Trace Analysis Tools Research Articles

The current role of high-resolution mass spectrometry in food analysis

High-resolution mass spectrometry (HRMS), which is used for residue analysis in food, has gained wider acceptance in the last few years. This development is due to the availability of more rugged, sensitive, and selective instrumentation. The benefits provided by HRMS over classical unit-mass-resolution tandem mass spectrometry are considerable. These benefits include the collection of full-scan spectra, which provides greater insight into the composition of a sample. Consequently, the analyst has the freedom to measure compounds without previous compound-specific tuning, the possibility of retrospective data analysis, and the capability of performing structural elucidations of unknown or suspected compounds. HRMS strongly competes with classical tandem mass spectrometry in the field of quantitative multiresidue methods (e.g., pesticides and veterinary drugs). It is one of the most promising tools when moving towards nontargeted approaches. Certain hardware and software issues still have to be addressed by the instrument manufacturers for it to dislodge tandem mass spectrometry from its position as the standard trace analysis tool.

Maintenance of service oriented architecture composite applications: static and dynamic support

SUMMARYSeveral authors have suggested that service‐oriented architecture (SOA) applications will present new program comprehension challenges for future software maintainers. We review the literature on program comprehension for SOA and describe exploratory work on static and dynamic program analysis, using two prototype tools to aid in addressing these challenges. SOAMiner is a static search tool to extract information from XML‐structured SOA files such as Web Services Description Language, XML Schema Definition Language, and Business Process Execution Language. Feature sequence viewer is a dynamic message trace analysis tool that extracts a sequence diagram highlighting the path of messages involved in processing a particular Web service request. Several case studies were conducted involving both static and dynamic analysis. Use of these tools has helped to clarify what SOA maintainers will need to know and how software tools might help them. Results revealed various types of static and dynamic information that can be useful to maintainers of SOA composite applications. Copyright © 2011 John Wiley & Sons, Ltd.

Memory Trace Compression and Replay for SPMD Systems Using Extended PRSDs

Concurrency levels in large-scale supercomputers are rising exponentially, and shared-memory nodes with hundreds of cores and non-uniform memory access latencies are expected within the next decade. However, even current petascale systems with tens of cores per node suffer from memory bottlenecks. As core counts increase, memory issues will become critical for the performance of large-scale supercomputers. Trace analysis tools are thus vital for diagnosing the root causes of memory problems. However, existing memory tracing tools are expensive due to prohibitively large trace sizes, or they collect only statistical summaries and omit potentially valuable information. In this paper, we present ScalaMemTrace, a novel technique for collecting memory traces in a scalable manner. ScalaMemTrace builds on prior trace methods with aggressive compression techniques to allow lossless representation of memory traces for dense algebraic kernels, with near-constant trace size irrespective of the problem size or the number of threads. We further introduce a replay mechanism for ScalaMemTrace traces, and discuss the results of our prototype implementation on the x86_64 architecture.

Memory Trace Compression and Replay for SPMD Systems using Extended PRSDs?

Concurrency levels in large-scale supercomputers are rising exponentially, and shared-memory nodes with hundreds of cores and non-uniform memory access latencies are expected within the next decade. However, even current petascale systems with tens of cores per node suffer from memory bottlenecks. As core counts increase, memory issues become critical for the performance of large-scale supercomputers. Trace analysis tools are vital for diagnosing the root causes of memory problems. However, existing tools are expensive due to prohibitively large trace sizes, or they collect only statistical summaries that omit valuable information. In this paper, we present ScalaMemTrace, a novel technique for collecting memory traces in a scalable manner. ScalaMemTrace builds on prior trace methods with aggressive compression techniques to allow lossless representation of memory traces for dense algebraic kernels, with nearconstant trace size irrespective of the problem size or the number of threads. We further introduce a replay mechanism for ScalaMemTrace traces, and discuss the results of our prototype implementation on the x86 64 architecture.

Liquid-phase microextraction as an attractive tool for multielement trace analysis in combination with X-ray fluorescence spectrometry: an example of simultaneous determination of Fe, Co, Zn, Ga, Se and Pb in water samples

In recent years, liquid-phase microextraction (LPME) has become one of the most valuable techniques for the preconcentration and separation of trace and ultratrace elements. LPME can be combined with an atomic technique which requires only a few microlitres of liquid to perform a measurement, e.g. electrothermal atomic absorption spectrometry. In this study, combining LPME with X-ray fluorescence spectrometry (XRF), a dried-spot technique is proposed. Since the X-ray beam can be focused on a small spot size and simultaneously LPME produces a very small drop of a volume ranging from 2 to 30 μL, the combination of these two techniques is a very promising tool for multielement trace and ultratrace analyses. The present research was performed using dispersive liquid–liquid microextraction (DLLME) with APDC as a chelating agent. Nevertheless, any LPME technique, e.g. single-drop microextraction (SDME), can be applied in combination with XRF. Because XRF measurement follows the microextraction, deposition and drying of the small drop, the influence of the diameter of the dried residue on the intensity of fluorescent radiation is discussed in detail. Pipetting and spray-on techniques are proposed for the deposition of the small drop onto the substrate (membrane filter or Mylar foil). Under the optimized conditions, the detection limits were 2.8, 1.6, 2.5, 1.7, 2.1 and 4.1 ng mL−1 for Fe, Co, Zn, Ga, Se and Pb, respectively, with a preconcentration factor of 250 for 5 mL of the water sample.

