纳米银/辣根过氧化物酶自组装免疫传感器测定蜂蜜中的青霉素

利用层层自组装技术,成功将氨基苯磺酸、纳米银和辣根过氧化物酶标记的青霉素抗体固定在玻碳电极表面。实现了聚氨基苯磺酸/纳米银放大型电化学免疫传感器的制备,建立了一种高灵敏度检测青霉素的电化学分析方法。辣根过氧化物酶催化过氧化氢氧化还原3,4-二氨基苯甲酸产生电流信号,进行电化学检测,实现蜂蜜中青霉素的定量测定。同时对测定缓冲液的pH、反应温度和时间等进行了优化,最佳条件下,在0.05~6.00μg/L浓度范围内传感器响应电流和青霉素浓度呈良好线性关系,线性方程为Δi(10-5A)=-0.7265C+4.1522,相关系数为0.9946,检出限为1.02μg/L。同时利用该传感器对蜂蜜样品中的青霉素进行了测定,测定结果与酶联免疫法进行了对比,可知该法测定青霉素灵敏度高,具有良好的选择性和稳定性,适用于检测蜂蜜样品中的青霉素残留。     

基于免标记电化学免疫传感的蔬菜中农药残留检测研究

本文利用层层自组装技术构建了一种用于农药残留高灵敏检测的免标记电化学免疫传感器。该免疫传感器首先通过在天然聚合物海藻酸钠修饰的玻碳电极上利用电化学方法原位聚合金纳米粒子,然后借助金纳米粒子与蛋白质抗体之间的较强吸附作用进一步原位组装农药抗体,从而成功构建了免标记电化学免疫传感器。实验中以呋喃丹农药为模型,呋喃丹分子通过特异性的免疫反应在抗体功能化电极表面生成免疫复合物,该复合物阻碍了电化学探针在电极表面的电子传递,从而减小了免疫传感器的电流响应,利用电流响应的变化与农药分子浓度的关系可以实现呋喃丹农药的快速、高灵敏检测。在优化的实验条件下,该传感器对呋喃丹农药的线性检测范围为1~105μg/L,检测限为1μg/L。同时,该免疫传感器还实现了多种蔬菜样品中呋喃丹农药残留的高灵敏检测。     

应用酶联免疫法快速检测乳品中β-内酰胺类抗生素残留

建立乳品中β-内酰胺类抗生素残留酶联免疫快速检测方法。应用氨苄青霉素抗体,通过人工制备了氨苄青霉素(Amp)和辣根过氧化物酶(HRP)的结合物Amp-HRP,建立直接ELisa竞争法检测β-内酰胺类抗生素,确定了各种β-内酰胺类抗生素的检出限,并对检测条件进行了优化。检测了已知阴性和阳性的生鲜牛乳样品,结果表明对于阴性和阳性牛奶样品的检测未出现假阳性或者假阴性结果。该方法检测结果准确可靠,可广泛应用于检测乳品中β-内酰胺类抗生素残留的检测。     

微生物抑制法快速检测鲜奶中多种抗生素残留

目的建立牛奶中多种抗生素残留的快速检验方法。方法以抗生素对敏感细菌能够产生抑制作用原理,采用微生物抑制法快速检测牛奶中10种抗生素残留。结果该方法最低检出限为：氨苄青霉素、青霉素0．001μg/ml,金霉素、土霉素、红霉素、四环素0．01μg/ml,链霉素、氯霉素、庆大霉素、卡那霉素0．1μg/ml,优于GB／T4789．27—2003TTC法的最低检出量：青霉素0．004μg/ml,链霉素0．5μg/ml、庆大霉素0．4μg/ml、卡那霉素5μg/ml。结论该方法成本低廉,稳定性好,灵敏度高,检测时间仅需18～22h,检测低限符合国家标准要求,能够同时检测10种抗生素。     

