蛋白芯片法同时检测食品中克伦特罗与莱克多巴胺的残留量

建立了食品中克伦特罗和莱克多巴胺残留含量同时检测的微阵列蛋白芯片法。结果显示:克伦特罗的线性范围为0.07～1.2 ng/g;莱克多巴胺的线性范围为0.05～0.8 ng/g。猪肉、猪肝中上述两种物质的加标回收率为74%～132%,相对标准偏差均小于10%。将所建立的方法与HPLC-MS方法进行对比,两者检测结果一致。该方法简单、快速、通量高,可用于实际样品中克伦特罗和莱克多巴胺残留量的检测。     

猪肉中过氧化物酶活性的TMB法研究

以3,5,3',5'-四甲基联苯胺(TMB)为底物对猪肉过氧化物酶(POD)的酶学特性以及猪肉不同部位过氧化物酶活性水平进行了较为系统的研究,并以辣根过氧化物酶(HRP)为标准酶获得了酶活性标准曲线.猪肉过氧化物酶在温度38℃,pH 4.80时活性最高.酶浓度与酶反应初始阶段的酶活性有较好的线性关系,氢供体底物TMB的最佳浓度为2.80×10-4 mol/L,浓度过大则会抑制酶的活性,氢受体底物过氧化氢的浓度与酶活性有较好的线性关系和较宽的线性范围(0～4.20×10-3 mol/L).猪肉不同部位如腰条(指外腰条)、里脊(指内腰条)、后腿、前腿、三层、腱子中POD活性大小不同,前三者的POD活性相近且活性较小,而后三者活性较为相近且活性较大.通过辣根过氧化物酶标准曲线可以求估待测样品中POD的活性值.     

基于液相色谱-串联质谱法的肉类特征肽段鉴别及掺假测定

建立了液相色谱-串联质谱技术鉴别肉类特征肽段及定量检测羊肉中常见外源肉掺假的方法。样品经蛋白质提取、胰蛋白酶水解和固相萃取小柱净化后,利用超高效液相色谱-四极杆/静电场轨道阱高分辨质谱（UPLC-Q/Exactive-HRMS）和Proteinpilot软件,实现蛋白质和多肽的鉴定;再通过基本局部比对搜索工具（BLAST）与Uniprot数据库对比分析,筛选出羊肉、鸭肉、猪肉和鸡肉的20个物种特征性多肽标志物;最后利用高效液相色谱-三重四极杆质谱（UPLC-QqQ-MS）系统对羊肉、鸭肉、猪肉和鸡肉的特征性多肽进行了验证和多反应监测（MRM）定量研究。将鸭肉、猪肉和鸡肉分别按照质量分数为1%、5%、10%、20%、50%的比例掺加到羊肉中,得到鸭肉最低掺假检出限为0.25%、猪肉最低掺假检出限为0.17%、鸡肉最低掺假检出限为0.10%。     

基于天然气敏材料猪肉中优势腐败菌的可视化检测

优势致腐菌是引起猪肉变质的重要原因之一,为了探索猪肉优势致腐菌绿色、快速的检测方法,本研究使用天然色素作为气体可视化传感器阵列的气敏材料,区分猪肉中的优势致腐菌。首先从植物中提取17种天然色素作为气敏材料,并将其固定在基底材料上,干燥后制成气体可视化传感器阵列。将3种优势致腐菌(梭状芽孢杆菌、热死环丝菌、假单胞菌)分别接种至3组猪肉样本中,在室温(20℃)条件下分别培养8、16和24 h,然后将传感器阵列与猪肉样本产生的挥发性物质接触并发生反应,用扫描仪获取传感器阵列与每个样本反应前后的图像信息,将传感器反应前后的颜色差值作为样本的特征值组成一个数据矩阵,并制成差值图像。最后采用主成分分析对培养8,16和24 h后的3种优势致腐菌进行检测,识别率分别为90%,90%和100%。结果表明,天然色素可以作为气体传感器的气敏材料,检测猪肉的优势致腐菌,且检测过程不会产生化学毒害。     

热解炭化病死猪残留重金属的激光诱导击穿光谱检测可行性分析

利用激光诱导击穿光谱(LIBS)分析方法具有的快速无污染优势,选择有代表性的病死猪为研究对象,探讨LIBS对病死猪中残留重金属元素的预测可行性。为了消除水分和有机基体对LIBS分析灵敏度的影响,对病死猪采取高温热解炭化前处理,分别比较了健康猪肉鲜样、健康猪肉真空抽湿压片样和病死猪热解炭化压片样在320~440 nm范围的LIBS光谱信息。结果显示,猪肉中含有丰富的Ca等矿质元素及有机质成分C,N等;真空抽湿可以消除水分的影响从而提高LIBS分析重金属的灵敏度,而热解炭化可以大大减弱含水量和有机质成分对金属元素的干扰,能够探测出更多的元素谱线信息,同时进一步提高重金属Cu,Pb和Cr的检测灵敏度。表明LIBS能对解热炭化病死猪中的残留重金属成分进行探测,并有望结合化学计量学分析方法实现猪肉中重金属含量的快速检测。     

