这项研究得到了基础科学研究项目 (项目编号: 2016R1A2B4013467) 的支持, 通过韩国国家研究基金会 (NRF), 由科学部、信息和通信技术 & 未来规划2016提供资金, 并得到韩国基础科学的支持。研究所研究计划 (项目编号: C36707)。

1. DMMTA 的合成V
<ol><li>
化学制剂和摩尔比混合 DMAV, Na2S, 和 H2, 所以4 注意: DMAV: Na2S: H2所以4 = 1:1. 6:1. 6<ol>
<li>将 5.24 g 的 DMAV溶解在40毫升去离子和 N2中 (在50毫升离心管中清洗至少30分钟) 水。</li>
		<li>通过溶解14.41 克 na2S·9H2O 在50毫升去离子和 N2-被清洗的水在250毫升瓶中, 准备 na2S 试剂。</li>
		<li>准备 H2, 以便4试剂通过在40毫升离心管中添加3.3 毫升的浓硫酸 (96%) 至2毫升去离子和 N50清除水。 注意:DMA 的最终摩尔比率V: Na2S: H2所以4 = 1:1. 6:1. 6 13,4,8,15。</li>
		<li>将已准备好的40毫升 DMAV解决方案 (步骤 1.1.1) 添加到250毫升烧瓶 (步骤 1.1.2) 中包含的 Na2S 解决方案的50毫升。冲洗包含 DMAV的10毫升清洗水的管, 并将其添加到250毫升烧瓶中。</li>
		<li>用装有玻璃管的三孔橡胶塞子关闭烧瓶。分别使用用于 N2气体流入、流出和 H2的玻璃管, 因此4解决方案入口。关闭烧瓶后立即, 允许 N2气体流入烧瓶中。 注: 应保持气体压力, 以在反应溶液表面流动而不飞溅。</li>
		<li>将耐酸油管连接到 H2的玻璃管, 使4溶液入口与50毫升注射器一起添加准备好的40毫升的 h2, 因此4解决方案 (步骤 1.1.3)。添加40毫升的 H2, 所以4解决方案, 慢慢地和逐步地。 警告:加入硫酸后, 会产生白烟;使用通风良好的油烟罩。</li>
		<li>定期添加硫酸时, 监测反应混合物在烧瓶中的颜色变化。保持间隔为 4-5 毫升的 H2, 因此4;混合物应该是一个白色的多云溶液。 注: 由于浓硫酸的快速添加, 瞬时黄沉淀可能出现。</li>
		<li>确保反应解决方案自1.1.4 开始以来一直保持1小时。</li>
	</ol>
</li>
	<li>
用液-液萃取法提取 DMMTAV
	<ol>
<li>1小时后, 将反应溶液倒入含有大约200毫升乙醚的部位漏斗中。</li>
		<li>摇动漏斗 5-10 分钟, 释放气体几次通过切换旋塞阀。 注意: 合成的 DMMTAV将被转移到二乙基醚 (0.713 g·mL-1) 的上层。 警告:乙醚气体可能有害;使用通风良好的油烟罩。</li>
		<li>在烧杯中收集反应溶液, 并分别收集含有 DMMTAV的二乙基醚。将反应溶液放回同一部位漏斗中, 加入约200毫升的新鲜二乙基醚 reshaking。重复步骤 1.2.2-1.2.3 三次。</li>
		<li>再将所收集的二乙基醚从步骤1.2.3 倒入同一部位漏斗中, 并添加约100毫升 N2-清除去离子水。摇动 5-10 分钟, 并丢弃 N2-清除去离子水和几毫升二乙基醚为纯净目的。在玻璃培养皿中收集剩余的二乙基醚 (最小内径为160毫米, 最小高度为50毫米)。</li>
		<li>将玻璃培养皿转移到 N2大气手套盒中, 以防止物种转化。 警告:确保溶剂不被拉入真空泵通过出口的通行证箱。</li>
		<li>干燥直到 dimethylmonothioarsinate 的白色沉淀 (结晶 DMMTAV) 在玻璃培养皿上形成。 注意: 协议可以在这里暂停。</li>
	</ol>
</li>
	<li>
对合成 DMMTAV和存储的验证
	<ol>
<li>采取结晶 DMMTAV的白色沉淀, 并测量并记录其总重量。 警告:使用通风良好的油烟罩或手套箱, 防止吸入硫化氢气体。</li>
		<li>将结晶 DMMTAV分解为50毫升的 N2-清除去离子水, 并通过 0.2-µm 注射器过滤器过滤黄色沉淀。</li>
		<li>假定已使用的 DMAv的总计转换为 DMMTAv,即≈9,649 mg As·L-1。稀释 DMMTAV库存解决方案≈1毫克·L-1和≈40µg·L-1分别使用电喷雾电离质量 Spectromtery (ESI) 和 HPLC-电感耦合-ms 进行验证分析。</li>
		<li>使用ESI (MS11)16和在m/z 155 中的片段在正离子模式下或m/z 153 中的负离子模式 (表 1) 中, 分析 DMMTAV的m/z 。 注意: 请参阅m/z的引用值 (表 1)。</li>
		<li>用高效液相色谱-ICP-MS11,16,17 , 用适当的淋洗条件分析股票溶液中 DMMTAV的色谱, 并确认主要峰值在文学. 注意: 应使用步骤1.3.5 中的分析结果计算合成 DMMTAV的纯度。</li>
		<li>用 ICP-质谱分析酸消化后的总砷浓度11 , 并用稀释因子和纯度计算合成 DMMTAv库存溶液中的真实 DMMTAv浓度, 如下面的公式所示: 分析合计为浓度 (µg·L-1) ·稀释因素·纯度 (%) = True DMMTAv集中在 DMMTAv库存解决方案 (µg·L-1)</li>
		<li>存储 DMMTAV库存解决方案在4°c 在黑暗中进一步定量形态分析18。</li>
	</ol>
</li>
</ol>2. DMDTA 的合成V
<ol><li>
化学制剂和摩尔比混合 DMAV , Na2S, 和 H2, 所以4 注意: DMAV: Na2S: H2所以4 = 1:7. 5:7. 5<ol>
<li>在50毫升离心管中, 将1.38 克的 DMAV溶解在40毫升去离子水中。</li>
		<li>通过在50毫升去离子水中溶解18.01 克 na2S·9H2O, 将钠2的试剂制备为一瓶。</li>
		<li>准备 H2, 使4试剂添加4毫升浓硫酸 (96%) 到40毫升的去离子水中, 其中含有50毫升离心管。 注意:DMA 的最终摩尔比率V: Na2S: H2所以4 = 1:7. 5:7. 513,4,8,15。</li>
		<li>将已准备好的40毫升 DMAV解决方案 (步骤 2.1.1) 添加到250毫升烧瓶 (步骤 2.1.2) 中包含的 Na2S 解决方案的50毫升。用10毫升去离子水冲洗含有 DMAV的管, 并将其添加到250毫升烧瓶中。</li>
		<li>将准备好的40毫升 H2, 使4解决方案 (步骤 2.1.3), 慢慢地和逐步地, 进入烧瓶。</li>
		<li>定期添加硫酸时, 监测反应混合物在烧瓶中的颜色变化。保持间隔为 4-5 毫升的 H2, 因此4;混合物应为白色/黄色多云溶液。 注: 由于浓硫酸的快速添加, 瞬时黄沉淀可能会出现。 警告:加入硫酸后, 会产生白烟;使用通风良好的油烟罩。</li>
		<li>在瓶中保持反应液过夜不覆盖。 注意: 协议可以在这里暂停。</li>
	</ol>
</li>
	<li>
使用固相萃取 (SPE) 方法提取的 DMDTAV
	<ol>
<li>在隔夜反应之后, 用 C18 注射器型硅基 SPE 过滤反应溶液, 以便在树脂上捕获合成的 DMDTAV 。 警告:使用通风良好的油烟罩。</li>
		<li>用10毫米醋酸铵 (pH 6.3) 将0.77 克醋酸铵溶解在去离子水的1升中。通过 C18 注射器 (步骤 2.2.1) 洗脱足够的10毫米醋酸铵, 提取吸附 DMDTA V.在玻璃培养皿中收集过滤过的醋酸铵 (最小内径为160毫米, 最小高度为50毫米)。</li>
		<li>将玻璃培养皿转移到 N2大气手套盒中, 以防止物种转化。 警告:确保溶剂不被拉入真空泵通过出口的通行证箱。</li>
		<li>干燥直到 dimethyldithioarsinate 的白色沉淀形成 (结晶 DMDTAV) 在玻璃培养皿上。 注意: 协议可以在这里暂停。</li>
	</ol>
</li>
	<li>
对合成 DMDTAV和存储的验证
	<ol>
<li>取结晶 DMDTAV的白色沉淀, 并测量其总重量, 记录测量结果。 警告:使用通风良好的油烟罩或手套箱, 防止吸入硫化氢气体。</li>
		<li>在50毫升的 N2中溶解结晶 DMDTAV -在50毫升离心管中清除去离子水, 并通过 0.2-µm 注射器过滤器过滤任何沉淀。</li>
		<li>假定已使用的 DMAV的总计转换为 DMDTAv,即≈2,539 mg As·L-1。稀释 DMDTAV库存解决方案≈1毫克·L-1和≈40µg·L-1分别使用 ESI-ms 和高效液相色谱-ms 进行验证分析。</li>
		<li>使用ESI (MS11)16和在m/z 171 中的片段在正离子模式下或m/z 169 中的负离子模式 (表 1) 中, 分析 DMDTAV的m/z 。 注意: 请参阅m/z的引用值 (表 1)。</li>
		<li>用高效液相色谱-ICP-MS11,16,17 ,用适当的淋洗条件分析 DMDTA 中的V的色谱, 并确认在保留时间内发现的峰值文学。 注意: 应使用步骤2.3.5 中的分析结果计算合成 DMDTAV的纯度。</li>
		<li>用 ICP-质谱分析酸消化后的总砷浓度11 , 并用稀释因子和纯度计算合成 DMDTAv库存溶液中的真 DMDTAv浓度如下方程式: 分析合计为浓度 (µg·L-1) ·稀释因素·纯度 (%) = True DMDTAv在库存解决方案中 DMDTAv的浓度 (µg·L-1)</li>
		<li>存储 DMDTAV库存解决方案在4°c 在黑暗中进一步定量形态分析18。</li>
	</ol>
</li>
</ol>

