Name: source and route of pyrrolizidine alkaloid contamination in tea samples
Uploaded: 2022-09-28T14:00:00
Description: Watch this Scientific Journal Video about Source and Route of Pyrrolizidine Alkaloid Contamination in Tea Samples at JoVE.com

这项工作得到了中国国家自然科学基金（32102244），国家农产品质量安全与风险评估项目（GJFP2021001），安徽省自然科学基金（19252002）和美国农业部（HAW05020H）的支持。

在本研究中，收集了以下杂草种类：路德维希亚匍匐罗克斯布，穆尔达尼亚特里克特拉（沃尔前C.B.克拉克）布鲁克，圆锥藜，藜藜，茉莉花气管（L.）莱姆，圆锥苣苔，艾米利亚松子（L.DC），圆锥苣苔L.和裂头螨 （本。S·摩尔。新鲜茶叶采摘自龙井43#茶树品种，干茶样品为市售茶叶，按绿茶制造工艺加工而成（见材料表</...

<ol>
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F., Herman, M., Van Hoeck, E., Goscinny, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Analytical+strategies+for+the+determination+of+pyrrolizidine+alkaloids+in+plant+based+food+and+examination+of+the+transfer+rate+during+the+infusion+process.">Analytical strategies for the determination of pyrrolizidine alkaloids in plant based food and examination of the transfer rate during the infusion process.</a> Food Chemistry. 266, 514-523 (2018).</li><li>Kowalczyk, E., Kwiatek, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Application+of+the+sum+parameter+method+for+the+determination+of+pyrrolizidine+alkaloids+in+teas.">Application of the sum parameter method for the determination of pyrrolizidine alkaloids in teas.</a> Food Additives &amp; Contaminants: Part A. 37 (4), 622-633 (2020).</li><li>EFSA Panel on Contaminants in the Food Chain (CONTAM). <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Risks+for+human+health+related+to+the+presence+of+pyrrolizidine+alkaloids+in+honey,+tea,+herbal+infusions+and+food+supplements.">Risks for human health related to the presence of pyrrolizidine alkaloids in honey, tea, herbal infusions and food supplements.</a> EFSA Journal. 15 (7), 04908 (2017).</li><li>Han, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Pyrrolizidine+alkaloids+in+tea:+A+review+of+analytical+methods,+contamination+levels+and+health+risk.">Pyrrolizidine alkaloids in tea: A review of analytical methods, contamination levels and health risk.</a> Food Science. 42 (17), 255-266 (2021).</li><li>Nowak, M., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interspecific+transfer+of+pyrrolizidine+alkaloids:+An+unconsidered+source+of+contaminations+of+phytopharmaceuticals+and+plant+derived+commodities.">Interspecific transfer of pyrrolizidine alkaloids: An unconsidered source of contaminations of phytopharmaceuticals and plant derived commodities.</a> Food Chemistry. 213, 163-168 (2016).</li><li>Selmar, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Transfer+of+pyrrolizidine+alkaloids+between+living+plants:+A+disregarded+source+of+contaminations.">Transfer of pyrrolizidine alkaloids between living plants: A disregarded source of contaminations.</a> Environmental Pollution. 248, 456-461 (2019).</li><li>Izcara, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Miniaturized+and+modified+QuEChERS+method+with+mesostructured+silica+as+clean-up+sorbent+for+pyrrolizidine+alkaloids+determination+in+aromatic+herbs.">Miniaturized and modified QuEChERS method with mesostructured silica as clean-up sorbent for pyrrolizidine alkaloids determination in aromatic herbs.