这项工作是由俄亥俄州立大学食品卫生发现主题和食品科学与技术在美国俄亥俄州立大学的部门支持。作者要感谢俄亥俄州立大学的NMR设施和宾夕法尼亚州立大学的核磁共振设备。

1. NMR样品制备注意:注意，使用前请咨询所有相关的材料安全数据表（MSDS）。在样品制备中使用的氘代氯仿（CDCL 3）是有毒的。进行样品制备，包括使用通风橱和个人保护设备的时，请使用所有的适当的安全实践（安全眼镜，手套，实验室外套，全长裤，封闭趾鞋）。 <ol><li> 1个 H和13个 C样品的制备 <ol><li>用注射器从膳食胶囊提取鱼油的120μL（〜110毫克），并将其放置在一个4姆·格拉斯小瓶中。记录鱼油的重量。 </li><li>溶样<ol><li>溶解约120μL鱼油中含有被用作1 H和13角 C化学位移的参考四甲基硅烷（TMS）的0.01％CDCL 3的500μL。 注:TMS是使用ð仅化学位移校准（见步骤编号2.2.1.2.7和2.2.2.2.7），而不是定量（见步骤编号2.2.1.3和2.2.2.3）的目的。 </li><li>制备2,6- 二叔丁基-4-甲基苯酚（BHT）的储备溶液中，如果量化以mg / g的需要，通过将BHT的约220毫克和15毫克铬（III），乙酰丙酮的（铬（ ACAC）3）在20ml CDCL 3的含TMS的0.01％。使用储备溶液的500微升溶解100毫克（±10毫克）的鱼油。 </li></ol></li><li>油（这需要几秒钟）溶解后，转移所有的溶液直接进入一个高品质5毫米NMR管和附连的盖。制备样品之后分析24个小时内的样本。 </li></ol></li></ol> 2. NMR仪器制备注:注意，提防强磁场的通过NMR仪器产生的存在可以影响医疗器械并实现了一套蚁如起搏器和外科假体，以及电子项目，如信用卡，手表等时使用非屏蔽磁体所执行的分析的附加警告是必需的。两个NMR仪器被用于获取1 H和13 C NMR谱的;分光计在850.23 MHz和213.81 MHz的分别用于1 H和13个 C核，操作，装配有三重共振氦冷却逆（TCI）5毫米探针和光谱仪在500.20 MHz和125.77 MHz的1 H和13 C操作核，分别配备有观察到宽波段（BBO）氮冷却5毫米探针。 （见材料列表），在25±0.1ºC进行所有实验和光谱通过一个标准的NMR数据分析采集和处理软件程序包进行处理。 <ol><li> 用于获取NMR谱制备 注:1 H和13 C NMR谱可以在不从仪器中取出样品因此获得的。 <ol><li>插入NMR管插入一个微调涡轮机（参见材料列表）。 </li><li>放置旋转器和一个分级深度计的顶部的管，轻轻地按压管的顶部，直至其底部接触轨距的底部。 </li><li>放置NMR样品中SampleCase的打开位置。注意样品被放置在槽号。 </li><li>加载在NMR样品，返回到控制计算机和类型"SX＃"，其中＃是在SampleCase保持你的样品槽中。 </li><li>等待CDCL 3的氘信号出现在锁定窗口画面上。如果没有自动出现，键入"lockdisp"。一旦氘信号是可见的，类型的命令行上的"锁定"，并且为了使用CDCL 3氘共振锁定样品从溶剂的列表中选择"CDCL 3"。 注:氘小号如果先前的用户所使用的不同的溶剂ignal可能不会出现。用户应该等待该样品是向下的指标，然后锁定。 </li><li>键入"bsmsdisp"在命令行中，以确保纺纱不活跃。如果"旋转"按钮为绿色，单击它停用纺纱。 </li><li>键入"新建"命令来创建一个新的数据集。该数据在"名称"选项卡，在"EXPNO"选项卡中的实验数设置输入一个名称。在"PROCNO"选项卡使用数字"1"。在"实验"选项卡，点击"选择"，然后选择"质子"参数文件。写实验的标题在"标题"选项卡。点击"确定"。 </li><li>在命令行键入"getprosol"，以获得用于当前NMR探针和溶剂的标准参数。 </li><li>重复步骤2.1.7 13 C，选择"C13IG"脉冲序列中的"实验"标签用于1D的13 C逆克ated分离实验。 </li><li>在命令行键入"getprosol"，以获得用于当前NMR探针和溶剂的标准参数。 </li><li>键入命令"灵魂"来执行自动调谐和探针的匹配为碳和质子核。 </li><li>用于NMR信号进行一维梯度匀场实现高度均匀的磁场，并且因此最佳线形状。 <ol><li>使用标准的自动过程来1D匀场，简单地通过顺序地执行这些命令"曲topshim 1dfast SS"，"曲topshim tuneb SS"，并且在命令行上"去topshim报告"。 </li></ol></li></ol></li><li> 参数优化 <ol><li>的90°脉冲校准<ol><li>创建1小时（见2.1.7步骤和2.1.8）新的数据集。 </li><li>在命令行上的命令"paropt"开始自动化程序用于校准90°PULSE。选择脉冲持续时间，P1，作为参数进行修改。 </li><li>开始"2"作为微秒p1的初始值，输入"2"μs的增量，并执行"16"的实验。 </li><li>创建一个新的数据的13 C设置（见步骤2.1.9）并重复此过程13个 C核（参见步骤2.2.1.2和2.2.1.3）。 </li></ol></li><li>通过零位法16 1小时测量的T 1个测量 注:空方法使用反转恢复脉冲序列，由延迟（TAU）由180°脉冲的后续的，以允许松弛沿着z轴和最终的90°脉冲，其产生可观察到的横向磁化。 <ol><li>创建1小时（见2.1.7步骤和2.1.8）新的数据集。 </li><li>输入"PULPROG t1ir1d"脉冲序列改变到反转恢复实验。 </li><li>输入在comman以下命令d线的设置以ppm光谱宽度，RF发射器的中心，扫描伪扫描的次数和数据点"SW 8"的数量，"O1P 3.8"，"NS 2"，"DS的数量2&quot; 和 "TD 64K"。 </li><li>类型"P1（值）"，并作为由脉冲校准确定为90°脉冲输入持续时间值（见步骤2.2.1），并输入"P2（值）"为180°脉冲（对于180°的持续时间值脉冲是90°脉冲持续时间乘以二）。 </li><li>通过键入"D1 10"循环延迟设置为一个非常大的值，如10秒。 </li><li>通过在命令行键入"D7 10ms的"设定的tau到短值，如10毫秒。 </li><li>设置使用命令"RGA"为RG的自动计算接收机增益（RG）到适当的值。 </li><li>通过键入命令"ZG"运行的频谱。 </li><li>通过键入"EFP"执行傅立叶变换在命令行。 </li><li>通过在命令行键入命令"APK"执行自动相位校正。如果需要额外的相位调整，以进一步提高频谱，点击中的"进程选项卡"，然后单击"调节相位"图标进入相位校正模式。 <ol><li>通过拖动鼠标，直到所有的信号在负吸收模式使用零阶（0）和一阶（1）的相位校正的图标。申请并通过点击"返回并保存"按钮退出相位校正模式保存相位修正值。 </li></ol></li><li>增加的tau，直到所有的峰是正或零化通过重复步骤2.2.2.6-2.2.2.9。为了确定T 1值，简单地划分在峰值零化与LN2的tau蛋白值。 </li></ol></li><li>通过零位法16 13℃下测定T 1个测量<ol><li>创建一个新的数据对13 C中（参见步骤2.1.9） </li><li>类型"PULPROG t1irpg"改变脉冲序列的反转恢复实验碳核。 </li><li>在命令行设置以ppm光谱宽度，RF发射器的中心，扫描的次数，虚设扫描次数和数据点的数量上的以下命令:"SW 200"，"O1P 98" ， "NS 8"， "DS 2" 和 "TD 64K"。 </li><li>类型"P1（值）"，并作为由脉冲校准确定为90°脉冲输入持续时间值（见步骤2.2.1）和类型"P2（值）"为180°脉冲（持续时间值是90°脉冲持续时间乘以二）。 </li><li>通过键入"D1 100"循环延迟设置为一个非常大的值，如100秒。 </li><li>集的tau到短值，如100毫秒通过在命令行键入"D7 100毫秒"。 </li><li>设置接收地ER增益（RG）到适当的值使用命令"RGA"为RG的自动计算。 </li><li>通过键入命令"ZG"运行的频谱。 </li><li>通过在命令行中键入"EFP"执行傅立叶变换。 </li><li>通过在命令行中输入命令"APK"执行自动相位校正。如果需要额外的相位调整，以进一步提高频谱，点击"调节相位"图标和用于零阶（0）和第一阶相（1）校正的相位校正的图标。 <ol><li>而在零阶和第一阶相位校正的图标点击，拖动鼠标，直到所有的信号在负吸收模式。申请并通过点击"返回并保存"按钮退出相位校正模式保存相位修正值。 </li></ol></li><li>增加的tau，直到所有的峰是正或零化通过重复步骤2.2.3.6-2.2.3.9。为了确定的T 1值，简单地划分在峰值零化与LN2的tau蛋白值。 </li></ol></li></ol></li><li> 一维（1D）。NMR谱 <ol><li> 1 H-NMR谱 <ol><li> NMR数据的采集 <ol><li>转到步骤2.1.7创建的1个 H数据集和通过在命令行键入"PULPROG ZG"使用标准的"脉冲获取"脉冲序列" ZG"。 </li><li>在命令行上下面的命令来设置，以ppm光谱宽度，RF发射器的中心，扫描的次数，虚设扫描的数量，数据点的数目和脉冲持续时间为90°脉冲角: "SW 8"， "3.8 O1P"， "NS 2"， "DS 2"， "TD 64K"和"P1（如通过脉冲校准测定）"（见步骤2.2.1）。 注:32K数据点可用于500 MHz仪器上。 </li><li>通过键入"D1 7S"或"D1 787-9"，分别在命令行上设置的7个S为500 MHz仪器上或9号为850 MHz仪器上的松弛延迟。 </li><li>设置使用命令"RGA"为RG的自动计算接收机增益（RG）到适当的值。 </li><li>键入"digmod baseopt"以获取与改善基线频谱。 </li><li>通过在命令行键入脉冲获取命令"ZG"开始采集。 </li></ol></li><li> NMR数据的处理 <ol><li>在命令行键入"SI 64K"应用零填充和所述真实频谱的大小设置为64K。 </li><li>通过在命令行键入"磅0.3"，以用线展宽0.3赫兹的因子前，傅立叶变换应用的加权函数（指数衰减）设置谱线增宽参数至0.3赫兹。 </li><li>通过在命令中键入"EFP"执行傅立叶变换线。 </li><li>通过在命令行中输入命令"APK"执行自动相位校正。如果需要额外的相位调整，以进一步提高频谱，点击中的"进程选项卡"，然后单击"调节相位"图标和用于零阶（0）和一阶（1）的相位校正的相位校正图标。 <ol><li>而在零阶和第一阶相位校正的图标点击，拖动鼠标，直到所有的信号都是正的吸收模式。申请并通过点击"返回并保存"按钮退出相位校正模式保存相位修正值。 </li></ol></li><li>通过键入命令"ABS N"时整合申请基线校正的多项式四阶函数。 注意:这确保了与最小强度平坦的光谱基线。 </li><li>由TMS以ppm报告化学位移（δ= 0）。点击校准（"CALIB。斧是"）的图标，并且将光标与上TMS NMR信号（峰最接近于0）的顶部上的红线。左键点击并输入‘0’。 </li></ol></li><li> NMR数据分析 <ol><li>整合的光谱区从δ1.1至在δ4.98δ0.6以及峰，δ5.05和δ5.81使用"整合"图标（"进程"标签下）和高亮（"定义新的区域"）的图标。通过积分右键单击并拖动。 注意:如果有需要关注的区域，点击高亮显示图标停用左键点击并拖动鼠标以放大的区域。调节阈值强度，如果需要的话使用鼠标按钮。再次点击高亮显示图标，使整合功能激活，然后移动到下一个高峰。 <ol><li>正常化有关显示的积分值以上的积分，以100通过右击的总和S的信号下，选择"归一化的积分之和"。输入框中的值"100"，然后单击"返回并保存"退出一体化模式。 </li></ol></li><li>当使用BHT作为内部标准，在整合δ6.98峰值和设定的积分等于BHT的每0.5毫升储备溶液的毫摩尔。 </li><li>整合的感兴趣的峰（参见步骤2.3.1.3.1）从峰值的每一侧延伸10赫兹，在可能的情况。 </li><li>进行到以类似的方式执行13 C-NMR谱的采集和处理。 </li></ol></li></ol></li><li> 13 C-NMR谱 <ol><li> NMR数据的采集 <ol><li>转至13 C数据集，并通过在命令行键入"PULPROG zgig"使用逆门控去耦脉冲序列" zgig"。 注意:要运行碳实验与标准的宽带decouPLED的脉冲序列，在命令行键入"PULPROG zgpg"。 </li><li>在命令行上下面的命令来设置，以ppm光谱宽度，RF发射器的中心，扫描的次数，虚设扫描的数量，数据点的数目和脉冲持续时间为90°脉冲角: "SW 200"， "95 O1P"， "NS 16" "DS 2"， "TD 64K" 和 "P1（如通过脉冲校准测定）"（见步骤2.2.1.4）。 </li><li>通过键入"D1 35S"或"D1 45S"，分别在命令行上设置的35秒为500 MHz仪器上或45秒为850 MHz仪器上的松弛延迟。当使用BHT，弛豫延迟应该是在500 MHz仪器上50秒和60秒在850兆赫的仪器。 </li><li>设置使用命令"RGA"为RG的自动计算接收机增益（RG）到适当的值。 </li><li>在命令行键入"digmod baseopt"来获取光谱瓦特第i个改进的基线。 </li><li>通过在命令行键入脉冲获取命令"ZG"开始采集。 </li></ol></li><li> NMR数据的处理 <ol><li>在命令行键入"SI 64K"应用零填充和所述真实频谱的大小设置为64K。 </li><li>通过在命令行键入"磅1.0"，以用线展宽1.0赫兹的因子前，傅立叶变换应用的加权函数（指数衰减）设置谱线增宽参数为1.0赫兹。 </li><li>通过在命令行中键入"EFP"执行傅立叶变换。 </li><li>通过在命令行中输入命令"APK"执行自动相位校正。如果需要额外的相位调整，以进一步提高频谱，点击中的"进程选项卡"，然后单击"调节相位"图标和用于零阶（0）和第一阶相（1）修正的相位校正图标。 <ol><lI&gt;虽然点击零阶和第一阶相位校正图标，拖动鼠标，直到所有的信号都是正的吸收模式。申请并通过点击"返回并保存"按钮退出相位校正模式保存相位修正值。 注:对于记录在214兆赫（850兆赫的仪器）的频率相关的错误（一阶）的校正的拉莫尔频率碳谱可以是具有挑战性的并且对于缺乏经验的用户的因大的偏共振效应耗时的90°脉冲。 </li></ol></li><li>通过在命令行键入命令"ABS N"时整合申请基线校正的多项式四阶函数。 </li><li>由TMS以ppm报告化学位移（δ= 0）。点击校准（"CALIB。轴"）的图标，并且将光标与NMR信号的顶部红线被引用。左键点击并输入"0"。 </li></ol></li><li> NMR数据分析 <ol><li>整合的光谱区从δ175使用"整合"图标（"进程"标签下）和高亮〜δ171（"定义新区域"）的图标。通过积分右键单击并拖动。 注意:如果有需要关注的区域，点击高亮显示图标停用左键点击并拖动鼠标以放大的区域。再次点击高亮显示图标，使整合功能激活，然后移动到下一个高峰。 <ol><li>这样做对信号下出现的整数值，右键点击设置积分为100，然后选择"校准电流积分"。输入框中的值"100"，然后单击"返回并保存"，退出一体化模式。 </li></ol></li><li>当使用BHT作为内标，在δ151.45整合的峰值和设定的积分等于每0.5 ml的储备溶液的BHT的毫摩尔。 </li><li>整合的延伸从所述峰值的每侧5赫兹感兴趣的峰（参见步骤2.3.2.3.1）。 </li></ol></li></ol></li></ol></li></ol>

