液相色谱-串联质谱法检测牛奶中4种阿维菌素类药物残留量的研究

建立了一种可同时检测牛奶中4种阿维菌素类药物(阿维菌素、伊维菌素、多拉菌素和埃谱利诺菌素)残留的液相色谱-串联质谱方法(LC-MS/MS)。牛奶样品经乙腈提取,高速离心去除蛋白质等杂质,C18柱净化。以0.1%甲酸水溶液和0.1%甲酸乙腈溶液为流动相进行洗脱,流速0.4 m L/min,采用基质匹配标准溶液外标法定量。结果表明:阿维菌素、伊维菌素、多拉菌素和埃谱利诺菌素在0.5~100 ng/m L浓度范围内均呈现良好的线性关系,相关系数(R2)均大于0.996;4种阿维菌素类药物的定量限均为0.5μg/kg。阿维菌素在0.5~5μg/kg添加浓度范围内,伊维菌素在0.5~20μg/kg添加浓度范围内,多拉菌素在0.5~30μg/kg添加浓度范围内,埃谱利诺菌素在0.5~40μg/kg添加浓度范围内,回收率为66.4%~120%;批内与批间相对标准偏差均小于20%。该方法具有简便快速、灵敏度高、定性准确,重复性好等特点,可以满足牛奶中4种阿维菌素类药物残留检测的要求。     

阿维菌素类药物残留检测衍生化研究

本文优化了猪、牛组织及奶和奶粉中阿维菌素类药物残留检测的衍生化方法。经过对反应温度、时间及光照的系统摸索,采用N-甲基咪唑-乙腈(1+1,v/v)与三氟乙酸酐-乙腈(1+2,v/v)为衍生化试剂,经65℃避光反应15 min进行衍生化。该衍生化方法用时短、效率高,进一步提高了检测方法的灵敏度,使得乙酰氨基阿维菌素、阿维菌素、伊维菌素和多拉菌素在牛、羊奶中的定量限为0.5μg/kg;在猪、牛组织和奶粉中的定量限为5μg/kg。     

动物性食品中阿维菌素类药物残留检测高效液相色谱法的优化

为探索方便快捷且符合兽药残留试验技术规范要求的阿维菌素类药物残留检测方法,对农业部1025号公告-5-2008动物性食品中阿维菌素类药物残留检测-酶联免疫吸附法、高效液相色谱法和液相色谱-串联质谱法中的高效液相色谱法进行优化,改进了样品提取后储存条件、净化条件和衍生化条件。牛肝样品经2次乙腈提取后,用乙腈-水-三乙胺储存备用,用C18固相萃取柱分离,1-甲基咪唑-乙腈、三氟乙酸酐-乙腈、冰乙酸和三乙胺衍生化,乙腈作流动相,高效液相色谱法分析。优化法试验结果显示,爱普菌素、阿维菌素、伊维菌素和多拉菌素等4种阿维菌素类药物在2～200μg/L的浓度范围内,标准曲线线性良好,相关系数均大于0.999 2;方法检测限2μg/kg,定量限5μg/kg;加标回收率在83%～93%,批内变异系数小于14%,批间变异系数小于11%。表明优化法符合兽药残留试验技术规范的要求,准确度和精密度较好,检测时间和成本低于标准法,可用于动物性食品中阿维菌素类药物残留的检测。     

高效液相色谱荧光检测法测定牛奶中4种氟喹诺酮类药物残留

为了建立一种同时测定牛奶中4种氟喹诺酮类药物(恩诺沙星、环丙沙星、沙拉沙星、二氟沙星)多残留高效液相色谱检测方法,将牛奶中的残留药物用磷酸-甲醇溶液重复提取2次,正己烷除去脂肪净化后浓缩,流动相溶解后用高效液相色谱-荧光检测器测定。结果表明,4种氟喹诺酮类药物在0.01~1.00μg/mL浓度范围内具有良好的线性关系(R=0.999 9),在0.01,0.05,0.10,0.50μg/mL和1.00μg/mL 5个浓度添加水平上,平均回收率为77%~93%,样品的批内和批间变异系数均值分别为5.29%和7.83%,定量限均为10 ng/mL。环丙沙星、恩诺沙星、沙拉沙星检测限均为5 ng/mL,二氟沙星检测限为8 ng/mL。本研究建立的检测方法简单、快速、灵敏度和回收率高,适用于牛奶中4种氟喹诺酮类药物残留检测。     

QuEChERS-高效液相色谱法检测牛肉中的阿维菌素类药物残留

旨在建立牛肉组织中阿维菌素、伊维菌素、多拉菌素和甲氨基阿维菌素等4种阿维菌素类药物残留的QuEChERS-高效液相色谱检测方法。牛肉组织样品搅碎后,乙腈两次提取,QuEChERS净化,氮气吹干,含1-甲基咪唑和三氟乙酸酐的乙腈溶液衍生化,高效液相色谱-荧光检测器检测(激发波长365nm,发射波长475nm)。在0.1μg/mL~2μg/mL范围内4种药物均呈线性相关,相关系数大于0.999。检测限为2μg/kg(S/N=3),当添加浓度为2、10、40μg/kg时,4种药物的平均回收率在77.3%~97.2%,日内相对标准偏差为2.05%~4.91%(n=5),日间相对标准偏差为0.27%~1.64%(n=3)。建立的方法简便、灵敏、高效、安全,可用于动物组织中阿维菌素类药物残留的检测。     

