Application of Multivariate Techniques in Optimization of Spectroanalytical Methods

Abstract

The present article describes fundamentals and applications of multivariate techniques used for the optimization of analytical procedures and systems involving spectroanalytical methods such as flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ETAAS), inductively coupled plasma optical emission spectrometry (ICP OES), and inductively coupled plasma mass spectrometry (ICP‐MS), considering the main steps of a chemical analysis. This way, applications of experimental designs in optimization of sampling systems, digestion procedures, preconcentration procedures, instrumental parameters of quantification steps of analytical methods, and robustness tests have been summarized in this work.     

Chemical Vapor Generation with Slurry Sampling: A Review of Applications to Atomic and Mass Spectrometry

Abstract

A critical review of published analytical methods and techniques for chemical vapor generation (CVG) with slurry sample introduction for detection by atomic and mass spectrometry is presented. The nstrumentation used for the reaction as well as separation and transport of the species, influence of chemical and physical factors, and efficiency of the process are considered. A brief comparison of detection limits obtained with atomic absorption, emission, and fluorescence as well as mass spectrometry along with practical applications to analytical samples are summarized. The current state-of-the-art, including advantages and limitations of this approach, is discussed.     

Analytical Methods for the Characterization of Organic Dyes in Artworks and in Historical Textiles

Abstract

Dyes are among the most significant components in works of art and archaeological findings. In the scientific examination of historical artefacts, the identification of natural dyestuffs is a challenging task, due to the complexity of their chemical composition and the possible presence of mixtures of chromophores and degradation products. For this reason, in the last few decades, new analytical procedures and techniques have been developed and improved for the characterization of organic dyes and their identification in microsamples. This review looks at the chemical composition of natural organic dyeing materials used in the field of the cultural heritage and focuses on several analytical methods based on spectrometric and chromatographic techniques that have contributed to the study of organic dyes in works of art and archaeological findings.     

Microplasma Technology and Its Applications in Analytical Chemistry

Abstract

This review article describes some existing microplasma sources and their applications in analytical chemistry. These microplasmas mainly include direct current glow discharge (DC), microhollow-cathode discharge (MHCD) or microstructure electrode (MSE), dielectric barrier discharge (DBD), capacitively coupled microplasmas (CCμPs), miniature inductively coupled plasmas (mICPs), and microwave-induced plasmas (MIPs). The historical development and recent advances in these microplasma techniques are presented. Fundamental properties of the microplasmas, the unique features of the reduced size and volume, as well as the advantageous device structures for chemical analysis are discussed in detail, with the emphasis toward detection of gaseous samples. The analytical figures of merit obtained using these microplasmas as molecular/elemental-selective detectors for emission spectrometry and as ionization sources for mass spectrometry are also given in this review article.     

Critical Evaluation of Analytical Procedures for the Determination of Lead in Seawater

Abstract: This article presents a critical evaluation of the analytical procedures used for the determination of lead in seawater, which is important because lead is a good indicator of marine pollution caused by human activities. Sampling, storage, and pretreatment techniques are briefly overviewed, including the significance of systematic errors that cannot be corrected later on. The main techniques in this article are electrothermal–atomic absorption spectrometry (ET-AAS), inductively coupled plasma–mass spectrometry (ICP-MS), and voltammetry. Flame atomic absorption spectrometry (FAAS) and inductively coupled plasma–optical emission spectrometry (ICP-OES) are treated as well, although their limits of quantification are not sufficient for a determination of lead in unpolluted seawater. Even when separation and preconcentration techniques are applied, these techniques are only capable of detecting lead in polluted coastal seawater. Separation and preconcentration are actually also required for ET-AAS and ICP-MS in order to determine the lowest concentrations of lead found in unpolluted open-ocean seawater, which is still a challenge for the analytical chemist.     

Molybdenum,Platinum, and Tantalum Metal Atomizers or Vaporizers in Analytical Atomic Spectrometry

Abstract

The application of metal (tantalum, molybdenum, and platinum) devices in analytical atomic spectrometry is reviewed in this article. These metal devices have been employed in various analytical atomic spectrometric techniques for more than three decades, mainly as electrothermal atomizers or electrothermal vaporizers, in various physical shapes, such as tubes, platforms, loops, and wires (or coils/filaments). Their application spans from atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) atomic fluorescence spectrometry (AFS), inductively coupled plasma atomic emission spectrometry (ICP‐AES) to inductively coupled plasma mass spectrometry (ICP‐MS). The analytical figures of merit and the practical applications reported for these metal devices are reviewed, and the atomization mechanism on these metal atomizers is briefly summarized, too. In addition, other applications of the metal devices are discussed, including analyte preconcentration by electrodeposition and sequential metal vapor elution analysis (SMVEA). Furthermore, the application of these metals in graphite furnaces encompasses the schemes with the metals in the form of furnace linings, platforms, or impregnated salts.     