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修改和策略疑难解答 光谱质量 。 NMR信号，从而NMR谱的分辨率的线宽是高度依赖于匀场，这是用于磁场的均匀性的优化的方法。对于常规分析，1D匀场是足够的，并不需要3D匀场，因为它是通过NMR人员定期进行。 D 2 O中（90:10）:如果不是这种情况下，3D匀场必须被分析之前，使用含有0.6毫升氧化氢的样品进行的。为了实现更好更快匀场，样品需要在射频（RF）线圈的激发/检测区域为中心，使用分级的深度计，它被放置在磁体膛之前。影响匀场的另一个因素是在10-20赫兹的旋转速率旋转的样本。虽然在这个旋转速度旋转该样品改善了径向垫片（X，Y，XY，XZ，YZ，X 2 -Y 2， 等等 ），它一般不以避免第一或更高阶的旋转边带的外观建议。然而，当对在拉莫尔操作工具的工作频率低于400兆赫，纺纱被推荐用于1D NMR实验。 分辨率，以及灵敏度，由接收器增益（RG）值的影响。接收器增益的低的值降低灵敏度，而值比模拟 - 数字转换器（ADC）的适当的原因溢出更高。在非对称线形状ADC溢出结果和信号不能用于定量目的，因为自由感应衰减（FID）的第一点可能会丢失。在大多数情况下，命令"RGA"计算出恰当的RG值。然而，在一些情况下，由软件计算出的RG值比理想值高并且在NMR信号的洛伦兹形状的失真。在这样的情况下，用户应通过在命令行键入"RG（值）"手动输入一个较小的RG的值。的样品，与该协议分析的典型RG值是8。 通常情况下，使用低温时冷却NMR探针具有高品质因子（Q因子），一个大的延迟（死区时间）&gt; 200us的最后一个脉冲和检测周期之间需要避免伪像，例如围绕所述发射器的频率的驼峰而在频谱的基线滚动。然而，这样的长延迟将导致大的负一阶相位误差，这也可以引入一个基线轧和大倾角的强信号的底座周围。在这些情况下，Z-恢复自旋回波脉冲序列可以被用于生产具有改进的显著基线NMR谱，虽然小灵敏度降低，可能会出现23。 磷脂 。除了鱼油的分析富含甘油三酸酯和乙基酯的样品，NMR可以用于鱼油样品富含磷脂（PLS）的分析。然而，需要特别注意对这样的样品，因为的PL形式的聚集体，这会导致在光谱分辨率和灵敏度的显著降低。对于这些样品的分析，氘代氯仿的混合溶剂:甲醇:以70:30的比率（CDCL 3 CD 3 OD）是必需的，用于获得高品质的光谱。 内部标准 。 BHT被选定为在该研究中的内标，因为它是通过简单的1 H和13 C NMR光谱的高度对称的分子和没有其峰与那些鱼油成分的重叠。 BHT具有在1 H NMR谱信号，该信号表现为一个单峰在δ6.97和属于两个等效芳香质子（ 对 -在相对于OH基团的位置），并且在信号δ151.45在属于芳族季碳带有-OH基团的13 C NMR光谱。这两个信号具有与任何在鱼油组分的没有重叠，因此可用于定量目的。如1,2,4,5-四氯-3-硝基苯（TCNB）或乙烯氯化物的其它化合物也可以用作替代的内部标准，然而，它们的特征在于长T 1的值。 该技术的局限性各种脂肪酸和脂质在鱼油补充剂的定量是通过在一维谱相应的诊断NMR信号的积分实现。这样的信号应该属于只对特定的样品组分，并且必须具有与来自其它化合物的信号没有干扰。由于1 H NMR谱的特征在于低的分辨率，这可能是用于1所 H NMR分析的问题，由于车的短程MICAL变化。另外，标量耦合的存在（J）产生多重峰，使分析更复杂。例如，乙酯（EE）可以使用1 H-NMR通过甲基的特征三重峰（J = 7.20赫兹）中的δ1.25量化和多重峰在δ4.12，属于酯基的亚甲基质子。然而，使用在拉莫尔操作NMR文书时，频率低于850兆赫，应避免EE的使用。1 H NMR的分析，因为该峰的部分重叠的在δ4.12与峰δ甘油三酯的4.14，并重叠在δ1.25信号与脂族的亚甲基质子的在δ1.23-1.35的宽信号。大的偏差也被一些样品中EPA的1个 H和13 C分析之间观察到，13 C NMR更接近于由吨提供的标记组合物他制造商。这可能是由于信号在δ1.69重叠，其用于EPA分析，与出现在一些类型的鱼油补充剂的其他化合物的信号。使用内标时由于内部标准的不确定纯度和从称重误差可能出现在的量化的附加误差。 的组成分析，可以在相对摩尔浓度在不使用内标来表示。如果结果需要在绝对浓度中表达，例如作为每克的油状物（毫克/克）脂肪酸毫克，需要使用内标。然而，在感兴趣的NMR信号属于具有不同分子量的多种化合物的情况下，结果不能使用内标甚至当表示为mg / g以下。此外，使用内标物通常增加了分析的长度，因为最常见的内部小号<html>标准协商，如BHT，是小分子与高分子对称性，这导致长的弛豫时间。由于重复时间（脉冲+采集时间之间的延迟）根据所述样品中的最长松弛时间T 1设定，采用内部标准的将增加的实验的持续时间，需要的脉冲之间更长的延迟。这是因为碳核的异常长T 1弛豫时间为13次 C NMR分析中的特别重要的因素。如Cr（ACAC）加入顺磁化合物的3能够有效地降低T 1弛豫时间。铬（ACAC）3的推荐浓度为0.75毫克/毫升的溶液。铬（ACAC）3的更高的浓度可考虑用于进一步减少T1 的 ，但是，谨慎，以避免在S / N降低所需由于谱线增宽。 ntent"&gt;虽然13 C NMR的特征在于高得多的光谱分辨率相比1个 H，13 C NMR实验的灵敏度显著较低，因为低天然丰度（1.1％）和低的旋磁比（67.26 10 6弧度秒-1 T -1）的13个 C核。此外，13 C中的长T 1弛豫时间的增加分析的长度，这可能是一个问题，当用于分析的可用的油是有限的，因为增加的扫描次数应该被用来实现一个合理的信噪比。 在灵敏度和NMR谱的分辨率限制防止可与其它技术，如GC分析在鱼油许多次要化合物的分析。例如，1ΗNMR无法个别甾醇或脂肪酸（ 例如棕榈酸和硬脂酸），而13 C分离是不能够确定在鱼油出现在非常低的浓度，其与所有饱和脂肪酸的信号重叠化合物，例如十二烷和十四烷酸，在δ173.24和172.82δ。虽然增加被分析的样品的量，使可行一些轻微的化合物的分析，需要非常浓的样品小心，因为它们的粘度增加。应避免含有超过150毫克的油非常粘稠的解决方案，因为存在由于减少引起的自旋-自旋Ť2弛豫时间线加宽在S / N的降低。另外，需要因为较长的T 1的脉冲之间的较长的延迟并有在匀场，因此在解决几个问题。 与NMR鱼油分析的所有化合物可以同时在一个快照进行量化，而无需使用任何分离或纯化步骤。该NMR的alysis是快速的，如通过1个 H光谱可以被记录在小于一分钟，而13 C NMR采集持续10分钟。但是，应该指出的是，有一些影响数据采集时间的几个因素。具体而言，13 C NMR，在10分钟的运行时间仅可在不使用内部标准实现的，并与使用低温冷却探针，其中，所述RF线圈和前置放大器被冷却，因此热噪声被最小化。在实验时间为10-15倍的增加应该预计为13种 C NMR分析时，室温下使用（常规的）的探针。 相对于现有方法的意义核磁共振光谱证明是定性和定量测定鱼油补充剂的组成的一个强大的工具，因为它的快速性的它有可能被应用为广大NU的高通量筛选<html>鱼油样品MBER。 NMR光谱是通过定义的定量方法，因为信号区域是直接比例于将引起信号的核的数量。而需要急性毒性化学品，以制备将NMR样品，因为使用这种化学物质（ 如 CDCL 3），例如少量的，而不是需要大量的溶剂来洗脱样品的其它方法该方法是环境友好的。另外，NMR相比于其他分析方法具有若干优点。与标准无需校准之前进行分析，并且没有任何分离和纯化步骤的最小样品制备通常被采用，这使得NMR非常快速的分析工具。此外，13 C NMR是用于确定在甘油骨架的各种脂肪酸的位置分布的最佳可用方法。而酶水解已被用作替代并不总是可靠= "外部参照"&gt; 24。这是特别重要的，因为在研究食物中的各种脂肪酸的区域专一一个显著的兴趣，因为它已经发现，这会影响他们在人类饮食中25，26功能。 未来应用尽管NMR分析，产品的标签之间的协议，以及一个事实，即有数字显示GC和NMR之间的协议的一些研究，我们认为，更加严格和全面的内部实验室研究需要考察NMR和传统之间的协议方法使用的样品，不同来源的鱼油产品更大数量的鱼油成分的分析，和认证的标准溶液。 鱼油分析NMR的另一个重要的应用前景将是氧化产物的决心。除了确定在鱼油的主要化合物，几个初级和次级氧化产物在鱼油，如醛和过氧化物，都存在。 1 H-NMR可潜在地应用于在鱼油补充剂氧化状态的评价中，不同的氧化条件下，如示于图3。在这种分析中，最大的挑战将是NMR分配与个人氧化产物的鉴定。在NMR硬件的灵敏度的进步也将允许使用13 C NMR个体固醇的识别。 NMR谱也可以通过使用高分辨率魔角旋转（HR-MAS）NMR应用于鱼组织的分析作为一个整体，即使没有任何萃取。 该协议中的关键步骤的影响定量NMR谱的准确性的最关键的步骤涉及两个90°脉冲的选择和使用的PU之间的延迟的LSES≥5×T 1。脉冲角度正比于它是依赖于仪器和样品校准NMR参数脉冲宽度。一个90°脉冲为纵向（z）的磁化与所述观察到的横向（XY）磁化的完全转化是必不可少的。需要注意的是脉冲校准之前，核磁共振探测需要很好地调整和匹配是非常重要的。这将优化RF功率的传送到样品，从而最大限度地提高S / N，并确保有效的去耦。探头调谐主要是由样品的介电常数的影响，因此，如果有在样本之间的浓度差，重复调谐处理为每一个。一维13 C NMR实验既包括13 C和1个 H通道以便自动调谐和匹配是必要的两个细胞核。 长于5×T 1的脉冲之间的延迟保证了完整REC净磁化至其初始值的卵巢中。如果在光谱中所有的共振都没有，每个脉冲之前完全放松，信号被部分抑制，这导致在积分误差。 T 1个值是影响实验的长度的一个重要因素，它依赖于磁场强度，以及样品的粘度。鉴于样品之间的粘度是相似的，T 1弛豫时间应为每个仪器仅在分析会议开始来确定。 鱼油分析用13 C NMR的另一个重要的特征是适当的脉冲序列的选择。进行定量的13 C分析的最可靠的方法是门控去耦的实验，其中，宽带质子去耦期间采集周期仅施加因此存在由1个 H没有极化转移至13逆通过核极化效应（NOE）C。然而，当完全去耦NMR实验可用于定量目的，因为存在必须避免碳与不同的多重和甲基，亚甲基，甲烷和羰基碳之间，因此积分比较中不同NOE因素使用此实验时，需要小心。尽管这样，当时只有类似的多重性和化学环境的碳在分析中认为，在完全脱钩方法是可靠的。这方面的一个例子是已被发现具有27解耦之后的NOE因素没有显著差异脂肪酸羰基碳。此外，对于碳轴承质子，完全去耦实验由于在NMR信号强度的NOE贡献提供更高的灵敏度。与所述两个脉冲序列获得的光谱之间的比较示于图S1。

