Gay Martha L, Musser Steven M
U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition, HFS-707, 5100 Paint Branch Pkwy, College Park, MD 20770, USA.
J AOAC Int. 2008 May-Jun;91(3):501-5.
Nordihydroguaiaretic acid (NDGA) occurs naturally in chaparral (Larrea tridentate Coville), a plant which commonly grows in the Southwest United States and has been used for medicinal purposes by Native Americans indigenous to that region. In addition to its traditional use as a tea, manufacturers of dietary supplements have marketed chaparral-containing products in a variety of formulations. Because of the hepatotoxicity of NDGA, and its occurrence in regulated products, we have developed a method for the determination of NDGA in dietary supplements and have tested this method in several dietary supplement formulations. Products were extracted with 80% methanol, filtered, and analyzed by high-performance liquid chromatography. NDGA was detected and determined with both a diode array detector and negative-ion electrospray. Fragmentation in the triple-quadrupole mass spectrometer was obtained by collisional activation of the M-H ion. Collisional activation produced sufficient fragmentation to provide unambiguous identification. Lack of a stable isotope labeled internal standard has led us to compare quantitations based on UV detection with quantitations based on tandem mass spectrometry (MS/MS). Presence of NDGA was confirmed in several dietary supplement products. Quantitative results from the 2 detection methods were comparable for most products. The limit of quantitation using MS/MS was lower and fewer interferences were observed, although UV detection provided better linearity.
去甲二氢愈创木酸（NDGA）天然存在于拉瑞阿三齿叶（Larrea tridentate Coville）中，这种植物常见于美国西南部，该地区的美洲原住民一直将其用于药用。除了传统上用作茶之外，膳食补充剂制造商还以多种配方销售含拉瑞阿三齿叶的产品。由于NDGA具有肝毒性，且存在于受监管的产品中，我们开发了一种测定膳食补充剂中NDGA的方法，并在几种膳食补充剂配方中对该方法进行了测试。产品用80%甲醇提取、过滤，然后通过高效液相色谱法进行分析。使用二极管阵列检测器和负离子电喷雾检测并测定NDGA。通过对M-H离子进行碰撞活化，在三重四极杆质谱仪中获得碎裂。碰撞活化产生了足够的碎裂以提供明确的鉴定。由于缺乏稳定同位素标记的内标，我们将基于紫外检测的定量与基于串联质谱（MS/MS）的定量进行了比较。在几种膳食补充剂产品中证实了NDGA的存在。对于大多数产品，两种检测方法的定量结果具有可比性。使用MS/MS的定量限较低，观察到的干扰较少，尽管紫外检测提供了更好的线性。
