乳与乳制品中甜蜜素检测方法的研究

使用毛细管色谱柱-气相色谱仪检测乳与乳制品中甜蜜素质量浓度。将样品称取后用亚铁氰化钾和乙酸锌沉淀蛋白,提取上清液加入硫酸和亚硝酸钠冰浴衍生,用正己烷提取后,用气相色谱仪氢火焰离子化检测器检测。该方法检测甜蜜素回收率范围在82.37%~109.15%之间,相对标准偏差在2.43%~5.02%之间,最低检出限为0.004 g/kg。该方法检测结果准确可靠、重复性好,可进行乳与乳制品中甜蜜素质量浓度的检测。     

改进QuEChERS-气相色谱-质谱法测定不同脂肪含量牛奶中19种酯类风味物质

采用改进QuEChERS-气相色谱- 质谱法（GC-MS）技术测定不同脂肪含量牛奶中19种酯类风味物质,研究牛奶中酯类风味物质与脂肪含量的关系。样品中的酯类风味物质经乙腈提取和PSA净化,净化后的样液经滤膜过滤后采用气相色谱-质谱法测定。19种酯类风味物质经DB-FFAP色谱柱分离,单离子监测模式测定,外标法定量。结果表明,19种酯类风味物质在5.0~500.0 μg/L质量浓度范围内具有很好的线性关系,相关系数均高于0.999。通过牛奶样品的加标回收试验,19种酯类风味物质的平均回收率在74.7%~109.2%之间,日内精密度（n=6）在1.9%~8.5%之间,方法检出限和定量限分别为3.5~14.0 μg/kg和10.0~40.0 μg/kg。实际样品检测发现牛奶中检出的δ-葵内酯、γ-十二内酯和δ-十二内酯的含量与脂肪含量正相关,且全脂纯牛奶＞低脂纯牛奶＞脱脂纯牛奶;此外,部分牛奶样品可能添加有香精香料,导致γ-壬内酯和γ-十一内酯的含量明显升高。该方法快速简便、准确度高、重现性好,可满足不同脂肪含量牛奶中19种酯类风味物质的检测要求。     

离子色谱法测定乳及乳制品中硫氰酸根含量

建立乳及乳制品中硫氰酸根的离子色谱分析方法。样品经提取净化后,采用Dionex Ion Pac AS11-HC阴离子分析柱进行分离,电导检测器进行检测,梯度洗脱,外标法定量。结果显示:硫氰酸根质量浓度在0.10μg/m L~5.0μg/m L范围内线性关系良好。硫氰酸根在不同添加水平中平均回收率为85.3%~110%,相对标准偏差为2.36%~4.52%,检出限为纯牛奶中0.19 mg/kg,乳粉中1.55 mg/kg。     

食品中环己基氨基磺酸钠检测方法

使用毛细管色谱柱-气相色谱仪检测食品中环己基氨基磺酸钠的质量浓度。将样品称取后放置在冰水浴中先加氯化钠摇匀,再加入三氯乙酸溶液轻轻摇匀,然后加入亚硝酸钠溶液冰浴衍生,用正己烷提取后,用气相色谱仪氢火焰离子化检测器检测。该方法检测环己基氨基磺酸钠回收率范围在86.07%~109.33%之间,相对标准偏差在3.16%~7.38%之间。该方法检测结果准确可靠、重复性好,可进行食品中环己基氨基磺酸钠质量浓度的检测。     

牛奶中残留麻保沙星的微生物学检测方法

建立牛奶中残留麻保沙星的微生物学检测方法。试验以金黄色葡萄球菌为敏感菌,采用滤纸片法进行测定,以牛奶为样设计了添加回收试验以证实该方法的有效性。磷酸盐缓冲溶液和牛奶基质麻保沙星标准曲线的工作范围是0.1~1.6μg/mL,最低检测限为0.1μg/mL。对纯牛奶样的3种添加水平,平均回收率范围在77.3%~93.3%之间,变异系数小于7.26%,该方法可以用于牛奶中麻保沙星残留的检测。     

气液微萃取仪联用气相色谱-质谱仪检测果蔬中农药残留量

目的建立气液微萃取仪(gas-liquid microextraction,GLME)与气相色谱质谱联用仪(gas chromatographymass spectrography,GC-MS)测定食品中农药残留。方法称取0.1 g匀浆样品直接加入GLME中进行萃取净化,定容至100μL,结合内标法通过GC-MS检测分析。结果 30种农药在0.001~1 mg/kg浓度范围内线性良好,相关系数在0.9951~0.9999,检出限为0.001~0.021 mg/kg,定量限为0.003~0.070 mg/kg,平均回收率为67%~119%(n=3),相对标准偏差在1%~26%之间。结论该方法快速、准确,能满足果蔬类中多种农药残留的定性定量分析。     