</a> Food Chemistry. 380, 132189 (2022).</li><li>Izcara, S., Casado, N., Morante-Zarcero, S., Sierra, I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+miniaturized+QuEChERS+method+combined+with+ultrahigh+liquid+chromatography+coupled+to+tandem+mass+spectrometry+for+the+analysis+of+pyrrolizidine+alkaloids+in+oregano+samples.">A miniaturized QuEChERS method combined with ultrahigh liquid chromatography coupled to tandem mass spectrometry for the analysis of pyrrolizidine alkaloids in oregano samples.</a> Foods. 9 (9), 1319 (2020).</li><li>Van Wyk, B. E., Stander, M. A., Long, H. S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Senecio+angustifolius+as+the+major+source+of+pyrrolizidine+alkaloid+contamination+of+rooibos+tea+(Aspalathus+linearis).">Senecio angustifolius as the major source of pyrrolizidine alkaloid contamination of rooibos tea (Aspalathus linearis).</a> South African Journal of Botany. 110, 124-131 (2017).</li><li>Johnson, A. E., Molyneux, R. J., Merrill, G. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chemistry+of+toxic+range+plants.+Variation+in+pyrrolizidine+alkaloid+content+of+Senecio,+Amsinckia,+and+Crotalaria+species.">Chemistry of toxic range plants. Variation in pyrrolizidine alkaloid content of Senecio, Amsinckia, and Crotalaria species.</a> Journal of Agricultural and Food Chemistry. 33 (1), 50-55 (1985).</li><li>Vrieling, K., de Vos, H., van Wijk, C. A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Genetic+analysis+of+the+concentrations+of+pyrrolizidine+alkaloids+in+Senecio+jacobaea.">Genetic analysis of the concentrations of pyrrolizidine alkaloids in Senecio jacobaea.</a> Phytochemistry. 32 (5), 1141-1144 (1993).</li><li>Han, H. L., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development,+optimization,+validation+and+application+of+ultra+high+performance+liquid+chromatography+tandem+mass+spectrometry+for+the+analysis+of+pyrrolizidine+alkaloids+and+pyrrolizidine+alkaloid+N-oxides+in+teas+and+weeds.">Development, optimization, validation and application of ultra high performance liquid chromatography tandem mass spectrometry for the analysis of pyrrolizidine alkaloids and pyrrolizidine alkaloid N-oxides in teas and weeds.</a> Food control. 132, 108518 (2022).</li><li>Bodi, D., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Determination+of+pyrrolizidine+alkaloids+in+tea,+herbal+drugs+and+honey.">Determination of pyrrolizidine alkaloids in tea, herbal drugs and honey.</a> Food Additives &amp; Contaminants: Part A. 31 (11), 1886-1895 (2014).</li><li>European Union Commission. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Commission+Regulation+(EU)+2020/2040+of+11+December+2020+amending+Regulation+(EC)+No+1881/2006+as+regards+maximum+levels+of+pyrrolizidine+alkaloids+in+certain+foodstuffs.">Commission Regulation (EU) 2020/2040 of 11 December 2020 amending Regulation (EC) No 1881/2006 as regards maximum levels of pyrrolizidine alkaloids in certain foodstuffs.</a> Official Journal of the European Union. 14 (12), 1-4 (2020).</li></ol>