液相色谱-四极杆飞行时间质谱法筛查猪肉中5类26种药物残留

建立了同时筛查测定猪肉组织中氟喹诺酮类、磺胺类、有机磷类、β-激动剂类、四环素类5类26种药物残留的液相色谱-四极杆飞行时间质谱分析方法。试样采用QuEChERS前处理方法,样品经酸化乙腈-甲醇(1%乙酸,10%甲醇)提取。提取液以C18分散剂和正己烷净化,氮吹浓缩、定容后过滤膜上机检测。液相色谱以甲醇-水(0.1%甲酸)作为流动相梯度洗脱,C18色谱柱分离;高分辨质谱采用正离子模式检测,以二级质谱特征离子定性,以分子离子精确质量数提取色谱峰面积定量。结果表明26种药物的定量下限为0.4~10μg/kg;加标回收率为56.7%~106.2%,相对标准偏差(RSD)为7.7%~15.8%。方法操作简单、快速、高效,可作为猪肉中26种药物残留的快速筛查检测方法。     

中国装备近400辆药品快速检测车

截至今年8月,中国已装备药品快检车近400辆,在全国覆盖涉药单位7万多个,监督覆盖面达70%。药品快检技术是对药品是否存在质量问题进行初步判断的系统方法。我国自2003年初开始研究药品快速检测技术,并开发研制成功具有中国自主知识产权的药品快速检测技术载体———药品快速检测车。药品快速检测车上配备了化学药品快检系统、中成药快检系统、中药材鉴别系统、药品质量信息查询系统和近红外光谱检测系统,可在几十秒至几分钟内完成对药品样品的初步筛查,还能对几十万条药品质量信息数据进行查询和识别。药品快检车的推广应用,改变了过去现场监管中靠“眼观手摸、鼻闻口尝”或是靠药品外观、包装来识别药品真伪的历史,显著提高了抽验覆盖面和针对性。目前药品快检车能对上市的所有药品进行质量信息数据查询,能对229种中药材进行现场快速筛查,并能通过近红外光谱检测系统在不损坏外包装的情况下对常用基本药物进行快速检测。目前我国第二代药品快检车已研制成功,其检测准确率可达90%左右。中国装备近400辆药品快速检测车@高     

猪肉中β-受体激动剂AlphaLISA检测方法的建立

建立了快速检测猪肉中克伦特罗、沙丁胺醇、溴布特罗和特布他林4种β-受体激动剂的光激化学发光纳米均相时间分辨荧光免疫(Alpha LISA)分析方法。样品经乙酸铵和β-葡萄糖醛酸酶/硫酸酯酶酶解提取过柱,浓缩至干后,用缓冲溶液定容。样品与生物素化抗原、抗体、供体微珠和受体微珠进行酶联免疫,Alpha LISA进行检测,基质标准曲线定量。结果表明:沙丁胺醇、克伦特罗、溴布特罗和特布他林在0.1~500ng/m L范围内呈良好线性,相关系数均大于0.98,沙丁胺醇与克伦特罗、溴布特罗和特布他林的交叉反应率分别为143.3%,179.2%和95.6%,检出限为0.03~0.08 ng/m L。在0.5,10,20μg/kg 3个添加水平下,4种化合物的平均回收率为82.5%~115.9%,相对标准偏差(RSD)均小于12.0%。该方法操作简单,快速准确,适用于猪肉中β-受体激动剂的筛选与检测。     

高效液相色谱-串联质谱法检测猪肉中3-甲基喹喔啉-2-羧酸残留

建立了高效液相色谱-串联质谱同时定量和确证猪肉中3-甲基喹喔啉-2-羧酸（MQCA）残留量的检测方法。试样用0.3 mol/L盐酸溶液水解提取，加入乙腈和乙酸乙酯萃取，再用0.1 mol/L氢氧化钠溶液反萃取，阴离子交换固相萃取柱净化，经Agilent Eclipse Plus C₁₈柱（50 mm×3.0 mm，1.8 μm）分离，采用液相色谱-串联质谱仪检测，基质匹配添加标准曲线定量。MQCA在1.0~50 μg/L范围内线性相关系数大于0.99，在0.5、1.0、5.0 μg/kg加标水平下其回收率为90.5%~119.6%，相对标准偏差为3.14%~4.22%。方法可用于猪肉中MQCA残留量的快速定量和确证检测。     

