Ultratrace analyses

Sampling. A sample used for trace or ultratrace analysis should always be representative of the bulk material. The principal considerations are determination of population or the whole from which the sample is to be drawn, procurement of a vaUd gross sample, and reduction of the gross sample to a suitable sample for analysis (15) (see Sampling). 

Because GDMS can provide ultratrace analysis with total elemental coverage, the technique fills a unique analytical niche, supplanting Spark-Source Mass Spectrometry (SSMS) by supplying the same analysis with an order-of-magnitude better accuracy and orders-of-magnitude improvement in detection limits. GDMS analy-... 

When the sample weight is small (0.1-1.0mg), the determination of a trace component at the 0.01 per cent level may be referred to as subtrace analysis. If the trace component is at the microtrace level, the analysis is termed submicrotrace. With a still smaller sample (not larger than 0.1 mg) the determination of a component at the trace level is referred to as ultratrace analysis, whilst with a component at the microtrace level, the analysis is referred to as ultra-microtrace. 

The apparatus required for classical procedures is cheap and readily available in all laboratories, but many instruments are expensive and their use will only be justified if numerous samples have to be analysed, or when dealing with the determination of substances present in minute quantities (trace, subtrace or ultratrace analysis). 

Vol. 85. Ultratrace Analysis of Pharmaceuticals and Other Compounds of Interest. Edited by S. Ahuja... 

Vol. 115. Trace and Ultratrace Analysis by HPLC. By Satinder Ahuja... 

S. Ahuja, in Ultratrace Analysis of Pharmaceuticals and Other Compounds of Interest (S. Ahuja, ed.), John Wiley Sons, Inc., New York, NY (1986), pp. 19-90. 

Trace and ultratrace analysis SSMS, GD-MS, LA-ICP-MS, (IDMS) Chapter 8... 

The isotope dilution method can be used for the measurement of molecules or elemental species (about 60 elements have stable isotopes). This approach allows ultratrace analysis because, contrary to radioactive labelling where the measurement relies on detecting atoms that decay during the period of measurement, all of the labelled atoms are measured. 

Applications NAA is a powerful technique for ultratrace analysis of metallic impurities in plastics. PE is one of the most important canning materials for NAA, mainly on account of its high purity and low price. The cross-section of PE for thermal neutrons amounts to... 

RC Tim, RA Kautz, BL Karger. Ultratrace analysis of drugs in biological fluids using affinity probe capillary electrophoresis analysis of dorzolamide with fluorescently labeled carbonic anhydrase. Electrophoresis 21 220—226, 2000. 

Another combination of magnetic and electric sector fields, together with a tandem accelerator, is realized in different types of accelerator mass spectrometers (AMS)17 applied for carbon-14 dating and extreme ultratrace analysis of long-lived radionuclides at natural isotope abundances (see Chapter 5). 

Instrumental developments (e.g., of sector field instruments with multiple ion collection, introduced in 1992, or the insertion of collision and reaction cells in order to reduce disturbing isobaric interferences), the progress in applications for ultratrace analysis, also in combination with on line hyphenated separation techniques (HPLC, CE), especially routine capability as well as decreasing price and user friendly maintenance mean that sales are increasing by 10 % every year. To improve the analytical performance of ICP mass spectrometers for precise isotope ratio measurements (e.g., for geochronology or for the study of fine isotope variation in nature) powerful instrumentation with high mass dispersion and multiple ion collector systems instead of single ion collection are commercially available on the analytical market. 

Further applications of ICP-MS with a collision/reaction cell in trace, ultratrace analysis and isotope ratio measurements are described in Chapter 8.16 17 20 22 27 28... 

In spite of the excellent capability and advantages (high selectivity and sensitivity) of RIMS for the ultratrace analysis of isotopes with naturally rare abundance in environmental, geological, medical and nuclear samples, no commercial instrumentation is available to date. In contrast to AMS and RIMS as mono-elemental (element-specific) analytical techniques, ICP-MS and LA-ICP-MS possess, in analogy to GDMS and SIMS, have the ability for multi-element analysis and thus could have the widest fields of application. 

In trace and ultratrace analysis with respect to minimal systematic errors, the following must be considered ... 

Chemical separation of matrix and preconcentration of analytes is used to avoid matrix effects, clogging effects on the cones and disturbing interferences of analyte ions with polyatomic ions of matrix elements and plasma gases. A trace/matrix separation method is required for ultratrace analysis. 

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