No abstract

Seven laboratories participated in an interlaboratory evaluation of a liquid chromatography / mass spectrometry (LC/MS) method for the analysis of 10 chlorinated phenoxy acid herbicides. The focus of this evaluation was to test the intercomparability of LC/MS data obtained from two types of LC/MS interfaces [i.e., thermospray (TS) and particle beam (PB)]. Eight simulated sample extracts were sent to each laboratory for LC/MS analysis. There were statistically significant differences between interfaces in the quantitative data for all analytes except 2-(2,4,5-trichlorophenoxy)propanoic acid (silvex). Particle beam exhibited a high positive bias and a low relative standard deviation at the highest sample extract concentration range, 500 pg/mL, while TS showed a low bias and a low relative standard deviation at the lowest sample extract concentration range, 5 pg/mL. Another factor of this study was to look for any performance differences between interfaces of the same type, but differing manufacturers. A statistical difference was observed, between PB interfaces, for 2-(l-methylpropyl)-4,6-dinitrophenol (dinoseb).

Introduction 1 2 Background and History 2 2.1 Overview of United States Environmental Protection Agency Regulatory Programs 2 2.2 Developmental History of Immunoassay Methods in United States Environmental Protection Agency Programs 3 3 Types of Immunoassay Technologies Employed in Environmental Programs 4 3.1 Enzyme-linked Immunosorbent Assay 4 3.2 Reporter Gene on a Human Cell Line 5 3.3 Immunosensors 6 3.4 Affinity Chromatography 6 3.5 Dissociation-enhancement Lanthanide Fluoroimmunoassay 6 4 Method Development 6 4.1 General Guidelines for Development of Screening Methods 6 4.2 Validation Criteria for Immunoassay Methods 7 5 Status of the United States Environmental Protection Agency Immunoassay Methods Development Program 8 5.1 Current Validated Methods 8 5.2 Methods under Development 9 5.3 List of Validated Immunoassay Test Products 11 6 Environmental Applications 11 6.1 Advantages and Disadvantages of Immunoassay Methods 11 6.2 Implementation Issues 12 6.3 Examples of Performance Based Measurement Systems 13 6.4 Applications as Screening Methods 13 6.5 Applications as Quantitative Methods 14 7 Future Directions 15 Acknowledgments 15 Abbreviations and Acronyms 15 Related Articles 16 References 16

No abstract

No abstract