液相色谱串联质谱法同时测定猪肉中氟雷拉纳和五氯酚残留量

采用基质分散固相萃取净化结合液相色谱-串联三重四极杆质谱分析技术,基于待测物的油水分配系数和样品前处理正交试验设计,建立了猪肉中氟雷拉纳和五氯酚残留量的检测方法。试样采用酸化乙腈均质提取,提取液加入QuEChERS萃取净化包快速净化,过膜直接上机测定。以5 mmol/L乙酸铵溶液和乙腈为流动相,氟雷拉纳和五氯酚经C18色谱柱梯度洗脱分离后,质谱负离子模式扫描检测。猪肉样品中分别添加1.0, 2.0, 10.0μg/kg 3个浓度水平待测物,氟雷拉纳和五氯酚的加标回收率分别在82.3%～104.0%和71.6%～79.8%之间,相对标准偏差（RSD）分别在3.7%～5.3%和1.2%～3.4%之间。本方法检测氟雷拉纳和五氯酚的定量限均为1.0μg/kg,适用于猪肉中氟雷拉纳和五氯酚残留量的测定。     

Development of a polymerase chain reaction and capillary gel electrophoresis method for the detection of chicken or turkey meat in heat-treated pork meat mixtures

A polymerase chain reaction and capillary gel electrophoresis (PCR-CGE) method with ultraviolet (UV) or laser induced fluorescence detection (LIF) was established for the detection of chicken or turkey in heat-treated pork meat mixtures. Mitochondrial DNA samples extracted from heat treated meat were amplified with their corresponding specific primers yielding PCR products between 200 and 300 bp. LIF detection was superior than UV detection in terms of precision and sensitivity for the study of DNA fragments. The CGE-LIF method was highly reproducible and accurate for determining DNA fragment size. The PCR-CGE-LIF was sensitive since a significant fluorescent signal was obtained at the minimum admixture level employed of 1% in meat mixtures. Thus, the PCR-CGE-LIF method established was useful for the detection of chicken or turkey in heat treated meat mixtures and may prove to be useful for the detection of poultry meat in pork processed products.     

Detection of pork in heat-processed meat products by monoclonal antibody-based ELISA

An enzyme-linked immunosorbent assay (ELISA) using a monoclonal antibody to a porcine thermal-stable muscle protein was developed for detection of pork in cooked meat products. The assay specifically detects porcine skeletal muscle, but not cardiac muscle, smooth muscle, blood, and nonmuscle organs. No cross-reactivity was observed with common food proteins. Validity of the assay was evaluated with laboratory formulated and commercial meat samples. The detection limit was determined as 0.5% (w/w) pork in heterologous meat mixtures. Overall, intra- and inter-assay coefficients of variation were 5.8 and 7.9%, respectively. The accuracy in analyzing market samples was 100% as verified by product labeling and confirmed by a commercial polycolonal antibody test kit.     

Image-Feature Based Deep Learning Model for Plant Leaf Disease Detection

Currently, everyone is facing significant difficulties with food scarcity. There may be several causes for this, but food loss is a well-known issue. Specifically, crop losses bring on by plant and leaf diseases during farming operations. Plant disease is typically identified visually or through laboratory testing, which delays detection and reduces crop yields by the time it is finished. The wide use of smartphones along with recent advancements in computer vision has made it viable to diagnose any ailment by applying machine learning techniques. Smartphone-assisted disease diagnosis is now a reality. In this study, a multi-Support Vector Machine (SVM) model is used to detect four different diseases as well as healthy conditions of plant leaves. Using 13 feature vectors for each input, a total of 2400 leaves representing four distinct classes (four varieties) have been used to train and test the model. The experimental results give an average accuracy of 91.25% for diseased leaves detection and 99% accuracy for healthy leaves detection.     

Evaluation of the effects of Candidatus Liberibacter asiaticus on inoculated citrus plants using laser-induced breakdown spectroscopy (LIBS) and chemometrics tools

This study investigated the organic and inorganic constituents of healthy leaves and Candidatus Liberibacter asiaticus (CLas)-inoculated leaves of citrus plants. The bacteria CLas are one of the causal agents of citrus greening (or Huanglongbing) and its effect on citrus leaves was investigated using laser-induced breakdown spectroscopy (LIBS) combined with chemometrics. The information obtained from the LIBS spectra profiles with chemometrics analysis was promising for the construction of predictive models to identify healthy and infected plants. The major, macro- and microconstituents were relevant for differentiation of the sample conditions. The models were then applied to different inoculation times (from 1 to 8 months). The models were effective in the classification of 82-97% of the diseased samples with a 95% significance level. The novelty of this method was in the fingerprinting of healthy and diseased plants based on their organic and inorganic contents.     

