固相萃取-高效液相色谱测定奶粉中磺胺类抗生素残留

建立了测定奶粉中磺胺嘧啶和磺胺甲噁唑的固相萃取-高效液相色谱法。奶粉溶于水后经亚铁氰化钾和醋酸锌溶液处理后离心去除脂肪,过C18柱,用水淋洗,甲醇洗脱,洗脱液用于高效液相色谱分析。采用C18柱,流动相为甲醇∶0.08%乙酸=40∶60,检测波长272nm,流速0.8mL/min。结果表明,两种磺胺药物在0.05～1μg/mL的范围内线性良好,回收率为96.8%～97.5%。本方法具有灵敏度高,重复性好等特点。     

固相萃取-HPLC柱后氧化衍生荧光法测定运动营养食品中叶酸的含量

本文开发了固相萃取-HPLC柱后氧化衍生荧光法测定运动营养食品中叶酸含量的方法。分别考察了沉淀蛋白法、酶解蛋白法及固相萃取法的样品前处理方式及流动相的优化条件,最终选择反相弱阴离子交换Strata-X-AW固相萃取小柱纯化,Venusil MP C₁₈色谱柱分离,柱后衍生仪氧化衍生(5%过二硫酸钾溶液),以50 mmol磷酸二氢钾(pH3.5):乙腈=90:10(V/V)为流动相,再经荧光检测器进行检测。结果表明,在0.232~2.318 μg/mL范围内方法线性良好,R²=0.9971,进样量为10 μL,方法的仪器定量限为0.0774 μg/mL,灵敏度足以满足运动营养食品中叶酸的检测需要,方法回收率在96.98%~100.50%之间,标准品、样品溶液在8 h内稳定。本方法很好地解决复杂基质运动营养食品中叶酸的提取、净化除杂等问题。操作方便快捷,结果准确,线性范围广,灵敏度高,重现性、专属性、回收率及稳定性较为满意,能够满足日常运动营养食品中叶酸含量检测的需求。     

柱前衍生-固相萃取-高效液相色谱荧光法 测定蔬菜中草甘膦

目的建立快速、准确的蔬菜中草甘膦的柱前衍生-固相萃取-高效液相色谱荧光测定方法。方法蔬菜提取液样经衍生后经固相萃取,过C_(18)色谱柱,以甲醇-水(70:30,V:V)为流动相,流速1.0 mL/min,柱温为35℃,荧光检测激发波长为265 nm,发射波长为3 15 nm。结果草甘膦的加标回收率在89.2%~99.2%范围,其相对标准偏差均5.0%,在0.5~20.0 ng/mL范围呈现良好的线性,其回归系数0.999,最低定量检出限(LOQ)为0.02 mg/kg。结论本方法回收率高,净化效果好,杂质干扰少,可满足蔬菜中痕量草甘膦的残留检测要求。     

基于分子印迹整体柱的在线固相萃取-液相色谱联用测定奶粉中四环素类兽药残留

目的建立高交联结构的分子印迹整体柱(molecularly imprinted polymer monolithic column,MIP-MC)制备方法,利用在线固相萃取与液相色谱联用技术检测奶粉样品中四环素类兽药残留。方法在不锈钢色谱柱中,以土霉素为模板,甲基丙烯酸和甲基丙烯酸羟乙酯为功能单体,乙二醇二甲基丙烯酸酯和双季戊四醇六丙烯酸酯为交联剂,偶氮二异丁腈为引发剂,在丙酮-甲醇-十二醇混合溶剂中,制备了分子印迹整体柱。将整体柱与液相色谱联用,在线固相萃取奶粉中的四环素类兽药残留。结果在最佳在线固相萃取条件下,获得了较高的富集因子(19.3)和净化效果。四环素类在0.05、0.25和0.5 mg/kg 3个加标水平下,回收率为84.2%~103.4%,相对标准偏差为1.37%~4.87%,方法检出限(S/N=3)和定量限(S/N=10)分别为8.48~11.74?g/kg和28.24~39.09?g/kg。结论该在线固相萃取方法简单快速、灵敏性高、选择性好,适用于奶粉中四环素类抗生素残留的测定。     

在线固相萃取-二维色谱快速测定配方奶粉、米粉中维生素D的含量

建立了在线固相萃取结合二维色谱快速测定婴幼儿配方奶粉、米粉中维生素D(VD)含量的方法。样品溶液皂化后经简单定容便可直接检测,进样后样品溶液经第一个六通阀通过在线固相萃取小柱净化,净化液进入一维色谱,一维色谱采用C8色谱柱,进行初步分离,根据维生素D在一维色谱上的出峰时间,确定切换时间,将这一段时间内的流出液经另一六通阀上的捕获柱富集维VD转入二维色谱进一步分离,实现配方奶粉、米粉中VD的快速测定。通过该方法检测得到VD的加标回收率为91. 3%～97. 2%,相对标准偏差<5%,并通过配对t检验法与标准方法测定结果进行比较分析,测定结果无显著性差异。该方法简单、快速、准确,适用于大批量样品检测。     

