微波辅助-旋转回流提取仪的组装及其在叶下珠有机酸提取中的应用

组装了一种新型的微波辅助旋转回流装置,该装置的基本原理与微波辅助溶剂萃取的原理相同,但采用了旋转的技术以加速提取.应用该装置以正交实验筛选优化叶下珠中有机酸的提取工艺,并利用毛细管电泳技术分离测定了提取液中有机酸的含量以评价提取效果.最佳提取工艺:乙醚为溶剂,微波功率800 W,提取时间4 min,溶剂用量300 mL.在该提取条件下,平行5次提取叶下珠中丁二酸、原儿茶酸、没食子酸、咖啡酸、阿魏酸的平均含量分别为42.2、103.5、436.2、123.8、67.4 μg/g,相对标准偏差为0.87% ～3.7%,加标回收率为94% ～104%.将该法与常规的微波辅助提取法及回流提取法进行比较,结果表明,微波辅助旋转回流提取法提取效率明显优于其它2种方法.     

一种抗氧剂的剖析

利用傅里叶变换红外光谱法、X射线衍射法、电感耦合等离子体原子发射光谱法对一种抗氧剂进行了组成剖析。结果表明:该抗氧剂由吩噻嗪、碳酸钙、硝酸钾组成,其质量分数分别为85.25%,5.72%,9.03%。     

碱溶性茶多糖的提取及其分析

在煎煮后的低档绿茶茶渣中提取碱溶性茶多糖,经HPGPC-ELSD法分析其含有3种均一性多糖组分,依出峰顺序其质量分数约为5.96%、78.99%和15.05%;GC-MS法测得组成碱溶性茶多糖的6种单糖:鼠李糖、阿拉伯糖、木糖、甘露糖、葡萄糖和半乳糖,并分析了其摩尔比例.紫外-可见吸收光谱分析显示,碱溶性茶多糖在250～290 nm区段有"波浪状"吸收.红外光谱表征了碱溶性茶多糖的特征,圆二色谱分析了其水溶液的cotton效应.结果表明,在190 nm有正cotton效应,在203 nm有负cotton效应.     

紫外光谱法选择大叶茜草素印迹聚合物制备功能单体

为了制备对大叶茜草素具有仿生识别能力的分子印迹聚合物,建立了紫外光谱法选择大叶茜草素分子印迹聚合物制备功能单体及比例的方法.利用紫外光谱法,测定了大叶茜草素与甲基丙烯酸、丙烯酰胺和4-乙烯基吡啶3种常见功能单体在乙腈中的相互作用,发现大叶茜草素与甲基丙烯酸混合溶液紫外吸收的吸光度值发生了一定的增强,说明两者能够在乙腈中形成一定的氢键作用.通过测定大叶茜草素与不同比例的甲基丙烯酸混合溶液的紫外吸收光谱的变化,发现当大叶茜草素与甲基丙烯酸物质的量之比为1∶4时,混合溶液紫外吸收与大叶茜草素溶液的差值最大,表明该比例条件下两者之间形成的氢键最强、最稳定.因此,采用甲基丙烯酸为功能单体,功能单体与模板分子比例为4∶1时制备的分子印迹聚合物将对大叶茜草素具有最佳的识别能力.     

用双波长薄层色谱扫描法测定糖脂双降茶中菝契皂甙元的含量

应用双波长薄层色谱扫描法糖脂双降茶中菝契皂甙元的含量,回收率为98.18％,相对标准偏差为2.54％,相关系数为0 9977.该法糖脂双降茶中菝契皂甙元的含量,操作简便、结果稳定、重复性好,可作为质量检验的一个定量方法。     

