超高效液相色谱法同时测定食品中4种防腐剂和5种甜味剂

目的建立超高效液相色谱法(ultra performance liquid chromatography, UPLC)同时测定食品中4种防腐剂和5种甜味剂含量的分析方法。方法样品经乙腈水溶液提取,旋转蒸发仪浓缩后,经C_18)固相萃取柱净化。以CORTECS UPLC C18色谱柱(2.0 mm×100 mm, 1.6μm)分离,以0.02 mol/mL乙酸铵+0.02%(V/V)乙酸(A)、乙腈(B)为流动相进行梯度洗脱。采用二极管阵列检测器(photo-diodearray,PDA)进行紫外波长分析。结果 4种防腐剂和5种甜味剂在10 min内完成分析。在0.5～50.0 mg/L浓度范围内,各防腐剂和甜味剂的浓度与峰面积具有良好的线性关系,相关系数r~2在0.999716～0.999956之间。方法的检出限为0.1 mg/kg,定量限为0.3 mg/kg,在0.3、2.0、4.0 mg/kg 3个添加水平的回收率为83.5%～108.1%,相对标准偏差(relative standard deviations,RSD)小于4.6%(n=6)。结论本方法对食品安全国家标准中防腐剂和甜味剂的前处理方法和仪器分析过程进行优化,可同时检测食品中多种防腐剂和甜味剂的含量,结果准确、灵敏度更高。     

高效液相色谱法同时测定食品中12种防腐剂和甜味剂

目的建立高效液相色谱法同时测定食品中12种防腐剂和甜味剂的含量。方法样品经甲醇-水(30:70,V:V)提取,经Agilent TC C_(18)色谱柱分离,以甲醇/20 mmol/L乙酸铵水溶液为流动相进行梯度洗脱,流速为1.0mL/min,采用二极管矩阵检测器进行检测,检测波长为230 nm。结果 12种防腐剂和甜味剂在0.2~20μg/mL的浓度范围内呈现良好的线性关系,r~2≥0.9992,回收率在70.9%~115.6%之间,方法的检出限为0.001~0.005 g/kg。结论该方法具有高通量、操作简便等优点,可适用于食品中12种防腐剂和甜味剂的检测。     

超高效液相色谱法同时测定饮料中14种 食品添加剂

目的建立一种应用超高效液相色谱法同时测定饮料中14种着色剂、甜味剂和防腐剂的分析方法。方法样品经ZOXBAX SB-C_(18)色谱柱分离,以甲醇和100mmol/L磷酸二氢铵溶液为流动相进行梯度洗脱,流速0.2mL/min,柱温35℃。采用二极管阵列检测器,在190~600nm波长下进行扫描,230nm和200nm波长下进行检测,外标法定量。结果在最佳色谱条件下,这14种食品添加剂可在20min内有效分离,标准曲线线性关系良好(r0.996)。平均回收率为92.7%~97.1%,相对标准偏差为0.61%~2.54%。当取样量为5g,稀释体积为25mL时,检出限(limits of detection,LODs)为0.3~0.6mg/kg。结论建立的方法可实现对饮料中多种着色剂、甜味剂和防腐剂的同时检测,具有快速、准确、灵敏的特点。     

高压液相色谱法快速测定饮料中的五种食品添加剂

目的 建立一种高压液相色谱方法同时检测饮料制品中3种甜味剂(安赛蜜、糖精钠、阿斯巴甜)和2种防腐剂(苯甲酸、山梨酸)。方法 样品采用起始流动相稀释后直接过膜分析, 色谱分离在极性修饰XAqua C18色谱柱上进行, 流动相采用50 mmol/L pH 4.5 KH2PO4和乙腈, 梯度模式洗脱, 流速2 mL/min, 柱温40 ℃, 6 min内即可完成一次分离分析, 加上4 min梯度平衡时间, 10 min内即可完成平衡及分离。结果 5种食品添加剂在0.5~50 mg/L内线性关系良好, 相关系数r2均大于0.9999。在两种饮料基质中添加50、100、150 mg/kg 3个浓度水平, 方法回收率为96.48%~105.64%, 相对标准偏差为0.21%~5.39%; 以信噪比S/N =3计算, 方法检测限为0.02~0.08 mg/L。结论 建立的分析方法快速、准确, 可满足饮料中甜味剂和防腐剂的同时检测。     