本工作旨在开发一种有效、灵敏的方法来探索茶叶样品中PA的污染途径和来源，以及PAs在茶树不同部位的分布。然而，在这项研究中，色谱柱上仅成功分离了15个PA，与植物物种3，4中的大量生物碱相比，这是一个非常小的数字。这不仅与色谱柱本身的堆积特性有关，还与所检查茶样品的复杂基质有关。因此，更好的分离纯化方法检测多PA仍需进一步探索?...

作为次级代谢物，吡咯里西啶生物碱 （PA） 保护植物免受食草动物、昆虫和病原体的侵害1，2.到目前为止，已在全球6，000多种植物物种中发现了660多种具有不同结构的PA和PA-N-氧化物（PANO）3，4。产PA的植物主要分布在 菊科、 苜蓿科、 豆科和 顶生科5，6中。PAs易氧化成不稳定的脱氢吡咯里西啶生物碱，具有较强的亲电性，可攻击DNA和蛋白质等亲核试剂，导致肝细胞坏死、静脉闭塞、肝硬化、腹水等症状7，8。PA毒性的主要靶器官是肝脏。PA还可引起肺、肾和其他器官毒性以及致突变、致癌和发育毒性9，10。
许多国家报告了人类和动物中毒的病例，原因是摄入含有PAs的传统草药、补充剂或茶，或间接污染牛奶、蜂蜜或肉类等食物（摄入含有PAs的牧场有毒）11，12，13。欧洲食品安全局（EFSA）的调查结果显示，（草药）茶等物质是人类接触PAs/PANOs的重要来源14。茶样不产生PA，而产生PA的植物常见于茶园（例如，Emilia sonchifolia，Senecio angulatus和Ageratum conyzoides）15。以前怀疑茶叶可能在采摘和加工过程中被其生产植物的PA污染。然而，在一些手工采摘的茶叶中也检测到PAs（即没有产生PA的植物），这表明一定有其他途径或污染源16。对豚草（Senecio jacobaea）与Melissa（Melissa officinalis），薄荷（薄荷（薄荷），欧芹（Petrroselinum crispum），洋甘菊（Matricaria recutita）和金莲花（Tropaeolum majus）植物进行了共栽培实验，结果表明，在所有这些植物中都检测到PAs17。已经证实，PA确实通过土壤在活植物之间转移和交换18，19。Van Wyk等人20发现路易波士茶（Aspalathus linearis）在杂草丰富的地点受到严重污染，并且含有相同类型和比例的PA。然而，在无杂草地点的路易波士茶中没有检测到PA。
目前，具有高选择性和灵敏度的超高效液相色谱串联质谱（UPLC-MS/MS）已广泛应用于农产品和食品中PAs的定性和定量分析21，22。样品处理方法通常包括固相萃取（SPE）或QuEChERS（快速简便廉价坚固安全）对复杂食品基质提取物的净化，可以获得尽可能高的灵敏度12，19。然而，仍然缺少能够检测和定量土壤、杂草和新鲜茶叶等复杂基质中的PA的稳健分析方法。
本研究采用UPLC-MS/MS结合吸附纯化方法分析了干茶样品、鲜茶叶、杂草和杂草根际土壤样品中的15种PA。此外，从安徽省金寨茶园的5个采样点采集了15个配对杂草和杂草根际土壤样品和60个新鲜茶叶样品，并对15个PA进行了分析。这些结果可以提供茶样中PAs（污染）来源和途径的调查方法和一些信息，以确保茶叶的质量和安全。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Acetonitrile (99.9%)</td>
			<td>Tedia Company,Inc.</td>
			<td>21115197</td>
			<td>CAS No:75-05-8</td>
		</tr>
		<tr>
			<td>Ammonia (25%-28%)</td>
			<td>Wuxi Zhanwang Chemical Reagent Co., Ltd.</td>
			<td>181210</td>
			<td>CAS No:1336-21-6</td>
		</tr>
		<tr>
			<td>Ammonium formate (97.0%)</td>
			<td>Anpel Laboratory Technoiogies (shanghai)</td>
			<td>G0860050</td>
			<td>CAS No:540-69-2</td>
		</tr>
		<tr>
			<td>Carbon-GCB</td>
			<td>CNW</td>
			<td>B7760030</td>
			<td>120-400 MESH, 10g. per box&#160;</td>
		</tr>
		<tr>
			<td>Centrifuge Z 36 HK</td>
			<td>HERMLE</td>
			<td>Z36HK</td>
			<td>30000&#160;rpm (min:10 rpm), Dimensions (W x H x D):&#160;71.5 cm&#215; 42 cm &#215; 51 cm</td>
		</tr>
		<tr>
			<td>Commercially available tea product</td>
			<td>Lvming, Qingshan, Luyuchun, Changling, Huixing, Wuyunjian, Heshengchun</td>
			<td>loose tea</td>
			<td>Green tea</td>
		</tr>
		<tr>
			<td>Europine N-oxid (EuNO) (98.0%)</td>
			<td>BioCrick</td>
			<td>323256</td>
			<td>CAS No:65582-53-8</td>
		</tr>
		<tr>
			<td>Europine (Eu) (98.0%)</td>
			<td>BioCrick</td>
			<td>98222</td>
			<td>CAS No:570-19-4</td>
		</tr>
		<tr>
			<td>Formate (98.0%)</td>
			<td>Aladdin</td>
			<td>E2022005</td>
			<td>CAS No:64-18-6</td>
		</tr>
		<tr>
			<td>HC-C18</td>
			<td>CNW</td>
			<td>D2110060</td>
			<td>40-63 &#956;m,100g.per box</td>
		</tr>
		<tr>
			<td>Heliotrine (He) (98.0%)</td>
			<td>BioCrick</td>
			<td>906426</td>
			<td>CAS No:303-33-3</td>
		</tr>
		<tr>
			<td>Heliotrine-N-oxide (HeNO) (98.0%)</td>
			<td>BioCrick</td>
			<td>22581</td>
			<td>CAS No:6209-65-0</td>