硅胶表面铜离子印迹聚合物的制备和性能研究

以Cu2+为模板,1,4-二羟基蒽醌为单体,硅胶为载体,γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH-570)为偶联剂,利用表面离子印迹技术制备了Cu2+印迹聚合物。采用紫外光谱法、傅里叶变换红外光谱法(FT-IR)、扫描电镜对Cu2+印迹聚合物进行结构和表面形貌表征,并用原子吸收光谱法考察了吸附时间、吸附酸度、吸附温度、吸附浓度等对聚合物吸附性能的影响,研究了印迹聚合物在混合溶液中对Cu2+的选择性,将该聚合物重复利用6次,吸附量达到第一次的82%,并将该印迹聚合物应用到河水和自来水中,能够有效地测出水中铜离子的浓度,回收率分别为95.5%和107.2%。     

反相-高效液相色谱分析茶条槭叶中多酚类化合物

本文建立了反相高效液相色谱法( RP-H PLC)测定茶条槭叶中多酚类化合物含量的方法.采用XTerra-C18色谱柱,选择流动相为甲醇-乙酸-水,检测波长分别为278nm(0～30 min)和360 nm(30～35 min),流速0.5 mL/min的色谱条件,对茶条槭叶进行定性、定量分析.结果表明,此方法精密度高...     

原子吸收光谱法测定粽叶中微量元素

用火焰原子吸收光谱法直接测定了粽叶中Fe、Cu、Zn、K、Ca、Na 6种微量元素的含量。结果表明,粽叶中含有丰富的人体必需微量元素。该法简单、准确,回收率在95.0%~105.0%之间,相对标准偏差(RSD)小于2.68%,结果令人满意。     

响应面法优化石榴叶多酚闪式提取的工艺研究

为建立快捷、高效、绿色的石榴叶多酚的提取工艺,通过单因素实验确定其主要影响因素,在单因素实验的基础上利用响应面法进行分析,确定提取石榴叶多酚的最佳提取条件为:乙醇浓度58%、料液比1∶9 (g/mL),提取时间4 min,在此条件下石榴叶多酚的理论提取量为:29.37 g GAE/100 g,实际提取量为:29.12 g GAE/100 g.     

化学浸提-分光光度法测定沙棘叶中不同形态铝

利用KCl、NH4Ac、HCl、NaOH四种浸提液将沙棘叶中的铝浸提溶出,得到沙棘叶中铝的不同化学形态,采用分光光度法定量测定,测定结果:沙棘叶中的Al3+为10.7%,Al(OH)2+和Al(OH)+2为2.1%,胶态Al(OH)03为34.3%,有机铝为53.0%.浸提液中铝的回收率为86.9%～101.0%.     

Simultaneous Determination of Flonicamid and its Metabolites in Tea by Liquid Chromatography–Tandem Mass Spectrometry

An analytical method was established to simultaneously quantify flonicamid and its metabolites 4-trifluoromethylnicotinic acid (TFNA), N-(4-trifluoromethylnicotinoyl) glycine (TFNG), and 4-trifluoromethylnicotinamide (TFNA-AM) in tea using orthogonal experimental design and liquid chromatography–tandem mass spectrometry (LC–MS/MS). Residues were extracted from the samples with acetonitrile containing 1% acetic acid and were purified with graphitized carbon black. The linearity of the method was excellent in the concentration range of 0.01–10?µg/mL, producing correlation coefficients greater than 0.996 for the target compounds. The limits of detection and quantification of all analytes in tea were 0.0013–0.013?mg/kg and 0.004–0.040?mg/kg, respectively. The average recoveries of flonicamid, TFNA, TFNG, and TFNA-AM ranged from 75.14 to 92.72%, with intra- and interday relative standard deviations of 1.07–9.75%. The proposed method was successfully applied to the terminal residue determination of flonicamid and its metabolites in dry tea processed from three field trials’ fresh samples. The determined total terminal residue concentrations of flonicamid 10?days after the last application at all three sites were below the maximum residue limit (MRL) set by the European Union (0.1?mg/kg) and the residues in all samples were lower than the MRL established by the United States Environmental Protection Agency (EPA) (8?mg/kg). This method may be used to meet the requirements for the determination of flonicamid and its metabolites that could provide guidance for establishing a MRL for flonicamid in tea in China.     