Mapping prehistoric ghosts in the synchrotron

The detailed chemical analysis of fossils has the potential to reveal great insight to the composition, preservation and biochemistry of ancient life. Such analyses would ideally identify, quantify, and spatially resolve the chemical composition of preserved bone and soft tissue structures, but also the embedding matrix. Mapping the chemistry of a fossil in situ can place constraints on mass transfer between the enclosing matrix and the preserved organism(s), and therefore aid in distinguishing taphonomic processes from original chemical zonation remnant within the fossils themselves. Conventional analytical methods, such as scanning electron microscopy (SEM) and pyrolysis–gas chromatography/mass spectrometry (Py-GC/MS) have serious limitations in this case, primarily, an inability to provide large (i.e., decimeter) scale chemical maps. Additionally, vacuum chamber size and the need for destructive sampling preclude analysis of large and precious fossil specimens. However, the recent development of Synchrotron Rapid Scanning X-ray Fluorescence (SRS-XRF) at the Stanford Synchrotron Radiation Lightsource (SSRL) allows the non-destructive chemical analysis and imaging of major, minor, and trace element concentrations of large paleontological and archeological specimens in rapid scanning times. Here we present elemental maps of a fossil reptile produced using the new SRS-XRF method. Our results unequivocally show that preserved biological structures are not simply impressions or carbonized remains, but possess a remnant of the original organismal biochemistry. We show that SRS-XRF is a powerful new tool for the study of paleontological and archaeological samples.     

Glow Discharge as a Tool for Surface and Interface Analysis

Abstract

This review article focuses on the analytical capabilities of glow discharge optical emission spectrometry (GD‐OES) and mass spectrometry (GD‐MS) to perform compositional depth profiling (GD‐CDP). The properties of the Grimm‐type glow discharge as well as basic processes of sputtering are described and their influence on the GD as a surface and interface analytical tool are discussed. A series of examples from recent literature ranging from computer hard disks to molecular monolayers on copper substrates are presented to illustrate the excellent depth resolution that can be achieved with GD surface analytical techniques. The conditions for obtaining nanometer or even atomic‐layer depth resolution are discussed. Following this introduction is the possibilities of the technique a selection of applications principally chosen from our laboratories, demonstrating that GD‐OES and GD‐MS can be successfully employed as an analytical tool assisting the development of new materials and coatings. The applications cover common industrial tasks such as heat treatments, studies of diffusion processes at interfaces, and electrochemical depositions for biocompatible material. However, limitations and known artifacts are also discussed.     

Slurry Sampling—An Analytical Strategy for the Determination of Metals and Metalloids by Spectroanalytical Techniques

Abstract

This article critically overviews the state-of-the-art of slurry sampling as an approach for the minimization of sample preparation prior to the determination of metals and metalloids in complex matrices by spectroanalytical techniques. Relevant factors involved in the optimization of slurry-based analytical procedures and the dependence of the quality of the results on the calibration method selected are discussed in detail. The advantages and limitations compared to solid sampling for the analysis of solid matrices are highlighted and discussed.

Analytical applications of slurry sampling reported in the literature emphasizing publications between 2004 and 2009 are comprehensively compiled covering detection by flame atomic absorption spectrometry (FAAS), electrothermal atomic absorption spectrometry (ET-AAS), cold vapor atomic absorption spectrometry (CV-AAS), hydride generation atomic absorption spectrometry (HG-AAS), hydride generation atomic fluorescence spectrometry (HG-AFS), inductively coupled plasma optical emission spectrometry (ICP-OES), and inductively coupled plasma mass spectrometry (ICP-MS).     

