Development of an analytical method for monitoring worker populations exposed to platinum-group elements

The increasing industrial use of platinum-group elements (PGEs), namely Ir, Pd, Pt and Rh, and related allergies such as rhinitis, conjunctivitis, asthma, urticaria and contact dermatitis, have led to a growing need to monitor selected populations of exposed workers. In this study, the levels of PGEs were measured in indoor airborne particulate matter and in biological samples taken from employees of a plant where car catalytic converters are produced and precious metals are recovered from spent carbon catalysts. The development of an analytical procedure based on quadrupole inductively coupled plasma mass spectrometry (Q-ICP-MS) for the analysis of PGEs in airborne particulate matter and on sector field inductively coupled plasma mass spectrometry (SF-ICP-MS) for the analysis of PGEs in blood, serum, urine and hair is described. For airborne particulate matter deposited on filters, the limits of detection (LoDs) were found to be 0.006 ng m⁻³, 0.020 ng m⁻³, 0.018 ng m⁻³ and 0.006 ng m⁻³ for Ir, Pd, Pt and Rh, respectively. Repeatability of measurements ranged from 1.8 to 8.5%, while recovery was in the range from 92 to 102%. For biological samples LoDs in blood, serum, urine and hair ranged from (in ng l⁻¹) 0.2–0.6 for Ir, 5–10 for Pd, 1–3 for Pt and 2–3 for Rh. For all biological materials, the repeatability varied from 1.1 to 12% for the four elements. Recovery data for the determination of PGEs in biological matrices were found to range from 84.0 to 107.8%. The method was applied to the determination of either total or respirable airborne PGEs collected from five different work areas in the plant. The difference between areas with high and low exposure correlates closely with metal levels in hair, blood and urine. The correlation coefficients between Pt in airborne particulate matter and Pt in biological materials was 0.994, 0.991 and 0.970 for blood, hair and urine, respectively.     

Differential spectrophotometric determination of micro amounts of metal ions in mixtures

A differential spectrophotometric method is described for the simultaneous determinations of iron and molybdenum, iron and titanium, iron and uranium, molybdenum and titanium, and molybdenum and uranium in mixtures, in a single solution at room temperature. The general method consists in treating the mixture with 5 ml of 1 M sodium acetate and 1 ml of 1% pyrocatechol in 25-ml volumetric flasks. The optical density of color of mixed complexes is determined at the corresponding pair of wavelengths suggested. From the optical density and molar extinction coefficient, the concentration of each ion in mixtures has been calculated. By this procedure, the metal ions can be determined even if they differ by large ratios. Procedures have been extended for the analysis of mixtures containing iron, molybdenum, and titanium (or uranium). These procedures can be applied for the analysis of any type of materials, like minerals, rocks, ores, alloys, steels and refractory materials. Spectra of each complex and their Beer's law were studied in detail. Experiments were also made to show that the calculated and observed optical density of mixture complexes is the same, thereby the additive of optical density of mixtures at each pair of wavelengths suggested for individual determinations of ions have been verified.     

机载光通信复合轴光路优化设计和跟瞄技术研究

根据机载激光通信的环境和链路距离,采用光电粗精复合轴结构,提出一种双探测器、双光轴机载激光通信复合轴捕获跟踪瞄准系统方案.对整个系统的光路结构进行了分析和优化设计,使粗跟踪精度达120μrad,精跟踪系统带宽大于300Hz,执行动态范围达5mrad,跟踪精度达3μrad,并成功实现通信距离17.5km、通信速率1.5Gbps,误码率达1E-7的飞机对地面激光通信实验.     

关键参数快速处理单元在飞行试验中的应用

用于飞行试验的传统数据处理模式及数据处理流程,在ARJ21定型试飞时就已经受到挑战,测试参数由三代机的2000个左右激增到6000个左右,传统模式的处理时间大致是飞行时间的1.5～2倍,这种数据处理模式已经严重制约了型号的试飞效率。新一代试验机测试参数已经达到15000个左右,显然传统的数据处理模式已经无法适应。针对海量数据快速处理的需求,全球各大试飞机构及设备供应商都在探索快速处理的方法,研制快速处理的设备。本文介绍了具有自主知识产权的关键参数快速处理单元的设计思路,以及在新型号飞行试验过程中关键参数快速处理单元的应用情况。     

Review of Recent Progress in Micro-Systems for the Detection and Analysis of Airborne Microorganisms

The spread of airborne microorganisms such as measles, anthrax, and influenza is a major public health threat because it causes severe infectious diseases with high mortality rates. Robust and real-time detection systems are necessary to prevent and control such dangerous biological particles in public places and dwellings. For effective detection, the collection of aerosol particles, the separation of airborne microbes, the concentration of the samples, and the discrimination or detection of pathogens are areas that need to be addressed. Although environmental and social needs are appreciated and required systems have been considered, no complete system has yet been constructed that adequately meets these needs at a level deemed appropriate by the requisite authorities. However, given the advancement in technology outlined herein, the delivery of such a system appears imminent. In this paper, we will review recent advances in microsystem detection and analysis of airborne microorganisms, and concede that some methods were not directly applied to the airborne microbes, but may be useful in the future.     

