Search

This Update is part of a series of annual reviews which cover the various aspects of analytical atomic spectrometry and follows the same format as last year's.1 Although an attempt is made to consider all relevant refereed papers, conference abstracts, reports, book chapters and patents for inclusion in this review, the content of the review is highly selective. The selection of papers is based on criteria applied to focus sharply on the most significant developments in instrumentation and methodology or improved understanding of the fundamental phenomena involved in the MS process. The increasing importance of speciation and the blurring of boundaries between atomic and molecular MS require a high degree of judgement to be made in considering papers for inclusion. The main ruling criterion for all speciation papers is that the work should involve or be intended for the study of natural systems. For example, the study of synthetic metal clusters is generally not included, whereas the determination of organometallic compounds in environmental samples is.Applications of atomic MS are not covered in this Update and readers are referred to the Updates on Industrial Analysis: Metals, Chemicals and Advanced Materials,2 Environmental analysis3 and Clinical and Biological Materials, Food and Beverages.4Throughout this review, the term molecular ion will be restricted to denote only the positive or negative radical ion formed by removal or capture, respectively, of an electron. In contrast, addition of a proton or cation to a neutral molecule gives molecular adduct ions. Deprotonated molecules are considered as fragments.Although reproducibility or precision is a key figure of merit in MS, there is no agreed format for quoting it. The reader can assume that values of precision given in this Update as a percentage correspond to the RSD unless otherwise specified. In isotope analyses, however, values of precision are generally given as the SD of a permil value.It is a widespread phenomenon that analytical techniques in general and MS in particular spawn a large number of abbreviations and acronyms. A glossary of terms used in this Update appears at the end. Commonly used abbreviations are not defined in the text: others are defined in the text when used first and again in the glossary.

This Update follows the same format as last year's.1 Although an attempt is made to consider all relevant refereed papers, conference abstracts, reports, book chapters and patents for inclusion in this review, the content of the review is highly selective. The selection of papers is based on criteria applied to focus sharply on the most significant developments in instrumentation and methodology or improved understanding of the fundamental phenomena involved in the MS process. With the increasing importance of speciation and the blurring of boundaries between atomic and molecular MS, a high degree of judgement is required in considering papers for inclusion. The main ruling criterion for all speciation papers is that the work should involve or be intended for the study of natural systems. For example, the study of synthetic metal clusters is generally not included whereas the determination of organometallic compounds in environmental samples is.Applications of atomic MS are not covered in this Update and readers are referred to the Updates on Industrial analysis: metals, chemicals and advanced materials,2 Environmental analysis3 and Clinical and biological materials, food and beverages.4 There have been few general reviews of note. That of Walczyk5 gave a good introduction to the use of inorganic MS in human nutrition research.The trends noted over the last few years have continued. In particular, the growing interest in speciation studies has been reflected by the number of papers on the subject. As the number of species identified increases then the danger of relying solely on chromatographic retention times for identification has become a recurring warning in papers. For this reason, the importance of GDMS, ESMS and S-SIMS for species identification has been widely recognised. In all these studies, sample preparation and introduction have generally received most attention, with the aim of ever improved analysis. The increasing use of multicollector ICP-MS instruments for isotope geology studies has resulted in common ground with traditional TIMS methods, in particular in sample preparation.Throughout this review, the term molecular ion will be restricted to denote only the positive or negative radical ion formed by removal or capture, respectively, of an electron. In contrast, addition of a proton or cation to a neutral molecule gives molecular adduct ions. Deprotonated molecules are considered as fragments.

