超高效液相色谱-蒸发光散射检测法测定蜂蜜中12种糖组分

建立了蜂蜜中果糖、葡萄糖、蔗糖、松二糖、麦芽酮糖、麦芽糖、曲二糖、异麦芽糖、吡喃葡糖基蔗糖、松三糖、蜜三糖和麦芽三糖含量的超高效液相色谱－蒸发光散射测定方法。试样经去离子水溶解,乙腈定容,用0.22 μm滤膜过滤后,采用Amide色谱柱分离,蒸发光散射检测器检测,外标法定量。在优化实验条件下,12种糖得到良好分离,线性相关系数为0.997 7～0.999 8,果糖和葡萄糖的检测结果与示差折光检测法无显著性差异,其余10种糖的平均回收率为90.0 %～105 %,相对标准偏差为0.70%～5.8%。该方法灵敏度高,准确度高,重复性好,适用于蜂蜜中多种糖组分的同时定量分析。用于72批不同蜜种蜂蜜样品中糖组分的检测,发现中国主要蜜源蜂蜜中普遍含有松二糖、麦芽酮糖、麦芽糖等糖组分。该方法和检测数据可为蜂蜜品质和质量评价提供重要支撑。     

高效液相色谱法测定烟草料液中的糖

研究了用蒸发光散射检测器检测，高效液相色谱法测定烟草料液中糖的方法。料液中的糖用固相萃取预分离，然后以Waters carbohydrate高效糖柱为固定相，V（乙腈）：V（水）=70：30作为流动相分离，蒸发光散射检测器检测；样品中鼠李糖、木糖、阿拉伯糖、果糖、甘露糖、葡萄糖、蔗糖、麦芽糖8种糖的加标回收率分别为：97．0％、95．6％、102％、102．1％、95．0％、101．8％、102．6％、97．8％；线性范围分别为：鼠李糖、果糖、葡萄糖、蔗糖0．1～20pg，木糖、阿拉伯糖、甘露糖、麦芽糖0．2～25μg。相对标准偏差均小于3．2％。方法的检出限达：鼠李糖20ng、木糖26ng、阿拉伯糖28ng、果糖14ng、甘露糖20ng、葡萄糖10ng、蔗糖12ng、麦芽糖15ng，用该方法测定了烟草料液中的糖。     

高效液相色谱法测定浓缩果汁中5种可溶性糖

建立同时测定浓缩果汁中木糖、果糖、葡萄糖、蔗糖和麦芽糖的高效液相色谱–蒸发光散射检测方法(HPLC–ELSD)。样品采用乙腈–水(50∶50)稀释,用酰胺键合色谱柱BEH Amide分离,蒸发光散射检测器检测,在10 min内完成木糖、果糖、葡萄糖、蔗糖、麦芽糖的分离。浓缩果汁中5种可溶性糖的质量浓度在0.1～2.0 mg/m L与色谱峰面积均呈线性关系,相关系数为0.991 0～0.993 1,检出限为0.23%～0.98%,样品加标回收率为88.6%～104.3%,测定结果的相对标准偏差为2.2%～6.3%(n=6)。该方法快速、准确,可作为浓缩果汁中糖含量的质量控制方法。     

阴离子交换色谱-积分脉冲安培检测法分离测定烟草料液中的山梨醇和糖

采用阴离子交换色谱-积分脉冲安培检测法分离测定了烟草料液中山梨醇、葡萄糖、果糖、蔗糖和麦芽糖,研究了山梨醇和糖在阴离子交换色谱中的保留行为。采用优化的水和氢氧化钠二元梯度淋洗条件,CarboPac PA10阴离子交换色谱柱进行分离,积分脉冲安培检测器检测一次进样测定烟草料液样品中的山梨醇、葡萄糖、果糖、蔗糖和麦芽糖。各组分在测试条件下线性关系良好,线性范围为0.005～20 mg/L,检测限为0.2～1.0 μg/L,加标回收率为95.1%~102.4%,相对标准偏差为1.2%～1.9%。     