超高效液相色谱-串联质谱法测定鸡组织中泰乐菌素的残留量

建立了鸡组织中泰乐菌素残留的超高效液相色谱-串联质谱法检测方法,样品用甲醇(含2%氨水)提取,经C18固相萃取柱净化,洗脱液氮气吹干,残渣用甲醇:乙腈(20∶80,V/V)复溶,超高效液相色谱-串联质谱法检测,基质添加标准溶液外标法定量。结果表明泰乐菌素在5~1000μg/kg的浓度范围内呈现良好的线性关系。在鸡组织中中泰乐菌素的检测限为4μg/kg,定量限为10μg/kg。在10~200μg/kg添加浓度范围内,泰乐菌素在鸡组织中的回收率均在85.9%~110.4%之间,批内批间变异系数在1.2%~4.0%之间。该方法各项技术指标均能满足残留检测要求,且方法的重现性良好,满足国内外兽药残留相关法规规定。     

超高效液相色谱-串联质谱法测定水产品中群勃龙残留方法研究

建立了牛奶中苯并咪唑类药物及代谢物残留的超高效液相色谱-串联质谱检测方法。水产样品经乙酸乙酯提取,C18固相萃取柱净化,采用超高效液相色谱-串联质谱多反应监测模式检测,外标法定量。不同基质中,群勃龙在2-100 ng/mL的浓度范围内呈现良好的线性相关,相关系数为0.994以上;本方法对群勃龙群勃龙在鱼、虾、鳖、蟹类产品中的检测限为0.5μg/kg,定量限为1μg/kg;在贝类产品中的检测限为1μg/kg,定量限2μg/kg;不同水产品的基质中添加1-10μg/kg浓度范围内,其回收率为74.2%-119%,批内变异系数在1.0%-9.0%之间,批间变异系数在0.3%-8.5%之间。本方法分析速度快,灵敏度高,重现性好,各项技术指标均满足国内外相关法规要求,可用于水产品中群勃龙的残留检测。     

液相色谱-串联质谱法检测牛奶中林可胺类与大环内酯类药物

牛奶食品中林可胺类药物残留可引起肾功能障碍和革兰氏阳性菌的耐药性增加;大环内酯类药物残留可引起过敏反应和导致携带耐药因子的菌株扩散。本试验利用液相色谱-串联质谱法检测牛奶中林可胺类与大环内酯类药物残留。牛奶样品中的残留药物用乙腈提取后,用正己烷去除脂肪等杂质,浓缩后供液相色谱-串联质谱法测定。经试验:系列浓度范围内呈现良好的线性关系,相关系数(R2)均大于0.990,方法的回收率为70%~120%,批内、批间相对标准偏差均小于20%。检测限为1μg/kg,定量限为2.5μg/kg。     

牛肝中阿维菌素类药物残留的高效液相色谱荧光检测方法的研究

采用高效液相色谱分离,荧光检测器检测,建立了固相萃取分析牛组织中埃普利诺菌素、阿维菌素、多拉菌素和伊维菌素残留的方法.样品用乙腈提取,碱性氧化铝和C18SPE柱净化,用乙酸酐和1-甲基咪唑的乙腈溶液作衍生化试剂,在96℃条件下,完全衍生化需要100min.4种药物的平均回收率为70.02%～88.75%,日内变异系数小于8.52%,日间变异系数小于7.13%.埃普利诺菌素、阿维菌素、多拉菌素和伊维菌素的检出限为0.4～0.5μg/kg,定量限为2ug/kg.该方法可靠、灵敏,可用于常规残留分析.     

牛奶中氯唑西林残留量的高效液相色谱法测定

为建立高效液相色谱法测定牛奶中氯唑西林残留的方法,牛奶样品用乙腈沉淀蛋白,三氯甲烷反萃取,有机相旋干用流动相溶解,正己烷除脂。0.02mol/L磷酸二氢钾溶液(pH 5.0)-乙腈(68∶32)比例为流动相,C18反相色谱柱分离,紫外检测。结果氯唑西林在15μg/kg～1 000μg/kg范围内呈现良好的线性关系,相关系数大于0.999 0;在15、30、60μg/kg三个添加水平,氯唑西林在牛奶中的平均回收率为70.25%～94.38%,批内变异系数小于8.34%,批间变异系数小于3.52%。方法检出限为5μg/kg,定量限为15μg/kg。表明该检测方法简单、灵敏、可靠,适用于牛奶中氯唑西林残留的分析检测。     