This Update follows on from last year's 1 but covers a longer period. The system we use to access abstracts has been improved with the result that abstracts have become available more quickly and the review more timely. This review effectively covers a period of about 15 months up to the beginning of 2001. Although an attempt is made to consider all relevant refereed papers, conference abstracts, reports, book chapters and patents for inclusion, this review does not aim at being comprehensive in its coverage. The selection of papers is based on criteria applied to focus sharply on the most significant developments in instrumentation and methodology or improved understanding of the fundamental phenomena involved in the MS process. With the boundaries between atomic and inorganic molecular MS, and indeed organic MS, becoming less well defined, the judgement of the authors of this Update becomes important in considering papers for inclusion. The main ruling criterion for all papers is that the work should involve or be intended for the study of natural systems. For example, the study of synthetic metal clusters is generally not included whereas the determination of organometallic compounds in environmental samples is.Applications of atomic MS are not covered in this Update and readers are referred to the Updates on Industrial Analysis: Metals, Chemicals and Advanced Materials,2 Environmental analysis 3 and Clinical and Biological Materials, Food and Beverages. 4 Becker and Dietze 5 have produced yet another excellent review (210 references) covering in detail the inorganic MS techniques that are used for trace, isotope and surface analysis. Barshick et al.6 discussed the fundamentals and applications of inorganic MS in their substantial review. Although not focused specifically on MS techniques, the review (484 references) of Rao and Biju 7 on the determination of REEs was interesting in that it presented most of its data in tabular form.The trends noted over the last few years have continued. In particular, the growing interest in speciation studies has been matched by the number of papers on the subject. The renaissance of GC-MS has continued and the niche of ESMS for species identification has been confirmed, in particular to complement the elemental information provided by ICP-MS. In all of these studies, sample preparation and introduction have generally received most attention with the aim of further improving analysis. The very wide range of applications of AMS was made apparent by the papers presented at a major international conference. 8 The encroachment by ICP-MS into areas of traditional TIMS studies has continued with some success but ultimate levels of precision and accuracy can often only be achieved by the latter technique even if procedures are complex and time-consuming. A number of interesting trends were noted for ICP-MS in this review period. The use of LA, particularly for geological and environmental samples, continued to grow and has almost become a routine application. The use of collision or reaction cells for reduction/removal of polyatomic species has gained momentum and the use of both single- and multiple-collector magnetic sector MS systems has also increased significantly. There has been some interest in ICP-TOFMS systems, but it is not yet clear whether they offer any significant advantages over existing systems.

This Update follows on from last year's, but only covers a period of approximately ten months as the production schedule has been brought forward by two months. The format remains the same with some minor changes in the section headings. Although an attempt is made to consider all relevant refereed papers, conference abstracts, reports, book chapters and patents for inclusion, this review does not aim at being comprehensive in its coverage. The selection of papers is based on criteria applied to focus sharply on the most significant developments in instrumentation and methodology or improved understanding of the fundamental phenomena involved in the MS process. Routine applications of atomic MS are not covered in this Update and readers are referred to the Updates on Industrial analysis: metals, chemicals and advanced materials, Environmental analysis and Clinical and biological materials, foods and beverages.Trends noted in last year's Update have generally been maintained. Although the scope of this review includes the rapidly increasing use of MS for speciation analysis, reported developments should involve or be intended for studies of speciation in natural systems. However, some degree of judgement has still been required to set the limits. Attention has continued to be paid mainly to sample preparation and introduction, in particular to meet the need for analysis of smaller samples. The sensitivity of many of the MS techniques is exemplified by the growing use of AMS in biomedical and pharmaceutical studies, made possible through the use of such low levels of radiocarbon tracers that the doses fall below natural background levels and regulatory limits. The overall trend in published material on ICP-MS continues to grow mainly in the applications and sample introduction areas, at the expense of fundamental studies. The exception to this is a considerable activity in the development and application of collision and reaction cells for reduction or removal of polyatomic species. Many applications exploit the isotope capability of MS, identified in last year's review as a growth area for ICP-MS.