小麦粉中黄曲霉毒素B_1现场检测用纳米修饰传感器

在印刷电极表面涂覆一层壳聚糖(Chit)膜,在膜上同时固定四羧基酞菁铁(Ⅲ)(FePc)和HRP酶标黄曲霉毒素B_1抗体(HRP-Ab-AFB_1)包被纳米金,制备了可用于小麦粉中黄曲霉素B_1(AFB_1)快速检测的新型安培免疫传感器(SPCI Chit/FePc/Au/HRP-Ab-AFB_1).FePc对H_2O_2的还原具有催化作用,可作为HRP酶与电极之间电子传递媒介体.当该传感器在含AFB_1样品的30℃溶液中温育8 min后,AFB_1与Ab-AFB_1的免疫结合导致HRP的活性中心与FePc之间的电子传递被部分阻碍,使HRP对H_2O_2电催化氧化电流I_0降低.△I_0与AFB_1浓度在1.0～200μg/L成线性关系,标准样品的组内和组间变异系数<3.5%;回收率97%～104%,检测限为0.3μg/L.该传感器检测AFB_1温育时间短,一步测定免分离,为小麦粉中的AFB_1现场分析提供了新技术.     

基于纳米金电化学免疫传感器测定牛奶中的青霉素G

利用吸附法将青霉素G抗体固定于纳米金修饰的玻碳电极表面,制备用于检测青霉素G的电化学免疫传感 器,建立高度灵敏的一步直接电化学免疫法。纳米金的强吸附和导电作用,提高了青霉素G抗体的固定量和电化学 灵敏度。在优化条件下,该传感器的响应电流与青霉素质量浓度的对数在0.04～40.00 ng/mL范围内呈良好的线性关 系,相关系数为0.988 4,检测限为2.49 ng/mL,该法成功的实现了对牛奶中青霉素G的检测。     

基于量子点二抗偶联物的荧光免疫分析法测定牛奶中的氨苄青霉素

目的建立基于量子点二抗偶联物的荧光免疫分析法测定牛奶中的氨苄青霉素。方法采用共价偶联的方法将Qdot 655红色荧光量子点(quantum dots, QDs)与二抗偶联,利用制备好的QDs-二抗偶联物代替传统酶标二抗应用到检测牛奶中氨苄青霉素残留检测的荧光免疫分析方法中,并将该方法与酶联免疫吸附法(enzyme linked immunosorbent assay, ELISA)和高效液相色谱法(high performance liquid chromatography, HPLC)进行比较。结果该方法 50%抑制浓度(IC50)为8.3μg/L;检测限为2.5μg/L。空白牛奶加标回收率为94.0%～106.2%,变异系数为2.1%～9.2%。在实际样品的检测中,该方法与ELISA方法和HPLC方法测定的结果相比无显著差异(P0.05)。结论该方法准确、灵敏,适用于牛奶中氨苄青霉素残留的检测。     

免疫亲和柱结合超高效液相色谱-串联质谱法测定牛奶中的16种真菌毒素比较研究

目的 通过比较5种不同商品化多合一免疫亲和柱的可检测目标毒素种类、回收率和稳定性,筛选性能最优的免疫亲和柱,建立免疫亲和前处理-超高效液相色谱串联质谱（ultra performance liquid chromatography-tandem mass spectrometry, UPLC-MS/MS）测定牛奶中16种真菌毒的方法。方法 牛奶样品分别经5种不同多毒素免疫亲和柱进行净化富集,用优化后的超高效液相色谱-串联质谱法,在多反应监测模式下测定,同位素内标法定量,筛选覆盖牛奶中真菌毒素污染种类全面、回收率和稳定性最佳的免疫亲和柱,并进行免疫亲和柱性能评价和方法学验证,最终将方法应用于实际样品检测。结果 免疫亲和柱A对牛奶中16种真菌毒素在低、中、高三个添加水平均具有良好的准确度和精密度,加标回收率83.6%~126.8%之间, 相对标准偏差(relative standard deviations,RSDs)为0.2%~18.4%。柱A内各毒素残留水平低于仪器检出限,柱容量在21.8~1317ng之间。使用免疫亲和柱A富集净化样品,各目标毒素在线性范围内线性有良好,相关系数（r）均大于 0. 998,定量限（limits of quantification,LOQs）为0.0010 ng/g~0.2000 ng/g。应用该方法对牛奶质控样品和实际样品进行检测,质控样品测定值均在标示范围内;实际样品中能够检出较低水平的AFM1,DOM-1和FB1。结论 本研究验证筛选免疫亲和柱A应用于牛奶中16 种真菌毒素的测定,其柱残留和柱容量能够满足牛奶中真菌毒素污染的测定;经方法学验证该方法准确可靠,灵敏度高,适用于牛奶中16种真菌毒素的日常检测。     

