Indoor matrices

The use of pesticides indoors can lead to very large concentrations not only of the pesticide but of the additional VOCs used as a matrix for the pesticide, which represent most (>95%) of the mass of the material as purchased. For example, Bukowski and... 

The 3-OH FAs have had great utility in the determination of LPS levels in indoor air. However, in tissues and body fluids it has been determined that 3-OH FAs are naturally present at low levels as products of mammalian metabolism (mitochondrial fatty acid p oxidation). Due to this background GC-MS/MS for 3-OH FAs is not recommended as a general marker to determine trace LPS levels in clinical samples [14]. However, in certain situations the assessment of 3-OH FAs has been successfully used, for example, in the diagnosis of chronic peridontitis [15]. There is great potential for the utility of 3-OH FAs as markers for LPS contamination in pharmaceutical products, where often the background matrix would be anticipated to be much less complex. 

There are also a number of approaches taken to sampling indoor dust. It is important to emphasise that the matrix under study is settled dust for which the exposure pathway is ingestion (usually accidental, but for a small number of individuals, particularly young... 

These techniques reduce a large number of indoor VOCs to a few factors that can account for most of the cumulative variance in the VOC data [54,81 ]. A factor loading matrix, which shows the correlation between the factors and the variables is often obtained. Edwards et al. [81] used this method to reduce 23 indoor VOCs in environmental tobacco smoke (ETS) free microenvironments to six factors and to apportion the most likely sources of the VOCs. A summary of the VOC classes loaded on each factor and the probable sources is presented in Table 5. It is, however, noteworthy that UNMIX and positive matrix factorisation, both of which are based on factor analysis and have been applied frequently to ambient air quality data [82], have not featured prominently in indoor VOC source apportionment reports. 

Starting from the 1960s, many scholars made indoor and field test and research on the law of transport of solute and radioactive elements in single fracture systems (Moreno, 1982 Novakowski, 1994 Hadamman, 1991) and there have been large number of numerical simulation research results (Noorishad and Mehran, 1982 Christopher, 1995) considering influential factors such as diffusion of solute from fracture to matrix, the absorption action of fracture surface, variation of water flow speed and dispersivity and radioactivity decaying. However, all simulations hitherto made assume that tracer transports in... 

Matrix solid-phase dispersion (MSPD) integrates extraction and clean-up in a single step, and greatly speeds-up sample throughput. It has also been proposed for the isolation of several organophosphate esters, mainly flame retardants and plasticizers in indoor dust samples (Garcia et al. 2007). 

The major alkaloids in the vapor phase of environmental tobacco smoke are discussed and detailed procedures for their determination are outlined. Time-integrated sampling involves concentrating the alkaloids from the air matrix by trapping on either XAD-4 sorbent resin or on bisulfate-treated glass fiber filters with extraction and analysis by gas chromatography and N-selective detection. These methods are widely used in studying the impact of ETS on indoor air quality in real-life situations. 

There are three SRMs that are available from NIST for QA/QC assessment in the laboratory for dust lead measurements (SRM, matrix, and lead level, ppm) 1649a, mban dust, 12,400 2583, indoor dust, 85.9 2584, indoor dust, 9,761. 

All polymer composites absorb substantial amounts of moisture or water in humid environment as well as in water. The most important concern in indoor and outdoor applications of natural fiber-based biocomposites with polymer matrices is their sensitivity to water absorption, which can reduce considerably their mechanical, physical, and thermal properties and performances. The water absorption of biocomposites results in the debonding or gap in the natural fiber-polymer matrix interfacial region, leading to poor stress transfer efficiency from the matrix to the fiber and reduced mechanical and dimensional stabilities as well [158]. It has been known that the hemiceUulose component in cellulose-based natural fibers may be mainly responsible for water absorption because it is more susceptible to water molecules than the crystalline cellulose component. Also, poor interfacial adhesion... 

House dust has been widely used as an important environmental matrix to monitor BFRs contamination in indoor environments. Dust from U.S. homes contains the highest measured amounts of total PBDEs worldwide (median range 3,600-42,000... 

---