紫外分光光度法快速测定废菌丝体中麦角甾醇的含量

为了快速测定废菌丝体中麦角甾醇的含量,本文对紫外分光光度法进行了考察.以二氯甲烷为提取溶剂,麦角甾醇在0.005～0.025 mg/mL范围内线性关系良好,相关系数为0.999 79,平均回收率为98.87％～103.65％,RSD值为2.03％～3.07％,样品在10h内稳定.本方法具有设备操作简便、检测快速的特点,...     

气相色谱-内标法测定白酒中3种高级脂肪酸乙酯含量

以乙酸正戊酯为内标物,建立了白酒中棕榈酸乙酯、油酸乙酯和亚油酸乙酯的气相色谱-内标法检测方法,并对市售不同香型白酒、不同品牌酱香型白酒中3种高级脂肪酸乙酯的含量分布规律进行探究。结果表明,3种高级脂肪酸乙酯的分离效果良好,线性范围为0.300 0～0.400 0 mg/mL,相关系数(R²)均>0.999,精密度试验结果相对标准偏差(RSD)<5%,加标回收率为94.01%～116.97%,检出限为0.003 2～0.003 5 mg/mL,定量限为0.010 9～0.011 7 mg/mL。11种不同香型白酒样品的3种高级脂肪酸乙酯含量在0～0.062 2 mg/mL之间,其中,酱香型白酒含量最高(0.062 2 mg/mL);35种不同品牌酱香型白酒中3种高级脂肪酸乙酯总含量在0.003 5～0.075 8 mg/mL之间。该方法准确、灵敏度高,能对白酒中3种高级脂肪酸乙酯进行有效的分析,可用于酒类企业日常白酒分析检测。     

高效液相色谱法测定饮料中的4-甲基咪唑

建立了高效液相色谱法检测饮料中的4-甲基咪唑的检测方法.样品经过萃取、洗涤,利用高效液相色谱仪在波长210nm处检测.该方法对4-甲基咪唑的检测限为1.0mg/kg,在1μg/mL～ 100μg/mL的范围内有很好的线性,样品的加标回收率为(80.90±0.05)％～(115.50±0.05)％.该方法有很好的准确度和重复性,为各种饮料中4-甲基咪唑的检测提供了依据.     

调味品中罗丹明B的HPLC-FLD-DAD测定方法研究

建立了高效液相色谱(HPLC)-荧光检测器(FLD)-二极管阵列检测器(DAD)测定调味品中罗丹明B的方法.不同基质样品采用适宜的提取液提取后,以甲醇和0.02 mol/L的乙酸铵溶液(70 ∶ 30)为流动相,经C18色谱柱分离,用荧光-二极管阵列检测器串联测定,FLD激发波长为547 nm,发射波长为573 nm,DAD检测波长为550 nm,外标法定量.实验结果表明:罗丹明B用FLD检测在1～2000 ng/mL浓度范围内呈良好的线性关系,定量限为0.005 mg/kg;DAD检测在100～2000 ng/mL浓度范围内呈良好的线性关系,定量限为0.5 mg/kg.方法回收率在83.1％～105.1％之间,RSD为1.64％～5.42％(n=6).该方法准确、灵敏,前处理简单,适用于调味品中罗丹明B的定性、定量分析.     

肉制品中3,4-苯并(α)芘检测方法的改进

确立通过乙酸乙酯超声提取、旋蒸浓缩、甲醇反提净化对肉制品进行前处理,进而结合高效液相色谱仪—荧光检测器测定肉制品中3,4-苯并(α)芘的检测方法.结果表明:3,4-苯并(α)芘在0.5～100 ng/mL范围内呈线性,其线性回归方程Y=4.095×10-5X-4.449× 10-2,相关系数R=0.999 9,回收率为87.4％ ～88.1％,精确度为1.83％～2.37％,检出限(3S/N)为0.15μg/kg.     

