材料从源头进行安全监管具有重要意义。然而目前的大多数研究只针对食品接触材料中有害物迁移量的测定,对于食品接触材料中有害物含量的测定方法仅局限于残留单体、低聚体、重金属,以及邻苯二甲酸酯类、双酚类化合物等环境污染物,对食品接触材料中添加剂残留量的测定较少。该研究系统地优化了样品前处理过程及仪器分析中影响8种添加剂分析准确度与响应灵敏度的各主要因素,建立了超高效液相色谱同时测定聚乙烯材料中8种添加剂的定量分析方法。聚乙烯样品冷冻研磨后,取2.0 g样品采用甲苯作为萃取溶剂,80 ℃, 10.34~11.72 MPa (1500~1700 psi)下对其进行加速溶剂萃取,取10 mL上清液,氮气吹干后用10 mL初始流动相(甲醇-水,7∶3, v/v)定容。采用ACQUITY UPLC BEH C₈色谱柱(100 mm×2.1 mm, 1.7 μm)进行分离,柱温30 ℃,进样量5 μL,以乙腈和水作为流动相进行梯度洗脱,流速0.3 mL/min,二极管阵列检测器(DAD)在210~400 nm范围内扫描,230、250、280、330 nm监测,外标法定量。8种目标物在0.2~10 μg/mL质量浓度范围内线性关系良好,相关系数(R ²)>0.999。空白聚乙烯样品添加含量为0.05%时,加标回收率在83.8%~103.4%之间,RSD在0.14%~7.86%之间。对于含量为0.2%~0.9%之间的质控样品,8种目标物的平均回收率在63.5%~118.5%之间,RSD在4.61%~15.6%之间。8种目标物的定量限为0.02%。应用该方法测定10份市售聚乙烯食品包装袋和手套,其中6份样品均检测出含有亚磷酸三(2,4-二叔丁苯基)酯(抗氧剂168),含量为0.02%~0.07%,均小于GB 9685-2016规定的聚乙烯类食品接触材料中抗氧剂168的最大使用量(0.2%)。该方法能够满足聚乙烯类产品中8种添加剂的分析要求,可用于食品接触材料风险监测。     

Comparison of micellar electrokinetic chromatography, liquid chromatography, and microbiologic assay for analysis of cephalexin in oral suspensions

Two well-accepted methodologies, based on a microbiologic assay (MA) and liquid chromatography (LC), and a novel methodology using micellar electrokinetic chromatography (MEKC), were compared for the determination of cephalexin in commercially available and simulated samples of oral suspensions. The MA, described in the Brazilian Pharmacopeia, was performed with a strain of Staphylococcus aureus ATCC 6538 as the test organism, following the cylinder-plate method. The LC analysis followed the European Pharmacopoeia, 3rd Ed., and was used with minor modifications. The MEKC analysis was based on a previous work of the group. Estimates of the repeatability relative standard deviations of the MA, LC, and MEKC methods in the analysis of a commercial sample were 0.34, 0.42, and 0.37%, respectively. The recovery obtained with LC was 99.90 +/- 1.11%; for MEKC, it was 100.09 +/- 0.56%. Although the 3 methodologies were statistically equivalent for the determination of cephalexin in oral suspensions, MA gave suitable repeatability despite being nonspecific and time-consuming. MEKC provided faster analysis and higher column efficiency, whereas LC presented superior sensitivity. The results indicated that MEKC can be used as an alternative method to MA and LC in routine quality control laboratories.     

Chromatographic determination of amino acids in foods

Amino acids in foods exist in a free form or bound in peptides, proteins, or nonpeptide bonded polymers. Naturally occurring L-amino acids are required for protein synthesis and are precursors for essential molecules, such as co-enzymes and nucleic acids. Nonprotein amino acids may also occur in animal tissues as metabolic intermediates or have other important functions. The development of bacterially derived food proteins, genetically modified foods, and new methods of food processing; the production of amino acids for food fortification; and the introduction of new plant food sources have meant that protein amino acids and amino acid enantiomers in foods can have both nutritional and safety implications for humans. There is, therefore, a need for the rapid and accurate determination of amino acids in foods. Determination of the total amino acid content of foods requires protein hydrolysis by various means that must take into account variations in stability of individual amino acids and resistance of different peptide bonds to the hydrolysis procedures. Modern methods for separation and quantitation of free amino acids either before or after protein hydrolysis include ion exchange chromatography, high performance liquid chromatography (LC), gas chromatography, and capillary electrophoresis. Chemical derivatization of amino acids may be required to change them into forms amenable to separation by the various chromatographic methods or to create derivatives with properties, such as fluorescence, that improve their detection. Official methods for hydrolysis and analysis of amino acids in foods for nutritional purposes have been established. LC is currently the most widely used analytical technique, although there is a need for collaborative testing of methods available. Newer developments in chromatographic methodology and detector technology have reduced sample and reagent requirements and improved identification, resolution, and sensitivity of amino acid analyses of food samples.     

Chromatographic determination of carotenoids in foods

In recent years, there has been particular emphasis on obtaining more accurate data on the types and concentrations of carotenoids in foods for various health and nutrition activities. The analysis of carotenoids is complicated because of the diversity and the presence of cis-trans isomeric forms of this group of compounds. In addition, a wide variety of food products of vegetal and animal origin, vegetables and animal samples contain carotenoids, and a great range of carotenoids can be found in these samples. The characteristic conjugated double bond system of carotenoids produces the main problem associated with work and manipulation on carotenoids, that is their particular instability, especially towards light, heat, oxygen and acids. For this reason, several precautions are necessary when handling carotenoids. Another problem associated with analysis of carotenoids is the difficulty in obtaining standard compounds. High-performance liquid chromatographic methods for the determination of carotenoids in foods are reviewed. The sample extraction and treatment, carotenoid purification and standard manipulation are briefly commented on. We present a critical assessment of chromatographic methods developed for the determination of carotenoids in foods. Finally, some methods for carotenoid ester separation are reviewed.     