		</tr>
		<tr>
			<td>High speed centrifuge TG16-WS</td>
			<td>cence</td>
			<td>203158000</td>
			<td>Max:16000 r/min, 330 &#215; 390 &#215; 300 mm (L &#215; W &#215; H), Capacity: 6 &#215; 50 mL</td>
		</tr>
		<tr>
			<td>HSS T3 column</td>
			<td>Waters</td>
			<td>186004976</td>
			<td>ACQUITY UPLC HSS T3 (2.1 &#215; 100 mm 1.8 &#956;m)</td>
		</tr>
		<tr>
			<td>Intermedine (Im) (98.0%)</td>
			<td>BioCrick</td>
			<td>114843</td>
			<td>CAS No:10285-06-0</td>
		</tr>
		<tr>
			<td>Intermedine-N-oxide (ImNO) (98.0%)</td>
			<td>BioCrick</td>
			<td>340066</td>
			<td>CAS No:95462-14-9</td>
		</tr>
		<tr>
			<td>Jacobine (Jb) (98.0%)</td>
			<td>BioCrick</td>
			<td>132282048</td>
			<td>CAS No:6870-67-3</td>
		</tr>
		<tr>
			<td>Jacobine-N-oxide (JbNO) (98.0%)</td>
			<td>ChemFaces</td>
			<td>CFN00461</td>
			<td>CAS No:38710-25-7</td>
		</tr>
		<tr>
			<td>Methyl Alcohol (99.9%)</td>
			<td>Tedia Company,Inc.</td>
			<td>21115100</td>
			<td>CAS No:67-56-1</td>
		</tr>
		<tr>
			<td>PSA</td>
			<td>Agela</td>
			<td>P19-00833</td>
			<td>40-60 &#956;m, 60 &#197; 100g.per box</td>
		</tr>
		<tr>
			<td>Retrorsine (Re) (98.0%)</td>
			<td>BioCrick</td>
			<td>5281743</td>
			<td>CAS No:480-54-6</td>
		</tr>
		<tr>
			<td>Retrorsine-N-oxide (ReNO) (98.0%)</td>
			<td>BioCrick</td>
			<td>5281734</td>
			<td>CAS No:15503-86-3</td>
		</tr>
		<tr>
			<td>Senecionine (Sc) (98.0%)</td>
			<td>BioCrick</td>
			<td>5280906</td>
			<td>CAS No:130-01-8</td>
		</tr>
		<tr>
			<td>Senecionine-N-oxide (ScNO) (98.0%)</td>
			<td>BioCrick</td>
			<td>5380876</td>
			<td>CAS No:13268-67-2</td>
		</tr>
		<tr>
			<td>Seneciphylline N-oxid (SpNO) (98.0%)</td>
			<td>BioCrick</td>
			<td>6442619</td>
			<td>CAS No:38710-26-8</td>
		</tr>
		<tr>
			<td>Seneciphylline (Sp) (98.0%)</td>
			<td>BioCrick</td>
			<td>5281750</td>
			<td>CAS No:480-81-9</td>
		</tr>
		<tr>
			<td>Senkirkine (Sk) (98.0%)</td>
			<td>BioCrick</td>
			<td>5281752</td>
			<td>CAS No:2318-18-5</td>
		</tr>
		<tr>
			<td>SPE PCX</td>
			<td>Agilent Technologies</td>
			<td>12108206</td>
			<td>Cation Mixed Mode, 6 mL</td>
		</tr>
		<tr>
			<td>Sulfuric acid (97%)</td>
			<td>Wuxi Zhanwang Chemical Reagent Co., Ltd.</td>
			<td>1003019</td>
			<td>CAS No:7664-93-9</td>
		</tr>
		<tr>
			<td>Trisodium citrate</td>
			<td>Sinpharm Chemical Reagent Co., Ltd.</td>
			<td>20121009</td>
			<td>CAS No:6132-04-3</td>
		</tr>
		<tr>
			<td>Ultrasonic cleaner</td>
			<td>Supmile</td>
			<td>KQ-600B</td>
			<td>Inner slot size: 500 &#215; 300 &#215; 150 mm; Capacity: 22.5 L</td>
		</tr>
		<tr>
			<td>UPLC-xevoTQMS</td>
			<td>Waters</td>
			<td>ZPLYY-003</td>
			<td>Triple four-stage rod mass analyzer, Waters Alliance 2695/Waters ACQUITY UPLC Liquid Phase System</td>
		</tr>
		<tr>
			<td>Water bath thermostat oscillator</td>
			<td>Guoyu instrument</td>
			<td>SHY-2AHS</td>
			<td>Oscillation times:&#160; 60-300 times/min, Constant temperature range: room temperature to 100 &#176;C</td>
		</tr>
	</tbody>
</table>