固相萃取-高效液相色谱-荧光法测定辣椒制品中罗丹明B

目的建立固相萃取-高效液相色谱-荧光检测法测定辣椒制品中罗丹明B的分析方法。方法样品分别经乙腈和20%丙酮-正己烷溶液提取后,采用Welchrom~P-SCX强阳离子交换固相萃取小柱和Welchrom~中性氧化铝固相萃取小柱进行净化,并采用Welch Ultimate~XB-C18色谱柱(250 mm×4.6 mm,5μm)以75%甲醇-水溶液为流动相进行分离,荧光检测器检测。结果采用Welchrom~P-SCX强阳离子交换小柱对辣椒制品进行前处理净化具有去除杂质效果更好,稳定性更强,方法重现性更好等优势,因而采用Welchrom~P-SCX小柱对辣椒制品进行前处理净化。罗丹明B在1.0~100.0μg/L范围具有良好的线性(r~20.9995),2种辣椒制品的回收率在91.4%~106.5%范围内,相对标准偏差RSD在2.1%~4.3%之间。结论该方法的灵敏度、准确度和精密度均符合罗丹明B的检测技术要求,且简便快速,适用于辣椒制品中罗丹明B的准确测定。     

柱后光化学衍生高效液相色谱法测定调味品中黄曲霉毒素

建立了柱后光化学衍生高效液相色谱法同时测定调味品中黄曲霉毒素B1、B2、G1、G2和M1的方法。对四种调味品进行加标回收和精密度实验,黄曲霉毒素的回收率均在85%以上,相对标准偏差(RSD)为1.27%～4.82%。实验结果表明,该方法操作简单,检测速度快,重现性好,可以满足调味品中黄曲霉毒素检测的要求。     

高效液相色谱-柱后衍生法测定保健品中维生素B_1的含量

文章建立了测定保健品中维生素B_1含量的高效液相色谱-柱后衍生法。方法采用色谱柱:Ultimate XB-C18(4.6mm×150mm,5μm);流动相:(0.01%辛烷磺酸钠+1.5%乙酸+5%甲醇+0.12%三乙胺)-甲醇(65∶35);流速:1.0 mL/min;柱温:35℃;检测波长:Ex=375nm,Em=435nm。研究发现该柱后衍生法测定同一样品中维生素B_1含量得到的峰面积是柱前衍生法测定结果的1.6-18.8倍,维生素B_1含量在0.01-32μg/mL范围内线性良好,R2=0.999,检出限为1 ng/mL。该方法灵敏、简便、准确,重现性好,可用于保健品中维生素B_1含量的测定。     

固相萃取- 高效液相色谱检测法测定食用菌中三聚氰胺残留量

建立食用菌中三聚氰胺的固相萃取- 高效液相色谱检测法。样品经三氯乙酸、乙腈提取,离心,混合型固相萃取小柱净化后,过0.45μm 滤膜,用配有二极管阵列检测器(PAD)的液相色谱仪检测,外标法定量。同时,以三聚氰胺标准品进行添加回收率测定,结果显示,本方法对三聚氰胺的测定低限为2.0mg/kg,回收率为81.3%～91.7%,测定的相对标准偏差均不大于5.6%。本方法能满足食用菌中三聚氰胺残留量常规检测的需要。     

复合固相萃取净化-液相色谱法同时测定奶粉中的5种核苷酸

目的 建立了复合固相萃取净化液相色谱法同时测定婴幼儿配方奶粉中的5种核苷酸含量的分析方法。方法 样品用纯水涡旋提取, 10%乙酸水溶液调pH到4.1,离心将上清液全部转移到25ml容量瓶中,用纯水定容到刻度线,混匀。提取液用复合固相萃取小柱（弱阴离子交换和强阳离子交换固相萃取小柱）净化,以磷酸盐缓冲液和甲醇为流动相,等度洗脱,Spursil C18柱(250 mm×4.6 mm,5 μm)色谱分离,高效液相色谱－紫外检测器进行测定,外标法定量。结果 5种核苷酸在一定范围内（0.1-10 mg/L、0.2-20 mg/L）线性关系良好,相关系数（R2）均大于0.999,定量限为1.0、 2.0mg/kg,检出限为0.3、0.6 mg/kg。方法的3水平加标浓度（1.0、5.0、10.0mg/kg,2.0、10.0、20.0 mg/kg）的回收率在91%-103%之间,精密度在8% 以内。结论 该方法具有操作简单、灵敏度高、重现性好等特点,为奶粉中核苷酸含量测定提供一个简单准确的方法。     