Determination of total taurine in pet foods by liquid chromatography of the dansyl derivative: collaborative study

A liquid chromatographic (LC) method for the determination of total taurine in pet foods was evaluated in a collaborative study. Ten laboratories assayed 6 blind duplicate pairs of wet and dry pet foods. The taurine in the 6 sample pairs ranged from low (170 mg/kg) to high (2250 mg/kg) concentrations as is. Collaborators also assayed a sample of known taurine concentration for familiarization purposes. Samples were hydrolyzed to release bound taurine, which was subsequently converted to the dansyl derivative and quantitated by gradient-elution LC with fluorescence detection. Repeatability relative standard deviations, RSDr, ranged from 3.2 to 10.0%; reproducibility relative standard deviations, RSDR, ranged from 6.1 to 16.1%. The method has been adopted Official First Action status by AOAC INTERNATIONAL.     

胰岛素的色谱分析方法

随着糖尿病的发病率不断攀升,有必要建立简单易行的胰岛素的分析方法。胰岛素制剂的纯度检验,胰岛素生产及纯化过程的监控,生物体液及胰岛细胞分泌胰岛素的状况,重组胰岛素结构的测定及活性研究等都离不开胰岛素的测定。而胰岛素的色谱分析是一个年轻的领域。本文按照体内外样品、检测方法和样品制备总结了近年胰岛素的色谱分析方法。     

胶束毛细管电动色谱法在线富集联用技术灵敏检测乳制品和饲料样品中的三聚氰胺

建立了胶束毛细管电泳(MEKC)在线富集技术灵敏检测三聚氰胺的方法,采用场放大进样(FASS)联用胶束扫集(Sweep)测定多种样品中的三聚氰胺.试样用乙腈反复提取3次,在优化实验条件下,三聚氰胺的检测灵敏度提高了约1000倍,检出限由原来的2 mg/L降到1.8 μg/L(S/N=3).本方法用于配方奶粉和动物饲料中...     

Chromatographic quantitation at losses of analyte during sample preparation. Application of the modified method of double internal standard

Known methods of quantitative chromatographic analysis (calibration, external standard, internal standard and standard addition) require the application of sample preparation techniques without significant losses of analytes. If this condition cannot be satisfied, the compensation of these losses should be provided. The modification of known method of quantitative chromatographic analysis (double internal standard), implying the addition of two homologues (previous and following) of target analytes as internal standards into initial samples is considered. This approach permits us to compensate significant losses both analytes and standards at all stages of sample preparation. The advantages of this method are demonstrated on the examples of liquid-liquid extraction, head space analysis (HSA), distillation of volatile compounds with volatile solvents (concentration in condensates) and evaporation of volatile solvents (concentrating in the residues of solvents). In all cases the application of two homologues as internal standards provides accurate results (the typical relative errors are within 1-6%) at the values of a factor of composition distortion of initial samples (K', the definition is suggested) from 0.2 up to 4. These results are in accordance with general relationships between variations in any physicochemical properties of organic compounds within homologous series. The single found exception was the evaporation of volatile solvents (the open phase transition process) when to get the results with relative errors not more then +10% requires the minimal changes in the composition of initial samples (K' values should not be more then approximately 1.5).     

Determination of total vitamin C in fruit juices and related products by liquid chromatography: interlaboratory study

A interlaboratory study was conducted to evaluate a liquid chromatographic (LC) procedure for the determination of total vitamin C in foods at levels of 5-60 mg/100 g. Emphasis was placed on fruit juices, although selected foods were also included in the study. Following dissolution of sample in water, endogenous dehydroascorbic acid was converted to ascorbic acid by precolumn reduction with dithiothreitol at neutral pH. Total ascorbate was determined by C18 reversed-phase LC with a phosphate eluent at pH 2.5, incorporating dithiothreitol to maintain vitamin C in the reduced form, and UV detection at 254 nm. Seven types of fruit juices and foods were tested by 19 collaborators in 7 countries. Three duplicate juices and foods met the criteria for Youden pairs and yielded repeatability relative standard deviation of 5.80-14.66%. Reproducibility relative standard deviation ranged from 6.36 to 35.54% (n = 10) with HORRAT values of 0.82-4.04. The LC method is suitable for routine use in fruit products and foods containing > 5 mg/100 g vitamin C and is recommended for further validation by AOAC INTERNATIONAL and International Fruit Juice Union.     

水环境中痕量有机致害物的系统色谱分析

本文提出了水环境（包括饮用水）中痕量有机致害物的系统色谱分析方案。把顶端空间－气相色谱作为易挥发物（或液相色谱）作为难挥发有机物的检测途径。整个系统只需一个高效气相色谱和一个高效液相色谱系统即可满足优先监测物分析的基本要求。文中对分析方案中的若干关键过程作了讨论。     

Chromatographic determination of vitamins in foods.

Chromatographic methods for the determination of water- and fat-soluble vitamins in foods are reviewed. For each vitamin, sample preparation, detection problems and chromatographic conditions are presented and discussed. High-performance liquid chromatography (HPLC) is becoming a standard method in vitamin assay, especially for routine work. HPLC systems can be automated using in-line solid-phase extraction and column switchings, resulting in very sensitive methods, even when simple UV detection is employed.