<ol><li>Suzuki, K. T., et al. <a target="_blank" href="https://www.ncbi.nlm.nih.gov/pubmed/15257616">Dimethylthioarsenicals as arsenic metabolites and their chemical preparation.</a> Chem. Res. Toxicol. 17, 914-921 (2004).</li>
<li>Kuroda, K., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Microbial+metabolite+of+dimethylarsinic+acid+is+highly+toxic+and+genotoxic%5BTitle%5D)+AND+%22Toxicol.+Appl.+Pharmacol%22%5BJournal%5D)">Microbial metabolite of dimethylarsinic acid is highly toxic and genotoxic.</a> Toxicol. Appl. Pharmacol. 198, 345-353 (2004).</li>
<li>Naranmandura, H., Iwata, K., Suzuki, K. T., Ogra, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Distribution+and+metabolism+of+four+different+dimethylated+arsenicals+in+hamsters%5BTitle%5D)+AND+%22Toxicol.+Appl.+Pharmacol%22%5BJournal%5D)">Distribution and metabolism of four different dimethylated arsenicals in hamsters.</a> Toxicol. Appl. Pharmacol. 245, 67-75 (2010).</li>
<li>Naranmandura, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Comparative+toxicity+of+arsenic+metabolites+in+human+bladder+cancer+EJ-1+cells%5BTitle%5D)+AND+%22Chem.+Res.+Toxicol%22%5BJournal%5D)">Comparative toxicity of arsenic metabolites in human bladder cancer EJ-1 cells.</a> Chem. Res. Toxicol. 24, 1586-1596 (2011).</li>
<li>Wallschlager, D., London, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Determination+of+methylated+arsenic-sulfur+compounds+in+groundwater%5BTitle%5D)+AND+%22Environ.+Sci.+Technol%22%5BJournal%5D)">Determination of methylated arsenic-sulfur compounds in groundwater.</a> Environ. Sci. Technol. 42, 228-234 (2008).</li>
<li>Zhang, J., Kim, H., Townsend, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Methodology+for+assessing+thioarsenic+formation+potential+in+sulfidic+landfill+environments%5BTitle%5D)+AND+%22Chemosphere%22%5BJournal%5D)">Methodology for assessing thioarsenic formation potential in sulfidic landfill environments.</a> Chemosphere. 107, 311-318 (2014).</li>
<li>Shimoda, Y., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Proposal+for+novel+metabolic+pathway+of+highly+toxic+dimethylated+arsenics+accompanied+by+enzymatic+sulfuration%2C+desulfuration+and+oxidation%5BTitle%5D)+AND+%22Trace+Elem.+Med.+Biol%22%5BJournal%5D)">Proposal for novel metabolic pathway of highly toxic dimethylated arsenics accompanied by enzymatic sulfuration, desulfuration and oxidation.</a> Trace Elem. Med. Biol. 30, 129-136 (2015).</li>
<li>Naranmandura, H., Suzuki, T. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Formation+of+dimethylthioarsenicals+in+red+blood+cells%5BTitle%5D)+AND+%22Toxicol.+Appl.+Pharmacol%22%5BJournal%5D)">Formation of dimethylthioarsenicals in red blood cells.</a> Toxicol. Appl. Pharmacol. 227, 390-399 (2008).</li>
<li>Leffers, L., Ebert, F., Taleshi, S. M., Francesconi, A. K., Schwerdtle, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((In+vitro+toxicological+characterization+of+two+arsenosugars+and+their+metabolites%5BTitle%5D)+AND+%22Mol.+Nutr.+Food+Res%22%5BJournal%5D)">In vitro toxicological characterization of two arsenosugars and their metabolites.</a> Mol. Nutr. Food Res. 57, 1270-1282 (2013).</li>
<li>Wang, Q. Q., Thomas, J. D., Naranmandura, H. <a target="_blank" href="https://www.ncbi.nlm.nih.gov/pubmed/25531277">Important of being thiomethylated: Formation, Fate and Effects of methylated thioarsenicals.</a> Chem. Res. Toxicol. 25, 281-289 (2015).</li>
<li>Kim, Y. T., Lee, H., Yoon, H. O., Woo, N. C. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Kinetics+of+dimethylated+thioarsenicals+and+the+formation+of+highly+toxic+dimethylmonothioarsinic+acid+in+environment%5BTitle%5D)+AND+%22Environ.+Sci.+Technol%22%5BJournal%5D)">Kinetics of dimethylated thioarsenicals and the formation of highly toxic dimethylmonothioarsinic acid in environment.</a> Environ. Sci. Technol. 50, 11637-11645 (2016).</li>
<li>Cullen, W. R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Methylated+and+thiolated+arsenic+species+for+environmental+and+health+research+-+A+review+on+synthesis+and+characterization%5BTitle%5D)+AND+%22J.+Environ.+Sci%22%5BJournal%5D)">Methylated and thiolated arsenic species for environmental and health research - A review on synthesis and characterization.</a> J. Environ. Sci. 49, 7-27 (2016).</li>
<li>Fricke, M., et al. <a target="_blank" href="https://www.ncbi.nlm.nih.gov/pubmed/16359172">Chromatographic separation and identification of products form the reaction of dimethylarsinic acid with hydrogen sulfide.</a> Chem. Res. Toxicol. 18, 1821-1829 (2005).</li>