自动参比流动注射光度法测定环境水样中硫化物

利用亚甲基兰光度法与自动参比流动注射分析（FIA）联用直接测定环境水样中的硫化物而不需对样品进行H2S的固定处理，建立了快速、简便、准确和高灵敏度的在线分析硫化物的方法。结果表明，在最佳检测条件下利用该方法测定硫化物可以得到线性良好的工作曲线，该曲线线性范围为0．017～0．05、0．051～1．62和1．62～2．16μg／mL，检测限为16．9ng／mL，相对标准偏差（RSD）为2．5％（n=8）。利用该方法分析环境水样中的硫化物，回收率为94．0％-102．5％，结果令人满意。     

应用超高效液相色谱结合荧光检测法测定酿造原料和啤酒中的赭曲霉毒素A

在2008～2009年,使用超高效液相色谱（UPLC）结合荧光检测法（FLD）,对237种样品的啤酒大麦、麦芽、啤酒花、麦汁和啤酒进行了赭曲霉毒素A（OTA）污染的分析。相比于其他常用的方法,UPLC法是一种具有低检测限和定量限（LOD和LOQ）的快速检测技术。啤酒的LOD和LOQ值分别为0．0003nWmL和0．001ng／mL,大麦或麦芽为0．05μg／kg和0．2μg／kg,啤酒花为0．16μg／kg和0．5μg／kg。赭曲霉毒素A在其中一种大麦样品（0．3μg／kg）,一种麦芽样品（0．7μg／kg）和一种啤酒花样品（0．6μg／kg）中被检测到,对啤酒酿造过程中的OTA含量也做了检测。此外,对从当地商店购买的国内外啤酒样品也进行了分析,OTA在其中的39％啤酒样品中被检测到,水平介于0．001～0．0544ng／mL之间,只有一个啤酒样品中OTA含量达到了0．2438ng／mL。     

HPLO法测定发酵乳中Y-氨基丁酸条件的优化

本文优化了乳酸菌发酵乳中7-氨基丁酸（GABA）的HPLC检测方法。以三氟乙酸．水溶液为提取液,通过60℃水浴、10000r／min离心10min等方法去除样品中的杂质,对乳酸菌发酵乳制品中的GABA进行提取。通过调整流动相的洗脱方式、流动相比例与pH、柱温等条件,使用专用氨基酸分析柱、恒温柱温箱、自动进样器和仪器自动衍生程序,建立了一种高效快速检测发酵乳制品中GABA的方法。该方法对GABA的检出限LOD（S／N=3）为0．005gg／mL（质量浓度）,定量限LOQ（S／N=10）为0．02gg／mL（质量浓度）。线性范围是0．005-500lag／mL（质量浓度）,相关系数R2=l。该方法具有准确度高、快速、环保、经济等特点。采用该方法对功能食品样品、红曲米样品、乳酸菌发酵液样品中的GABA进行检测,均能得到满意的效果,证明该法具有较广泛的适用性。     

