Bioassays of SPMD

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... 

When using purified triolein, most samples are amenable to bioassay after di-alytic enrichment. For example, Microtox bioassay of dialysates of SPMDs shows that the SPMDs made with the purified triolein have lower acute toxicities than dialysates from SPMDs made from unpurified triolein (Johnson, 2001). Finally, examination of the dialysates using the yeast estrogen screen (YES) assay (Routledge and Sumpter, 1996) demonstrated that the purification procedure removes all background estrogenic activity (Lebo et ah, 2004). Use of triolein purified by this process expands the potential applicability of SPMD sample extracts to include numerous bioassay procedures (see Chapter 6) and GC-MS as a standard analysis technique. 

SPMD dialysates (extracts), rinses of the exterior membrane surface (only SPMDs exposed to air), and aliquots thereof often contain a number of classes of chemicals. Figure 6.1 shows various levels of processing and enrichment used for SPMD derived bioassay samples. We strongly recommend the use of SPMDs with triolein purified by the method of Lebo et al. (2004) for bioassays to reduce the probability of false-positive results or for controls that fail to meet quality control... 

Conceptually, SPMD data fills a gap between exposure assessments based on direct analytical measurement of total residues in water and air, and the analysis of residues present in biomonitoring organisms. SPMDs provide a biomimetic approach (i.e., processes in simple media that mimic more complex biological processes) for determining ambient HOC concentrations, sources, and gradients. Residues accumulated in SPMDs are representative of their environmental bioavailability (see Section 1.1.) in water and air and the encounter-volume rate as defined by Landrum et al. (1994) is expected to be proportional to the uptake rate. SPMD-based estimates of water concentrations can be readily compared to aquatic toxicity data (generally based on dissolved phase concentrations) and SPMD extracts can be used to screen for toxic concentrations of HOCs using bioassays or biomarker tests. 

Figure 6.1 Illustration of the SPMD in vitro bioassay and immunoassay protocol, which includes sampling, different levels of processing and enrichment, and bioassay or immunoassay. Reprinted with permission from the American Petroleum Institute (Huckins et al., 2002).

The following sections describe several commonly used bioassay tests that have been successfully used in conjunction with SPMDs. However, no attempt was made to cover all of the in vitro assays used for SPMD extracts. 

Rastall, A.C. Neziri, A. Vukovic, Z. Jung, C. Mijovic, S. Hollert, H. Nikcevic, S. Erdinger, L. 2004, The identification of readily bioavailable pollutants in Lake Shkodra/Skadar using semipermeable membrane devices (SPMDs), bioassays and chemical analysis. Environ. Sci. Pollut. R. 11 240-... 

Isidora, M. Ferrara, M. Lavorgna, M. NardelU, A. Parrella, A. 2003, In situ monitoring of urban air in Southern Italy with the Tradescantia micronucleus bioassay and semipermeable membrane devices (SPMDs). Chemosphere 52 121-126. 

Rastall, A.C., D. Getting, J. Goddard, D.R. Roberts, and L. Erdinger. 2006. A biomimetic approach to the detection and identification of estrogen receptor agonists in surface waters using semipermeable membrane devices (SPMDs) and bioassay-directed chemical analysis. Environ. Sci. Pollut. Res. 13 256-267. 

Amide herbicides - preconcentration using SPMDs then bioassay. (2) Diethanol amides by solid-phase extraction-liquid chromatography-atmospheric pressure chemical ionization/electrospray ionization mass spectrometry (SPE-LC-APCI/ESI-MS) o-Phthaldialdehyde derivatization then reversed-phase LC with fluorescence defecfion. Chiral derivafizafion permifs separation of optical isomers on standard LC columns Anion exchange LC Ion-pair liquid chromatography... 

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