采用三硝基苯磺酸法测定乳基婴幼儿配方奶粉中的有效赖氨酸

采用三硝基苯磺酸法建立了乳基婴幼儿配方奶粉中有效赖氨酸的测定方法,研究了乙醚用量、水解时间以及三硝基苯磺酸的孵化时间对水解液吸光度的影响。方法线性范围为0.02～0.12 mg/mL,相关系数r2=0.999 3,检出限为3.72μg/mL,定量限为10.23μg/mL,样品重复性相对标准偏差RSD为1.55%～5.57%,回收率为86%～115%。     

凝胶渗透色谱/气相色谱法测定食用油脂中抗氧化剂特丁基对苯二酚

应用凝胶渗透色谱(GPC)和气相色谱(GC)技术,建立了食用油脂中抗氧化剂叔丁基对苯二酚(TB-HQ)的分析方法。TBHQ在检测范围内具有良好的线性,线性范围在1～1000mg/L之间,相关系数为1。其检出限为0.002mg/mL。加标油样的回收率在87.2%～95.1%之间,相对标准偏差(RSD)小于6.95%。     

同位素稀释气相色谱-质谱联用法测定白酒中16种邻苯二甲酸酯

白酒样品经正己烷提取,采用气相色谱-质谱(GC-MS)在选择离子检测模式(SIM)下测定,内标法定量。添加水平分别为0.05、0.15、0.25 mg/L时,白酒中16种邻苯二甲酸酯的回收率为80.6%¹17.7%,相对标准偏差RSD为0.8%117.7%,相对标准偏差RSD为0.8%¹4.4%。该方法在0.0514.4%。该方法在0.05².00 mg/L范围内线性关系良好,相关系数大于0.999,方法的定量限为0.05 mg/L。     

高效液相色谱法测定枸杞相关食品中枸杞酸和玉米黄质二棕榈酸酯的含量

目的 建立高效液相色谱法分析枸杞原料、提取物和相关配方产品中枸杞酸和玉米黄质二棕榈酸酯的含量。方法 采用Poroshell 120 HILIC柱,以乙腈-磷酸水（90:10, V:V）为流动相进行分离枸杞酸,在紫外检测波长235 nm下进行检测,外标法定量。用Dionex Acclaim C30柱,以甲醇-甲基叔丁基醚为流动相进行梯度分离玉米黄质二棕榈酸酯,在紫外检测波长452 nm下进行检测,外标法定量。结果 枸杞酸的检出限为10 mg/kg,定量限为30 mg/kg;在10～200 mg/L的浓度范围内线性良好,相关系数为0.9999;枸杞原料、提取物和相关配方产品中的加标回收率在84.3%～98.1%之间,相对标准偏差(relative standard deviation, RSD)在1.3%～4.7%之间;精密度的RSD在0.74%～1.2%之间;重复性的RSD分别为1.3%～3.1%之间。玉米黄质二棕榈酸酯的检出限为10 mg/kg,定量限为30 mg/kg;在0.5～10 mg/L的浓度范围内线性良好,相关系数为0.999;枸杞原料、提取物和相关配方产品中的加标回收率在88.6%～98.6%之间,RSD在1.5%～4.5%之间;精密度的RSD在1.2%～2.1%之间;重复性的RSD在2.0%～4.5%之间。结论 本方法操作简便,快速,分离度和准确度高,可用于枸杞原料、提取物和相关配方产品的质量控制。     

超高效液相色谱法同时测定包衣糖果中5种铝色淀

目的 建立包衣糖果中柠檬黄、日落黄、胭脂红、诱惑红和亮蓝5种铝色淀的超高效液相色谱测定方法.方法 用NaOH溶液浸泡提取包衣糖果中的色淀,以乙腈-乙酸铵(10 mmol/L)为流动相,梯度洗脱,多波长检测定量.结果 5种目标化合物在0.25～50 mg/L范围内呈良好的线性,相关系数R2 ＞0.999.该方法中5种目标化合物的定量限(LOQ)均为1.0 mg/kg.在1、5、25 mg/kg三个添加浓度水平下,5种目标化合物的加标回收率为79.5％ ～116.4％,RSD为0.92％ ～6.48％.结论 该方法简单、快速、准确,适于包衣糖果中5种铝色淀的同时检测.     