Sensitivity enhancement of fluorescence detection in CE by coupling and conducting excitation light with tapered optical fiber

This paper reports the enhancement of sensitivity of detection for in-column fiber optic-induced fluorescence detection system in CE by tapered optical fiber (TOF). Two types of optical fiber, TOF and conventional cylindrical optical fiber (COF), were employed to construct the CE (TOF-CE and COF-CE) and were compared for sensitivity to riboflavin (RF). The fluorescence intensities from a RF sample with excitation light sources and fibers at various coupling angles were investigated. The fluorescence signal from TOF-CE was ca. ten times that of COF-CE. In addition, the detection performance of four excitation light source-fiber configurations including Laser-TOF, Laser-COF, LED-TOF, and LED-COF were compared. The LODs for RF were 0.21, 0.82, 0.80, and 7.5 nM, respectively, for the four excitation light source-fiber configurations. The results demonstrate that the sensitivity obtained by LED-TOF is close to that of Laser-COF. Both Laser-TOF and LED-TOF can greatly improve the sensitivity of detection in CE. TOF has the major attribute of collecting and focusing the excitation light intensity. Thus, the sensitivity obtained by LED-TOF without focusing lens is just same as that of LED-COF with a focusing lens. This demonstrates that the CE system can be further simplified by eliminating the focusing lens for excitation light. LED-TOF-CE and LED-COF-CE system were applied to the separation and determination of RF in real sample (green tea), respectively. The tapered fiber optic-induced fluorescence detection system in CE is an ideal tool for trace analysis.

A metamodel for the compact but lossless exchange of execution traces

Understanding the behavioural aspects of a software system can be made easier if efficient tool support is provided. Lately, there has been an increase in the number of tools for analysing execution traces. These tools, however, have different formats for representing execution traces, which hinders interoperability and limits reuse and sharing of data. To allow for better synergies among trace analysis tools, it would be beneficial to develop a standard format for exchanging traces. In this paper, we present a graph-based format, called compact trace format (CTF), which we hope will lead the way towards such a standard. CTF can model traces generated from a variety of programming languages, including both object-oriented and procedural ones. CTF is built with scalability in mind to overcome the vast size of most interesting traces. Indeed, the design of CTF is based on the idea that call trees can be transformed into more compact ordered acyclic directed graphs by representing similar subtrees only once. CTF is also supported by our trace analysis tool SEAT (Software Exploration and Analysis Tool).

Targeted three-dimensional liquid chromatography: A versatile tool for quantitative trace analysis in complex matrices

Targeted multidimensional liquid chromatography (MDLC), commonly referred to as ‘coupled-column’ or ‘heartcutting’, has been used extensively since the 1970s for analysis of low concentration constituents in complex biological and environmental samples. A primary benefit of adding additional dimensions of separation to conventional HPLC separations is that the additional resolving power provided by the added dimensions can greatly simplify method development for complex samples. Despite the long history of targeted MDLC, nearly all published reports involve two-dimensional methods, and very few have explored the benefits of adding a third dimension of separation. In this work we capitalize on recent advances in reversed-phase HPLC to construct a three-dimensional HPLC system for targeted analysis built on three very different reversed-phase columns. Using statistical peak overlap theory and one of the most recent models of reversed-phase selectivity we use simulations to show the potential benefit of adding a third dimension to a MDLC system. We then demonstrate this advantage experimentally by developing targeted methods for the analysis of a variety of broadly relevant molecules in different sample matrices including urban wastewater treatment effluent, human urine, and river water. We find in each case that excellent separations of the target compounds from the sample matrix are obtained using one set of very similar separation conditions for all of the target compound/sample matrix combinations, thereby significantly reducing the normally tedious method development process. A rigorous quantitative comparison of this approach to conventional 1DLC–MS/MS also shows that targeted 3DLC with UV detection is quantitatively accurate for the target compounds studied, with method detection limits in the low parts-per-trillion range of concentrations. We believe this work represents a first step toward the development of a targeted 3D analysis system that will be more effective than previous 2D separations as a tool for the rapid development of robust methods for quantitation of low concentration constituents in complex mixtures.