Preparation and characterization of an immunoaffinity column for the selective extraction of salbutamol from pork sample

A rapid, simple, and reliable determination method for salbutamol in pork was developed with immunoaffinity column (IAC) extraction followed by HPLC analysis. The salbutamol immunoaffinity column was prepared by coupling CNBr-activated Sepharose-4B with the anti-salbutamol polyclonal antibody which was purified by caprylic acid-ammonium sulfate. The coupling rate of the antibody and Sepharose-4B was 98.6%, and the dynamic column capacity of IAC was 400 ng/mL gel. The average recoveries of salbutamol from spiked pork samples at levels of 2, 10, 20, and 50 ng/g ranged from 83.3% to 92.2%, with the relative standard deviations of 2.8-7.0% (n=5), and the limits of detection and qualification were 0.25 ng/g and 0.5 ng/g, respectively.     

Determination of amoxicillin residues in animal tissues by solid-phase extraction and liquid chromatography with fluorescence detection

Trace levels of amoxicillin residues were determined in animal tissues by liquid chromatography (LC) with fluorescence detection. An improved solid-phase extraction (SPE) procedure requiring less flammable solvent (diethyl ether) was developed for sample preparation. Muscle samples of beef, pork, chicken, and tilapia were extracted with a phosphate buffer followed by the modified SPE procedure for cleanup and concentration prior to the LC-fluorescence analysis. Average recoveries of fortified amoxicillin at 5, 10, and 20 micrograms/kg ranged from 83.9 to 85.8% in beef, 86.1 to 88.1% in pork, 81.7 to 82.9% in chicken, and 92.5 to 95.4% in tilapia. Relative standard deviations were < 4%.     

HPLC-DAD法测定猪肝中的盐酸克伦特罗

建立了用5％高氯酸溶液酸化提取,SCX固相小柱净化,高效液相色谱（HPLC）法测定猪肝中的盐酸克伦特罗的方法,利用二极管阵列检测器（DAD）定量并辅助定性。该方法的平均加标回收率为79％,检出限为0．01mg／kg。     

Water-based slow injection ultrasound-assisted emulsification microextraction for the determination of deoxynivalenol and de-epoxy-deoxynivalenol in maize and pork samples

A novel water-based slow injection ultrasound-assisted emulsification microextraction (SI-USAEME) method followed by ultra-high performance liquid chromatography-tandem mass spectrometry analysis was developed for the rapid pretreatment and determination of deoxynivalenol (DON) and its metabolite, de-epoxy-deoxynivalenol (DOM-1), in maize and pork samples. After optimization, the method recoveries for DON and DOM-1 ranged from 73 to 85 % with intraday and interday variations less than 9.4 and 9.2 %, respectively. The limits of detection for DON were 4.2 μg?kg^?1 in maize and 6.2 and 5.9 μg?kg^?1 for DON and DOM-1, respectively, in pork. In addition, an immunoaffinity column (IAC) was prepared. A study comparing the IAC cleanup method, the solid-phase extraction (SPE) cleanup method, and the proposed SI-USAEME method was presented. The water-based SI-USAEME method could become a simple, low-cost alternative to the conventional IAC and SPE method. The method was successfully applied to the analysis of commercial maize and pork products.     

Monitoring of streptomycin and dihydrostreptomycin residual levels in porcine meat press juice and muscle via solid-phase fluorescence immunoassay and confirmatory analysis by liquid chromatography after post-column derivatization

A solid-phase fluorescence immunoassay (SPFIA) that was primarily developed for detection of antibiotic residues in milk was qualitatively applied for the pre-screening of the residues of aminoglycoside antibiotics, streptomycin and dihydrostreptomycin, in meat press juice. The confirmation of both analytes was performed using a validated method of highperformance liquid chromatography with post-column derivatization. The analytical performance was demonstrated by the analysis of pork meat samples spiked at three concentration levels, ranging from 0.25 to 2.5 ppm for each analyte. In general, the recoveries ranged from 80.4 to 81.5% and from 79.6 to 84.4% for streptomycin and dihydrostreptomycin, respectively, with relative standard deviations lower than 6%. The limits of detection were 0.1 and 0.15 ppm for streptomycin and dihydrostreptomycin, respectively, and the limits of quantification of 0.35 and 0.5 ppm are below the maximum residue limits of Codex, the European Union, and the Korean Food and Drug Administration (ranging from 0.5 to 0.6 ppm). Eight real samples collected from the Seoul area were first monitored using SPFIA, and none of them were found positive. These findings are in good accordance with those observed by HPLC analysis. To the best of our knowledge, this is the first report to monitor the aminoglycoside residues in pork meat press juice using SPFIA.