液液萃取—接受相固化—反萃取—气相色谱/质谱法测定奶粉中的香兰素

建立液液萃取—接受相固化—反萃取技术联用气相色谱/质谱法检测奶粉中香兰素的新方法。该方法选用乙醚为提取剂,0.01 mol/L 100μL氢氧化钠溶液为接受相,二氯甲烷为反萃取剂,采用GC—MS测定,选择离子监测(SIM)模式,外标法定量。结果表明,在优化试验条件下,方法的线性范围为0.20~10.0"g/m L,相关系数为0.999 5,检出限为(S/N=3)0.004 mg/kg。应用该方法分析实际样品,加标回收率为82.0%~98.0%,相对标准偏差(RSD)2.83%~6.83%。该法简便、快速、准确和灵敏度好,适用于奶粉中香兰素含量的检测。     

气相色谱-质谱/质谱法测定牛奶和奶粉中的肌醇

建立了一种用GC-MS/MS测定牛奶和奶粉中肌醇质量分数的方法。奶粉样品溶于水后,牛奶直接称量,试样中的肌醇用水和乙醇提取后,与硅烷化试剂衍生,正己烷提取,用GC-MS/MS测定。该方法回收率为86.9%~108.6%,相对标准偏差为3.6%,最低检出限为0.1 mg/kg,且检测结果准确可靠,重复性好,灵敏度高,可进行牛奶和奶粉中肌醇的检测。     

ICP-MS测定奶粉中痕量钛的方法研究

报道应用ICP-MS测定73种奶粉中痕量钛。样品前处理采用微波消解法,并对微波消解条件作了优化;仪器分析时针对样品特性,优化仪器工作条件,采用以钪作内标的外部校正法。结果表明,在0.50~10.00ng/mL范围内呈良好线性关系(r=0.9996),回收率为96.0%~103%,相对标准偏差为1.4%~3.1%。     

快速测定婴幼儿配方乳粉中的维生素B1及B2

建立高效液相色谱-荧光法快速测定婴幼儿配方乳粉中维生素B₁及维生素B₂。方法优化了前处理条件,采用高压酸提法提取目标化合物,样品沉淀蛋白后直接测定维生素B₂,取部分清液用碱性铁氰化钾衍生后测定维生素B₁。目标物在对应的浓度范围内呈现良好的线性关系（R²≥0.9998）,样品加标回收率在92.4%～102%之间。该方法快速,准确,适用于婴幼儿配方乳粉中维生素B₁、B₂的测定。     

Use of powdered vegetable coagulant in the manufacture of ewe's milk cheeses

A powdered vegetable coagulant obtained from the cardoon Cynara cardunculus and characterised as free of viable micro‐organisms, soluble and stable without the need for preservatives was evaluated, and compared with crude aqueous extract, in batches of Los Pedroches cheese, by determining various chemical, biochemical, microbiological and sensory parameters. Parameters were monitored over 3 months of ripening. High casein hydrolysis was observed after 2 days of ripening. The soluble nitrogen values reached at the end of ripening were over 34% of the total nitrogen in cheeses produced with both types of coagulant. For most parameters studied, no differences were observed between the two types of coagulant, although higher counts were observed for some microbiological groups in cheeses produced with crude aqueous extracts. The sensory quality of cheeses was practically identical with both types of coagulant. © 2002 Society of Chemical Industry     

柱前衍生—高效液相色谱荧光检测法测定乳制品中6种母乳寡糖

目的：建立一种普及性强、灵敏度高,并能同时测定乳制品中6种母乳寡糖的高效液相色谱—荧光检测分析方法。方法：样品经冰醋酸沉淀,滤纸过滤后,经2-氨基苯甲酰胺溶液衍生,离心后经有机滤膜过滤,用AdvanceBio Glycan Map色谱柱分离,以乙腈-50 mmol/L甲酸铵溶液（pH 4.4）为流动相,梯度洗脱分离,并使用荧光检测器检测。结果：6种母乳寡糖在1.00～400.0 mg/L质量浓度范围内线性关系良好,相关系数均＞0.999,方法检出限为4.1～10.9 mg/kg,回收率为71.3%～90.2%,日内相对标准偏差（RSD）为1.0%～6.3%,日间相对标准偏差＜10.0%。结论：该方法简单、快捷,可有效降低衍生峰的干扰,适用于乳制品中3′-岩藻糖基乳糖、2′-岩藻糖基乳糖、乳糖-N-四糖、乳糖-N-新四糖、3′-唾液乳糖和6′-唾液乳糖6种母乳寡糖的日常检测。     