Ionic wind generator derived from a liquid filled capillary pin. Application to particle capture

A new fluid pin-based ionic wind generator applied to airborne pathogen collection combines the processes of air flow generation by ionic wind, electrospray and electrostatic particle collection. This new concept brings a breakthrough in integration as it combines these three phenomena with a single driving force in order to perform the four functions of an airborne pathogen sampler, namely air flow production, particle capture, sample phase transfer and collecting electrode decontamination. The characterizations presented in this article led to a proof of concept and demonstrated the device's performance for a compact and portable airborne pathogen collection system.     

Novel method for determining DDT in vapour and particulate phases within contaminated indoor air in a malaria area of South Africa

The organochlorine insecticide DDT (1,1,1-trichloro-2,2-bis(p-chlorophenyl)ethane) is still used for malaria vector control in certain areas of South Africa. The strict Stockholm Convention on Persistent Organic Pollutants (POPs) allows spraying on the inside of traditional dwellings with DDT. In rural villages contaminated dust presents an additional pathway for exposure to DDT. We present a new method for the determination of DDT in indoor air where separate vapour and particulate samples are collected in a single step with a denuder configuration of a multi-channel open tubular silicone rubber (polydimethylsiloxane (PDMS)) trap combined with a micro quartz fibre filter. The multi-channel PDMS trap section of the denuder concentrates vapour phase insecticide whereas particle associated insecticide is transferred downstream where it is collected on a micro-fibre filter followed by a second multi-channel PDMS trap to capture the blow-off from the filter. The multi-channel PDMS trap and filter combination are designed to fit a commercial thermal desorber for direct introduction of samples into a GC–MS. The technique is solvent-free. Analyte extraction and sample clean-up is not required. Two fractions, vapour phase and particulate phase p,p′-DDT, o,p′-DDT; p,p′-DDD, o,p′-DDD; p,p′-DDE and o,p′-DDE in 4 L contaminated indoor air, were each quantitatively analysed by GC–MS using isotopically labelled ring substituted ¹³C₁₂ – p,p′-DDT as an internal standard. Limits of detection were 0.07–0.35 ng m⁻³ for p,p′-DDT, o,p′-DDT, p,p′-DDD, o,p′-DDD, p,p′-DDE and o,p′-DDE. Ratios of airborne p,p′-DDD/p,p′-DDT and of o,p′-DDT/p,p′-DDT are unusual and do not match the ideal certified ingredient composition required of commercial DDT. Results suggest that the DDT products used for indoor residual spraying (IRS) prior to, and during 2007, may have been compromised with regards to insecticidal efficacy, demonstrating the power of this new environmental forensics tool.     

Extraction of arsenic species from airborne particulate filters—Application to an industrial area of Greece

In the present study, the extraction of the arsenic species arsenite (As(III)), arsenate (As(V)), monomethyarsonic (MMA) and dimethylarsinic acid (DMA) from airborne particulate filters was investigated and optimized. For this purpose, total suspended particulate matter as well as size fractionated aerosol samples were collected from the industrial area of Aspropyrgos, Greece, in glass fibre and polycarbonated filters, respectively. Among H₃PO₄ and HCl, tested in various concentrations, concentrated HCl was found to be the most effective extractant for arsenic from both polycarbonated and glass fibre filters, without provoking any arsenic species transformation. However, the quantitative extraction of arsenic species from glass fibre filters required the subsequent washing of the filters with ultrapure water after their leaching with concentrated HCl. The developed procedure was applied to airborne particulate filters for arsenic speciation in Aspropyrgos' atmosphere. The results showed an enrichment of As in the fine (PM_2.5) compared with the coarse (PM_10–2.5) fraction of airborne particulates, while As(V) was found to be the predominant arsenic species in all samples. Finally, As concentration in the PM₁₀ fraction, for the investigated area and time period from December 2004 to June 2006, was below the target value of 6 ng As m^− 3, referred in the Directive 2004/107 of European Union.     

Assessment of environmental contamination risk by Pt, Rh and Pd from automobile catalyst

The main active components of present-day car catalysts are the noble metals Pt, Pd and Rh, belonging to the platinum group elements (PGEs). It is recognized that these elements are being spread into the environment to an as-yet incompletely known extent, mainly due to surface abrasion of the catalyst during car operation. These new pollutants have motivated extensive research on PGE determination. Our work is planned to ascertain the health and ecosystem risks of these PGEs emitted through a series of interrelated objectives that address the pathway of these elements from the catalyst to the different environmental compartments. Combined studies of catalyst surface abrasion and exhaust fumes analysis, the monitoring of Pt, Pd and Rh in airborne particles and road dust sediments and bioaccumulation studies in aquatic organisms, plants and urine enable a realistic assessment of the risk that this release represents for man and environment. In this work some previous results are presented.     

Impact of scene changes during data acquisition in Fourier spectroscopy

The impact of changes of the spectral radiance in a Fourier transform spectrometer's field of view (FOV) during recording time of an interferogram is examined. Particularly systematic changes, with a time constant which is in the order of the time required to record one interferogram, are of interest here. Both an analytic and a simulative approach is made to examine the impact on the measured spectrum. Airborne measurements of fire scenes are a typical example where changes of spectral radiance during data acquisition time are inevitable. In such cases, flight velocity causes the scene in the spectrometer's FOV to change continuously, and the scene elements (fire, for example) might be expected to be dynamical even by themselves.