在饮食Ñ-3脂肪酸的消费已被证明是对几个条件有利如心脏疾病1，2，3，炎性疾病4和糖尿病5。西方饮食被认为是穷人的N-3脂肪酸，因此建议鱼油补充剂的消费，提高n个 -6 / N -3平衡消费者的营养1。尽管鱼油补充剂的消费，最近越来越多，问题仍然是关于安全性，真实性，以及一些产品的质量。鱼油补充剂的快速和准确的成分分析是必不可少的，以正确评估这些商业产品的质量，保证消费者的安全。 鱼油补充评估的最常见方法s为气相色谱法（GC）和红外光谱（IR）。虽然这些都是高度敏感的方法，他们从几个缺点遭受6。 GC分析是因为单独的化合物的分离和衍生化，需要7和分析8,9期间可能发生的脂质氧化耗时（4-8小时）。虽然IR光谱可以是定量，需要一个预测模型，使用偏最小二乘回归（PLSR）构造，但也有例外，其中IR带可以归因于一个单一的化合物10。 PLSR需要大量的样品，从而增加了分析11的时间的分析。出于这个原因，存在的新的分析方法，使大量的鱼油样品的准确，快速分析发展的越来越大的兴趣。组织，如OFFI在健康（NIH）和美国食品和药物管理局（FDA）全国学院膳食补充剂（ODS）的CE与官方分析化学师协会（AOAC）合作开发这些新方法12，13。 一个用于筛选和多组分基质，如膳食补充品的评价最有前途的分析方法，是核磁共振（NMR）光谱14,15。 NMR光谱法有几个优点:它是一种非破坏性的和定量技术，它需要极少的无样品制备，并且其特征在于优良的精确度和再现性。此外，NMR光谱是一种环境友好的方法，因为它仅使用少量的溶剂。 NMR光谱法的主要缺点是其相对低的灵敏度相比其他analytiCAL方法，但是，例如更强的磁场，各种直径的低温探针，先进的数据处理，和通用的脉冲序列和技术在仪表最近的技术进步增加了灵敏度高达nM范围内。虽然核磁共振仪器是成本高，核磁共振波谱仪的长寿命和NMR的许多应用降低了分析的，从长远来看成本。这个详细的视频协议的目的是帮助本领域从业者新避免与1个 H和13个 C NMR光谱分析鱼油补充剂的相关联的缺陷。