柱前衍生-高效液相色谱荧光法测定婴幼儿配方乳粉中低聚半乳糖含量

建立了柱前衍生测定婴幼儿配方乳粉中低聚半乳糖的高效液相色谱法。样品经乙酸调节pH到4.5,使用淀粉葡萄糖苷酶和β-半乳糖苷酶酶解、2-氨基苯甲酰胺衍生。经色谱柱分离,荧光检测器检测。通过响应曲面设计优化衍生关键因素水平：衍生剂浓度、衍生温度与衍生时间。定量化合物3"-半乳糖基乳糖在10.0~100 mg/L范围内线性良好(R²为0.9993)。在低聚半乳糖添加水平为2.5、10.0、40.0 g/kg时,回收率在92.5~102.7%之间,RSD(n=6)在3.69~6.69%之间,方法检测限为0.8 g/kg,定量限为2.5 g/kg。本方法操作简单、回收率高和重现性好,可使用3"-半乳糖基乳糖对婴幼儿配方乳粉中的低聚半乳糖进行定量分析。     

Short communication: Rapid antibiotic screening tests detect antibiotic residues in powdered milk products

Rapid antibiotic screening tests are widely used in the dairy industry to monitor milk for the presence of antibiotic residues above regulated levels. Given the persistent concern over contamination of milk products with antibiotic residues, we investigated the utility of IDEXX Snap test devices (IDEXX Laboratories Inc., Westbrook, ME) as tools for detecting antibiotic residues in powdered milk products. Five powdered milk products were reconstituted according to manufacturer specification with distilled water: Carnation (Nestlé USA Inc., Solon, OH), Nido youth and Nido adult (Nestlé Mexico Inc., Mexico City, Mexico), ELK (Campina, Eindhoven, the Netherlands), and Regilait (Saint-Martin-Belle-Roche, France). Positive samples were generated by spiking reconstituted milk with penicillin G, cephapirin, or tetracycline to either the European Union-regulated maximum residue limit or the FDA-regulated safe/tolerance level, whichever was lower. Control, unspiked negative milk samples and positive samples were tested with appropriate IDEXX Snap test kits (penicillin G and cephapirin with New Beta-Lactam, tetracycline with New Tetracycline). All samples yielded definitive results consistent with expectations, and there were no instances of false-positive or false-negative readings. These results suggest that both the New Beta-Lactam and New Tetracycline IDEXX Snap test kits effectively detect antibiotic residues in commercially available powdered milk samples and are useful tools for monitoring antibiotic residues in reconstituted powdered milk products.     

Determination of polycyclic aromatic hydrocarbons in Italian milk by HPLC with fluorescence detection

The presence of polycyclic aromatic hydrocarbons (PAHs) in Italian commercial milk samples is reported. The study was carried out on lactating (cow and goat) and plant (rice, soya, oat) milk. The quantitative determination involved liquid–liquid extraction of PAHs, a pre-concentration and determination by HPLC using a fluorescence detector. The recovery of analytes was in the range of 70–115%. The precision of the method was found to be between 6% and 24%. The detection limit ranged from 0.66 to 33.3 µg l^–1 corresponding to 0.03–1.66 µg kg^–1 milk (wet weight), at a signal-to-noise ratio of 3, depending on the compound. By this procedure, the levels of more volatile PAHs (two to three aromatic rings) were confirmed in 34 commercial milk and three plant milk samples, whereas benzo[a]pyrene was found only in five pasteurised milk samples at a mean concentration of 0.17 µg kg^–1 milk. These results provide evidence that PAH levels are influenced by heat treatments and skimming processes of milk production.     

Vitamins B1 and B2 contents in cultivated mushrooms

Mushrooms have long been treated as a delicacy. Nowadays however, many researchers consider them to be nutraceutical foods, which has stimulated new and existing Brazilian producers to search for more productive techniques and to introduce other species. The objective of this study was to determine the vitamin B₁ and B₂ contents in mushrooms. The main species of mushroom cultivated in Brazil and analysed in this study are: Agaricus bisporus (white button mushroom and portobello), Lentinula edodes (shiitake) and Pleorotus spp. (shimeji and oyster mushroom). The methodology employed used acid hydrolysis followed by enzymatic hydrolysis and separation of the vitamins by high performance liquid chromatography using a C₁₈ reverse phase column and fluorescence detector. The results obtained for thiamine (vitamin B₁) were from 0.004 to 0.08 mg/100 g and for riboflavin (vitamin B₂), from 0.04 to 0.3 mg/100 g.