<li>Fricke, M., Zeller, M., Cullen, W., Witkowski, M., Creed, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Dimethylthioarsinic+anhydride%3A+a+standard+for+arsenic+speciation%5BTitle%5D)+AND+%22Anal.+Chim.+Acta%22%5BJournal%5D)">Dimethylthioarsinic anhydride: a standard for arsenic speciation.</a> Anal. Chim. Acta. 583, 78-83 (2007).</li>
<li>Suzuki, K. T., Iwata, K., Naranmandura, H., Suzuki, N. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0041008X06004078">Metabolic differences between twon dimethylthioarsenicals in rats.</a> Toxicol. Appl. Pharmacol. 218, 166-173 (2007).</li>
<li>Jeong, S., et al. <a target="_blank" href="http://www.sciencedirect.com/science/article/pii/S0026265X17300383">Development of a simultaneous analytical method to determine arsenic speciation using HPLC-ICP-MS: Arsenate, arsenite, monomethylarsonic acid, dimethylarsinic acid, dimethyldithioarsinic acid, and dimethylmonothioarsinic acid.</a> Microchem. J. 134, 295-300 (2017).</li>
<li>Li, Y., Low, C. -K., Scott, A. J., Amal, R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Arsenic+speciation+in+municipal+landfill+leachate%5BTitle%5D)+AND+%22Chemosphere%22%5BJournal%5D)">Arsenic speciation in municipal landfill leachate.</a> Chemosphere. 79, 794-801 (2010).</li>
<li>Conklin, D. S., Fricke, W. M., Creed, A. P., Creed, J. T. <a target="_blank" href="http://pubs.rsc.org/en/Content/ArticleLanding/2008/JA/b713145c">Investigation of the pH effects on the formation of methylated thio-arsenicals, and the effects of pH and temperature on their stability.</a> J. Anal. At. Spectrom. 23, 711-716 (2008).</li>
<li>Hansen, H. R., Raab, A., Jaspara, M., Milne, F. B., Feldmann, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Sulfur-containing+arsenical+mistaken+for+dimethylarsinous+acid+%5BDMA%28III%29%5D+and+identified+as+a+natural+metabolite+in+urine%3A+major+implications+for+studies+on+arsenic+metabolism+and+toxicity%5BTitle%5D)+AND+%22Chem.+Res.+Toxicol%22%5BJournal%5D)">Sulfur-containing arsenical mistaken for dimethylarsinous acid [DMA(III)] and identified as a natural metabolite in urine: major implications for studies on arsenic metabolism and toxicity.</a> Chem. Res. Toxicol. 17, 1086-1091 (2004).</li>
<li>Mandal, B. K., Suzuki, K. T., Anzai, K., Yamaguchi, K., Sei, Y. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+SEC-HPLC-ICP-MS+hyphenated+technique+for+identification+of+sulfur-containing+arsenic+metabolites+in+biological+samples%5BTitle%5D)+AND+%22J.+Chromatogr.+B%22%5BJournal%5D)">A SEC-HPLC-ICP-MS hyphenated technique for identification of sulfur-containing arsenic metabolites in biological samples.</a> J. Chromatogr. B. 874, 64-76 (2008).</li>
<li>Bartel, M., Ebert, F., Leffers, L., Karst, U., Schwerdtle, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Toxicological+characterization+of+the+inorganic+and+organic+arsenic+metabolite+thio-DMAV+in+cultured+human+lung+cells%5BTitle%5D)+AND+%22J.+Toxicol%22%5BJournal%5D)">Toxicological characterization of the inorganic and organic arsenic metabolite thio-DMAV in cultured human lung cells.</a> J. Toxicol. 2011, (2011).</li>
<li>An, J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Formation+of+dimethyldithioarsinic+acid+in+a+simulated+landfill+leachate+in+relation+to+hydrosulfide+concentration%5BTitle%5D)+AND+%22Environ.+Geochem.+Health%22%5BJournal%5D)">Formation of dimethyldithioarsinic acid in a simulated landfill leachate in relation to hydrosulfide concentration.</a> Environ. Geochem. Health. 38, 255-263 (2016).</li>
<li>Chen, B., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Arsenic+speciation+in+the+blood+of+arsenite-treated+F344+rats%5BTitle%5D)+AND+%22Chem.+Res.+Toxicol%22%5BJournal%5D)">Arsenic speciation in the blood of arsenite-treated F344 rats.</a> Chem. Res. Toxicol. 26, 952-962 (2013).</li>
<li>Alava, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((HPLC-ICP-MS+method+development+to+monitor+arsenic+speciation+changes+by+human+gut+microbiota%5BTitle%5D)+AND+%22Biomed.+Chromatogr%22%5BJournal%5D)">HPLC-ICP-MS method development to monitor arsenic speciation changes by human gut microbiota.</a> Biomed. Chromatogr. 26, 524-533 (2012).</li>
<li>Kurosawa, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+novel+metabolic+activation+associated+with+glutathione+in+dimethylmonoarsinic+acid+%28DMMTAV%29-induced+toxicity+obtained+from+in+vitro+reaction+of+DMMTAV+with+glutathione%5BTitle%5D)+AND+%22J.+trace+Elem.+Med.+Biol%22%5BJournal%5D)">A novel metabolic activation associated with glutathione in dimethylmonoarsinic acid (DMMTAV)-induced toxicity obtained from in vitro reaction of DMMTAV with glutathione.</a> J. trace Elem. Med. Biol. 33, 87-94 (2016).</li>
</ol>