高效液相色谱-蒸发光散射法测定食品中的单糖、双糖、低聚果糖和糖醇

建立了食品中常用的木糖、果糖、葡萄糖、蔗糖、麦芽糖、乳糖、蔗果三糖、蔗果四糖、蔗果五糖、赤藓糖醇、木糖醇、甘露糖醇、麦芽糖醇等13种单糖、双糖、低聚果糖和糖醇的高效液相色谱同时分离检测的方法。该法采用NH₂色谱柱,以乙腈-水为流动相梯度洗脱,蒸发光散射检测器检测;13种糖在0.1~5 g/L内均具有良好的线性关系,检出限均在0.1 g/L以下,精密度(RSD)为2.69%~7.21%,回收率为96.1%~105.2%,结果较为理想。将该法用于实际样品检测,结果显示食品标签明示和实际成分相差较大。     

超高效液相色谱-串联质谱法测定卷烟中果糖、葡萄糖、蔗糖、麦芽糖

建立超高效液相色谱–串联质谱法测定卷烟中果糖、葡萄糖、蔗糖、麦芽糖4种水溶性糖的含量。样品用水超声提取,稀释过滤后直接进样,以Acquity BEH Amide色谱柱为分析柱,乙腈和水为流动相,梯度洗脱,采用负离子多反应监测模式分析。果糖和葡萄糖的线性范围为2.5～30μg/mL,蔗糖和麦芽糖的线性范围为0.25～3μg/mL,线性相关系数均大于0.997,方法检出限均为0.03 mg/g。加标样品的平均回收率为93.6%～101.0%,测定结果的相对标准偏差为0.7%～2.9%(n=6)。该方法简便、快速,可用于卷烟样品中果糖、葡萄糖、蔗糖、麦芽糖的测定。     

高效阴离子交换色谱-脉冲安培检测法测定烤烟中的水溶性葡萄糖、果糖和蔗糖

用高效阴离子交换色谱-脉冲安培检测法（HPAEC-PAD）测定了烤烟中的水溶性葡萄糖、果糖和蔗糖。采用水浸取及膜过滤法处理烤烟样品,以Dionex CarboPac PA-1阴离子交换柱为色谱柱,0.2 mol/L NaOH水溶液为淋洗液进行分离测定。葡萄糖、果糖和蔗糖的含量与其峰面积的线性关系良好,回收率均在97%以上。方法简便易行,灵敏度高,重现性良好,可以实现对烟草中单糖的快速分离和测定。     

高效液相色谱内标法分离和测定植物中的单糖

 建立了一种以 β 吲哚乙酸为内标物 ,用高效液相色谱内标法直接分离和测定植物中游离糖的新方法。木糖、果糖、葡萄糖、蔗糖、麦芽糖、乳糖和棉子糖的分离在 18min内完成 ;检出限分别达到 1 8μg ,2 3μg ,2 7μg ,1 8μg ,3 5 μg ,4 1μg和 4 3μg ,线性范围为 5 μg/L～ 75 0 μg/L。研究了流动相中乙腈的浓度、pH值对分离 7种糖和 β 吲哚乙酸的影响。方法用于枣和苹果样品的测定并进行回收率试验 ,结果为木糖、果糖、葡萄糖、蔗糖的 5次测定的回收率分别为 97 4%～ 10 2 1% ,97 3%～ 10 1 8% ,98 7%～ 10 2 2 % ,97 7%～ 10 2 5 %,。     

乙二胺改善硅胶柱高效液相色谱法分离和测定糖

本文研究了用乙二胺作为硅胶柱改善剂的高效液相色谱法，对操作条件进行了探讨。采用示差折光检测器检测，含０．０１％乙二胺的乙腈－水（７２：２８，Ｖ／Ｖ）作流动相，在硅胶柱上成功地分离了果糖，葡萄糖，蔗糖，麦芽糖，乳糖和棉三糖。定量地分析了几种鲜桃汁中糖的含量。     

HPLC测定饮料中糖类

我们采用高效液相色谱仪,以国产固定相YWG—NH_2,示差检测器测定果汁、果酒、啤酒,甜高梁秸杆汁等中的蔗糖、葡萄糖、果糖,麦芽糖含量,获得满意结果。     

高效液相色谱法测定啤酒、发酵液和麦汁中的糖类和乙醇

Cheethan和Rajkyla提出以十八烷基修饰的硅胶作为固定相,以纯水作洗脱液,来分离单糖和寡糖,类似方法应用于啤酒工业分析的国内报道,仅见一篇文章,国外文献报道、美国酿造化学家协会(ASBC)和欧洲酿造协会(EBC)推荐的高效液相色谱法(HPLC),多采用阳离子交换柱分析酿造用辅料,麦汁,发酵液,啤酒中的糖类.目前国内大啤酒厂多采用啤酒分析仪测定乙醇,很少采用气相色谱法(GC)和液相色谱法(HPLC).采用GC直接测定乙醇含量,由于啤酒中乙醇含量远高于其它杂醇油,GC法测定杂醇油时,难以定量测定乙醇,除非采用填充柱,单独测定乙醇.本文方法采用Nucleosil C18柱,测定啤酒,发酵液和麦汁中的糖类时,同时测定乙醇.     

