SPMD Calibration Data

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

POTENTIAL EFFECTS OF DISSOLVED ORGANIC CARBON (DOC) ON SPMD CALIBRATION DATA... 

Any length of SPMD with an A V ratio of about 460 cm mL of >95% triolein, having an approximate 0.25 lipid-to-membrane-mass ratio (i.e., 20% lipid) and a 70-95 pm wall thickness is considered a standard SPMD. However, the aforementioned QC certification requirements for the membrane and triolein must be met. Because most SPMD calibration data and field data are based on the standard configuration, the use of non-standard designs for monitoring must be weighed against the lack of data comparability. 

When environmental conditions at an exposure site differ from those used for laboratory calibrations or when calibration data for an analyte are not available, at least one SPMD per site is spiked with PRCs. The type of compounds used for PRCs and their spiking levels were discussed earlier. PRC samples and standard SPMD samples (i.e., field-deployed SPMDs) differ only by the presence of the PRCs. Handling, processing and analysis are also identical. As implied above, the purpose of the PRC sample is to provide data for estimation of in situ sampling rates of target compounds. 

A relatively large surface area of nonpolar membrane is required because these chemicals often occur at ultra-trace levels. SPMDs are commercially available and the most widely used type of passive samplers to date. Some advantages for SPMDs over other passive sampler types are the availability of the largest set of calibration data together with an extensive literature and the use of performance reference compounds for in situ calibration is routine. 

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