作者没有什么可透露的。

已开发的协议澄清了以前研究的关键步骤1,3,4,8,15省略或缩写, 这可能导致困难或失败期间DMMTAv和 DMDTAv合成。由于 DMMTAV是氧化敏感的1,5, 使用 N2清除的去离子水 (步骤 1.1.1-1.1.3) 来制备合成试剂, 以防...

由于 dimethylarsinic 酸 (DMAV) 已被证明表现出急性毒性和遗传毒性由于正在接受甲基化和 thiolation 在摄取1,2, 砷 thiolation 的代谢途径有深入研究了体外和体内3,4以及环境介质 (例如,垃圾渗滤液)5,6。以前的研究在活细胞中发现了 DMAV的减少和 thiolated 类似物, 例如、 dimethylarsinous 酸 (DMAIII)、dimethylmonothioarsinic 酸 (DMMTAV) 和 dimethyldithioarsinic 酸 (DMDTAV)7,8,9, 与 dimethylated thioarsenicals 如 DMMTAV显示更大的毒性比其他已知的无机或有机砷10。高毒性 thioarsenicals 的丰度具有严重的环境影响, 因为它们在高度 sulfidic 条件下可能对人类和环境构成风险11。然而, DMMTAv和 DMDTAv (横贯) 形成的机制及其在环境媒体中的命运仍然需要进一步研究。因此, 需要对 thioarsenicals 进行定量分析, 以提高对 DMMTAv和 DMDTAv的环境影响的理解。
虽然标准化学品是定量分析的关键要求, 但由于物种转化为其他物种的风险很高, DMMTAv和 DMDTAv的标准很难通过复制以前的研究获得。原始社会合成过程12。此外, 所提到的方法有局限性, 可能会导致在合成标准化学品和进行定量分析的实际困难。DMMTAv和 DMDTAv通常是通过 dmav 2的解决方案混合 dmav、Na2和 H2, 所以4在某摩尔比率1或冒泡 H1314的气体中进行的。冒泡方法使用 H2S 气体的直接供应, 以硫磺代替氧气, 这是剧毒和难以控制的经验不足的用户。相反, 上述混合方法1, 广泛用于定性分析 DMMTAv和 DMDTAV在环境研究5,6,12, 功能 thiolation使用 H2生成的 DMAV由混合 Na2s 和 H2, 因此4和生产 DMMTAv和 DMDTAv, 允许更容易的化学计量控制生产目标化学品, 与直接使用 H2的气体。
参考混合方法过程1,3,4,8,15在本研究中提到的一些关键实验步骤的局限性, 这可能导致实验失败。例如, 具体溶剂的详细情况 (即,去离子水) 的制备和合成砷的提取和结晶是过于缩写或没有充分详细说明。有关程序性步骤的这种分散和有限的信息可能导致 thioarsenicals 的不一致形成和不可靠的量化分析。因此, 本文所开发的修改后的协议描述了 DMMTAv和 DMDTAv库存解决方案的合成, 并进行了定量的物种分离分析。

<table><tbody><tr><td>Cacodylic acid</td><td>Sigma-Aldrich</td><td>20835-10G-F</td><td></td></tr><tr><td>Sodium sulfide nonahydrate</td><td>Sigma-Aldrich</td><td>S2006-500G</td><td></td></tr><tr><td>Sulfuric acid 96%</td><td>J.T.Baker</td><td>0000011478</td><td></td></tr><tr><td>Ammonium acetate</td><td>Sigma-Aldrich</td><td>A7262-500G</td><td></td></tr><tr><td>Formic acid 98%</td><td>Wako Pure Chemical Industries, Ltd.</td><td>066-00461</td><td></td></tr><tr><td>Diethyl ether (Extra Pure)</td><td>Junsei Chemical</td><td>33475-0380</td><td></td></tr><tr><td>Adapter cap for 60 mL Bond Elut catridges</td><td>Agilent Technologies</td><td>12131004</td><td>Syringe type of SPE</td></tr><tr><td>Bond Elut C18 cartridge</td><td>Agilent Technologies</td><td>14256031</td><td>Syringe type of SPE</td></tr><tr><td>HyPURITY C-18</td><td>Thermo Scientific</td><td>22105-254630</td><td>5 um, 125 x 4.6 mm</td></tr><tr><td>Glovebox</td><td>Chungae-chun, Rep. of Korea</td><td></td><td>Customized&amp;nbsp;</td></tr><tr><td>Agilent 1260 Infinity Bio-inert LC</td><td>Agilent Technologies</td><td>DEAB600252, DEACH00245</td><td></td></tr><tr><td>Agilent Technologies 7700 Series ICP-MS</td><td>Agilent Technologies</td><td>JP12031510</td><td></td></tr><tr><td>Finnigan LCQ Deca XP MAX Mass Spectrometer System</td><td>Thermo Electron Corporation</td><td>LDM10627</td><td></td></tr></tbody></table>

