SPMDs

USE OF SEMI PERMEABLE MEMBRANE DEVICES (SPMDs) TO INDOOR AIR MONITORING OF PYRETHROID INSECTICIDES... 

An easy, rapid and environmentally friendly methodology was developed for the extraetion of pyrethroid inseetieide residues from semi permeable membrane deviees (SPMD), based in a mierowave-assisted extraetion, in front of a dialysis method nowadays widely employed. Several solvent sueh as hexane, toluene, aeetonitrile, eyelohexane and ethyl aeetate were tested as mierowave-assisted extraetion solvent. Mixtures of hexane and toluene with aeetone were also assayed and provide better results than single solvents. 

The proposed proeedure are detailed next eaeh SPMD was mierowave-assisted extraeted twiee with 30 mL hexane aeetone, and irradiated with 250 W power output, until 90°C in 10 minutes, being this temperature held for another 10 minutes. Clean-up of extraet was performed by aeetonitrile-hexane partitioning eoupled by a solid-phase extraetion with a eombined eartridge of 2 g basie-alumina (deaetivated with 5% water) and 0.5 g C. ... 

Limits of deteetion values ranging from 0.2 to 0.8 ng/SPMD and repeatability from 2.0 % to 8.3 % were aehieved. Pyrethroid reeoveries for spiked SPMD (100 ng eaeh pyrethroid) were from (57 5) to (101 4) % for mierowave-assisted extraetion, versus from (34 3) to (91 3) % for dialysis referenee method. A substantially reduetion of solvent amount and analysis time were aehieved. 

The most widely employed techniques for the extraction of water samples for triazine compounds include liquid-liquid extraction (LLE), solid-phase extraction (SPE), and liquid-solid extraction (LSE). Although most reports involving SPE are off-line procedures, there is increasing interest and subsequently increasing numbers of reports regarding on-line SPE, the goal of which is to improve overall productivity and safety. To a lesser extent, solid-phase microextraction (SPME), supercritical fluid extraction (SEE), semi-permeable membrane device (SPMD), and molecularly imprinted polymer (MIP) techniques have been reported. 

Prest, H.F., W.M. Jarman, S.A. Bums, T. Weismuller, M. Martin, and J.N. Huckins. 1992. Passive water sampling via semipermeable membrane devices (SPMDs) in concert with bivalves in the Sacramento/San Joaquin river delta. Chemosphere 25 1811-1823. 

Due to the predicted and previously detected low concentrations of pesticides in environmental samples (usually around the nanogram per liter level), a preconcentration step of the water samples is necessary prior to measurement. In this way, a preconcentration factor of several orders of magnitude (200-1,000-fold) is mandatory to reach the low detection limits necessary for the identification of pesticides, especially in complex wastewater samples. Also, the use of surrogate standards (e.g., triphenyl phosphate) added before the extraction step is a common practice in order to account for possible errors during the extraction process and for quantitative purposes. The commonly used extraction methods for polar compounds from water matrices involve isolation using liquid-liquid extraction (LLE) and solid-phase extraction (SPE), which are commented on below. Other methods such as semipermeable membrane devices (SPMD) are also mentioned. 

SPMD have gained widespread use for sampling hydrophobic chemicals from water. In these membranes the more hydrophobic compounds are retained and are further recovered with organic solvents. As an example, SPMD have been applied to the analysis of pesticides in wastewater samples [26]. 

Petty JD, Huckins JN, Martin DB. 1995. Use of semipermeable membrane devices (SPMDS) to determine bioavailable organochlorine pesticide residues in streams receiving irrigation drainwater. Chemosphere 30(10) 1891-1903. 

In the following sections we highlight only selected works that have contributed toward the further development of passive samplers for SVOCs and/or HOCs. The literature related to the development and use of passive samplers for monitoring gases or VOCs in occupational environments is large. However, these publications are discussed only briefly, because lipid-containing semipermeable membrane devices (SPMDs) are primarily designed for SVOCs. 

SPMDs SPMEs POGs LDPE strips PISCES POCIS PSSs... 

PESs by the end of the exposure. Differences in exposure concentrations did not affect the sampling rates of PESs, which indicate that these devices obey first-order uptake kinetics. The sampling rate of " C-2,2 ,5,5 -TCB by PESs (4.8 L d ) was similar to that observed for 1 mL triolein SPMDs, with the same surface area. 

Table 1.1 compares key aspects and performance characteristics of selected passive samplers, including the triolein-containing SPMD. Of the eight devices examined, only a few appear to have overlapping functions. Clearly, no one device can provide the desired data for all exposure scenarios. 

Lipid-Containing SPMDs and Closely Related Devices... 

Similar to the previous section, we discuss only selected works to highlight the development of SPMDs. Also, we include some discussion of several unpublished pilot smdies (Huckins, 1989) that influenced our early development of SPMDs. These pilot studies were directed solely toward sampling the aqueous phase. The flrst application of SPMDs for sampling organic vapors did not occur until several years later (Petty et al., 1993). To our knowledge, only SPMDs, PESs and SPMEs are being applied in both air and water, because the use of many passive samplers is limited to a specific medium and exposure scenario. 

Based on earlier work (Lieb and Stein, 1969 Chiou, 1985 Sddergren, 1987 Zabik, 1988) Huckins etal. (1989,1990a, 1993) flrstdeveloped and tested two types of lipid-containing semipermeable membrane devices (SPMDs) for in situ passive sampling of bioavailable dissolved aqueous-phase HOCs. The lipid-containing... 