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Avance III 850 NMR instrument</td>
			<td>Bruker</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Avance III 500 NMR instrument</td>
			<td>Bruker</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>TCI 5mm probe</td>
			<td>Bruker</td>
			<td></td>
			<td>Helium cooled inverse (proton deetected) NMR probe featuring three independent channels (1H, 13C, 15N)</td>
		</tr>
		<tr>
			<td>BBO prodigy 5mm probe</td>
			<td>Bruker</td>
			<td></td>
			<td>Nitrogen cooled observe (X-nuclei detected) probe, featuring two channels; one for 1H and 19F detectionand one for X-nuclei (covering from 15N to 31P)</td>
		</tr>
		<tr>
			<td>Spinner turbin</td>
			<td>Bruker</td>
			<td></td>
			<td>NMR spinners are made by polymer materials and they have a rubber o-ring to hold the NMR tube securely in place</td>
		</tr>
		<tr>
			<td>Topspin 3.5</td>
			<td>Bruker</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>deuterated chloroform</td>
			<td>Sigma-Aldrich</td>
			<td>&#160;865-49-6</td>
			<td>99.8 atom % D, contains 0.03 TMS</td>
		</tr>
		<tr>
			<td>2,6-Di-tert-butyl-4-methylphenol,</td>
			<td>Sigma-Aldrich</td>
			<td>&#160;128-37-0</td>
			<td>purity &#62;99%</td>
		</tr>
		<tr>
			<td>Fish oil samples</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>NMR tubes</td>
			<td>New Era</td>
			<td>NE-RG5-7</td>
			<td>5mm OD Routine &#8220;R&#8221; Series NMR Sample Tube</td>
		</tr>
		<tr>
			<td>BSMS</td>
			<td>Bruker</td>
			<td></td>
			<td>Bruker Systems Management System; control system device</td>
		</tr>
	</tbody>
</table>