3种方法测定替加环素对鲍曼不动杆菌的体外药敏结果比较

比较替加环素对鲍曼不动杆菌的体外药敏试验不同方法之间的差异。分别采用微量肉汤稀释法、琼脂稀释法和K-B法测定119株临床分离鲍曼不动杆菌对替加环素的敏感性,比较不同检测方法结果的差异。微量肉汤稀释法MIC_(50)0.5μg/m L、MIC901μg/m L,FDA/EUCAST的耐药率0.0%(0/119)/0.0%(0/119),中介率0.0%(0/119)/5.0%(6/119),敏感率100%(119/119)/95.0%(113/119);琼脂稀释法MIC_(50)1μg/m L、MIC904μg/m L,FDA/EUCAST耐药率11.7%(14/119)/45.4%(54/119),中介率33.6%(40/119)/21.0%(25/119),敏感率54.7%(65/119)/33.6%(40/119);K-B法Jone/EUCAST的敏感率47.1%(56/119)/31.9%(38/119)、中介率48.74%(58/119)/31.9%(38/119),耐药率4.2%(5/119)/36.2%(43/119)。替加环素对鲍曼不动杆菌体的外药敏实验中,微量肉汤稀释法、琼脂稀释法和K-B法之间存在差异。以微量肉汤稀释法为参考方法,MH琼脂稀释法总误差41.2%~60.5%,K-B法总误差47.9%~63.9%。     

敌百虫分子印迹聚合物的制备及应用

目的制备分子印迹聚合物,为敌百虫的分离富集提供参考。方法以敌百虫为模板,3-氨基三丙基乙氧基硅烷(3-aminotripropylethoxysilane,APTES)为功能单体,正硅酸乙酯(ethyl orthosilicate,TEOS)为交联剂,采用溶胶-凝胶法制备分子印迹聚合物。将制备的印迹聚合物作为固相萃取填料应用于实际样品中敌百虫的分离富集,结合高效液相色谱法(high performance liquid chromatography,HPLC)对白菜、甘蓝、西红柿中的敌百虫含量进行测定。结果该方法可有效去除基质干扰,检出限为0.92μg/kg,回收率在87.66%～100.0%之间,RSD≤4.5%。结论本实验为实际样品的前处理提供了新思路,为敌百虫的检测发展了新方法,有望广泛应用于实际样品中敌百虫的分离检测中。     

部分牛奶中雌二醇和孕酮的含量分析

目的检测市售全脂纯牛奶中雌性激素的含量水平,为牛奶中的雌性激素安全性研究提供基础数据。方法运用免疫化学发光分析法对6个品牌市售全脂纯牛奶中的雌二醇和孕酮进行检测。结果6个品牌全脂纯牛奶中的雌二醇浓度分别为32.3±13.4、36.3±16.0、36.8±14.2、37.2±13.4、19.8±7.3、14.8±4.4 pg/ml。孕酮的浓度分别为7.54±1.56、5.93±0.74、6.12±0.23、7.98±1.56、7.70±1.90、8.64±1.02 ng/ml。结论市售全脂纯牛奶中含有一定数量的雌性激素,应进行对人体健康影响的研究。     

同位素稀释-气相色谱-质谱法同时测定食用油中16种邻苯二甲酸酯类化合物

目的建立一种同位素稀释-气相色谱-质谱法(GC-MS)同时测定食用油中16种邻苯二甲酸酯类化合物含量的方法。方法样品经正己烷溶解,乙腈提取,经固相萃取柱净化,以GC-MS在选择离子监测模式(SIM)下测定,并采用同位素内标法定量分析。结果空白基质加标回收实验添加水平分别为500.0、1000.0、2500.0μg/kg时,大豆油中16种邻苯二甲酸酯的回收率在67.4%~110.5%之间,相对标准偏差在0.3%~12.7%之间;黄油中16种邻苯二甲酸酯的回收率在60.5%~108.3%之间,相对标准偏差在0.6%~12.7%之间。该方法在50.0~1000.0μg/kg浓度范围内线性关系良好,相关系数大于0.999,方法检出限为500.0μg/kg。结论该方法灵敏度、精密度和检出限均符合实际样品检测要求,适用于食用油中PAEs化合物的同时检测。     

Simultaneous determination of residues of trichlorfon and dichlorvos in animal tissues by LC-MS/MS

Trichlorfon is a thermally unstable insecticide that can be easily decomposed to dichlorvos at high temperatures. In this study, a liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for simultaneous determination of the residues of trichlorfon and dichlorvos in animal tissues. Trichlorfon and dichlorvos in animal tissues were extracted with dichloromethane, homogenized/shaken, concentrated, and determined by LC-MS/MS. The two insecticides can be effectively separated and individually determined. The limits of detection (LODs) of trichlorfon and dichlorvos were 0.04 and 0.07 µg kg^?1, respectively; the limits of quantification (LOQs) of the two insecticides were both 5 µg kg^?1. The average recoveries for three spiked blank samples at 10, 20 and 40 µg kg^?1 were in the range 85–106%, with relative standard deviations (RSDs) below 10.6%, which falls in a reasonable range for the analysis of the two insecticides in animal-derived foods. The method is fit-for-purpose for the simultaneous determination of residues of trichlorfon and dichlorvos in animal tissues.     