Fast and Selective Pressurized Liquid Extraction with Simultaneous In-Cell Cleanup for the Analysis of Ethyl Carbamate in Fermented Solid Foods

A novel analytical methodology that could be used to identify ethyl carbamate (EC) in fermented solid foods was developed and validated. The method was based on selective pressurized liquid extraction with a simultaneous in-cell cleanup combined with gas chromatography–tandem mass spectrometry. The final method was performed at 50 °C for 2 × 5 min using ethyl acetate. Florisil was placed inside the extraction cell downstream of the sample to remove interfering compounds. The proposed method showed a limit of detection of 0.3 μg kg^?1 and a limit of quantitation of 1.0 μg kg^?1. The recoveries ranged from 98 to 107 % with relative standard deviations of <7 %. The validated method was successfully applied for the determination of EC in French bread, sauerkraut and fermented bead curd samples.     

超高效液相色谱-四极杆-飞行时间质谱法快速检测发酵黑茶中黄曲霉毒素B_1

以直接提取稀释结合黄曲霉毒素免疫亲和柱净化的方法,利用超高效液相色谱-四极杆-飞行时间质谱(UPLC-Q-TOF-MS),建立了发酵黑茶中黄曲霉毒素B1(AFB1)的快速分析方法。样品采用甲醇-水溶液(7∶3,体积比)提取,以HSS T3色谱柱(100 mm×2.1 mm,1.8μm)进行色谱分离,通过正离子扫描,Full ms-dd-MS/MS模式进行分析。结果表明:33种发酵黑茶中的AFB1在一定范围内具有良好的线性关系,相关系数(r2)大于0.999,4种样品的加标回收率(n=4)为86.4%~98.0%,相对标准偏差(RSD)为0.3%~1.7%,检出限(LOD,S/N≥3)和定量下限(LOQ,S/N≥10)分别为0.06μg/kg和0.19μg/kg。结果显示33种样品中的AFB1含量均在合理范围内。该方法准确、快速、简单,适用于发酵黑茶中AFB1的检测。     

橙色红曲菌As3.4384及其诱变体发酵产物中的桔霉素和色素的高效液相色谱研究

对橙色红曲菌As3.4384及其诱变菌株大米固态发酵物中桔霉素和色素的HPLC分离进行了优化,采用Symmetry C18(250mm×4.6mmi.d.,5μm)色谱柱,流动相为乙腈-水(磷酸调pH3.0,77∶23,V/V),分别采用紫外检测器(UV=254nm)、荧光检测器(λex=331nm,λem=500nm)及两者串联对桔霉素和色素进行了监测。通过ESI-MS对色素进行了鉴定,并测定了经橙色红曲菌As3.4384及其诱变菌株于30℃发酵14d后的大米、糯米、小黄米、燕麦米和红米中桔霉素含量。结果表明:ESI-MS鉴定的两种色素分别为红曲菌素和红曲黄素,橙色红曲菌As3.4384发酵后的大米、糯米、小黄米、燕麦米和红米中桔霉素含量分别为151.4、100.5、5.06、80.5和150.5mg/kg,而诱变菌株发酵后的大米、糯米、小黄米、燕麦米和红米中桔霉素含量分别为0.218、3.86、0.223、2.45和4.05mg/kg。     

Liquid Metals and Liquid Semiconductors

Numerous liquid systems have electrical properties which resemble those of crystalline and amorphous semiconductors. The existence of “semiconducting” behavior in these liquids is mostly related to a continuous transition from a metallic to a “semiconducting” state when a thermodynamic variable such as temperature, density or concentration is changed. Changes in the nature of the chemical interaction and the associated changes in the structure of the liquid are of fundamental importance for the transition to a “semiconducting” state. This will be demonstrated for the ionic liquid CsAu, for covalent liquid selenium, and for expanded liquid metals.     