Adsorptive micro-extraction techniques—Novel analytical tools for trace levels of polar solutes in aqueous media

A novel enrichment technique, adsorptive μ-extraction (AμE), is proposed for trace analysis of polar solutes in aqueous media. The preparation, stability tests and development of the analytical devices using two geometrical configurations, i.e. bar adsorptive μ-extraction (BAμE) and multi-spheres adsorptive μ-extraction (MSAμE) is fully discussed. From the several sorbent materials tested, activated carbons and polystyrene divinylbenzene phases demonstrated the best stability, robustness and to be the most suitable for analytical purposes. The application of both BAμE and MSAμE devices proved remarkable performance for the determination of trace levels of polar solutes and metabolites ( e.g. pesticides, disinfection by-products, drugs of abuse and pharmaceuticals) in water matrices and biological fluids. By comparing AμE techniques with stir bar sorptive extraction based on polydimethylsiloxane phase, great effectiveness is attained overcoming the limitations of the latter enrichment approach regarding the more polar solutes. Furthermore, convenient sensitivity and selectivity is reached through AμE techniques, since the great advantage of this new analytical technology is the possibility to choose the most suitable sorbent to each particular type of application. The enrichment techniques proposed are cost-effective, easy to prepare and work-up, demonstrating robustness and to be a remarkable analytical tool for trace analysis of priority solutes in areas of recognized importance such as environment, forensic and other related life sciences.

An exchange format for representing dynamic information generated from High Performance Computing applications

High Performance Computing (HPC) systems tend to be complex to debug and analyze due to the large number of processes they involve and the way they communicate with each other to perform specific tasks. Recently, there has been an increase in the number of tools to help software engineers analyze the behavior of HPC applications. These tools provide several features that facilitate the understanding and analysis of the information contained in inter-process communication traces generated from running an HPC application. They, however, use different formats to represent traces, which hinders interoperability and sharing of data. In this paper, we address this by proposing an exchange format called MTF (MPI Trace Format) for representing and exchanging traces generated from HPC applications based on the MPI (Message Passing Interface) standard, which is a de facto standard for inter-process communication for high performance computing systems. The design of MTF is validated against well-known requirements for a standard exchange format, with an objective being to lead the work towards standardizing the way MPI traces are represented in order to allow better synergy among tools. We have also developed an MTF toolkit that supports the generation of MTF traces equipped with a query engine to facilitate the retrieval of data from MTF traces. Finally, we show how MTF can carry a large trace generated using a commercial off the shelf MPI trace analysis tool.

Laser Processing of Novel Functional Materials

Laser processing and laser ablation are the subject of fascinating fundamental studies and are used in various industrial processes. The applications of laser ablation range from microstructuring of nearly all materials, to the production of thin crystalline films with special properties, and micro-spectroscopy. Our projects in the field of laser ablation encompass both applied and fundamental research. In detail, we are working on the design and structuring of novel photopolymers for laser applications, on the development of advanced methods for the microstructuring of glassy carbon, and the pulsed laser deposition of perovskite films used in electrocatalysis. Additionally, emission or plasma spectroscopy is used to study the pulsed laser deposition process, and as tool for trace analysis of heterogeneous samples.

Feature interaction detection: a LOTOS-based approach

A methodology to detect feature interactions in the design of telephone systems is presented. First, the system with its features is specified in language of temporal ordering specification (LOTOS). With the use of tools, the specification is then expanded into a state transition model, representing either the entire global state space or significant portions of it. Properties describe proper system and feature behavior; violations to these properties are symptoms of feature interaction. Observers, watchdogs, and trace analysis tools are constructed to check for deviations from these properties. These processes are used to search the state transitions, both during and after the construction of the state transition model. Traces presenting violation of properties are printed as message sequence charts (MSCs).

Analysis, Prediction, Template Toolkit (APTT) for object-based computation

The Analysis, Prediction, Template Toolkit (APTT) is an integrated set of visualisation tools aimed at the design of continuous-flow, multi-algorithm embedded applications in the multimedia, signal-processing domain. APTT is constrained by a pipelined design pattern, with each stage of the pipeline capable of supporting internal parallelism. APTT includes three tools. The graphical simulation tool predicts pipeline metrics: memory, interconnect bandwidth; throughput; and latency (both mean and maxima); before parallel partitioning is carried out. A post-mortem trace analysis tool with the same format as the predictor tool enables performance of parallelised applications to be checked and optimised. A semi-manual code generator tool has been designed to support APTT templates, a means of rapidly prototyping processing pipelines. The results for performance prediction with the predictor tool on a machine-vision application are compared with actual execution times for a realistic application, and show a prediction accuracy within 10%. The worked example also includes details of a form of high-level codesign whereby cross-architectural comparisons of performance can be made. The paper discusses a template for an actor software object, a semi-dynamic structure with object-loading and reflection based around Java Remote Method Invocation (RMI).

