Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air: Part 1: Sorbent-based air monitoring options

Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Target compounds range in volatility from acetylene and freons to phthalates and PCBs and include apolar, polar and reactive species. Airborne vapour concentrations will vary depending on the nature of the location, nearby pollution sources, weather conditions, etc. Levels can range from low percent concentrations in stack and vent emissions to low part per trillion (ppt) levels in ultra-clean outdoor locations. Hundreds, even thousands of different compounds may be present in any given atmosphere. GC is commonly used in combination with mass spectrometry (MS) detection especially for environmental monitoring or for screening uncharacterised workplace atmospheres. Given the complexity and variability of organic vapours in air, no one sampling approach suits every monitoring scenario. A variety of different sampling strategies and sorbent media have been developed to address specific applications. Key sorbent-based examples include: active (pumped) sampling onto tubes packed with one or more sorbents held at ambient temperature; diffusive (passive) sampling onto sorbent tubes/cartridges; on-line sampling of air/gas streams into cooled sorbent traps; and transfer of air samples from containers (canisters, Tedlar^® bags, etc.) into cooled sorbent focusing traps. Whichever sampling approach is selected, subsequent analysis almost always involves either solvent extraction or thermal desorption (TD) prior to GC(/MS) analysis. The overall performance of the air monitoring method will depend heavily on appropriate selection of key sampling and analytical parameters. This comprehensive review of air monitoring using sorbent tubes/traps is divided into 2 parts. (1) Sorbent-based air sampling option. (2) Sorbent selection and other aspects of optimizing sorbent-based air monitoring methods. The paper presents current state-of-the-art and recent developments in relevant areas such as sorbent research, sampler design, enhanced approaches to analytical quality assurance and on-tube derivatisation.     

Chemometrics-Based Process Analytical Technology (PAT) Tools: Applications and Adaptation in Pharmaceutical and Biopharmaceutical Industries

Process analytical technology (PAT) is used to monitor and control critical process parameters in raw materials and in-process products to maintain the critical quality attributes and build quality into the product. Process analytical technology can be successfully implemented in pharmaceutical and biopharmaceutical industries not only to impart quality into the products but also to prevent out-of-specifications and improve the productivity. PAT implementation eliminates the drawbacks of traditional methods which involves excessive sampling and facilitates rapid testing through direct sampling without any destruction of sample. However, to successfully adapt PAT tools into pharmaceutical and biopharmaceutical environment, thorough understanding of the process is needed along with mathematical and statistical tools to analyze large multidimensional spectral data generated by PAT tools. Chemometrics is a chemical discipline which incorporates both statistical and mathematical methods to obtain and analyze relevant information from PAT spectral tools. Applications of commonly used PAT tools in combination with appropriate chemometric method along with their advantages and working principle are discussed. Finally, systematic application of PAT tools in biopharmaceutical environment to control critical process parameters for achieving product quality is diagrammatically represented.     

Portable capillary LC for in-line UV monitoring and MS detection: Comparable sensitivity and much lower solvent consumption

Pharmaceutical development currently relies on quality separation methods from early discovery through to line-of-site manufacturing. There have been significant advancements made regarding the column particle packing, internal diameter, length connectivity, the understanding of the impact key parameters like void volume, flow rate, and temperature all that affects the resultant separation quality, that is, resolution, peak shape, peak width, run time, and signal-to-noise ratio. There is however a strong need to establish better alternatives to large bulky high-performance liquid chromatography racks either for process analytical reaction monitoring or mass spectrometry analysis in establishing product quality. Compact, portable high-pressure liquid chromatography can be a more efficient alternative to traditional ultra-high pressure liquid chromatography and traditional liquid chromatography. The compact versatile instrument evaluated here allows good separation control with either the on-board column with fixed ultra-violet wavelength cartridge or for use with a high-resolution mass spectrometry. Significant space reduction results in greener lab spaces with improved energy efficiency for smaller labs with lower energy demands. In addition, this compact liquid chromatography was used as a portable reaction monitoring solution to compare forced degradation kinetics and assess portable liquid chromatography-mass spectrometry capability for the analyses required for pharmaceutical drug product testing.     