source and route of pyrrolizidine alkaloid contamination in tea samples

在茶叶样品中发现了有毒的吡咯里西啶生物碱（PAs），对人体健康构成威胁。然而，茶叶样品中PA污染的来源和途径尚不清楚。本研究采用吸附剂方法结合UPLC-MS/MS测定了松 柏 根际土壤、圆 锥孢子草 根际土壤、新鲜茶叶和干茶样品中的15个PA。平均回收率为78%-111%，相对标准差为0.33%-14.8%。以安徽省金寨茶园为研究对象，采集了15对圆 锥苣 苔和 圆锥苣苔 根际土壤样品和60个鲜茶叶样品，并对15个茶叶进行了分析。并非所有15种PA都在新鲜茶叶中检测到，除了中间体-N-氧化物（ImNO）和Senecionine（Sn）。ImNO（34.7 μg/kg）的含量大于Sn（9.69 μg/kg）。此外，ImNO和Sn均集中在茶树的嫩叶中，而在老叶中含量较低。结果表明：茶叶中的PAs通过茶园产PA杂草-土壤-鲜茶叶的路径转移。

建立了对干茶样品、鲜茶叶、杂草和土壤中15种PA的优化吸附纯化分析方法，并与常用的SPE滤芯纯化方法进行了比较。结果表明，使用SPE滤芯的干茶样品、杂草和鲜茶叶中15个PA的回收率为72%-120%，而使用吸附剂纯化为78%-98%（图1）。使用吸附剂纯化对土壤中15种PA的回收率为79%-111%（图1）。随机收集四十（40）个真实样品以检测PA的含量，以比较两种净化?...

Watch this Scientific Journal Video about Source and Route of Pyrrolizidine Alkaloid Contamination in Tea Samples at JoVE.com

Source and Route of Pyrrolizidine Alkaloid Contamination in Tea Samples

本协议描述了茶园中产生PA的杂草的茶样中吡咯里西啶生物碱（PA）的污染。

茶叶样品中吡咯里西啶类生物碱污染的来源及途径

Toxic pyrrolizidine alkaloids (PAs) are found in tea samples, which pose a threat to human health. However, the source and route of PA contamination in ...

开发杂草、土壤、鲜茶叶和干茶样品中15种吡咯里西啶生物碱的检测方法，可为探索茶叶中吡咯里西啶生物碱污染源提供技术支持。与固相萃取相比，土壤样品吸附法对吡咯里西啶生物碱分析可以节省时间、降低成本和更好的回收率。要开始提取预热的干茶产品，新鲜茶叶或杂草，在50毫升离心管中称取1克样品，并向管中加入10毫升每升0.1摩尔的硫酸溶液。接下来，如果要使用固相萃取分析样品，则涡旋样品两分钟，如果要使用吸附剂净化进行分析，则涡旋一分钟。然后将样品超声提取15分钟，然后在室温下以9， 390 G离心10分钟。然后使用塑料尖端滴管，将上清液转移到50毫升离心管中。进行两次提取后，将上清液合并管中。要在准备好的土壤上开始提取，请在50毫升离心管中称取一克样品。加入0.1毫升每升0.1摩尔的柠檬酸三钠溶液，将土壤pH值调节至6.0，并让样品静置两分钟。然后将10毫升每升0.1摩尔的硫酸甲醇溶液加入管中，将样品涡旋两分钟，然后摇动30分钟。接下来，如前所述进行30分钟的超声提取。然后将样品以9， 390 G离心10分钟。并使用塑料滴管将上清液转移到50毫升离心管中。进行两次提取后，合并上清液。用五毫升甲醇激活固相萃取或SPE滤芯，然后用五毫升去离子水激活。活化后，将样品提取中的10毫升上清液加入到预活化的柱中。样品溶液液位达到上层柱后，用5毫升1%甲酸溶液洗脱样品基质，然后加入5毫升甲醇，弃去淋洗液。接下来，用含有0.5%氨水的5毫升甲醇洗脱分析物。通过0.22微米膜过滤器过滤淋洗液，通过UPLC-MS/MS进行分析。要使用吸附剂进行样品净化，请准备一个 10 毫升离心管，吸附剂以 10 至 20 至 15 毫克的比例影响 GCB、PSA 和 C18。然后加入两毫升样品处理后得到的上清液。接下来，将样品和吸附剂混合物涡旋一分钟，并在室温下以9， 390 G离心8分钟。通过0.22微米膜过滤器将1毫升所得上清液过滤到样品瓶中，然后通过UPLC-MS / MS进行分析。在研究中，与SPE滤芯法相比，使用吸附剂纯化技术从新鲜茶叶，干茶样品和杂草中获得了更高的15种吡咯里西啶生物碱的回收率。吸附剂纯化土壤中生物碱的回收率为79%-111%在5个采样点采集的鲜茶叶中，检测到的中间N-氧化物含量高于塞尼西奥宁。在一号和二号采样点的成熟叶中未检测到Senecionine。在11种吡咯里西啶生物碱中，土壤中仅检测到中间体N-氧化物，而在茶树的不同部位检测到塞尼西奥宁和中间素N-氧化物。此外，发现两片叶子的一个芽中中间N-氧化物的含量最高。在第一次尝试时，最重要的是添加0.1毫升每升0.1摩尔的柠檬酸三钠溶液，以将土壤pH值调节到6.0。该方法可应用于其他食用植物中生物碱的分析，也为探索其中生物碱的来源提供了天然技术。