preparation of dmmtav and dmdtav using dmav for environmental applications: synthesis, purification, and confirmation

Dimethylated thioarsenicals, 如 dimethylmonothioarsinic 酸 (DMMTAV) 和 dimethyldithioarsinic 酸 (DMDTAv), 是由 dimethylarsinic 酸 (DMAV) thiolation 的新陈代谢途径产生的, 最近在环境和人体器官中发现的。DMMTAv和 DMDTAv可以量化, 以确定 dimethylated thioarsenicals 的生态效应及其在环境介质中的稳定性。这些化合物的合成方法是原始社会的, 使得复制以前的研究具有挑战性。此外, 缺乏关于储存技术的信息, 包括没有物种转化的化合物的储存。此外, 由于只有有限的合成方法信息, 在合成标准化学品和进行定量分析方面可能存在实验困难。本文提出的协议为 dimethylated thioarsenicals、DMMTAv和 DMDTAv提供了一个实际改进的合成方法, 并将有助于利用高性能液体进行物种分离分析的量化。用电感耦合等离子体质谱 (HPLC-ICP) 相结合的色谱法。通过对化学试剂的制备、过滤方法和贮存的研究, 对该过程的实验步骤进行了改进。

由于 DMAIII合成方法19错误地编写了 DMMTAV , 因此对合成的 DMMTAv和 DMDTAv的验证是合成和提取和确定理想标准的关键步骤。化学材料。合成化学物质可以通过 DMMTAV (兆瓦 154 g·mol-1) 和 DMDTAV (兆瓦 170 g·mol-1) 质量-电荷比 (m/z) 的峰值来验证, 使用的是电喷雾电离质量的正负离子模式。通过?...

Watch this Scientific Journal Video about Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation at JoVE.com

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

使用 DMAv为环境应用 DMMTAv和 DMDTAv的准备: 合成、纯化和确认

本文介绍了 dimethylmonothioarsinic 酸 (DMMTAv) 和 dimethyldithioarsinic 酸 (DMDTAv) 合成、诱导 dimethylarsinic 酸 (dmav) thiolation 通过混合 DMAv 的改进实验协议。, Na2S, 和 H2, 所以4。修改后的协议提供了实验指导, 从而克服了在定量分析过程中可能导致实验失败的综合步骤的局限性。

Dimethylated thioarsenicals such as dimethylmonothioarsinic acid (DMMTAV) and dimethyldithioarsinic acid (DMDTAV), which are produced by the metabolic ...

preparation-dmmtav-dmdtav-using-dmav-for-environmental-applications

Research

JoVE Journal

Environment

Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

5.5K 次观看.  Korea Basic Science Institute, Seoul Center. 本文介绍了 dimethylmonothioarsinic 酸 (DMMTAv) 和 dimethyldithioarsinic 酸 (DMDTAv) 合成、诱导 dimethylarsinic 酸 (dmav) thiolation 通过混合 DMAv 的改进实验协议。, Na2S, 和 H2, 所以4。修改后的协议提供了实验指导, 从而克服了在定量分析过程中可能导致实验失败的综合步骤的局限性。

视频: Preparation of DMMTAV and DMDTAV Using DMAV for Environmental Applications: Synthesis, Purification, and Confirmation

Controlling the Size, Shape and Stability of Supramolecular Polymers in Water

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do so is highly important in view of a number of applications in functional soft matter including electronics, biomedical engineering, and sensors. In the past, successful strategies to control the size and shape of supramolecular polymers typically focused on the use of templates2,3, end cappers4 or selective solvent techniques5. 
Here we disclose a strategy based on self-assembling discotic amphiphiles that leads to the control over stack length and shape of ordered, chiral columnar aggregates. By balancing electrostatic repulsive interactions on the hydrophilic rim and attractive non-covalent forces within the hydrophobic core of the polymerizing building block, we manage to create small and discrete spherical objects6,7. Increasing the salt concentration to screen the charges induces a sphere-to-rod transition. Intriguingly, this transition is expressed in an increase of cooperativity in the temperature-dependent self-assembly mechanism, and more stable aggregates are obtained. 
For our study we select a benzene-1,3,5-tricarboxamide (BTA) core connected to a hydrophilic metal chelate via a hydrophobic, fluorinated L-phenylalanine based spacer (Scheme 1). The metal chelate selected is a Gd(III)-DTPA complex that contains two overall remaining charges per complex and necessarily two counter ions. The one-dimensional growth of the aggregate is directed by &pi;-&pi; stacking and intermolecular hydrogen bonding. However, the electrostatic, repulsive forces that arise from the charges on the Gd(III)-DTPA complex start limiting the one-dimensional growth of the BTA-based discotic once a certain size is reached. At millimolar concentrations the formed aggregate has a spherical shape and a diameter of around 5 nm as inferred from 1H-NMR spectroscopy, small angle X-ray scattering, and cryogenic transmission electron microscopy (cryo-TEM). The strength of the electrostatic repulsive interactions between molecules can be reduced by increasing the salt concentration of the buffered solutions. This screening of the charges induces a transition from spherical aggregates into elongated rods with a length &gt; 25 nm. Cryo-TEM allows to visualise the changes in shape and size. In addition, CD spectroscopy permits to derive the mechanistic details of the self-assembly processes before and after the addition of salt. Importantly, the cooperativity -a key feature that dictates the physical properties of the produced supramolecular polymers- increases dramatically upon screening the electrostatic interactions. This increase in cooperativity results in a significant increase in the molecular weight of the formed supramolecular polymers in water.