nmr spectroscopy as a robust tool for the rapid evaluation of the lipid profile of fish oil supplements

西方饮食同n-3脂肪酸差，因此建议鱼油补充剂的消费，以增加这些必需营养素的摄入量。这个工作的目的是利用高分辨率1个 H和13利用两个不同的NMR仪器C NMR光谱法证实包封的鱼油补充剂的定性和定量分析;一个500兆赫和850兆赫的仪器。两个质子（1个 H）和碳（13 C）NMR谱可用于定量测定鱼油补充剂的主要成分。在鱼油补充剂脂质的定量是通过适当的NMR信号的积分在相关1D光谱来实现。通过1 H和13 C NMR得到的结果彼此一致，尽管在两个核和两个仪器之间的分辨率和灵敏度的差异。 1 H-NMR报价SA的快速分析相比13 C NMR，作为频谱可被记录在小于1分钟，而相比之下，13点 C NMR分析，它从10分钟持续到一小时。 13 C NMR谱，然而，更加丰富。它可以用于单个脂肪酸更大数量提供定量数据，并可以被用于确定在甘油骨架的脂肪酸的位置分布。两者的核可以提供仅在一个实验中的定量信息，而无需纯化或分离步骤。的磁场的强度主要影响:1个 H NMR谱由于相对于13 C NMR其较低的分辨率，但是，即使是更低的成本NMR仪器可以有效地应用为食品工业和质量控制实验室的标准方法。

Watch this Scientific Journal Video about NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements at JoVE.com

NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements

这里，高分辨率1 H和13 C核磁共振（NMR）光谱被用作包封的鱼油补充剂的定量和定性分析的快速和可靠的工具。

核磁共振作为鱼油补充剂的血脂的快速评价一个强大的工具

The western diet is poor in n-3 fatty acids, therefore the consumption of fish oil supplements is recommended to increase the intake of these essential ...

nmr-spectroscopy-as-robust-tool-for-rapid-evaluation-lipid-profile

Nanyang Technological University

Research

JoVE Journal

Chemistry

25.9K 次观看.  The Ohio State University. 这里，高分辨率1 H和13 C核磁共振（NMR）光谱被用作包封的鱼油补充剂的定量和定性分析的快速和可靠的工具。 

视频: NMR Spectroscopy as a Robust Tool for the Rapid Evaluation of the Lipid Profile of Fish Oil Supplements

Isolation and Chemical Characterization of Lipid A from Gram-negative Bacteria

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS can be subdivided into three domains: the distal O-polysaccharide, a core oligosaccharide, and the lipid A domain consisting of a lipid A molecular species and 3-deoxy-D-manno-oct-2-ulosonic acid residues (Kdo). The lipid A domain is the only component essential for bacterial cell survival. Following its synthesis, lipid A is chemically modified in response to environmental stresses such as pH or temperature, to promote resistance to antibiotic compounds, and to evade recognition by mediators of the host innate immune response. The following protocol details the small- and large-scale isolation of lipid A from gram-negative bacteria. Isolated material is then chemically characterized by thin layer chromatography (TLC) or mass-spectrometry (MS). In addition to matrix-assisted laser desorption/ionization-time of flight (MALDI-TOF) MS, we also describe tandem MS protocols for analyzing lipid A molecular species using electrospray ionization (ESI) coupled to collision induced dissociation (CID) and newly employed ultraviolet photodissociation (UVPD) methods. Our MS protocols allow for unequivocal determination of chemical structure, paramount to characterization of lipid A molecules that contain unique or novel chemical modifications. We also describe the radioisotopic labeling, and subsequent isolation, of lipid A from bacterial cells for analysis by TLC. Relative to MS-based protocols, TLC provides a more economical and rapid characterization method, but cannot be used to unambiguously assign lipid A chemical structures without the use of standards of known chemical structure. Over the last two decades isolation and characterization of lipid A has led to numerous exciting discoveries that have improved our understanding of the physiology of gram-negative bacteria, mechanisms of antibiotic resistance, the human innate immune response, and have provided many new targets in the development of antibacterial compounds.

Isolation and characterization of the lipid A domain of lipopolysaccharide (LPS) from gram-negative bacteria provides insight into cell surface based mechanisms of antibiotic resistance, bacterial survival and fitness, and how chemically diverse lipid A molecular species differentially modulate host innate immune responses.

隔离和脂质A的化学表征革兰氏阴性菌

Lipopolysaccharide (LPS) is the major cell surface molecule of gram-negative bacteria, deposited on the outer leaflet of the outer membrane bilayer. LPS ...

科研

化学

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Copper (I) binding by metallochaperone transport proteins prevents copper oxidation and release of the toxic ions that may participate in harmful redox reactions. The Cu (I) complex of the peptide model of a Cu (I) binding metallochaperone protein, which includes the sequence MTCSGCSRPG (underlined is conserved), was determined in solution under inert conditions by NMR spectroscopy.
NMR is a widely accepted technique for the determination of solution structures of proteins and peptides. Due to difficulty in crystallization to provide single crystals suitable for X-ray crystallography, the NMR technique is extremely valuable, especially as it provides information on the solution state rather than the solid state. Herein we describe all steps that are required for full three-dimensional structure determinations by NMR. The protocol includes sample preparation in an NMR tube, 1D and 2D data collection and processing, peak assignment and integration, molecular mechanics calculations, and structure analysis. Importantly, the analysis was first conducted without any preset metal-ligand bonds, to assure a reliable structure determination in an unbiased manner.

Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

The NMR-solution structure of a metallochaperone model peptide with Cu (I) was determined, and a detailed protocol from sample preparation and 1D and 2D data collection to a three-dimensional structure is described.

Copper (I) binding by metallochaperone transport proteins prevents copper oxidation and release of the toxic ions that may participate in harmful redox ...

Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins

Nuclear magnetic resonance (NMR) spectroscopy is a proven technique for protein structure and dynamic studies. To study proteins with NMR, stable magnetic isotopes are typically incorporated metabolically to improve the sensitivity and allow for sequential resonance assignment. Reductive 13C-methylation is an alternative labeling method for proteins that are not amenable to bacterial host over-expression, the most common method of isotope incorporation. Reductive 13C-methylation is a chemical reaction performed under mild conditions that modifies a protein&#39;s primary amino groups (lysine &#949;-amino groups and the N-terminal &#945;-amino group) to 13C-dimethylamino groups. The structure and function of most proteins are not altered by the modification, making it a viable alternative to metabolic labeling. Because reductive 13C-methylation adds sparse, isotopic labels, traditional methods of assigning the NMR signals are not applicable. An alternative assignment method using mass spectrometry (MS) to aid in the assignment of protein 13C-dimethylamine NMR signals has been developed. The method relies on partial and different amounts of 13C-labeling at each primary amino group. One limitation of the method arises when the protein&#39;s N-terminal residue is a lysine because the &#945;- and &#949;-dimethylamino groups of Lys1 cannot be individually measured with MS. To circumvent this limitation, two methods are described to identify the NMR resonance of the 13C-dimethylamines associated with both the N-terminal &#945;-amine and the side chain &#949;-amine. The NMR signals of the N-terminal &#945;-dimethylamine and the side chain &#949;-dimethylamine of hen egg white lysozyme, Lys1, are identified in 1H-13C heteronuclear single-quantum coherence spectra.

Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins

Two methods for assigning the &#945;- and &#949;-dimethylamine nuclear magnetic resonance signals of a reductively 13C-methylated N-terminal lysine are described. One method utilizes the pH-induced selectivity of the reductive methylation reaction, and the other uses aminopeptidase to selectively remove the N-terminal lysine.

Nuclear magnetic resonance (NMR) spectroscopy is a proven technique for protein structure and dynamic studies. To study proteins with NMR, stable magnetic ...

HKUST-1 as a Heterogeneous Catalyst for the Synthesis of Vanillin

Vanillin (4-hydoxy-3-methoxybenzaldehyde) is the main component of the extract of vanilla bean. The natural vanilla scent is a mixture of approximately 200 different odorant compounds in addition to vanillin. The natural extraction of vanillin (from the orchid Vanilla planifolia, Vanilla tahitiensis and Vanilla pompon) represents only 1% of the worldwide production and since this process is expensive and very long, the rest of the production of vanillin is synthesized. Many biotechnological approaches can be used for the synthesis of vanillin from lignin, phenolic stilbenes, isoeugenol, eugenol, guaicol, etc., with the disadvantage of harming the environment since these processes use strong oxidizing agents and toxic solvents. Thus, eco-friendly alternatives on the production of vanillin are very desirable and thus, under current investigation. Porous coordination polymers (PCPs) are a new class of highly crystalline materials that recently have been used for catalysis. HKUST-1 (Cu3(BTC)2(H2O)3, BTC = 1,3,5-benzene-tricarboxylate) is a very well known PCP which has been extensively studied as a heterogeneous catalyst. Here, we report a synthetic strategy for the production of vanillin by the oxidation of trans-ferulic acid using HKUST-1 as a catalyst.

The conversion of trans-ferulic acid to vanillin was achieved by heterogeneous catalysis. HKUST-1 was employed in this synthesis and the essential step in the catalytic process was the generation of unsaturated metal sites. Thus, when the catalyst was activated under vacuum, full vanillin conversion (yield of 95%) was obtained.

科大-1作为香兰素的合成的非均相催化剂

Vanillin (4-hydoxy-3-methoxybenzaldehyde) is the main component of the extract of vanilla bean. The natural vanilla scent is a mixture of approximately ...

Spin Saturation Transfer Difference NMR (SSTD NMR): A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

This detailed protocol describes the new Spin Saturation Transfer Difference Nuclear Magnetic Resonance protocol (SSTD NMR), recently developed in our group to study processes of mutual-site chemical exchange that are difficult to analyze by traditional methods. As the name suggests, this method combines the Spin Saturation Transfer method used for small molecules, with the Saturation Transfer Difference (STD) NMR method employed for the study of protein-ligand interactions, by measuring transient spin saturation transfer along increasing saturation times (build-up curves) in small organic and organometallic molecules undergoing chemical exchange.
Advantages of this method over existing ones are: there is no need to reach coalescence of the exchanging signals; the method can be applied as long as one signal of the exchanging sites is isolated; there is no need to measure T1 or reach steady state saturation; rate constant values are measured directly, and T1 values are obtained in the same experiment, using only one set of experiments.
To test the method, we have studied the dynamics of the hindered rotation of N,N-dimethylamides, for which much data is available for comparison. The thermodynamic parameters obtained using SSTD are very similar to the reported ones (spin-saturation transfer techniques and line-shape analysis). The method can be applied to more challenging substrates that cannot be studied by previous methods.
We envisage that the simple experimental set up and the wide applicability of the method to a great variety of substrates will make this a common technique amongst organic and organometallic chemists without extensive expertise in NMR.

Spin Saturation Transfer Difference NMR SSTD NMR: A New Tool to Obtain Kinetic Parameters of Chemical Exchange Processes

A detailed protocol describing the SSTD NMR method is presented here to help new users apply this new method to obtain the kinetic parameters of their own systems undergoing chemical exchange.

自旋饱和转移差异核磁共振（NMR SSTD）:一种新的工具来获得化学交换过程的动力学参数

This detailed protocol describes the new Spin Saturation Transfer Difference Nuclear Magnetic Resonance protocol (SSTD NMR), recently developed in our ...