Dry Ashing Preparation of (Quasi)solid Samples for the Determination of Inorganic Elements by Atomic/Mass Spectrometry

Abstract:

This work presents an overview of the development of dry ashing preparation techniques for solid and quasisolid sample analysis by atomic and inorganic mass spectrometry, including flame/graphite furnace atomic absorption spectrometry, chemical vapor generation atomic absorption/fluorescence spectrometry, and inductively coupled plasma–optical emission/mass spectrometry. This article also summarizes all of the dry ashing methods reported in the past 20 years. The dry ashing methods applied to sample preparation are classified as electrothermal ashing, microwave ashing, oxygen combustion, and other special ashing methods including laser, ultraviolet (UV)/ozone, and plasma. Moreover, the development of relevant devices is discussed in context.     

Determination of Trace Elements in Vegetable Oils and Biodiesel by Atomic Spectrometric Techniques—A Review

Abstract

The determination of trace elements in edible oils and biodiesel using atomic spectrometric methods is reviewed. Problems related to sample pretreatment for appropriate sample introduction and calibration are addressed as well as the strategies to overcome them. Recent trends aimed at simplifying sample manipulation are presented. The applications and scope of atomic absorption spectrometry (AAS), flame optical emission spectrometry (F-OES), inductively coupled plasma–optical emission spectrometry (ICP-OES), and inductively coupled plasma–mass spectrometry (ICP-MS) techniques for the determination of trace metals in edible oils and biodiesel are discussed, as well as some current instrumental new developments.     

Vibrational Spectroscopy in Clinical Analysis

Abstract: Vibrational spectroscopy includes several different techniques, the most important of which are mid-infrared (IR), near-IR, and Raman spectroscopy. Raman and mid-IR spectroscopy are complementary techniques and usually both are required to completely measure the vibrational modes of a molecule. Vibrational spectrometry covers a series of well-established analytical methodologies suitable to be employed for both qualitative and quantitative purposes. In the first part of this review, we will focus on theoretical aspects related to vibrational techniques; in the second part, the most important papers, published during the period 2005–2014, related to clinical analysis performed with vibrational spectroscopy techniques will be critically discussed.     

Application of Preconcentration and Separation Techniques in Atomic Fluorescence Spectrometry

Abstract

With 135 references, this review presents the recent application of various preconcentration and separation techniques in atomic fluorescence spectrometry for the sensitive determination and speciation of various elements and their species. It focuses on sample pretreatment, separation, and enrichment-related techniques, including liquid–liquid extraction, solid-phase (micro)extraction, microwave/ultrasound-assisted extraction, pressurized liquid extraction, as well as chemical vapor generation. In this review, the historical development and overview of these preconcentration and separation methodologies are briefly discussed, together with a comprehensive collection of application of these methods in combination with atomic fluorescence spectrometry for determination of ultratrace amounts of elements and their species in various sample matrices (liquids and solids).     

Recent Advance of Hydride Generation–Analytical Atomic Spectrometry: Part I—Technique Development

Abstract Hydride generation is the most popular and widely used chemical vapor generation technique and is interesting to analytical chemists as an effective sample introduction method, especially for elemental determination and speciation analysis by analytical atomic spectrometry. The present review provides a literature survey on the hydride generation technique coupled to analytical atomic spectrometry during the past several years, covering the literature on both tetrahydroborate-based hydride generation and non-tetrahydroborate-based hydride generation techniques. Development of other related methods coupled to hydride generation for better analytical performance of analytical atomic spectrometry is included as well.     

Production of reference “ancient” Cu-based alloys and their accelerated degradation methods

A large number of bronze artefacts found during archaeological excavations carried out in Italy in different contexts have been studied. Their chemical composition and metallurgical features have been determined by the combined use of different analytical surface and bulk techniques, such as optical microscopy (OM), scanning electron microscopy with energy dispersive X-ray micro-analysis (SEM-EDS), X-raydiffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The study of the corrosion products grown on the archaeological Cu-based artefacts and of their metallurgical features has revealed the quite ubiquitous and nearly constant presence of chlorine as the main corroding agent, and the different structures of the alloys. This information has been used to produce reference Cu-based alloys, whose chemical composition and micro-chemical structure is similar to that of the ancient alloys, and to propose the guidelines for carrying out the accelerated degradation tests to produce corroded samples for testing corrosion inhibiting products. The proposed tests were based on soil, chemical and (chemical+soil)-induced degradation, and the micro-chemical structure of the artificially produced corrosion layers has been compared to those grown on archaeological artefacts during burial. The comparison shows that the (chemical+soil)-induced degradation produces “patinas” that are similar to those grown on archaeological artefacts from a chemical, structural and micro-morphological point of view. PACS 68.55.Jk; 68.35.Dv; 68.37.Hk; 68.55.Nq; 81.05.Ba     