纳米二氧化铈化学发光抑制法测定抗坏血酸

基于抗坏血酸抑制纳米二氧化铈-过氧化氢-鲁米诺体系的发光强度,建立流动注射化学发光法检测抗坏血酸含量的新方法。考察过氧化氢浓度、鲁米诺浓度、纳米二氧化铈质量浓度及pH值对发光强度的影响。在优化条件下,该方法对抗坏血酸检测的线性范围为0.001～1.0 mg/mL（r = 0.983 1）,检出限（3 σ）为0.2 ng/mL,对质量浓度为1.0 mg/mL的抗坏血酸进行11 次平行测定,相对标准偏差为2.9%。该法已成功用于水果、果汁和蔬菜中抗坏血酸含量的测定,方法简单、灵敏、快速。     

HPLC-ELSD法测定微胶囊中阿拉伯糖、果糖、葡萄糖、蔗糖、麦芽糖、乳糖含量

建立高效液相色谱-蒸发光散射法(High performance liquid chromatography with evaporative light-scattering detection,HPLC-ELSD)同时测定微胶囊中阿拉伯糖、果糖、葡萄糖、蔗糖、麦芽糖、乳糖含量的高效液相色谱方法。样品经乙腈水超声波浸取,采用Waters Amide色谱柱(4.6×250mm3.5μm)分离,以1%氨水和乙腈为流动相,使用蒸发光散射检测器进行检测。结果表明,阿拉伯糖:0.44~7.06mg/mL、果糖:0.30~4.74mg/mL、葡萄糖:0.40~6.45mg/mL、蔗糖:0.32~5.04mg/mL、麦芽糖:0.40~6.47mg/mL及乳糖:0.41~6.61mg/mL范围内线性关系良好;方法检出限为0.02~0.03mg/mL;回收率为95.31%~105.33%,6种糖含量相对标准偏差在2.30%~3.50%之间。该方法前处理简单、灵敏度高和检测速度快,适用于微胶囊中阿拉伯糖、果糖、葡萄糖、蔗糖、麦芽糖、乳糖的定量检测。     

UPLC法测定香蕉、皇帝蕉皮及其果肉中羽扇豆酮含量

目的:建立超高效液相色谱法分离和测定不同收集期的香蕉和皇帝蕉皮及其果肉中羽扇豆酮含量的方法,并优化提取条件。方法:采用甲醇回流提取法对2种蕉皮及其果肉的羽扇豆酮进行提取分离,减压浓缩,选用Waters ACQUITY UPLC BEH C18色谱柱(2.1 mm×50 mm,1.7μm),流动相为乙腈-水(85∶15,V/V)溶液,流速0.3 mL/min,柱温30℃,检测波长206 nm。结果:香蕉和皇帝蕉果肉中均未检测出羽扇豆酮,但2种蕉皮中有较高含量的羽扇豆酮,并且在16.70~59.96 mg/100 mL质量浓度范围内有良好线性关系(r=0.999 6),羽扇豆酮平均回收率为99.00%,相对标准偏差为3.0%。结论:该法回收率高、重复性好,且具有专属性强、准确性高和简便快捷等特点,适用于香蕉、皇帝蕉皮中羽扇豆酮的含量测定。     

An improved sample preparation method for quantification of ascorbic acid and dehydroascorbic acid by HPLC