高效液相色谱法同时测定食品中安赛蜜、苯甲酸、山梨酸、糖精钠以及脱氢乙酸

建立食品中安赛蜜、苯甲酸、山梨酸、糖精钠、脱氢乙酸等甜味剂和防腐剂的高效液相色谱测定法。方法采用C18(5um,4.6mm×150mmi.d)反相色谱柱,流动相:v(甲醇)∶v(0.02moL/L乙酸铵溶液)=(5∶95),流速1.0mL/min,检测波长230nm,柱温30℃,进样量5μL。样品的检出限1.5～4.4mg/kg,线性范围1～10mg/L,加标回收率95.5%～103.6%,相对标准偏差为0.95%～2.81%(n=6)。该法具有样品预处理简单,灵敏度高,分析时间短等优点,可用于食品样品的直接测定。     

高效液相色谱法同时测定食品中安赛蜜、糖精钠、苯甲酸钠、山梨酸、脱氢乙酸

构建食品当中安赛蜜、苯甲酸、山梨酸、糖精钠及脱氢乙酸等甜味剂和防腐剂的高效液相色谱测定法。测定的过程中使用到的是C18反相色谱柱,流动相V(甲醇)∶V(0.02 mol/L乙酸铵溶液)=(5∶95),流速为1.0 mL/min,检测波长是230 nm,柱温为30℃,进样量是5μL。     

高效液相色谱法同时测定食醋和酱油中的6种防腐剂和甜味剂

建立了高效液相色谱法同时测定酱油和食醋中6种常见的防腐剂和甜味剂的方法。样品采用40%的甲醇水溶液提取沉淀,过滤后进入高效液相色谱仪分析。色谱柱为Welch Xtimate C18色谱柱(250mm×4.6mm,粒径为5μm),以甲醇-0.02 mol/L乙酸铵溶液为流动相梯度洗脱,检测波长为230nm,检测的线性范围为10~100μg/mL,相关系数≥0.9994,加标回收率为97.24%~103.50%,相对标准偏差(RSD)为1.45%~2.89%(n=6),该方法简单、快速、灵敏度高,适用于酱油和食醋中常见添加剂的检测。     

高效液相法同时测定葡萄酒中3种防腐剂和2种甜味剂

建立了一种高效液相色谱法同时测定葡萄酒中3种防腐剂（苯甲酸、山梨酸、脱氢乙酸）和2种甜味剂（安赛蜜、阿斯巴甜）。样品去除乙醇后,加入乙酸锌与亚铁氰化钾溶液处理,用C18色谱柱分离,甲醇和乙酸铵（0.02 mol/L）溶液进行梯度淋洗,流速1.0 mL/min,测定波长为230nm和209 nm,进样量20μL。在此条件下,5种组分能够完全分离,呈现良好的线性关系。加标回收率87.3%~110.0%,相对标准偏差为0.5%~3.6%。     

高效液相色谱-蒸发光散射检测器同时测定食品中5种甜味剂

建立了高效液相色谱-蒸发光散射检测器同时测定食品中安赛蜜、糖精钠、甜蜜素、三氯蔗糖、阿力甜5种甜味剂的方法.样品中的甜味剂提取后经固相萃取净化, 并通过C18柱分离, 蒸发光散射检测器测定.结果表明5种甜味剂在5～160 mg/L的浓度范围内, 相关系数为0.9991～0.9994;方法回收率为92.0%～97.0%, 相对标准偏差为0.67%～3.23%.方法最低检出限:安赛蜜为2 mg/kg, 糖精钠为2.5 mg/kg, 甜蜜素、阿力甜和三氯蔗糖为5 mg/kg.该方法准确、灵敏, 是同时检测食品中5种甜味剂的有效方法.     

高效液相色谱法测定糖果、蜜饯和饮料中 19种食品添加剂

目的 建立了高效液相色谱同时测定糖果、蜜饯和饮料中19种常用食品添加剂的分析方法。方法 样品经亚铁氰化钾和乙酸锌溶液沉淀蛋白后,采用Poroshell 120 EC- C18(4.6×100 mm,2.7 μm)色谱柱分离,甲醇和0.02 mol/L乙酸铵水溶液为流动相进行梯度洗脱,二极管阵列检测器多波长(230、254、274、480和630 nm)检测,外标法定量。结果 19种食品防腐剂、甜味剂和色素组分得以有效分离。色素和咖啡因线性范围为0.5~12.5 mg/L,对羟基苯甲酸酯类线性范围为1.0~25.0 mg/L,其他添加剂线性范围为2.0~50.0 mg/L,相关系数均大于0.999。方法检出限为1.0 mg /L,测定低限为10.0 mg/kg。加标回收率为81%~106%,相对标准偏差值为0.34%~4.6%(n≥6)。结论 此方法具有快速、准确且样品处理简单等优点,适用于糖果、蜜饯和饮料中多种添加剂的快速测定。     