Fast Atom BombardmenUMass Spectrometry (FABMS) and Its Industrial Applications

Abstract

“Soft ionization” techniques which permit direct desorptton of gasphase analyte ions without the need for vaporization have greatly expanded the potential applications of mass spectrometry (MS). By using such techniques as field desorption (FD), desorption chemical ionization (DCI), and fast atom bombardment (FAB), thermally labile and higher molecular weight compounds are now amenable to MS exambation without significant thermal degradation. This ability to ionize higher molecular weight species has been paralleled by high field, inhomogeneous magnet development, allowing magnetic sector mass spectrometers to reach 10,000ν at full accelerating voltage. These advancements in ionization techniques and instrument design now permit useful MS data for organic compounds of several thousand molecular weight to be produced on a near routine basis in many laboratories.     

Iron contamination in silicon technology

This article continues the review of fundamental physical properties of iron and its complexes in silicon (Appl. Phys. A 69, 13 (1999)), and is focused on ongoing applied research of iron in silicon technology. The first section of this article presents an analysis of the effect of iron on devices, including integrated circuits, power devices, and solar cells. Then, sources of unintentional iron contamination and reaction paths of iron during device manufacturing are discussed. Experimental techniques to measure trace contamination levels of iron in silicon, such as minority carrier lifetime techniques (SPV, μ-PCD, and ELYMAT), deep-level transient spectroscopy (DLTS), total X-ray fluorescence (TXRF) and vapor-phase decomposition TXRF (VPD-TXRF), atomic absorption spectroscopy (AAS), mass spectrometry and its modifications (SIMS, SNMS, ICP-MS), and neutron activation analysis (NAA) are reviewed in the second section of the article. Prospective analytical tools, such as heavy-ion backscattering spectroscopy (HIBS) and synchrotron-based X-ray microprobe techniques (XPS, XANES, XRF) are briefly discussed. The third section includes a discussion of the present achievements and challenges of the electrochemistry and physics of cleaning of silicon wafers, with an emphasis on removal of iron contamination from the wafers. Finally, the techniques for gettering of iron are presented. Received: 16 November 1999 / Accepted: 7 January 2000 / Published online: 5 April 2000     

Determination of Cadmium in Biological Samples

Abstract

Even though normal exposure levels to Cd may be small, the human body is inefficient at excreting the heavy metal, so it slowly accumulates over the period of a lifetime. Eventually, the Cd level in the body may become toxic and give rise to harmful effects. Cadmium exposure could therefore be linked to diseases associated with aging such as osteoporosis, prostate cancer, and pancreatic cancer. These potential links have driven the development of a myriad of analytical techniques for the determination of Cd in biological samples. Natural biological Cd concentrations are typically low, so preconcentration steps and sensitive instruments are frequently a necessity. In addition, the complex matrices of biological specimens such as blood, urine, serum, and tissue often require a form of matrix modification or separation. This review provides an overview of these methods with 200 references from the literature published between 1995 and 2005. The analytical methods for the determination of Cd in biological samples include: spectrophotometry, atomic emission spectrometry, atomic absorption spectrometry, atomic fluorescence spectrometry, inductively coupled plasma mass spectrometry, and electrochemistry. In addition, Cd speciation techniques, using high‐performance liquid chromatography and capillary electrophoresis, are briefly discussed.     

An Overview of the Use of Yttrium for Internal Standardization in Inductively Coupled Plasma–Atomic Emission Spectrometry

Abstract

Internal standardization is a widely used method for compensating nonspectral interference in inductively coupled plasma (ICP) spectrometry. Emphasis is given on the choice of the suitable element and its specific spectral line as an efficient internal standard. This choice is the result of multi-variable evaluations and analytical applications. In inductively coupled plasma–atomic emission spectrometry (ICP-AES) and other spectrometric techniques several spectral lines of the same or different elements have been evaluated as potential internal standards. Yttrium spectral lines fulfill certain prerequisites and they are favored by a large number of researchers. In our discussed review, we present several reports of ICP-AES techniques that employ yttrium as the internal standard. These reports are classified according to specific sample origin and aim of the research.