Chemical Constitution and Antimicrobial Activity of Kefir Fermented Beverage

Kefir beverage (KB) is a fermented milk initiated by kefir grains rich with starter probiotics. The KB produced in this study seemed to contain many chemical compounds elucidated by gas chromatography–mass spectrometry (GC-MS) and IR spectra. These compounds could be classified into different chemical groups such as alcohols, phenols, esters, fatty esters, unsaturated fatty esters, steroids, polyalkenes, heterocyclic compounds and aromatic aldehydes. Both KB and neutralized kefir beverage (NKB) inhibited some pathogenic bacteria including Escherichia coli ATCC11229 (E. coli), Listeria monocytogenes ATCC 4957 (L. monocytogenes), Bacillus cereus ATCC 14579 (B. cereus), Salmonella typhimurium ATCC 14028 (Sal. typhimurium) as well as some tested fungal strains such as Aspergillus flavus ATCC 16872 (A. flavus) and Aspergillus niger ATCC 20611 (A. niger), but the inhibitory activity of KB was more powerful than that obtained by NKB. It also appeared to contain four lactic acid bacteria species, one acetic acid bacterium and two yeast species. Finally, the KB inhibited distinctively both S. aureus and Sal. typhimurium bacteria in a brain heart infusion broth and in some Egyptian fruit juices, including those made with apples, guava, strawberries and tomatoes.     

Encapsulation and Stability Study of Monascus Fermented Rice Extract

Monascus fermented rice (MFR) or angkak is a product resulting from rice fermentation using Monascus sp. For the application in functional food of MFR extract, the encapsulation and stability of this pigment have been studied. The extract of MFR was evaluated its stability to that of pH (2-6), temperature (40-70^oC) and UV light exposure. Encapsulation of MFR was carried out by spray drying (SD) and freeze drying (FD) methods with dextrin as encapsulating agent. The encapsulated products was analyzed the encapsulation yields, hygroscopicity and monacolin K content. The absorbance of MFR extracts was increased by increasing the pH. The extract was stable after heat treatment at 50^oC, but the absorbance was increased gradually when heating elevated up to 70^oC. The absorbance tend to stable after exposed to UV light for 5 hours. Encapsulation yields of MFR extract by SD method (34.00%) was lower than by FD method (89.71%). Monacolin K content of encapsulated product by SD method was 898.7 μg g^-1 and by FD method was 1458.3 μg g^-1. However, the product by FD method was more hygroscopic compared to SD method.     

Chemical Constitution and Antimicrobial Activity of Kombucha Fermented Beverage

Kombucha is a traditional beverage of sweetened black tea fermented with a symbiotic association of acetic acid bacteria and yeasts. In this study, kombucha fermented beverage (KFB) appeared to include nine chemical groups (alcohols, acids, lactones, condensed heterocyclic compounds, antibiotics, esters, aldehydes, fatty acids, and alkaloids) of many bioactive metabolites, as elucidated by gas chromatography–mass spectrometry (GC-MS) and IR spectra. The fermented metabolic components of KFB seem collectively to act in a synergistic action giving rise to the antimicrobial activity. Four types of kombucha preparations (fermented, neutralized, heat-treated and unfermented) were demonstrated with respect to their antimicrobial activity against some pathogenic bacterial and fungal strains using agar well diffusion assay. KFB exerted the strongest antimicrobial activities when compared with neutralized and heat-treated kombucha beverages (NKB and HKB). Staphylococcus aureus ATCC6538 (S. aureus) and Escherichia coli ATCC11229 (E. coli) were the organisms most susceptible to the antimicrobial activity of kombucha beverage preparations. Finally, the KFB preparation showed remarkable inhibitory activity against S. aureus and E. coli bacteria in a brain heart infusion broth and in some Egyptian fruit juices (apple, guava, strawberry, and tomato). These data reveal that kombucha is not only a prophylactic agent, but also appears to be promising as a safe alternative biopreservative, offering protection against pathogenic bacteria and fungi.     

顶空固相微萃取-气相色谱-质谱分析发酵香肠挥发性成分

采用固相微萃取-气相色谱-质谱(SPME-GC-MS)联用分析技术对发酵香肠挥发性成分进行了分析。共鉴定了33种化合物。结果表明，发酵香肠的挥发性成分主要为醇类、酮类、酯类、有机酸类、酚类及醛类等。