API Publ 4751:2005 pdf download

API Publ 4751:2005 pdf download.Evaluation of Water Quality Translators for Mercury.
2.2.1 Method 1630
EPA Method 1630 is the main method for quantifying methylmercury in fish tissue and aqueous samples (EPA). although it has not yet been promulgated. The specific steps in Method 1630 include: I) distillation to remove the methylmercury from the sample: 2) ethylation to a mnethylcthylmcrcury form and collection on a graphitic carbon adsorbent trap: and 3) thermal desorption through a gas chromatography column to separate the rncrcui’y spccics hcfnrc reduction to clcmcntal mercury in a decomposition furnace. The clemental mercury is detected using CVAFS. Method l630 has a method detection limit i MDU of 0.02 ngfL (or nglg but has the ability to detect as low as 0.00) ng/L.
Also included in this Method is Appendix A for the determination of dimethylinereury. The method for dimethylmercury vanes from the original Method l630 by eliminating the distillation step and purging the entire sample onto the graphitic carbon absorbent trap. The elemental mercury is separated from the dirneihylmercury by using gas chromatography. Two mercury peaks. representing the elemental and dimethylinercury species. are separated in time and are detected by CVAFS. Appendix A for the determination of dimetliylmcrcury has a MDL of 2 pgL. This is a performance based method and actual criteria data are determined before and during analysis. Precision is based on replicate analysis of actual samples and has a limit of3l% RSD. Accuracy is determined using NIST standards for OPR and MS’MSD. OPR samples must fall within 67 – l33% and MS1MSD samples between 65 — 135%. Several studies have been performed citing the Appendix A method that may be eventually used for validation. In the interim, Appendix A is still considered draft. Unlike EPA Method 1630. the method for dimcihylmcrcury does not specifically discuss how to analyze solids such as fish tissue.
2.2.2 UW-Madison SOP
The UW-Madison SOP was developed at the University of Wisconsin-Madison (Hurley et al. 191(S). It is virtually identical to Method 1634) with the major exception being the distillation of a larger sample volume, resulting in a lower method detection limit.
2.2.3 USGS Method
Similar to the UW-Madison SOP, the USGS methxl is virtually identical to Method 1630 with a slightly larger sample volume used in the distillation t DeWild et al. 2001). Copper sulfate is also added to the distillation to bind sultjrjes, The USGS method has a MDL of 44) pgL for niethylmercurs. The same laboratories that perform Method 1630 could perform this analysis and the cost is approximately $201) per sample with a four week reporting time.
2,3 CLEAN HANDS SAMPLING
EPA Method l669 covers the sampling and preservation of samples using clean hands techniques EPA l996a). Specifically, the method details the procedures for collecting water samples using a two person team, wherein one person becomes the “clean hands” sampler. while the second person. the “dirty hands” sampler, is available to operate equipment and perform tasks where contamination may bc present, Procedures sLich as preparation of blanks, duplicates, spikes. sample filtration, and preservation are described in this method.