The goal of this experiment is to determine and control the size, shape and stability of self-assembled discotic amphiphiles in water. For aqueous based supramolecular polymers such level of control is very difficult. We apply a strategy using both repulsive and attractive interactions. The experimental techniques applied to characterize this system are broadly applicable.

控制的大小，形状和稳定性超分子聚合物在水

For aqueous based supramolecular polymers, the simultaneous control over shape, size and stability is very difficult1. At the same time, the ability to do ...

科研

工程学

Production of Disulfide-stabilized Transmembrane Peptide Complexes for Structural Studies

Physical interactions among the lipid-embedded alpha-helical domains of membrane proteins play a crucial role in folding and assembly of membrane protein complexes and in dynamic processes such as transmembrane (TM) signaling and regulation of cell-surface protein levels. Understanding the structural features driving the association of particular sequences requires sophisticated biophysical and biochemical analyses of TM peptide complexes. However, the extreme hydrophobicity of TM domains makes them very difficult to manipulate using standard peptide chemistry techniques, and production of suitable study material often proves prohibitively challenging. Identifying conditions under which peptides can adopt stable helical conformations and form complexes spontaneously adds a further level of difficulty. Here we present a procedure for the production of homo- or hetero-dimeric TM peptide complexes from materials that are expressed in E. coli, thus allowing incorporation of stable isotope labels for nuclear magnetic resonance (NMR) or non-natural amino acids for other applications relatively inexpensively. The key innovation in this method is that TM complexes are produced and purified as covalently associated (disulfide-crosslinked) assemblies that can form stable, stoichiometric and homogeneous structures when reconstituted into detergent, lipid or other membrane-mimetic materials. We also present carefully optimized procedures for expression and purification that are equally applicable whether producing single TM domains or crosslinked complexes and provide advice for adapting these methods to new TM sequences.

Biophysical and biochemical studies of interactions among membrane-embedded protein domains face many technical challenges, the first of which is obtaining appropriate study material. This article describes a protocol for producing and purifying disulfide-stabilized transmembrane peptide complexes that are suitable for structural analysis by solution nuclear magnetic resonance (NMR) and other analytical applications.

生产二硫键稳定的跨膜肽复合物的结构研究

Physical  interactions among the lipid-embedded alpha-helical domains of membrane  proteins play a crucial role in folding and assembly of membrane ...

化学

Compact Quantum Dots for Single-molecule Imaging

Single-molecule imaging is an important tool for understanding the mechanisms of biomolecular function and for visualizing the spatial and temporal heterogeneity of molecular behaviors that underlie cellular biology 1-4. To image an individual molecule of interest, it is typically conjugated to a fluorescent tag (dye, protein, bead, or quantum dot) and observed with epifluorescence or total internal reflection fluorescence (TIRF) microscopy. While dyes and fluorescent proteins have been the mainstay of fluorescence imaging for decades, their fluorescence is unstable under high photon fluxes necessary to observe individual molecules, yielding only a few seconds of observation before complete loss of signal. Latex beads and dye-labeled beads provide improved signal stability but at the expense of drastically larger hydrodynamic size, which can deleteriously alter the diffusion and behavior of the molecule under study.
Quantum dots (QDs) offer a balance between these two problematic regimes. These nanoparticles are composed of semiconductor materials and can be engineered with a hydrodynamically compact size with exceptional resistance to photodegradation 5. Thus in recent years QDs have been instrumental in enabling long-term observation of complex macromolecular behavior on the single molecule level. However these particles have still been found to exhibit impaired diffusion in crowded molecular environments such as the cellular cytoplasm and the neuronal synaptic cleft, where their sizes are still too large 4,6,7.
Recently we have engineered the cores and surface coatings of QDs for minimized hydrodynamic size, while balancing offsets to colloidal stability, photostability, brightness, and nonspecific binding that have hindered the utility of compact QDs in the past 8,9. The goal of this article is to demonstrate the synthesis, modification, and characterization of these optimized nanocrystals, composed of an alloyed HgxCd1-xSe core coated with an insulating CdyZn1-yS shell, further coated with a multidentate polymer ligand modified with short polyethylene glycol (PEG) chains (Figure 1). Compared with conventional CdSe nanocrystals, HgxCd1-xSe alloys offer greater quantum yields of fluorescence, fluorescence at red and near-infrared wavelengths for enhanced signal-to-noise in cells, and excitation at non-cytotoxic visible wavelengths. Multidentate polymer coatings bind to the nanocrystal surface in a closed and flat conformation to minimize hydrodynamic size, and PEG neutralizes the surface charge to minimize nonspecific binding to cells and biomolecules. The end result is a brightly fluorescent nanocrystal with emission between 550-800 nm and a total hydrodynamic size near 12 nm. This is in the same size range as many soluble globular proteins in cells, and substantially smaller than conventional PEGylated QDs (25-35 nm).

We describe the preparation of colloidal quantum dots with minimized hydrodynamic size for single-molecule fluorescence imaging. Compared to conventional quantum dots, these nanoparticles are similar in size to globular proteins and are optimized for single-molecule brightness, stability against photodegradation, and resistance to nonspecific binding to proteins and cells.

紧凑型量子点的单分子成像

Single-molecule imaging is an important tool for  understanding the mechanisms of biomolecular function and for visualizing the  spatial and temporal ...