SELECT NUTRIENT COMPARISON OF IMITATION SHELLFISH WITH REAL SHELLFISH

Select nutrients of three real shellfish, three imitation surimi based shellfish, and two imitation soy based shellfish were measured by gas chromatography, high pressure liquid chromatography and AOAC methods. The lipid was extracted, methylated and analyzed on a wide bore capillary column with temperature programming to separate the fatty acid methyl esters. Carbohydrates were analyzed isocratically by high performance liquid chromatography on a polar column. Sodium and potassium were analyzed by atomic absorption spectrophotometry. AOAC methods were used to determine percent moisture, protein, and fat. Analysis of variance for the select nutrients showed significant differences among the imitation and real shellfish products (P 0.05) for sodium, potassium, carbohydrate, moisture, fat and protein content. Significant differences were also present in the fatty acid methyl ester analysis. The data suggested that the imitation shellfish products differed significantly in nutrient content from the corresponding real shellfish.     

Effect of replacing potassium by sodium on growth and on inorganic and organic composition of Italian ryegrass

Two pot experiments, one with 2³ factorial (1969) the other with 3³ factorial (1970) N × K × Na design, showed that yields of Italian ryegrass (Lolium multiflorum) were increased by both potassium and sodium, when sufficient nitrogen was given but responses to potassium were larger than to sodium. Yields were only increased by potassium fertiliser when the grass contained less than 2.0 % K in the dry matter, irrespective of the Na content. The main effect of potassium and sodium on the soluble carbohydrates was to increase the production of fructosan; again potassium was more effective than sodium. Total N concentrations in the grass decreased with the increased production of dry matter from potassium and sodium fertilisers. Ammonium N, nitrate N and soluble organic N (expressed as the percentage of total N) were also decreased by potassium and sodium. In 1969, both potassium and sodium increased the percentages of most amino acids and decreased the percentages of asparagine and glutamine within the free amino acid pool; potassium was more effective than sodium. In 1970, sodium alone had little effect on the percentage distribution of free amino acids. Under conditions of severe potassium deficiency sodium can substitute to some extent for potassium in its effects on yields, soluble carbohydrates and various N fractions.     

Interacting properties of bovine lactoferrin with immobilized cibacron blue F3GA in column chromatography

Bovine lactoferrin, isolated from colostral milk, interacted strongly with immobilized Cibacron blue F3GA column. Lactoferrin, adsorbed on the dye column, could not be eluted by 8 M urea, 1% Triton X-100, and 75% ethylene glycol, but was eluted by .1 M sodium hydroxide, 1 M potassium thiocyanate, 3 M potassium chloride, and free Cibacron blue F3GA. Electrostatic forces between the sulfonic groups of Cibacron blue F3GA and the basic side-chain groups in lactoferrin molecule probably are responsible for the observed interaction. The elution profile for lactoferrin differed from those of lactoperoxidase and serum albumin, which might allow efficient isolation of lactoferrin from whey via affinity chromatography.     

The effect of chemical treatment on reduction of aflatoxins and ochratoxin A in black and white pepper during washing

The effect of 18 different chemicals, which included acidic compounds (sulfuric acid, chloridric acid, phosphoric acid, benzoic acid, citric acid, acetic acid), alkaline compounds (ammonia, sodium bicarbonate, sodium hydroxide, potassium hydroxide, calcium hydroxide), salts (acetate ammonium, sodium bisulfite, sodium hydrosulfite, sodium chloride, sodium sulfate) and oxidising agents (hydrogen peroxide, sodium hypochlorite), on the reduction of aflatoxins B(1), B(2), G(1) and G(2) and ochratoxin A (OTA) was investigated in black and white pepper. OTA and aflatoxins were determined using HPLC after immunoaffinity column clean-up. Almost all of the applied chemicals showed a significant degree of reduction on mycotoxins (p < 0.05). The lowest and highest reduction of aflatoxin B(1), which is the most dangerous aflatoxin, was 20.5% ± 2.7% using benzoic acid and 54.5% ± 2.7% using sodium hydroxide. There was no significant difference between black and white peppers (p < 0.05).     

钠盐替代物对西式火腿品质的影响

通过肉汤模拟得出西式火腿中各替代盐的最大添加比例,并根据比例制作对照组、低钠盐组、氯化钾组、氯化钙组、乳酸钾组西式火腿,研究不同替代盐对西式火腿品质的影响。结果表明：通过模拟肉汤的感官评价,确定各替代盐的最适添加比例分别为氯化钾30%、氯化钙25%、乳酸钾35%;不同替代盐会对西式火腿的水分含量、汁液流失、质构及感官评分等造成显著差异（P＜0.05）,但并不会造成明显的色泽变化;其中低钠盐组西式火腿的综合品质最差,具体表现为水分含量最低（59.8%）、硬度最高（3 704 g）及口感得分最低（7.8 分）等,而乳酸钾相比低盐钠组品质仅有略微提升;氯化钾组和对照组西式火腿品质最为相似,感官评分、水分含量及质构等均无显著差异;氯化钙组西式火腿品质最好,表现为蒸煮损失最低（6.51%）及感官得分最高（9.1 分）等。因此,从最大钠盐替代量方面考虑,30%氯化钾组最为适合,而从提升西式火腿品质方面考虑,25%氯化钙组更为适合。     