离子色谱法测定那屈肝素钙中亚硝酸盐含量

目的建立那屈肝素钙原料中亚硝酸盐测定方法。方法采用离子色谱法,电化学检测器,工作电极为玻碳电极,参比电极为Ag/AgCl,流速1.0 mL/min,进样体积100μL,色谱柱为Waters Anion HC(150 mm×4.6 mm,10μm)。结果亚硝酸根离子与其他离子分离度良好,在0.004~0.056μg/mL范围内浓度与峰面积线性关系良好,r=0.999,重复性试验的RSD为2.1%,检出限为0.002μg/mL,定量限为0.0032μg/mL。平均回收率为101.2%,RSD为2.6%(n=9)。结论该方法可用于那屈肝素钙中亚硝酸盐测定。     

Evaluation of a microbiological indicator test for antibiotic detection in ewe and goat milk

Antibiotics are widely used for therapeutic and prophylactic purposes in dairy animals. The presence of residual antibiotics in milk could cause potentially serious problems in human health and have technological implication in the manufacturing of dairy products. The aim of this study was to evaluate Delvotest Accelerator (DSM Food Specialties, Delft, the Netherlands), a new system for a fully automated microbial test to detect antibiotic residues in ewe and goat milk. Forty-three samples of raw, whole, refrigerated bulk-tank milk samples (22 of ewe milk and 21 of goat milk) were analyzed during the whole lactation period. Four concentrations of 4 antibiotics were diluted in milk: penicillin G at 1, 2, 3, and 4 μg/L; sulfadiazine at 25, 50, 100, and 200 μg/L; tetracycline at 50, 100, 200, and 400 μg/L; and gentamicin at 25, 50, 100, and 200 μg/L. The detection limit of the Delvotest Accelerator was calculated as the range of antibiotic concentrations within which 95% of positive result lie. The range of detection limit of penicillin G and sulfadiazine was easily detected by Delvotest Accelerator at or below the European Union maximum residue limits, both for ewe and goat milk samples. In contrast, the system showed a lower ability to detect tetracycline and gentamicin both for ewe and goat milk samples. Very low percentages of false-positive outcomes were obtained. Lactation phase did not seem to be a crucial factor affecting the ability of the Delvotest Accelerator to detect spiked milk samples. A higher detection ability was observed for goat milk samples compared with ewe milk samples. A negative correlation between the percentage of positive milk samples detected and milk fat, protein, and lactose contents was observed for gentamicin only.     

Quantitative Analysis of γ-Nonalactone in Wines and Its Threshold Determination

Thirty-eight California and French wines were analyzed for γ-nonalactone by Freon extraction and gas chromatography. The California white wines had from 0 to 16 pg/L (average for 6 samples was 7 μg/L and the red wines from 12 to 43 μg/L (average for 20 samples was 24 μgL). French red wines obtained similar amounts, 14 to 41 μgL (average for 12 samples was 21 μgL). The sensory threshold for γ-nonalaconte was determined to be 30 μg/L.     

A MINIATURIZED INTERTEST AND OXOID (AIM) TEST FOR THE DETECTION OF INHIBITORY SUBSTANCES IN MILK

The work described here was undertaken to assess the suitability of the miniaturized Intertest and Oxoid (AIM) tests compared to their standard counterparts. Fresh raw bulk antibiotic-free milk samples were employed and to these were added a range of dilutions of a standard solution of penicillin prior to carrying out the comparative tests. The results obtained show that there was agreement between the standard and miniaturized Intertests where milk samples contained up to and including 0·02 IU/ml added penicillin but although this was not so where levels of added penicillin exceeded 0·02 IU/ml, the disagreement between the two tests was consistent. With the Oxoid (AIM) tests only where milk samples contained 0·00 IU/ml added penicillin was there agreement between the standard and miniaturized tests although again where milk samples contained levels greater than this the disagreement was consistent. Both miniaturized tests are considered suitable for use as initial screening tests for the detection of inhibitory substances in milk.     