Insights into the Interactions of Amino Acids and Peptides with Inorganic Materials Using Single-Molecule Force Spectroscopy

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals leads to the formation of composite materials with unique properties. In addition, the undesirable process of biofouling is initiated by the adsorption of biomolecules, mainly proteins, on surfaces. This organic layer is an adhesion layer for bacteria and allows them to interact with the surface. Understanding the fundamental forces that govern the interactions at the organic-inorganic interface is therefore important for many areas of research and could lead to the design of new materials for optical, mechanical and biomedical applications. This paper demonstrates a single-molecule force spectroscopy technique that utilizes an AFM to measure the adhesion force between either peptides or amino acids and well-defined inorganic surfaces. This technique involves a protocol for attaching the biomolecule to the AFM tip through a covalent flexible linker and single-molecule force spectroscopy measurements by atomic force microscope. In addition, an analysis of these measurements is included.

Here we present a protocol to measure the force of interactions between a well-defined inorganic surface and either peptides or amino acids by single-molecule force spectroscopy measurements using an atomic force microscope (AFM). The information obtained from the measurement is important to better understand the peptide-inorganic material interphase.

洞察氨基酸和多肽与无机材料的使用相互作用的单分子力谱

The interactions between proteins or peptides and inorganic materials lead to several interesting processes. For example, combining proteins with minerals ...

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the average content of fluorinated drugs in their formulated drug product forms: tablets or capsules. This method is specific to fluorinated drugs because it detects only the content of fluorine, avoiding interference from the excipients that lack fluorine. The advantages of measuring the active content of fluorinated drugs using low-field 19F TD-NMR versus high-field 19F solid-state (SS) NMR are the simplicity of the method; the low cost; and the non-destructive nature of the technique, with all samples recoverable in intact forms (e.g., powders, tablets, and capsules), making this technique affordable for any laboratory.
We have tested the method with three fluorinated drug products available on the market - cinacalcet, lansoprazole, and ciprofloxacin - with doses ranging from 15 to 500 mg. The results of the analyses, measured by low-field 19F TD-NMR, supported the reported label claims for the average drug content.
Based on the simplicity and reproducibility of the analysis, we envision this methodology being implemented in any laboratory, including manufacturing plants, as a process analytical technology (PAT) tool in the pharmaceutical industry.

Application and Methodology of the Non-destructive 19F Time-domain NMR Technique to Measure the Content in Fluorine-containing Drug Products

A simple and non-destructive technique that measures the average content of drug substances in formulated drug products containing fluorine using low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) is presented here. The technique can be applied to the development and manufacturing of drugs in the pharmaceutical industry.

应用程序和非破坏性19F 时间域核磁共振技术的方法来衡量中含氟药物产品的内容

Here, we describe a protocol developed by our group that uses low-field fluorine-19 (19F) time-domain (TD) nuclear magnetic resonance (NMR) to measure the ...

Electrochemical Impedance Spectroscopy as a Tool for Electrochemical Rate Constant Estimation

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). In the case of fast reversible electrochemical processes, current is predominantly affected by the rate of diffusion, which is the slowest and limiting stage. EIS is a powerful technique that allows separate analysis of stages of charge transfer that have different AC frequency response. The capability of the method was used to extract the value of charge transfer resistance, which characterizes the rate of charge exchange on the electrode-solution interface. The application of this technique is broad, from biochemistry up to organic electronics. In this work, we are presenting the method of analysis of organic compounds for optoelectronic applications.

Electrochemical impedance spectroscopy (EIS) of species that undergo reversible oxidation or reduction in solution was used for determination of rate constants of oxidation or reduction.

电化学阻抗谱作为电化学速率常数估计的一种工具

Electrochemical impedance spectroscopy (EIS) was used for advanced characterization of organic electroactive compounds along with cyclic voltammetry (CV). ...

Color Spot Test As a Presumptive Tool for the Rapid Detection of Synthetic Cathinones

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and other border protection agencies globally. Color testing is a presumptive identification technique indicating the presence or absence of a particular drug class using rapid and uncomplicated chemical methods. Owing to their relatively recent emergence, a color test for the specific identification of synthetic cathinones is not currently available. In this study, we introduce a protocol for the presumptive identification of synthetic cathinones, employing three aqueous reagent solutions: copper(II) nitrate, 2,9-dimethyl-1,10-phenanthroline (neocuproine) and sodium acetate. Small pin-head sized amounts (approximately 0.1-0.2 mg) of the suspected drugs are added to the wells of a porcelain spot plate, and each reagent is then added dropwise sequentially before heating on a hotplate. A color change from very light blue to yellow-orange after 10 min indicates the likely presence of synthetic cathinones. The highly stable and specific test reagent has the potential for use in the presumptive screening of unknown samples for synthetic cathinones in a forensic laboratory. However, the nuisance of an added heating step for the color change result limits the test to laboratory application and decreases the likelihood of an easy translation to field testing.

Here we present a simple, inexpensive, and selective chemical spot test protocol for the detection of synthetic cathinones, a class of new psychoactive substances. The protocol is suitable for use in various areas of law enforcement that encounter illicit material.

色斑试验作为合成 Cathinones 快速检测的推定工具

Synthetic cathinones are a large class of new psychoactive substances (NPS) that are increasingly prevalent in drug seizures made by law enforcement and ...

A New Straightforward Method for Lipophilicity (logP) Measurement using 19F NMR Spectroscopy

Fluorination has become an effective tool to optimize physicochemical properties of bioactive compounds. One of the applications of fluorine introduction is to modulate the lipophilicity of the compound. In our group, we are interested in the study of the impact of fluorination on lipophilicity of aliphatic fluorohydrins and fluorinated carbohydrates. These are not UV-active, resulting in a challenging lipophilicity determination. Here, we present a straightforward method for the measurement of lipophilicity of fluorinated compounds by 19F NMR spectroscopy. This method requires no UV-activity. Accurate solute mass, solvent and aliquot volume are also not required to be measured. Using this method, we measured the lipophilicities of a large number of fluorinated alkanols and carbohydrates.

A New Straightforward Method for Lipophilicity logP Measurement using 19F NMR Spectroscopy

A novel and straightforward variation of the shake-flask method was developed for accurate lipophilicity measurement of fluorinated compounds by 19F NMR spectroscopy.

一种利用19f 核磁共振光谱测定脂质性 (日志 p) 的新方法

Fluorination has become an effective tool to optimize physicochemical properties of bioactive compounds. One of the applications of fluorine introduction ...