Ascorbic acid (AA) and dehydroascorbic acid (DHA) are reduced and oxidized forms of vitamin C, which are ubiquitously found in various fruits and vegetables. The present study has evaluated and optimized various factors responsible for AA and DHA stability in grapefruit samples. Furthermore, the optimized method was used to quantify these compounds in different fruits and vegetables. The AA stability in the samples was evaluated by extracting grapefruit juice using 1, 3 and 5 g/100 mL metaphosphoric acid (MPA) and trichloro acetic acid (TCA). The AA levels were stable in grapefruit samples extracted with 1, 3 and 5 g/100 mL MPA, whereas TCA extracts showed degradation in 48 h. Among the three reducing agents studied, tris(2-carboxy ethyl) phosphine hydrochloride (TCEP) has efficiently converted DHA at all concentrations and the samples were stable for 48 h at 2.5 mmol/L TCEP. Lower pH favored complete conversion of DHA by TCEP than dithiothreitol. Among various fruits and vegetables analyzed, the highest levels of AA (260.1 mg/100 g) were observed in guava and DHA (58.6 mg/100 g) in parsley samples. The current optimized method prevents the degradation of AA and DHA from fruit and vegetable samples stored at room temperature for two days.     

Reductions of Salmonella enterica on chicken breast by thymol, acetic acid, sodium dodecyl sulfate or hydrogen peroxide combinations as compared to chlorine wash

Poultry products are important vehicles for Salmonella transmission to humans and have been incriminated in several Salmonella outbreaks. Thymol (THY) from thyme oil has wide inhibitory effects against foodborne pathogens including Salmonella, and has shown great potential as a natural alternative to chlorine. In order to improve the cost-effectiveness of thymol-based washing solutions, formulas of THY with combination of organic acid or surfactant were developed and their efficacies to reduce Salmonella on chicken breast were investigated in the current study. Surface-inoculated chicken breasts were washed with the two thymol-based washing solutions: 0.2 mg/mL THY+5% (w/v) sodium dodecyl sulfate (SDS)+2 mg/mL acetic acid (AA) or 0.2 mg/mL THY+2 mg/mL AA for 2 min. Both solutions achieved around 2.2 log reductions of Salmonella on chicken breast and their efficacy was comparable to log reduction obtained by 200 ppm chlorine washing. Addition of SDS did not result in more log reduction of Salmonella on chicken meat samples. More than 3.3 log reduction in the used THY washing solutions was determined and it was similar to log reduction from the spent chlorine solution. None of these antimicrobial agents changed the pH and texture values of chicken breasts. Therefore, 0.2 mg/mL THY+2 mg/mL AA has great potential to be a natural alternative to chlorine-based washing solution for reducing Salmonella contamination on chicken breast meat.     

A novel miniaturised electrophoretic method for determining formaldehyde and acetaldehyde in food using 2-thiobarbituric acid derivatisation

A novel miniaturised capillary electrophoresis with electrochemical detection (mini-CE-ED) method has been developed for fast determination of formaldehyde (FA) and acetaldehyde (AA) in several food products without preconcentration. Because FA and AA usually exist as uncharged molecules with zero electrophoretic mobility, plus the fact that these two compounds lack of chromophore for sensitive ultraviolet (UV) detection, effective and sensitive determination of FA and AA in real samples is often a challenging task. In this work, an electroactive compound 2-thiobarbituric acid (TBA) was selected as the ideal derivatisation reagent to facilitate the electrochemical determination of FA and AA. Under the optimum conditions, FA-TBA and AA-TBA adducts can be well separated by mini-CE-ED with low detection limit of 9.10 × 10⁻⁹ g/mL (13.2 fg) for FA (S/N = 3). The proposed method should find a wide range of analytical applications in food products as an alternative to conventional and microchip CE approaches.     