Biochemical Measurement of Neonatal Hypoxia

Neonatal hypoxia ischemia is characterized by inadequate blood perfusion of a tissue or a systemic lack of oxygen. This condition is thought to cause/exacerbate well documented neonatal disorders including neurological impairment 1-3. Decreased adenosine triphosphate production occurs due to a lack of oxidative phosphorylation. To compensate for this energy deprived state molecules containing high energy phosphate bonds are degraded 2. This leads to increased levels of adenosine which is subsequently degraded to inosine, hypoxanthine, xanthine, and finally to uric acid. The final two steps in this degradation process are performed by xanthine oxidoreductase. This enzyme exists in the form of xanthine dehydrogenase under normoxic conditions but is converted to xanthine oxidase (XO) under hypoxia-reperfusion circumstances 4, 5. Unlike xanthine dehydrogenase, XO generates hydrogen peroxide as a byproduct of purine degradation 4, 6. This hydrogen peroxide in combination with other reactive oxygen species (ROS) produced during hypoxia, oxidizes uric acid to form allantoin and reacts with lipid membranes to generate malondialdehyde (MDA) 7-9. Most mammals, humans exempted, possess the enzyme uricase, which converts uric acid to allantoin. In humans, however, allantoin can only be formed by ROS-mediated oxidation of uric acid. Because of this, allantoin is considered to be a marker of oxidative stress in humans, but not in the mammals that have uricase.
We describe methods employing high pressure liquid chromatography (HPLC) and gas chromatography mass spectrometry (GCMS) to measure biochemical markers of neonatal hypoxia ischemia. Human blood is used for most tests. Animal blood may also be used while recognizing the potential for uricase-generated allantoin. Purine metabolites were linked to hypoxia as early as 1963 and the reliability of hypoxanthine, xanthine, and uric acid as biochemical indicators of neonatal hypoxia was validated by several investigators 10-13. The HPLC method used for the quantification of purine compounds is fast, reliable, and reproducible. The GC/MS method used for the quantification of allantoin, a relatively new marker of oxidative stress, was adapted from Gruber et al 7. This method avoids certain artifacts and requires low volumes of sample. Methods used for synthesis of MMDA were described elsewhere 14, 15. GC/MS based quantification of MDA was adapted from Paroni et al. and Cighetti et al. 16, 17. Xanthine oxidase activity was measured by HPLC by quantifying the conversion of pterin to isoxanthopterin 18. This approach proved to be sufficiently sensitive and reproducible.

A method is described to measure biochemical markers of neonatal hypoxia-ischemia. The approach utilizes high pressure liquid chromatography (HPLC) and Gas Chromatography Mass Spectrometry (GC/MS).

新生儿缺氧的生化测量

Neonatal hypoxia ischemia is characterized by inadequate blood perfusion of a tissue or a systemic lack of oxygen. This condition is thought to ...

医学

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance imaging (MRI). Their purpose is to enhance the relaxation rate of water protons in tissue, thus increasing the MR image contrast and the specificity of the MRI measurements. Current clinically approved contrast agents are low molecular weight molecules that are rapidly cleared from the body. The use of dendrimers as carriers of paramagnetic chelators can play an important role in the future development of more efficient MRI contrast agents. Specifically, the increase in local concentration of the paramagnetic species results in a higher signal contrast. Furthermore, this CA provides a longer tissue retention time due to its high molecular weight and size. Here, we demonstrate a convenient procedure for the preparation of macromolecular MRI contrast agents based on poly(amidoamine) (PAMAM) dendrimers with monomacrocyclic DOTA-type chelators (DOTA &#8211; 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetate). The chelating unit was appended by exploiting the reactivity of the isothiocyanate (NCS) group towards the amine surface groups of the PAMAM dendrimer to form thiourea bridges. Dendrimeric products were purified and analyzed by means of nuclear magnetic resonance spectroscopy, mass spectrometry, and elemental analysis. Finally, high resolution MR images were recorded and the signal contrasts obtained from the prepared dendrimeric and the commercially available monomeric agents were compared.

Preparation and In Vitro Characterization of Dendrimer-based Contrast Agents for Magnetic Resonance Imaging

This protocol describes the preparation and characterization of a dendrimeric magnetic resonance imaging (MRI) contrast agent that carries cyclen-based macrocyclic chelates coordinating paramagnetic gadolinium ions. In a series of MRI experiments in vitro, this agent produced an amplified MRI signal when compared to the commercially available monomeric analogue.

制备及<em&gt;体外</em&gt;磁共振成像基于树状大分子造影剂的表征

Paramagnetic complexes of gadolinium(III) with acyclic or macrocyclic chelates are the most commonly used contrast agents (CAs) for magnetic resonance ...

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid

Continuous flow technology has been identified as instrumental for its environmental and economic advantages leveraging superior mixing, heat transfer and cost savings through the &#34;scaling out&#34; strategy as opposed to the traditional &#34;scaling up&#34;. Herein, we report the reaction of diphenyldiazomethane with p-nitrobenzoic acid in both batch and flow modes. To effectively transfer the reaction from batch to flow mode, it is essential to first conduct the reaction in batch. As a consequence, the reaction of diphenyldiazomethane was first studied in batch as a function of temperature, reaction time, and concentration to obtain kinetic information and process parameters. The glass flow reactor set-up is described and combines two types of reaction modules with &#34;mixing&#34; and &#34;linear&#34; microstructures. Finally, the reaction of diphenyldiazomethane with p-nitrobenzoic acid was successfully conducted in the flow reactor, with up to 95% conversion of the diphenyldiazomethane in 11 min. This proof of concept reaction aims to provide insight for scientists to consider flow technology&#39;s competitiveness, sustainability, and versatility in their research.

Continuous Flow Chemistry: Reaction of Diphenyldiazomethane with p-Nitrobenzoic Acid

Flow chemistry carries environmental and economic advantages by leveraging superior mixing, heat transfer and cost benefits. Herein, we provide a blueprint to transfer chemical processes from batch to flow mode. The reaction of diphenyldiazomethane (DDM) with p-nitrobenzoic acid, conducted in batch and flow, was chosen for proof of concept.

连续流动化学: Diphenyldiazomethane 与p硝基苯甲酸的反应

Continuous flow technology has been identified as instrumental for its environmental and economic advantages leveraging superior mixing, heat transfer and ...

Fabricating Reactive Surfaces with Brush-like and Crosslinked Films of Azlactone-Functionalized Block Co-Polymers

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl dimethyl azlactone) (PGMA-b-PVDMA), are presented. Due to the high reactivity of azlactone groups towards amine, thiol, and hydroxyl groups, PGMA-b-PVDMA surfaces can be modified with secondary molecules to create chemically or biologically functionalized interfaces for a variety of applications. Previous reports of patterned PGMA-b-PVDMA interfaces have used traditional top-down patterning techniques that generate non-uniform films and poorly controlled background chemistries. Here, we describe customized patterning techniques that enable precise deposition of highly uniform PGMA-b-PVDMA films in backgrounds that are chemically inert or that have biomolecule-repellent properties. Importantly, these methods are designed to deposit PGMA-b-PVDMA films in a manner that completely preserves azlactone functionality through each processing step. Patterned films show well-controlled thicknesses that correspond to polymer brushes (~90 nm) or to highly crosslinked structures (~1-10 &#956;m). Brush patterns are generated using either the parylene lift-off or interface directed assembly methods described and are useful for precise modulation of overall chemical surface reactivity by adjusting either the PGMA-b-PVDMA pattern density or the length of the VDMA block. In contrast, the thick, crosslinked PGMA-b-PVDMA patterns are obtained using a customized micro-contact printing technique and offer the benefit of higher loading or capture of secondary material due to higher surface area to volume ratios. Detailed experimental steps, critical film characterizations, and trouble-shooting guides for each fabrication method are discussed.