农业杀虫剂敌百虫对杜氏盐藻的毒性作用

本文以一种具有环境耐性的单细胞绿藻杜氏盐藻(Dunaliella salina)作为受试生物,检测杀虫剂敌百虫的毒性作用.实验中检测了敌百虫对盐藻细胞生长、β胡萝卜素水平及超氧化物歧化酶(Superoxide dismutase,SOD)和过氧化氢酶(Catalase,CAT)活性的影响.当敌百虫浓度小于0.050 g...     

Residue levels of captan and trichlorfon in field-treated kaki fruits, individual versus composite samples, and after household processing.

The dissipation of residue levels of captan and trichlorfon in field-treated kaki crops was studied according to good laboratory practices to propose maximum residue limits (MRLs). Residue levels of captan and trichlorfon were analysed by GC/MS and LC-MS/MS, respectively. Residue levels of captan and trichlorfon permitted one to propose MRLs in kaki of 3 and 5 mg kg(-1), respectively. The behaviour of these residues was also studied after peeling and cooking, and in individual fruits versus composite samples. Residue levels of these compounds for individual fruits suggested that a variability factor up to three could be set for the acute risk assessment. Levels of captan decreased by more than 90% after peeling and completely after cooking. Trichlorfon penetrates into the flesh in a proportion of 70% of the residue at the pre-harvest interval. Cooking resulted in a decrease of 27% of residue levels of trichlorfon.     

气相色谱-氢火焰离子化检测器测定婴幼儿乳粉中37种脂肪酸含量

目的：建立气相色谱-氢火焰离子化检测器测定乳粉中37种脂肪酸含量的分析方法。方法：婴幼儿乳粉样品运用乙酰氯-甲醇法（10%乙酰氯甲醇溶液于80℃±1℃水浴2 h）甲酯化,离心取上清液过0.22μm的有机滤膜后经SP-2560(100 m×250μm×0.2μm)分离,气相色谱法检测,外标法定量。结果：37种脂肪酸甲酯在0.002～0.2 mg/mL浓度范围内线性良好,相关系数均大于0.999,回收率低梯度在85.5%～100.0%之间,中梯度在91.2%～104.2%之间,高梯度在86.8%～103.8%之间,精密度在0.88%～3.81%之间,实际样品测定结果符合相关标准要求。结论：该方法是在国标基础上建立了一种更为快速、分离度更好的脂肪酸检测技术,有很好的实用价值,方法稳定性好,成本低,重现性好,准确度高,适用于婴幼儿乳粉中37种脂肪酸含量的测定。     

气相色谱-质谱法测定东盟进口小食品中的 反式脂肪酸

目的建立气相色谱-质谱法检测东盟进口小食品中反式脂肪酸的分析方法。方法样品经油脂的提取、甲酯衍生化,在气相色谱中采用安捷伦CP-Sil 88 for FAME毛细管色谱柱进行分析,质谱分析采用全扫描模式。对柱长、载气流速和和柱温进行了优化,采用优化后的条件对样品进行测定。结果反-9-十八碳烯酸甲酯和反-9,12-十八碳二烯酸甲酯标准品在10~80 mg/L范围内线性关系良好,r~2分别为0.9989和0.9985,方法的检出限(limit of detection,LOD)和定量限(limit of quantification,LOQ)分别为0.4 mg/L和1.0 mg/L。2种物质在3个添加水平的平均回收率为90.5%~105.6%,相对标准偏差为3.5%~8.2%。样品中反-9-十八碳烯酸甲酯和反-9,12-十八碳二烯酸甲酯的分离度好。结论该方法准确度和精密度良好,分离效果好,可以用于对东盟小食品中反式脂肪酸的检测。     

Corn bran versus corn grain at 2 levels of forage: Intake,apparent digestibility,and production responses by lactating dairy cows