Estimation of exposure levels by measurements and models

Summary Results from environmental and biological monitoring programs are abundant, but it is a question to what extent such data can be used for exposure assessments. The quality of such data depends not only on sampling and analytical errors, but also, and probably more, on the sampling strategy used. Therefore, uncritically use of such results can be biased and associated with large variations. The size of bias between two studies carried out in the same industry was found to be a factor of 5–7. Samples that are not representative of the exposed population studied are misleading. An estimation of exposure to cobalt in the porcelain industry illustrates the distinction between biological measurement data and air cobalt measurement data done on selected individuals. Following improvement of the working environment during the period 1983–1990, the change of cobalt concentration in urine indicates a reduction of cobalt exposure with a factor of 10, but air monitoring data do not verify that figure. Furthermore, results must always be interpreted with caution, when used beyond the purpose for what they were originally made. Great care should be taken to secure that data are representative and a quality assurance-quality control program should be used to ensure data quality.     

Application of quality by design to the development of analytical separation methods

Recent pharmaceutical regulatory documents have stressed the critical importance of applying quality by design (QbD) principles for in-depth process understanding to ensure that product quality is built in by design. This article outlines the application of QbD concepts to the development of analytical separation methods, for example chromatography and capillary electrophoresis. QbD tools, for example risk assessment and design of experiments, enable enhanced quality to be integrated into the analytical method, enabling earlier understanding and identification of variables affecting method performance. A QbD guide is described, from identification of quality target product profile to definition of control strategy, emphasizing the main differences from the traditional quality by testing (QbT) approach. The different ways several authors have treated single QbD steps of method development are reviewed and compared. In a final section on outlook, attention is focused on general issues which have arisen from the surveyed literature, and on the need to change the researcher’s mindset from the QbT to QbD approach as an important analytical trend for the near future.

New challenges in environmental analytical chemistry: Identification of toxic compounds in complex mixtures

Toxic effects evidenced in the environment are most often caused by mixtures of known and unknown pollutants. One of the key challenges in environmental chemistry and ecotoxicology is to characterize and identify those toxicants in relation with the effect. However, many of the current bottlenecks in the assessment of organic contaminants in our environment are related to the difficulty of evaluating various chemical classes and biological effects within complex mixtures and more precisely to link both approaches. To tackle these analytical challenges, the bioanalytical concept has emerged during the last decade. In this article, we describe through some outstanding examples the current limitations in the chemical-driven approach such as problems encountered for a correct evaluation of water quality when the continuous introduction of new chemicals has to be taken into account in monitoring for correct evaluation of this quality and could led to tremendous analytical costs or some of the integrated bioanalytical approaches as promising powerful tools to improve environmental risk assessment by taking into account the link presence/effect.     

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. Received: 19 October 1995 Accepted: 15 November 1995     

Toxicity assays applied to wastewater treatment

The utility and validity of toxicity tests for monitoring of wastewater treatment have been assessed. The evaluated acute toxicity tests have been Vibrio fischeri, Selenastrum capricornotum and Daphnia magna tests. The validation studies indicated that the acute toxicity tests can be considered as high sensitivity analytical tools to detect common environmental concentrations of the pollutants at concentration levels as low as ng l⁻¹. The toxicity tests showed to have discriminatory ability to distinguish between different degrees of toxicity, and the toxic specificity of the compounds on target organisms. Synergistic, additive or antagonistic effects were evaluated indicating the capacity of the toxicity test to assess the combined effects of chemicals in wastewaters. The reproducibility of these tests, calculated as relative standard deviation, is acceptable in the range of 5-22.3%. The application of multivariate date analysis proved that toxicity and chemical measures are complementary analytical tools for monitoring of wastewaters quality. The toxicity tests are useful analytical tools for screening of chemical analysis and as an early warning system to monitor the treatment of WWTPs. The use of single toxicity test or battery of tests is the best approach to evaluate the risk because they are reliable indices of the toxic impact of effluents in the aquatic environment. The toxicity tests were applied in the quality control of different European WWTPs.     