牦牛乳各乳成分间相关性分析

为掌握牦牛乳常规营养成分以及不同成分间的相关关系,为下一步牦牛乳用性能选育提供理论基础,本试验对青海高原型牦牛纯放牧条件下(7月底)牦牛乳成分进行了测定,利用SPSS软件对各营养成分间的相关性进行了分析。结果表明∶纯放牧条件下,牦牛乳乳脂率为7.42±1.8956%,乳蛋白率为3.91±0.1619%,乳糖为5.88±0.2375%,非脂乳固体为10.78±0.4238%,密度为1033.45±2.3144kg/m^3,冰点为-0.7377±0.0346℃,盐为0.82±0.041%,电导率为4.74±0.0821s/m。相关性分析表明乳脂肪与密度和盐呈极显著负相关,乳蛋白质、乳糖、非脂乳固体、密度、盐两两间呈极显著正相关(P<0.01),冰点与乳糖、乳蛋白、非脂乳固体呈极显著负相关(P<0.01),冰点与密度和盐没有相关性,电导率与各乳成分之间没有相关性。     

浅谈人工乳、代乳料应用与推广

随着人们生活水平不断提高,对奶的需求也在逐步增加,乳牛饲养在辽宁省迅速发展起来.为满足市场需求解决供求之间的矛盾,在大力发展乳牛数量的同时,要不断改进乳牛的培育方法.     

Detection of staphylococcal enterotoxins in milk and milk products

For food evaluation the determination of the number of Staphylococcus aureus (hereinafter S. aureus) colonies is insufficient in view of present scientific knowledge. The results, advantages and shortcomings of diagnostic methods are demonstrated on an example of three methods of detection of staphylococcal enterotoxins in milk and milk products. 133 strains were investigated by the method of biotyping of S. aureus strains. Four strains of S. aureus were included in biotype A, seven xin-producing strains were isolated seventeen times by detection of 96 S. aureus strains were not included in any biotype, the other strains belonged to biotypes C and E. This method can be used as an auxiliary method of evaluation of foods containing S. aureus bacteria. The agar-gel precipitation method of enterotoxin detection in isolated strains of S. aureus has just restricted validity. The enteroto-strains. The main shortcoming of this method is a fact that the result concerning the isolated strains need not be identical with the result of enterotoxin detection in food. Direct assays of staphylococcal enterotoxins in milk and milk products using an enzymoimmunological method seem to be the most promising, mainly due to their high sensitivity (0.0001-0.001 micrograms.ml1-) and other advantages. Positive and negative results are presented on an example of two model trials with winter sheep milk cheese.     

Role of milk immunoglobulins in the Brucella milk ring test

Milk immunoglobulins were extracted from the stained cream layer of positive milk ring tests from experimentally inoculated or naturally infected cows. IgA was always found, associated with IgM in most cases (15/17) and with IgG in a smaller number of cases (11/17). An additional incubation at 20 degrees C for 18 h gave clearer positive and negative results and a lower limit of detection than that of the usual milk ring test.     

生乳与巴氏杀菌乳中糠氨酸含量及其测定方法研究

本试验研究了生乳与巴氏杀菌乳中糠氨酸含量及其测定方法,并提出糠氨酸作为巴氏杀菌乳中复原乳成分的标示物质,可鉴定巴氏杀菌乳中是否掺入复原乳.研究结果表明,生乳中糠氨酸含量应低于7 mg/100 g;乳粉中糠氨酸含量大于135 mg/100 g;不含复原乳的巴氏杀菌乳中糠氨酸含量应小于12 mg/100 g.使用高效液相色谱(HPLC)紫外检测糠氨酸平均偏差＜5%(n=5);回收率为98.2%.     

Relation of milk production loss to milk somatic cell count.

Milk production loss was studied in relation to increased somatic cell count (SCC). Available data were weekly test-day milk yields and SCC (in 1,000 cells/ml), and mastitis incidences. In total, 18,131 records from 274 cows were used. Production loss was determined for test-day kg milk, kg protein, and kg energy-corrected milk. Least-squares analysis of variance was used to estimate the direct effect of Log10(SCC) on production. The recorded measures of production were first corrected for fixed effects, with adjustment factors estimated from a healthy data-set. The average daily milk yield was 19.7 kg/day in first lactation and 22.0 in later lactations. The geometric mean of SCC was 63.1 in first lactation and 107.2 in later lactations. The incidence of clinical mastitis treated by a veterinarian was 19.8% of the lactations-at-risk. Linear relationships were found between the production parameters and Log10(SCC). Quadratic and cubic effects were evaluated, but were found to contribute little to the overall fit of the models. The individual milk yield loss was 1.29 kg/day for each unit increase in Log10(SCC) for cows in first lactation. Milk yield decreased by 2.04 kg/day per unit Log10(SCC) for older cows. Corresponding values for protein yield were 0.042 and 0.067 kg/day for first and later lactations, respectively.