DETECTION OF ANTIMICROBIAL DRUG RESIDUES IN KENYAN MILK

The improved Dutch tube diffusion test was used to study the occurrence of inhibitory substances in raw bulk milk samples within the Nakuru District in Kenya. Initially the detection limits of the method were verified using milk standards spiked with selected antibiotics. Addition of penicillinase to inhibitor-positive samples was used for preliminary identification of penicillin G-type antibiotics and residue levels were estimated against a standard curve constructed by means of a B. stearothermophilus disc assay. The two-tube test was used to screen 1109 field samples of which 229 (21%) were suspect positive. The identification procedure confirmed 165 samples (14.9%) to contain penicillin G-type residues of which 118 contained levels exceeding the established EU MRL for penicillin G (4 μg/kg). This study indicates that antibiotic residues are prevalent in milk within the Nakuru district of Kenya. It suggests that the improved tube diffusion test in combination with a multiplate system could be useful for qualitative and quantitative identification of antimicrobial drug residues in milk.     

超高效液相色谱-串联质谱法测定牛奶中4种β-内酰胺类抗生素及其主要代谢产物

目的建立超高效液相色谱-串联质谱法检测牛奶中青霉素G、青霉素V、氨苄西林、阿莫西林及其代谢产物脱羧噻唑酸含量的分析方法。方法样品经0.2%氨水乙腈溶液超声离心提取,通过Oasis PRiME HLB固相萃取柱进行净化,采用超高效液相色谱-串联质谱法进行测定。结果青霉素G、青霉素V、氨苄西林、阿莫西林及其代谢产物脱羧噻唑酸在所考察的线性范围内线性良好,相关系数不低于0.999;方法回收率为70.9%~101.6%,相对标准偏差(relative standard deviation, RSD)为4.0%~7.5%。市售的35份样品中,均未检出青霉素G、青霉素V、阿莫西林、氨苄西林及其代谢产物。结论该方法操作简单、重现性好,可用于牛奶中青霉素G、青霉素V、阿莫西林、氨苄西林及其代谢产物脱羧噻唑酸的检测。     

牛肉、牛奶中可的松和氢化可的松含量分析

采用液相色谱-串联质谱技术分析我国部分地区市售牛肉、牛奶中可的松和氢化可的松的含量水平。均质的牛肉或牛奶样品在乙酸-乙酸钠缓冲液中酶解后用甲醇提取，提取液用石墨化碳黑固相萃取小柱和氨基固相萃取小柱净化，洗脱液氮吹至干并用甲醇溶液定容，液相色谱-串联质谱测定。采用SPSS?21.0软件进行数据分析。对采自我国9?省市的346?份牛肉和牛奶样品进行检测，分析牛肉和牛奶中可的松和氢化可的松的存在水平。牛肉和牛奶中均检出可的松和氢化可的松，检出率在86.1%～100.0%之间，检出含量范围为0.02～74.88?μg/kg。牛肉中可的松和氢化可的松的含量平均值（中位数）分别为1.69（1.14）?μg/kg和12.16（8.14）?μg/kg，牛奶中可的松和氢化可的松的含量平均值（中位数）分别为0.23（0.23）?μg/kg和0.72（0.72）?μg/kg。牛肉和牛奶中氢化可的松与可的松的含量均呈显著正相关。     

江西省产黄酒中氨基甲酸乙酯残留量的GC-MS分析

采用气相色谱-质谱法调查60份江西省内生产的黄酒产品中氨基甲酸乙酯(EC)残留量。酒样添加d5-EC同位素内标,经硅藻土层析住吸附,乙醚洗脱,用GC-MS测定,内标法定量。色谱柱为DB-INNOWAX石英毛细管柱(30m×0.25mm×0.25μm)。加标回收试验的平均回收率为107.5%,相对标准偏差为1.33%(n=2),黄酒中EC的污染水平中,EC的中位数为24.4μg/kg,均值为35.0μg/kg,检出率为70%,含量值范围为6.0~123.7μg/L。通过此次调查江西产黄酒中氨基甲酸乙酯残留量,将为我国制定国家标准和对黄酒中氨基甲酸乙酯的污染水平评估提供数据支持。