Sorbent-based sampling methods for volatile and semi-volatile organic compounds in air. Part 2. Sorbent selection and other aspects of optimizing air monitoring methods

Sorbent tubes/traps are widely used in combination with gas chromatographic (GC) analytical methods to monitor the vapour-phase fraction of organic compounds in air. Applications range from atmospheric research and ambient air monitoring (indoor and outdoor) to occupational hygiene (personal exposure assessment) and measuring chemical emission levels. Part 1 of this paper reviewed the main sorbent-based air sampling strategies including active (pumped) tube monitoring, diffusive (passive) sampling onto sorbent tubes/cartridges plus sorbent trapping/focusing of whole air samples that are either collected in containers (such as canisters or bags) or monitored online. Options for subsequent extraction and transfer to GC(MS) analysis were also summarised and the trend to thermal desorption (TD)-based methods and away from solvent extraction was explained. As a result of this trend, demand for TD-compatible sorbents (alternatives to traditional charcoal) is growing. Part 2 of this paper therefore continues with a summary of TD-compatible sorbents, their respective advantages and limitations and considerations for sorbent selection. Other analytical considerations for optimizing sorbent-based air monitoring methods are also discussed together with recent technical developments and sampling accessories which have extended the application range of sorbent trapping technology generally.     

Need and use of reference materials in a comprehensive countrywide monitoring of radionuclides

The reliability of measurement results is essential for forming a common database of a laboratory network, because a well-maintained and consistent database is the crucial point of countrywide monitoring. Reference materials are important tools in realizing some aspects of quality assurance; they are especially useful in harmonizing work within the network. Among usual types of reference materials in radio analytics solutions, matrix reference materials and some special reference objects are used. All classes of reference materials should be used depending on the purpose of the demonstration of quality, even in-house reference materials. Interlaboratory measurement comparison and performance evaluation programs play important quality assurance role in radio analytical laboratories. Fortunately, nowadays, the main task is to determine a very low radioactivity concentration in the environment; therefore, pre-concentration is necessary. Generally, the radionuclide bearing natural materials collected from sites where there had been sufficient time for natural processes to redistribute various chemically different species of radionuclides are more reliable reference materials than spiked materials—the main difference is the chemical bounding which is crucial from the point of view of the bioavailability. The need of reference material is summarized according to the intended use, like quality control, measurement validation, and instrument calibration.     

Quality criteria for residue analysis and reference materials. Relationship between legal procedures and materials

Summary For qualitative results objective reliability checks are often not present at all or applicable. Interlaboratory ring testing of methods, as sometimes required, showed often not to be applicable simply because enough adequate laboratories are not available. For instance this situation applied to the large number of methods of unclear reliability status, to be used for residue monitoring of hormonal growth promotors (anabolic agents), which are completely banned within the European Communities since January 1988. This impasse was circumvented in 1987 with the formulation by an international group of analytical experts of a set of quality criteria for common analytical techniques like TLC, GC and HPLC (separation), UV, MS and IR spectrometry (detection) and immunoassays (separation and detection). These criteria, now published, are overviewed, as well as the availability of the control and reference materials belonging to them for actual analytical quality control and for validation of laboratories. Although developed for anabolic agents this new approach is applicable in practice for nearly all organic analytes and since very recently also for heavy metals. This approach has clear consequences for the mandatory quality of legislative residue analyses of food stuffs. As based on, amongst others, the combined experience of regulatory residue chemists within the EC, a collection of experimental selectivity indices is presented to rank the required specificity of regulatory residue methods (ranging from within laboratory orientation to international forensic purposes) in an objective way. Finally an estimate is summarized of the financial consequences of the applicable analytical techniques.     