NiO/g-C_3N_4修饰电极的制备及电催化检测抗坏血酸

利用三聚氰胺制备石墨相的氮化碳,即g-C_3N_4,以氯化镍和g-C_3N_4为基础物质采用电沉积方法制备复合化学修饰电极。通过对裸电极、Ni O/GCE、g-C_3N_4/GCE和NiO/g-C_3N_4/GCE对抗坏血酸的催化效果的比较,发现NiO和g-C_3N_4的复合修饰电极对抗坏血酸具有良好的电催化氧化作用。扫描速率在70~200 m V/s范围内,峰电流与扫描速率呈良好的线性关系:I_(pa)=-34.14-1.167v,R=0.998;I_(pc)=53.42+0.357 8v,R=0.982。峰电位随扫描速率增大有一定的偏移,说明该修饰电极的氧化还原过程受表面控制。当抗坏血酸的质量浓度介于0.017 6~22.88μg/m L时,其氧化峰电流与质量浓度具有良好的线性关系,方程为:I_(pa)=-1.435+2.900C,R=0.998,检出限为0.008 8μg/m L。该传感器的选择性、重复性和稳定性良好,可用于果汁中抗坏血酸的检测。     

高效液相色谱-蒸发光散射法测定低聚乳果糖的含量

目的：建立简便、准确、灵敏地测定酶法合成中低聚乳果糖含量的液相色谱方法。方法：酶法合成低聚乳果糖的溶液经离心后稀释,使用氨基柱分离,乙腈- 水(体积比75:25)为流动相,流速1.0mL/min,蒸发光散射检测器漂移管温度70℃,载气为空气,压力0.35MPa。结果：低聚乳果糖的线性范围为0.1281～4.1000mg/mL(R2=0.9994),最低检出限为0.01mg/mL,平均加标回收率为100.28%,RSD 为3.07%。结论：该方法操作简便、快速、准确,用于酶法合成低聚乳果糖的测定,结果令人满意。     

流动注射抑制化学发光法测定食品中的铝

基于铝(Ⅲ)对鲁米诺-过氧化氢-Cr(Ⅲ)化学发光的抑制作用,建立了一种用于食品中铝含量测定的流动注射抑制化学发光法。化学发光信号降低的程度与铝的浓度在1.0×10-4～2.0×10-3mg/mL和2.0×10-3～1.0×10-2mg/mL范围内线性相关。对流速、样品环长度、Cr(Ⅲ)的浓度、Al(Ⅲ)溶液的酸度、鲁米诺和过氧化氢的浓度等实验参数进行了优化。方法的检出限为2.29×10-5mg/mL。利用所建立的新方法对大米、绿豆、小米等样品进行了测定,回收率为101%～104%,所得结果与ICP-MS方法的结果没有显著性差异。     

免疫磁珠-环介导等温扩增快速检测牛肉中的鼠伤寒沙门氏菌与金黄色葡萄球菌

建立免疫磁珠分离（immunomagnetic separation,IMS）联合环介导等温扩增（loop-mediated isothermal amplification,LAMP）技术检测牛肉中鼠伤寒沙门氏菌与金黄色葡萄球菌的方法。用生物素标记的鼠伤寒沙门氏菌抗体和生物素标记的金黄色葡萄球菌菌体蛋白抗体对链霉亲和素磁珠进行功能化,从牛肉中捕获和分离目标致病菌。结果表明：经优化后,每毫克磁珠与10 μL鼠伤寒沙门氏菌抗体偶联,400 μL鼠伤寒沙门氏菌免疫磁珠在45 min内对104 CFU/mL鼠伤寒沙门氏菌的捕获率为52.16%;每毫克磁珠与6 μL金黄色葡萄球菌抗体偶联,300 μL金黄色葡萄球菌免疫磁珠在30 min内对104 CFU/mL金黄色葡萄球菌的捕获率为56.80%;建立的IMS-LAMP方法特异性高,对牛肉中鼠伤寒沙门氏菌的检测灵敏度为1.2×103 CFU/mL,对金黄色葡萄球菌的检测灵敏度为4.4×104 CFU/mL;富集5 h后,鼠伤寒沙门氏菌的检测限可至1.2 CFU/mL,富集7 h后,金黄色葡萄球菌的检测限可降至4.4 CFU/mL。建立的IMS-LAMP方法用时短,灵敏度高,操作简单,可以有效检测牛肉中的鼠伤寒沙门氏菌和金黄色葡萄球菌。