Figure 1.1 A standard lipid-containing SPMD with three molecular welds near each end. Note the low interfacial tension causes intimate contact (i.e., the presence of a lipid film on the membrane interior surface) between the triolein and the membrane even where air bubbles exist. Reprinted with permission from the American Petroleum Institute (Huckins et al., 2002a).

The layflat-LDPE tubing used for making SPMDs was 2.6 cm wide and had a wall thickness of about 75 pm. The A of the 0.5 mL triolein SPMDs used in these flow-through tests was about 200 cm with an AV (lipid -I- membrane) ratio of about 80 cm The A of the 1 mL triolein SPMDs used in the static exposures was about 360 cm (i.e., = 72 cm ). The surface area of the 1 mL lipid... 

Einally, LDPE SPMDs with grass carp lipid were exposed for 21 d to 14C-2,2, 5,5 -TCB, 14c-3,3, 4,4 -TCB, i c-mirex and i c-fenvalerate, whereas SPMDs with triolein or lecithin were exposed to only " C-2,2, 5,5 -TCB. After 21 d, the largest mass fraction of these test chemicals ( " C-mirex was an exception) was in the triolein. The C-2,2, 5,5 -TCB log triolein-water partition coefficient was 6.01, whereas the " C-2,2, 5,5 -TCB partition coefficients for the grass carp lipid-water and lecithin-water systems were 30% and 35% lower, respectively. Comparison of these data to literature log AlowS of 2,2, 5,5 -TCB showed that the partition coefficients for the grass-carp lipid and the lecithin were not significantly different from median values reported for the log ATow of " C-2,2, 5,5 -TCB. However, the partition coefficient of 2,2, 5,5 -TCB in triolein and water in direct... 

Petty and Orazio (1996) developed an interesting variation in SPMD liquid phases. The approach consisted of both LDPE and silastic ffibes containing silicone fluid (50 cSt or 3200 MW) with 3% by weight PX-21 activated carbon. The presence of the activated carbon enhanced retention of planar molecules such as PAHs and the silicone fluid remains liquid at temperatures below freezing. However, the partition coefficients of HOCs for this type of silicone fluid are much lower than for triolein. 

Uptake of phenanthrene by replicate SPMDs was within 25% of the determined... 

Prest et al. (1992) first used phenanthrene as a PRC in a field exposure of SPMDs. The results of their study appeared to be consistent with PRC theory. However, it was several years later before the validity of the use of PRCs for biofouled SPMDs was further substantiated in controlled laboratory studies (Huckins et al., 1994b). 

A thin film of oil-like material was visible after 28 d on the exterior surfaces of the SPMD membrane. Analysis of this film indicated that the triolein impurities, oleic acid and methyl oleate, were the major constituents. This external lipid film (Petty et al., 1993) appeared to contain imbibed particulates. Although the film was removed from the SPMDs by solvent rinsing and analyzed separately, some lipid-mediated desorption of particle-associated PCBs and subsequent diffusion into the SPMD may have occurred prior to solvent-removal of the film. This observation suggests the potential for SPMD concentrations to reflect both vapor phase concentrations and to a lesser extent, lipid-extracted particulate-associated residues (see Section 3.9.2.). Unfortunately, concentrations of more chlorinated congeners in particulates collected on GFFs from the NIOSH method were often below quantitation limits, because only a small volume of air was sampled (1 m ) using this active method. 

In subsequent chapters, we provide an overview of SPMD fundamentals and applications (Chapter 2) the theory and modeling which includes the extrapolation of SPMD concentrations to ambient environmental concentrations (Chapter 3) study considerations such as the necessary precautions and procedures during SPMD transport, deployment, and retrieval (Chapter 4) the analytical chemistry and associated quality control for the analysis of SPMD dialysates or extracts (Chapter 5) a survey and brief description of bioassays-biomarkers used to screen the toxicity of SPMD environmental extracts (Chapter 6) discussions on how HOC concentrations in SPMDs may or may not relate to similarly exposed biomonitoring organisms (Chapter 7) and selected examples of environmental studies using SPMDs (Chapter 8). In addition, two appendices are included which provide... 

SPMD calibration data for many HOCs (Appendix A) and sources of additional information on SPMDs (Appendix B). 

Huckins, J.N. Petty, J.D. Orazio, C.E. Lebo, J.A. Qark R.C. Haverland, P.S. 1994b, A Laboratory Study to Demonstrate the Eeasibility of the use of SPMD Permeability Reference... 

Huckins, J.N. Prest, H.F. Petty, J.D. Lebo, J.A. Hodgins, M.M. Clark, R.C. Alvarez, D.A. Gala, W.R. Steen, A. Gale, R.W Ingersoll, C.G. 2004, Overview and comparison of lipid-containing semipermeable membrane devices (SPMDs) and oysters (Crassostrea gigas) for assessing chemical exposure. Environ. Toxicol. Chem. 23 1617-1628. 

Petty, J.D. and Orazio, C.E. 1996, Application of Semipermeable Membrane Devices (SPMDs) Ay Passive Monitors of the Environment of Antarctica. USGS, Midwest Science Center, Columbia, MO Unpublished report to National Science Foundation Washington, DC. 

Rantalainen, A.-L. Ikonomou, M.G. Rogers, I.H. 1998, Lipid-containing semipermeable-membrane devices (SPMDs) as concentrators of toxic chemicals in the Lower Fraser River, British Co mAA2LCheniosphere 37 1119—1138. 

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