Analytical tools for monitoring changes in physical and chemical properties of chromatography resin upon reuse

Protein A resins are often reused for multiple cycles to improve process economy during mAb purification. Significant reduction in binding capacity and product recovery are typically observed due to the presence of unwanted materials (foulants) deposited on the resin upon reuse. In this paper, we have used a wide spectrum of qualitative and quantitative analytical tools (particle size analysis, HPLC, fluorescence, SEM, MS, and FTIR) to compare the strengths and shortcomings of different analytical tools in terms of their capability to detect the fouling of the resin and relate it to chromatographic cycle performance. While each tool offers an insight into this complex phenomena, fluorescence is the only one that can be used for real‐time monitoring of resin fouling. A correlation could be established between fluorescence intensity and the process performance attributes (like yield or binding capacity) impacted upon resin reuse. This demonstration of the application of fluorescence for real‐time monitoring correlated empirically with process performance attributes and the results support its use as a PAT tool as part of a process control strategy. While the focus of this paper is on fouling of protein A chromatography resin, the approach and strategy are pertinent to other modes of chromatography as well.     

Hasse diagram technique as a tool for water quality assessment

The management of the quality large water catchments is a complex problem which requires intelligent data analysis on various levels – analytical, spatial, and temporal. Recently, a successful approach is developed combining advanced multivariate data treatment approaches like self-organizing maps of Kohonen (SOM) and Hasse diagram technique (HDT). In the first step of the environmetric analysis the monitoring data were subject to pre-processing using SOMs to reduce the number of objects and/or water quality parameters. In the next step HDT for partial ranking (both in spatial and temporal aspect) was applied according to the pre-selected set of the water quality parameters. The use of the water quality norms issued by the Bulgarian environmental authorities revealed important details in assessing the Maritsa River water quality. Thus, the relations between different water quality patterns and sampling stations could be used by water management authorities during the period of observation.     

Advanced Methodologies for Sampling and Analysis of Toxic Organic Chemicals in Ambient Outdoor,Indoor, and Personal Respiratory Air

Many different kinds of sampling devices and analytical techniques are required to assess the potential adverse effects of toxic air pollutants on human health and the ecosystem. The U.S. Environmental Protection Agency has an on-going research and development program designed to provide the necessary tools to monitor air quality both outdoors and indoors and to measure personal respiratory exposures. Particular emphasis in recent years has been placed on real-time and integrative methods for neutral and polar volatile organic chemicals (e.g., chlorinated hydrocarbons, single-ring aromatics, alcohols, aldehydes, ethers, thiols, nitriles) and semi-volatile organics (e.g., polynuclear aromatics, nitrated aromatics, pesticides, phenols). Samplers capable of obtaining sufficient quantities of chemicals for ultratrace analyses and sometimes bioassay, that are also quiet, unobtrusive and user-friendly, are being developed and evaluated for indoor, outdoor, and personal monitoring. New analytical techniques such as matrix-isolation GC/FTIR, and supercritical fluid extraction and chromatography are being adapted to characterize collected samples.     