Acoustically levitated droplets — a new tool for micro and trace analysis

First experiences with the technique of acoustical levitation of droplets in the field of analytical and atmospheric chemistry are reported. Acoustical levitation enables the contactless handling of solid and liquid microsamples. This avoids adsorption of analyte at and desorption of contaminants from container walls especially for liquid samples. Common experiments of sample preparation procedures were conducted in levitated drops like liquid/liquid extractions, solvent exchange, and analyte enrichment by evaporation of the solvent. A first approach was made to use acoustical levitation for the simulation of atmospheric chemistry situations.

Trace analysis of microcontaminations in compliance with ISO 9001: monitoring and diagnostics in large-scale silicon manufacturing

Severing principles are reported concerning the certification of and quality assurance in a trace-analysis laboratory that handles a large number of real samples, about 60 000 analyses/year with 50 validated methods. ISO 9001 emphasizes monitoring rather than diagnostics. For monitoring purposes the trace-analysis methods must be highly selective and of high precision, with high throughput and uptime within a justifiable economic framework in the analytical range of interest. All trace-analysis methods must be cross-checked using independent analytical tools. The analytical laboratory must be fully integrated in the total quality management of the plant. The analyst must know not only the performance of the trace-analysis tools but also the materials and processes involved in manufacturing.

An automatic trace analysis tool generator for Estelle specifications

This paper describes the development of Tango, an automatic generator of backtracking trace analysis tools for single-process specifications written in the formal description language, Estelle. A tool generated by Tango automatically checks the validity of any execution trace against the given specification, and supports a number of checking options. The approach taken was to modify an Estelle-to-C++ compiler. Discussion about nondeterministic specifications, multiple observation points, and on-line trace analysis follow. Trace analyzers for the protocols LAPD and TP0 have been tested and performance results are evaluated. Issues in the analysis of partial traces are also discussed.

On-line coupling of atomic spectrometry and ion chromatography with time resolved registration as a new tool for ultra trace analysis in refractory metals

On-line coupling of atomic spectrometry and ion chromatography with time resolved registration as a new tool for ultra trace analysis in refractory metals

On-line coupling of atomic spectrometry and ion chromatography with time resolved registration as a new tool for ultra trace analysis in refractory metals

On-line coupling of Inductively Coupled Plasma-Atomic Emission Spectrometry (ICP-AES) and Ion Chromatography (IC) offers unique features for ultra trace analysis. With an on-line preconcentration procedure based on cation exchange, sub-ng/g analysis is possible in complex matrices like molybdenum and tungsten. Results match with isotope dilution mass spectrometry (IDMS) and are comparable with glow discharge mass spectrometry (GDMS). The optimal dissolution reagent for these matrices is hydrogen peroxide whose clean up to ultra high purity is possible with metal-free chromatographic equipment. All elements with cationic chemistry can be preconcentrated in acidic peroxide solutions. In this study 21 elements are measured which are detrimental for microelectronic applications. The absolute detection limits of the IC-ICP combination, with time resolved registration, are at the lower ng-level. The reproducibility is not significantly lowered by the coupling, but a ten-fold sensitivity enhancement is observed in comparison to chemically similar off-line trace-matrix-separations. Other features are simultaneous matrix corrections, use of monitors lines for method enhancement, error recognition and correction using time resolved measurement and simple calibration of the method with aqueous standards.

Determination of Low Concentrations of the Azo-Dye Complex of Nitrite in Fresh Water and Seawater Using Surface-Enhanced Resonance Raman Spectroscopy (SERRS)

A highly sensitive and selective method for the determination of low concentrations of nitrite in aqueous solutions using surface-enhanced resonance Raman spectroscopy (SERRS) is presented. The SERRS-active substrate was silver hydrosol. In order to induce the SERRS effect, nitrite was transformed into a colored product (an azo dye) by a standard chemical reaction. The detection limit for nitrite is 0.02 nM in distilled water, and analytical calibration curves yield straight lines in the concentration range below 30 nM. The sensitivity of this method is better than that of colorimetry and other techniques such as chemiluminescence. This improvement indicates that SERRS shows great promise as a useful analytical tool for trace analysis of nitrite and dyes.

Negative ion chemical ionization/high-resolution gas chromatography - a powerful tool for airborne trace analysis

The determination of compounds with mutagenic or carcinogenic properties using high resolution gas chromatography (HRGC) combined with mass spectrometric detection is often disturbed by major compound classes in the air samples such as hydrocarbons and aliphatic substituted benzenes. Negative chemical ionization (NICI) improves the selectivity for compounds with biological activities (e.g. different groups of polyaromatic hydrocarbons (PAH) and halogenated hydrocarbons). Using OH −-ions or thermal electrons additional information is obtained for the safe identification of isomeric PAH, NO 2-PAH, aza-arenes and quinones down to the 100 pg level.