Research

JoVE Journal

Environment

Tracking Microbial Contamination in Retail Environments Using Fluorescent Powder - A Retail Delicatessen Environment Example

跟踪微生物污染在零售环境中使用荧光粉 - 零售熟食店环境范例

Cross contamination of foodborne pathogens in the retail environment is a significant public health issue contributing to an increased risk for foodborne ...

科研

环境科学

EPA Method 1615. Measurement of Enterovirus and Norovirus Occurrence in Water by Culture and RT-qPCR. I. Collection of Virus Samples

EPA方法1615测量肠道病毒和诺瓦克病毒发生水由文化和RT-qPCR的了。病毒样本的收集I.

EPA Method 1615 was developed with a goal of providing a standard method for measuring enteroviruses and noroviruses in environmental and drinking waters. ...

Use of a Filter Cartridge for Filtration of Water Samples and Extraction of Environmental DNA

滤芯水过滤样品和环境DNA的提取使用

Recent studies demonstrated the use of environmental DNA (eDNA) from fishes to be appropriate as a non-invasive monitoring tool. Most of these studies ...

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

Experimental Protocol for Detecting Cyanobacteria in Liquid and Solid Samples with an Antibody Microarray Chip

用于检测实验方案<em&gt;蓝藻</em&gt;与抗体基因芯片液体和固体样品

Global warming and eutrophication make some aquatic ecosystems behave as true bioreactors that trigger rapid and massive cyanobacterial growth; this has ...

A Lipid Extraction and Analysis Method for Characterizing Soil Microbes in Experiments with Many Samples

用于表征土壤微生物的脂质提取和分析方法在许多样品的实验中

Microbial communities are important drivers and regulators of ecosystem processes. To understand how management of ecosystems may affect microbial ...

Collection and Extraction of Occupational Air Samples for Analysis of Fungal DNA

真菌 DNA 分析用职业空气标本的收集与提取

Traditional methods of identifying fungal exposures in occupational environments, such as culture and microscopy-based approaches, have several ...

In Situ Hybridization Techniques for Paraffin-Embedded Adult Coral Samples

In Situ Hybridization Techniques for Paraffin-Embedded Adult Coral Samples

就地石蜡镶嵌成人珊瑚样品的杂交技术

Corals are important ocean invertebrates that are critical for overall ocean health as well as human health. However, due to human impacts such as rising ...

Choice and No-Choice Bioassays to Study the Pupation Preference and Emergence Success of Ectropis grisescens

Choice and No-Choice Bioassays to Study the Pupation Preference and Emergence Success of Ectropis grisescens

选择与无选择生物鉴定研究蛾 grisescens的化蛹偏好及出现的成功

Many insects live above the ground as larvae and adults and as pupate below the ground. Compared to the above-ground stages of their life cycles, less ...

BtM, a Low-cost Open-source Datalogger to Estimate the Water Content of Nonvascular Cryptogams

BtM, 一种低成本的开源数据采集器, 用于估算非血管化机制的含水量

Communities of nonvascular cryptogams, such as mosses or lichens, are an important part of the Earth's biodiversity, contributing to the regulation of the ...

Measuring the Shape and Size of Activated Sludge Particles Immobilized in Agar with an Open Source Software Pipeline

利用开源软件管道测量琼脂中固定活性污泥颗粒的形状和大小

Experimental bioreactors, such as those treating wastewater, contain particles whose size and shape are important parameters. For example, the size and ...