高效液相色谱内标法测定酱油中糖精钠和苯甲酸钠

以山梨酸钾为内标物,采用高效液相色谱法测定酱油中的糖精钠和苯甲酸钠的含量。样品经体积分数为50%的乙醇溶液提取后,采用Nova-Pak C18色谱柱(3.9 mm×15 mm×5 μm)分离,以甲醇-0.02 mol/L乙酸铵（5∶95,V/V）为流动相进行洗脱,流速1 mL/min,紫外检测波长230 nm。结果表明,在0.1～1.4 mg/kg的添加范围,糖精钠、苯甲酸钠的加标回收率分别为99.5%～102.3%,95.1%～102.1%,相对标准偏差(RSD)分别为0.69%和0.82%。所测酱油中糖精钠和苯甲酸钠的含量分别为3.27 mg/kg和0.133 mg/kg。采用该方法回收率高、准确性好,可用于酱油中糖精钠和苯甲酸钠含量分析。     

食品中多组分甜味剂和防腐剂同时快速测定方法的建立

采用高效液相色谱—串联质谱(LC-MS/MS),建立了同时测定食品中6种甜味剂(甜蜜素、糖精钠、安赛蜜、三氯蔗糖、阿斯巴甜和纽甜)和5种防腐剂(纳他霉素、苯甲酸钠、山梨酸钾、脱氢乙酸钠和双乙酸钠)的定性、定量方法。样品无需衍生和净化,经甲醇和水直接超声提取,以Shim-pack-ODSⅢ色谱柱(75L×2.0mm,1.6μm)分离,甲醇—10mmol/L乙酸铵为流动相梯度洗脱。同时分析了不同流动相对目标化合物在质谱中的离子化效率。结果表明:该6种甜味剂和5种防腐剂在所测浓度范围内与峰面积呈良好的线性关系,R2>0.996,平均加标回收率在73.4%~96.8%,相对标准偏差(RSD)在1.6%~7.8%。     

Pectin lyase and polygalacturonase of Aspergillus niger pathogenic for yam tubers (Diascorea rotundata)

Polygalacturonase and pectin lyase of Aspergillus niger partially purified by ethanol, ammonium sulphate precipitation, DEAE-cellulose and Sephadex G-150 column chromatography were characterized. Polygalacturonase gave optimum activity at pH 4–5, and at 35°C. It was stable at pH 3–7 and at 20–50°C. The molecular weight was 38020. For pectin lyase optimum activity occurred at pH 5 and 45°C. The enzyme was stable at pH 3–4 and at 40–50°C. The molecular weight was 30 900. Yam tissue was optimally macerated at pH 4–5 by the enzymes. At pH 4.5, potassium sorbate (0.6 mg/ml), benzoic acid (0.8 mg/ml) and sodium benzoate (1.0 mg/ml) caused complete inhibition of polygalacturonase activity. With pectin lyase, this effect was achieved with potassium sorbate and benzoic acid each at 0.9 mg/ml, but not with sodium benzoate.     

奶粉中钠、钾、镁、钙的"动态透析"离子色谱法测定研究

目的:探索出较为简便易行的奶粉中钠、钾、镁、钙同时测定的方法。方法:使用透析袋将溶解后的奶粉透析后取出分别过C18柱分离后使用20mol/L甲烷磺酸作为淋洗液,用离子色谱法同时分离和测定奶粉中钠、钾、镁、钙这四种物质。结果:选择转速为200r/min室温下动态透析平衡时间只要2h左右,四物质离子色谱峰形较好,其他离子对它的干扰较小,RSD%均小于5%,回收率在95%～105%之间。结论:奶粉中钠、钾、镁、钙的"动态透析"离子色谱法测定是一种较为实用的测定方法。     

二混蜜中钾的离子交换柱层析法分离和回收

在制糖工业中钾是一种影响糖分回收的造蜜剂.提出以离子交换柱层析分离和回收二混蜜中钾盐的新思路,研究了钾在离子交换层析柱上的分离和洗脱工艺条件.结果表明,实验条件下BK001树脂在层析柱中吸附K+的最佳的工艺条件为:操作流速2 BV/h、锤度50°Bx、温度60℃、高径比为8:1;各工艺条件对钾的分离影响大小顺序是:高径...