标准元素分析方法的变更及其性能的改进

本文详细地论述了标准元素分析方法的变更及其性能的改进。

Paradigm Shift in Classical Elemental Analysis

An inductively coupled plasma (ICP) spectrometer equipped with pneumatic nebulization sample introduction requires mL volumes of sample. For direct elemental analysis of small amounts of solids, an ICP equipped either with a direct sample insertion (DSI) or with an electro-thermal vaporization (ETV) sample introduction system would typically require mg amounts of sample. In my laboratories, we have been developing and characterizing a new sample introduction system we call in-torch vaporization (ITV). The ITV sample introduction system improved significantly the detection limits of ICP spectrometry (both atomic emission and mass spectrometry), thus enabling determinations for micro- and sub-micro size liquid or solid samples. In some cases, even microscopic, nano-size samples were successfully analyzed. In the first part of this paper, development of ITV-ICP for both Atomic Emission Spectrometry (AES) and Mass Spectrometry (MS) will be described. It will be shown that ITV has the potential to cause a paradigm shift in classical elemental analysis by ICP spectrometry by taking analysts from the milli-size (e.g., mg or mL) to the micro-size (e.g., microgram of microL), sub-micro and even nano-sample size-regime. Despite the success of ITV with tiny amounts of sample, such samples must still be collected in the field and must be brought to the laboratory (albeit in smaller containers) for elemental analysis by ICP spectrometry. Would it not be ideal if we could bring an ICP spectrometer to the sample, thus obtaining analytical results in the field (i.e., on-site) and in (near) real-time? Since the typical ICP spectrometer is bulky and heavy and has kWatt power requirements, it is nearly always tethered to a wall socket and it is not usually taken out to the field. Do we need such a large instrument to analyze such tiny samples? In the second part of this paper, current research in my laboratories toward the conceptual goal of miniaturizing elemental analysis instrumentation will be presented. For this, development and characterization of a portable, battery-operated instrument for (near) real-time Hg determination in the field from gases and from liquid and solid micro-samples will be used as an example. Future portable elemental analysis micro-instruments that can be taken out of the lab and into the field are poised to cause another paradigm shift in classical elemental analysis by allowing analysts to bring (part of) the lab to the sample.