Lisk D J
Science. 1974 Jun 14;184(4142):1137-41. doi: 10.1126/science.184.4142.1137.
One may conclude that it is impractical to confine oneself to any one analytical method since ever more sensitive instrumentation continues to be produced. However, in certain methods such as anodic stripping voltammetry and flameless atomic absorption it may be background contamination from reagent impurities and surroundings rather than instrument sensitivity which controls the limits of element detection. The problem of contamination from dust or glassware is greatly magnified when the sample size becomes ever smaller. Air entering laboratories near highways may contain trace quantities of lead, cadmium, barium, antimony, and other elements from engine exhaust. Even plastic materials contacting the sample may be suspect as a source of contamination since specific metals may be used as catalysts in the synthesis of the plastic and traces may be retained in it. Certain elements may even be deliberately added to plastics during manufacture for identification purposes. Nondestructive methods such as neutron activation and x-ray techniques thus offer great advantages not only in time but in the elimination of impurities introduced during sample ashing. Future improvements in attainable limits of detection may arise largely from progress in the ultrapurification of reagents and "clean-room" techniques. Finally, the competence of the analyst is also vitally important in the skillful operation of modern complex analytical instrumentation and in the experienced evaluation of data.
由于不断有更灵敏的仪器问世，只局限于使用任何一种分析方法是不切实际的。然而，在某些方法中，比如阳极溶出伏安法和无火焰原子吸收法，控制元素检测限的可能是试剂杂质和周围环境带来的背景污染，而非仪器的灵敏度。当样品量变得越来越小时，灰尘或玻璃器皿造成的污染问题就会被极大地放大。靠近高速公路的实验室所进的空气中可能含有来自汽车尾气的微量铅、镉、钡、锑及其他元素。甚至与样品接触的塑料材料也可能被怀疑是污染源，因为在塑料合成过程中可能使用了特定金属作为催化剂，并且可能会有痕量残留其中。在制造过程中，甚至可能会故意向塑料中添加某些元素用于识别目的。因此，诸如中子活化分析和X射线技术等无损方法不仅在时间上具有很大优势，而且在消除样品灰化过程中引入的杂质方面也具有很大优势。未来检测限的进一步提高可能很大程度上源于试剂超纯化和“洁净室”技术的进步。最后，分析人员的能力对于熟练操作现代复杂分析仪器以及对数据进行经验丰富的评估也至关重要。