The objective of this study was to determine the effect of substituting corn bran (CB) for dried ground corn grain (CG) in the nonforage portion of high-forage (HF) and low-forage (LF) diets. Twelve multiparous and 12 primiparous Holsteins were assigned to 4 diets using six 4 ×  Latin squares with 3-wk periods. Forage was 64 or 38% of the total mixed ration (% of dry matter). On a dry matter basis, the HFCG diet had 20% CG, the LFCG diet had 39% CG, the HFCB diet had 19% CB, and the LFCB diet had 38% CB. Digestible organic matter intake (OMI) and milk energy yield were lower for CB compared with CG within forage level. Digestible OMI was greater (1.9 kg/d) for the LFCG compared with the HFCG treatment. When CB replaced forage (LFCB vs. HFCB), digestible OMI was not different but milk energy yield was greater with the LFCB diet. The LFCG diet supported the greatest milk, milk protein, and milk energy yield. Decreased concentration of milk protein and increased concentration of milk urea nitrogen when feeding CB compared with CG suggests that lack of fermentable energy in the CB diets may have limited rumen microbial protein synthesis. Total substitution of CG with CB in the nonforage portion did not support maximum milk production, even when forage was reduced at the same time (HFCG vs. LFCB). Predicted neutral detergent fiber (NDF) digestibility at 1 times maintenance, based on chemical analysis of the individual feeds, was 22 percentage units greater for CB than for the forage mix (68.9 vs. 46.9%). In vitro NDF digestibility (30 h) was 19.4 percentage units greater for CB than for the forage mix (68.9 vs. 49.5%). However, in vivo NDF digestibility of the diet when CB replaced forage (HFCB vs. LFCB) was similar (44.1 vs. 44.5%). Similarly, predicted total digestible nutrients at the production level of intake, based on chemical analysis, were greater for the CB treatments and lower for the CG treatments than those observed in vivo.     

气相色谱法检测甘蓝及土壤中的氟铃脲残留

目的 建立氟铃脲在甘蓝及土壤中残留的气相色谱检测方法。方法 甘蓝和土壤样品用乙腈提取, 采用气相色谱电子捕获检测器进行检测。结果 在0.05~10 mg/L范围内, 氟铃脲浓度与色谱峰面积呈良好线性关系, 相关系数0.9998, 氟铃脲的最小检出量为0.018 ng。氟铃脲在甘蓝和土壤中的添加回收率分别为85.41%~93.44%和88.41%~96.05%, 相对标准偏差分别为2.17%~7.52%和 4.37%~7.33%, 最低检测浓度为0.02 mg/kg。结论 本方法具有操作简单、准确度高、重现性好、实用性强等特点, 符合农药残留分析的要求。     

优化气相色谱法检测牛奶中双甲脒残留标志物

目的改进国标中的气相色谱法测定牛乳中双甲脒残留标志物残留的前处理与色谱条件。方法样品使用1 mol/L的盐酸溶液提取,10000 r/min离心转速离心5 min,取上清液使用固相萃取(solid-phase extraction,SPE)小柱过滤净化。对气相色谱的色谱条件进行优化,使用外标法定量。结果通过使用优化处理条件,该方法的线性范围在10~400 ng/m L,线性关系良好。添加5、10、25?g/kg浓度水平,回收率均在90.5%~100.2%之间,相对标准偏差为1.4%~3.2%。结论改进后的方法回收率高、准确性高,对牛乳中双甲脒残留物的检测具有重要意义。     

超高效液相色谱-四极杆/静电场轨道阱高分辨质谱快速测定乳及乳制品中21种真菌毒素

建立利用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱联用技术同时测定乳及乳制品中21种真菌毒素的方法.乳及乳制品经酸化乙腈提取后,采用Captiva-EMR Lipid净化柱净化,以C18色谱柱进行色谱分离,质谱采用全扫描/数据依赖的二级扫描模式(full scan data-dependent MS/MS acqu...     

鸡蛋、鸡肉及奶粉中22种有机氯农药残留的测定

建立了在鸡蛋、鸡肉和奶粉中同时测定22种有机氯农药残留的方法。样品经乙腈提取、Captiva EMR-Lipid固相萃取柱净化、正己烷复溶后,用气相色谱仪检测,外标法定量。在0.005~0.2 mg/L范围内,22种有机氯农药的质量浓度与其对应的峰面积之间线性关系良好,R²均大于0.995。在0.01、0.02、0.1 mg/kg 3个添加水平下,重复测定6次,22种有机氯农药的回收率均在60%~110%,RSD均小于10%,符合GB 27404—2008的实验室内变异系数要求。该方法能够有效去除鸡蛋、鸡肉和奶粉中的动物脂肪及亲脂性干扰物,方法灵敏度、准确度和精密度均符合农药残留检测的要求,为有效监测鸡蛋、鸡肉和奶粉中有机氯农药残留量提供了一种高效、可靠的分析手段。