Analysis in workplace surveillance

The protection of the health against effects of chemical substances which are taken up at the workplace is controlled in Germany by the Gefahrstoffverordnung (Hazardous Substances Ordinance). The protection is based on the adherence to threshold limit values for the concentration of the toxic substance in the air or in body fluids of the human being. The adherence to the Maximum Concentrations at the Workplace (MAK) and the Technical Exposure Limits (TRK) for carcinogenic substances in the air of workplaces is achieved by the continuous measurement of the toxic substance in the air at the workplaces (ambient monitoring). The continuous monitoring of chemical substances and their metabolic products in blood and urine (biological monitoring) guarantees that the Biological Tolerance Values for Working Materials (BAT) and the Exposure Equivalents for Carcinogenic Working Materials (EKA) are adhered to. Ambient monitoring and biological monitoring complement each other with regard to the desired health protection of the individual. The possibilities of modern instrumental analysis guarantee today that practically all toxic substances in the air can be quantitatively determined. As intercomparison programmes show, a lot more could be done concerning the analytical reliability of air analyses. The introduction of laboratory-internal and -external quality control in the laboratory analysing air therefore seems to be of urgent necessity. The accrediting of laboratories and the use of reliable analysis procedures alone is not sufficient to guarantee the analytical reliability of the results. By means of biological monitoring today very many toxic substances in blood and urine can be routinely determined. An effective quality control prescribed by the Hazardous Substances Ordinance allows reliable analysis results up to the ppt-range. Certain groups of substances, such as e.g. many pesticides, are today still beyond the possibilities of biological monitoring. Increasingly methods are being developed which enable the influence of toxic substances on the human body to be quantified. The adducts of carcinogenic working materials at the germ plasm (DNA) or at the haemoglobin open up new perspectives.Awarded poster prize     

Proper use of certified reference materials?

Certified reference materials (CRMs) are important quality assurance tools in the laboratory. It is, however, not certain they are always used properly. Several guidelines are available on the use of CRMs, but appear to be mostly unknown. The users thus get very little help on the way to proper use. Many of the problems with CRMs are well known, but that does not mean they have disappeared. Better use of CRMs will require the involvement of producers and analytical societies, e.g. the AOAC. Editors of international analytical journals could have a great influence on how CRM results and other QA data are treated in publications.     

Analytical issues in monitoring drinking-water contamination related to short-term, heavy rainfall events

Heavy rainfall events, increasing in frequency and intensity with climate change, impact on the quality of the water resource used for drinking-water production. Small-scale water suppliers are particularly sensitive because of their management and the related difficulties of adapting treatment to variations. Decision-support systems, based on monitoring and analytical tools, need to be developed to improve crisis-management procedures related to such events. After presenting the issues related to heavy rainfall events, the article summarizes the tools currently used for quality control of drinking water within this framework, the need for developments and other requirements.     

Quantitative and qualitative determination of LiuweiDihuang preparations by ultra high performance liquid chromatography in dual‐wavelength fingerprinting mode and random forest

The classical traditional Chinese formulation LiuweiDihuang, shown to have clinical efficacy for “nourishing kidney‐yin” in traditional Chinese medicine, has been used for thousands of years in China. Little attention, however, has been paid to quality control methods for this formulation. Hence, a rapid and sensitive analytical technique is urgently needed for the evaluation of LiuweiDihuang preparations to assess its quality and pharmacological functionality. In this study, an ultra high performance liquid chromatography dual‐wavelength method was developed to simultaneously determine 11 constituents in LiuweiDihuang preparations. This robust approach provided a fast and comprehensive quantitative determination of the major bioactive markers within LiuweiDihuang preparations. To distinguish four dosage forms of LiuweiDihuang preparations, a random forest technique was applied on the spectrometric fingerprint data obtained. This combination approach of chromatographic techniques and data analyses might serve as a rapid and efficient tool to ensure the quality of LiuweiDihuang preparations and other Chinese medicinal formulations and can support quality control and scientific research into the pharmacological potential for these formulations.     

化妆品样品前处理与检测技术研究进展

随着我国经济和人民生活水平的不断提高,作为日常消费品的化妆品产业发展迅猛,其安全性日益受到广泛关注。随之而来的化妆品检测量的大幅增长对检测技术提出了更高的要求。传统样品前处理和检测技术因有机试剂消耗量大,检测通量低、检测周期长已无法满足当前绿色化学发展和高通量检测的需求。对此,科研人员开发了一系列环境友好型前处理技术以及高通量现场快速检测方法,为化妆品质量安全保驾护航。该文综述了当前化妆品样品前处理及检测技术的研究进展,并展望了其发展趋势和应用前景,以期为从事化妆品检测的科研和检验人员提供技术参考。