1 Accelerator mass spectrometry (AMS) 1.1 Small accelerators 1.2 Accelerator SIMS 1.3 Developments in radiocarbon analysis 1.4 Developments in the analysis of elements other than carbon 2 Glow discharge mass spectrometry (GDMS) 2.1 Review and fundamental studies 2.2 Instrumentation 2.3 Analytical methodology 3 Inductively coupled plasma mass spectrometry (ICP–MS) 3.1 Fundamental studies 3.2 Instrumentation 3.3 Sample introduction 3.3.1 Introduction 3.3.2 Laser ablation 3.3.3 Thermal vaporization 3.3.4 Chemical vaporization 3.3.5 Nebulization 3.3.6 Flow injection 3.3.7 Chromatography and electrophoresis 3.4 Interferences 3.5 Isotope ratio measurement 4 Laser ionization mass spectrometry (LIMS) 4.1 Fundamental studies 4.2 Instrumentation 4.3 Analytical methodology 5 Resonance ionization mass spectrometry (RIMS) 6 Secondary ion mass spectrometry (SIMS) 6.1 Instrumentation 6.2 Fundamental studies 6.3 Analytical methodology 6.4 Quantification 6.5 Single and multi-dimensional analysis 6.5.1 Depth profiling 6.5.2 Imaging 6.5.3 Three-dimensional (3-D) analysis 6.6 Multi-technique approaches 6.7 Static SIMS (S-SIMS) 7 Sputtered neutral mass spectrometry (SNMS) 7.1 Reviews 7.2 Analytical methodology 7.3 Depth profiling 8 Stable isotope ratio mass spectrometry (SIRMS) 8.1 Reviews 8.2 Instrumentation 8.3 Analytical methodology 8.4 Sample preparation 9 Thermal ionization mass spectrometry (TIMS) 9.1 Instrumentation 9.2 Negative ionization procedures 9.3 Positive ionization procedures 10 Other methods 10.1 Electrospray mass spectrometry (ESMS) and ion spray mass spectrometry (ISMS) 10.2 Fast atom bombardment mass spectrometry (FABMS) 10.3 Gas chromatography-mass spectrometry (GC-MS) 10.4 Noble gas mass spectrometry 10.5 Spark source mass spectrometry (SSMS) 10.6 New methodologies 11 References The format of this year's Update follows that used in last year's¹ with some minor changes in the section headings. Although an attempt is made to consider all relevant refereed papers, conference abstracts, reports, book chapters and patents for inclusion, this review does not aim at being comprehensive in its coverage. The selection of papers is based on criteria applied to focus sharply on the most significant developments reported during the period (approximately corresponding to 1998) covered by this Update. The prime consideration is that the reports should present advances in instrumentation and methodology or improved understanding of the fundamental phenomena involved in the MS process. As a general rule, conference abstracts are not included because they rarely provide sufficient information to judge whether or not they meet the criteria. We consider it better to wait for full details to appear in a refereed journal. A similar policy applies to those papers in a language other than English and unlikely to reach a wide readership. Routine applications of atomic MS are not covered in this Update and readers are referred to the Updates on Industrial analysis: metals, chemicals and advanced materials,² Environmental analysis³ and Clinical and biological materials, food and beverages.⁴ A book that can be thoroughly recommended is that edited by Gill⁵ on Modern Analytical Geochemistry. Chapters on most of the techniques included in this Update gave full yet concise descriptions of the underlying principles of the techniques, with examples of applications in geochemistry and environmental science. The substantial review (269 references) of Becker and Dietze⁶ covered in detail the inorganic MS techniques that are used for inorganic trace analysis. This Update follows the policy set by JAAS in deciding the scope of papers which can be considered for inclusion. With the increased use of atomic spectroscopy techniques, in particular MS, in speciation studies the scope has been widened to include not only elemental but also speciation studies, including those in which molecular species are determined as long as the focus of the study is the element and its chemical form. With the boundaries between atomic and molecular MS becoming less well defined, the judgement of the authors of this Update becomes important in achieving a correct balance. In general, studies of unstable nuclei are excluded but the determination of radioactive elements in ‘real’ samples are included.  The trends apparent for the various MS techniques are highlighted in the appropriate sections. In general, more attention continues to be paid to sample preparation and introduction rather than instrumentation. A common feature for many of the techniques reviewed is the need for analysis of smaller samples. This has presented challenges of reducing the levels of contamination and background noise and also calibration and standardization. The use of ICP-MS for the measurement of isotope ratios is noted as an increasingly important application.

Three different designs for skimmer cones, mounted in the interface region of an inductively coupled plasma mass spectrometric (ICP-MS) instrument, were evaluated with respect to their effect on analyte sensitivity, the magnitude of polyatomic ions, refractory oxide ions, doubly charged ions and background and non-spectroscopic matrix effects. Initial results for one particular design, termed ‘PolySkim’, conducted on both a standard commercial and the Surrey design ICP-MS instruments, show a significant reduction in the size of the ArO⁺ and other polyatomic peaks, with no corresponding deterioration of detection limits across the mass range, although a decrease in sensitivity did occur.