4-羟基香豆素及其衍生物的简便合成及其荧光性质的研究

用米氏酸和苯酚在无溶剂条件下以90.6%的收率合成丙二酸单苯基酯, 然后用Eaton试剂(五氧化二磷＋甲基磺酸)在温和条件下闭环, 以78.8%的收率得到4-羟基香豆素, 将这种方法扩展合成了苯环上带有各种取代基的4-羟基香豆素衍生物以及4-羟基硫代香豆素衍生物. 并对部分4-羟基香豆素衍生物的荧光性质进行了研究.     

原子吸收光谱法测定比较5种不同品牌茶叶中微量元素含量

对市售茶叶崂山绿茶、茯茶、安溪铁观音、乌龙茶、茉莉茶王中微量元素Ca、Mg、Fe、Cu、Zn的含量进行考察.采用V(高氯酸)∶V(硝酸)=1∶4混酸消解的方法将样品在低温下消解,火焰原子吸收光谱法定量.实验测得5种茶叶中均含丰富的Ca、Mg,其中茯茶含Fe最多;崂山绿茶含Cu最多;安溪铁观音和崂山绿茶含Zn多.各元素工作曲线相关系数r0.9948,加标回收率94.38%～105.00%,相对标准偏差在2.26%以下.实验方法快速、定量准确,测得各品牌茶叶中微量元素含量可为消费者提供参考.     

A method based on precolumn derivatization and ultra high performance liquid chromatography with high‐resolution mass spectrometry for the simultaneous determination of phthalimide and phthalic acid in tea

Phthalimide can be formed from either the degradation of folpet and phosmet, or reaction of phthalic anhydride with primary amino groups. Consequently, the sum of phthalimide and folpet, expressed as folpet‐residue definition, is highly prone to false‐positive levels of folpet in tea. An analytical method is thus urgently needed to investigate the residue level and source of phthalimide in tea. In this work, we developed an accurate method of determining phthalimide and phthalic acid (the indicator of phthalic anhydride) by acetonitrile extraction and 3‐bromopropyltrimethylammonium bromide derivatization coupled with ultra high performance liquid chromatography and high‐resolution mass spectrometry. The method was validated, and linearity (correlation coefficients > 0.99) was obtained. Satisfactory recoveries at 10, 20, 50, and 100 μg/kg ranged from 76 to 117%, and the intra‐ and interday accuracies were <23%. The limit of quantification for phthalimide and phthalic acid was 10 μg/kg. The developed method was further successfully used to determine phthalimide and phthalic acid in some tea samples. The positive rate of phthalimide and phthalic acid detected in the tea samples ranged from 30–75 and 50–90%, respectively.     

原子吸收法在有机分析中的应用（Ⅲ）：茶叶中茶多酚的测定

研究了间接测定茶叶中茶多酚的原子吸收，用甲基异丁酮和丁醇的混合溶剂萃取茶汤中的茶多酚，与氨基酸分离后，加入碱性Ｃｕ３（ＰＯ４）２悬浮液反萃取并同茶多酚作用，离心沉降未作用的Ｃｕ３（ＰＯ４）２后，用原子吸收法测定Ｃｕ，可求得茶多酚的含量，本法可消除茶叶共存氨基酸的干扰，测定结果同标准方法一致，回收率范围为９４％－１０４％，平均标准偏差为３．１％。     

气相色谱法快速测定茶叶中的八氯二丙醚残留量

建立了快速测定茶叶中八氯二丙醚(S-421)残留量的气相色谱方法。茶叶样品中的S-421经丙酮-石油醚混合液超声波辅助提取,用浓硫酸去除杂质,正己烷定容,用外标法定量,以气相色谱法(GC-μECD)进行测定。实验结果表明,样品中加入0.01~0.08 mg/kg浓度水平的八氯二丙醚,回收率为86.6%~106.5%,检出限为0.001 mg/kg,测定结果的相对标准偏差不大于8%(n=6)。     