Surface fabrication methods for patterned deposition of nanometer thick brushes or micron thick, crosslinked films of an azlactone block co-polymer are reported. Critical experimental steps, representative results, and limitations of each method are discussed. These methods are useful for creating functional interfaces with tailored physical features and tunable surface reactivity.

Azlactone 功能块共聚物的刷状和交联膜制备反应表面

In this paper, fabrication methods that generate novel surfaces using the azlactone-based block co-polymer, poly (glycidyl methacrylate)-block-poly (vinyl ...

Exploring the Arginine Methylome by Nuclear Magnetic Resonance Spectroscopy

Protein-bound arginine is commonly methylated in many proteins and regulates their function by altering the physicochemical properties, their interaction with other molecules, including other proteins or nucleic acids. This work presents an easily implementable protocol for quantifying arginine and its derivatives, including asymmetric and symmetric dimethylarginine (ADMA and SDMA, respectively) and monomethyl arginine (MMA). Following protein isolation from biological body fluids, tissues, or cell lysates, a simple method for homogenization, precipitation of proteins, and protein hydrolysis is described. Since the hydrolysates contain many other components, such as other amino acids, lipids, and nucleic acids, a purification step using solid-phase extraction (SPE) is essential. SPE can either be performed manually using centrifuges or a pipetting robot. The sensitivity for ADMA using the current protocol is about 100 nmol/L. The upper limit of detection for arginine is 3 mmol/L due to SPE saturation. In summary, this protocol describes a robust method, which spans from biological sample preparation to NMR-based detection, providing valuable hints and pitfalls for successful work when studying the arginine methylome.

The present protocol describes the preparation and quantitative measurement of free and protein-bound arginine and methyl-arginines by 1H-NMR spectroscopy.

用核磁共振波谱探索精氨酸甲基组

Protein-bound arginine is commonly methylated in many proteins and regulates their function by altering the physicochemical properties, their interaction ...

癌症研究

Evaluation of Oxidative Stress in Biological Samples Using the Thiobarbituric Acid Reactive Substances Assay

Despite its limited analytical specificity and ruggedness, the thiobarbituric acid reactive substances (TBARS) assay has been widely used as a generic metric of lipid peroxidation in biological fluids. It is often considered a good indicator of the levels of oxidative stress within a biological sample, provided that the sample has been properly handled and stored. The assay involves the reaction of lipid peroxidation products, primarily malondialdehyde (MDA), with thiobarbituric acid (TBA), which leads to the formation of MDA-TBA2 adducts called TBARS. TBARS yields a red-pink color that can be measured spectrophotometrically at 532 nm. The TBARS assay is performed under acidic conditions (pH = 4) and at 95 &#176;C. Pure MDA is unstable, but these conditions allow the release of MDA from MDA bis(dimethyl acetal), which is used as the analytical standard in this method. The TBARS assay is a straightforward method that can be completed in about 2 h. Preparation of assay reagents are described in detail here. Budget-conscious researchers can use these reagents for multiple experiments at a low cost rather than buying an expensive TBARS assay kit that only permits construction of a single standard curve (and thus can only be used for one experiment). The applicability of this TBARS assay is shown in human serum, low density lipoproteins, and cell lysates. The assay is consistent and reproducible, and limits of detection of 1.1 &#956;M can be reached. Recommendations for the use and interpretation of the spectrophotometric TBARS assay are provided.

The goal of the thiobarbituric acid reactive substances assay is to assess oxidative stress in biological samples by measuring the production of lipid peroxidation products, primarily malondialdehyde, using visible wavelength spectrophotometry at 532 nm. The method described here can be applied to human serum, cell lysates, and low density lipoproteins.

使用硫代巴比妥酸反应物质测定法评估生物样品中的氧化应激

Despite its limited analytical specificity and ruggedness, the thiobarbituric acid reactive substances (TBARS) assay has been widely used as a generic ...

顶空 GC-MS 检测动物源性药物中的三甲胺

An Improved Technique for Trimethylamine Detection in Animal-Derived Medicine by Headspace Gas Chromatography-Tandem Quadrupole Mass Spectrometry

Animal-derived medicines have distinctive characteristics and significant curative effects, but most of them have an obvious fishy odor, resulting in the poor compliance of clinical patients. Trimethylamine (TMA) is one of the key fishy odor components in animal-derived medicine. It is difficult to identify TMA accurately using the existing detection method due to the increased pressure in the headspace vial caused by the rapid acid-base reaction after the addition of lye, which causes TMA to escape from the headspace vial, stalling the research progress of the fishy odor of animal-derived medicine. In this study, we proposed a controlled detection method that introduced a paraffin layer as an isolation layer between acid and lye. The rate of TMA production could be effectively controlled by slowly liquefying the paraffin layer through thermostatic furnace heating. This method showed satisfactory linearity, precision experiments, and recoveries with good reproducibility and high sensitivity. It provided technical support for the deodorization of animal-derived medicine.

作者聚焦:一种改进的顶空气相色谱-串联四极杆质谱法检测动物源性药物中三甲胺的技术  

Here, a headspace gas chromatography-tandem quadrupole mass spectrometry (HS-GC-MS/MS) method suitable for the determination of trimethylamine (TMA) in animal-derived medicines is described. The protocol includes sample pretreatment, headspace treatment, analysis conditions, methodological validation, and the determination of TMA in animal-derived medicines.

一种改进的顶空气相色谱-串联四极杆质谱法检测动物源性药物中三甲胺的技术

Animal-derived medicines have distinctive characteristics and significant curative effects, but most of them have an obvious fishy odor, resulting in the ...

使用 DMA^v为环境应用 DMMTA^v和 DMDTA^v的准备: 合成、纯化和确认

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