超高效液相色谱-串联质谱法测定茶叶、代用茶和饮料食品中63种非法添加化合物

建立了超高效液相色谱-串联质谱（UPLC-MS/MS）同时测定茶叶、代用茶和饮料食品中63种非法添加化合物的分析方法。样品经甲醇超声提取后,采用Thermo Acclaim RSLC C18色谱柱（100 mm×2.1 mm,2.2 μm）分离,以5 mmol/L甲酸铵溶液（含体积分数为0.1%的甲酸）-0.1%（体积分数）甲酸乙腈为流动相进行梯度洗脱。在电喷雾离子源正离子模式下,采用动态多反应监测（dMRM）方式测定,外标法定量。63种待测化合物在相应的线性范围内呈良好的线性关系,相关系数（R²）均大于0.99;定量限为0.10~2.50mg/kg;在3个添加水平下,63种待测物的平均回收率为62.4%~129.4%,进样精密度和重复性的相对标准偏差为0.3%~9.6%（n=6）。该方法简便快捷、准确可靠,适用于茶叶、代用茶和饮料食品中非法添加具有解热镇痛效果的化合物检测。     

超高效液相色谱-串联质谱法测定茶叶中游离氨基酸成分

建立了使用超高效液相色谱-串联质谱（UHPLC-MS/MS）高效、快速直接测定茶叶中游离氨基酸的方法。通过对质谱、色谱条件及氨基酸提取条件的优化，以含0.2%（体积分数）甲酸的5 mmol/L乙酸铵水溶液和甲醇为流动相进行梯度洗脱，在电喷雾离子（ESI）源正离子扫描模式下检测，通过UHPLC-MS/MS测定，共解析了茶叶中的20种氨基酸。结果表明，茶氨酸（Thea）、Arg、Asn和Asp在50~500 μg/L范围内线性关系良好，其他氨基酸在10~250 μg/L范围内线性关系良好，相关系数均大于0.99；加标回收率为92.3%~109.2%，相对标准偏差为2.00%~9.88%，检出限为0.001~0.011 mg/L，定量限为0.010~0.053 mg/L。该方法灵敏、准确，具有良好的重复性和稳定性，可有效检测出茶叶中的20种氨基酸及氨基类成分。     

等离子体质谱法测定大米、茶叶中痕量稀土元素

采用ICP—MS等离子体质谱法和使用HNO3＋H2O2混酸体系高压密闭微波前处理样品联合技术,同时测定了大米、茶叶样品中15种稀土元素（La、Ce、Pr、Nd、Sm、Eu、Gd、Tb、Dy、Ho、Er、Tm、Yb、Lu、Y）含量。对消化条件、测定方法和等离子体质谱测定条件进行了优化选择,并进行了国家标准物质的对照分析质量验证。结果表明,检测方法的准确度达90％-110％,相对标准偏差（RSD）〈8％,仪器检出限为50—70ng／kg。该法快速灵敏,准确可靠,能够满足检测要求。     

Effects of different extraction methods and conditions on the phenolic composition of mate tea extracts

A simple and rapid HPLC method for determination of chlorogenic acid (5-O-caffeoylquinic acid) in mate tea extracts was developed and validated. The chromatography used isocratic elution with a mobile phase of aqueous 1.5% acetic acid-methanol (85:15, v/v). The flow rate was 0.8 mL/min and detection by UV at 325 nm. The method showed good selectivity, accuracy, repeatability and robustness, with detection limit of 0.26 mg/L and recovery of 97.76%. The developed method was applied for the determination of chlorogenic acid in mate tea extracts obtained by ethanol extraction and liquid carbon dioxide extraction with ethanol as co-solvent. Different ethanol concentrations were used (40, 50 and 60%, v/v) and liquid CO? extraction was performed at different pressures (50 and 100 bar) and constant temperature (27 ± 1 °C). Significant influence of extraction methods, conditions and solvent polarity on chlorogenic acid content, antioxidant activity and total phenolic and flavonoid content of mate tea extracts was established. The most efficient extraction solvent was liquid CO? with aqueous ethanol (40%) as co-solvent using an extraction pressure of 100 bar.