Detection limits in environmental

Geifi S, Einax JW (2001) Comparison of detection limits in environmental analysis - is it possible An approach on quality assurance in the lower working range by verification. Fresenius J Anal Chem 370 673... 

Detector sensitivity is best explained in terms of signal to noise ratio, which is the minimum detectable quantity with a signal to noise ratio of two (Willard, 1988). Detector sensitivity is linked to the method detection limit, a concept that we routinely use in environmental project work. (The definitions of detection limits in environmental pollutant analysis are discussed in Chapter 4.5.1.) The MDLs, however, while being related to detector sensitivity, greatly depend on the analytical method, sample matrix, and the analyte itself. In this chapter, we will address detector sensitivity in relative terms by comparing sensitivities of various chromatography detectors. 

Much is made of detection limits in environmental analysis. Much of the modern concern about chemicals in the environment stems from the ability of the analytical chemist to analyse ever lower concentrations. Less attention is given to a limit of determination. Usually the RSD is the best possible for the given method, and because intra-laboratory precision, or even simple repeatability, is quoted, this is usually accepted. 

Kirchner, C. J. Estimation of Detection Limits for Environmental Analytical Procedures, In Currie, L. A., ed. Detection in Analytical Chemistry Importance, Theory and Practice. American Chemical Society Washington, DC, 1988. 

Because of the increasing emphasis on monitoring of environmental cadmium the detemiination of extremely low concentrations of cadmium ion has been developed. Table 2 Hsts the most prevalent analytical techniques and the detection limits. In general, for soluble cadmium species, atomic absorption is the method of choice for detection of very low concentrations. Mobile prompt gamma in vivo activation analysis has been developed for the nondestmctive sampling of cadmium in biological samples (18). 

The purpose of this chapter is to describe the analytical methods that are available for detecting and/or measuring and monitoring lead in environmental media and in biological samples. The intent is not to provide an exhaustive list of analytical methods that could be used to detect and quantify lead. Rather, the intention is to identify well-established methods that are used as the standard methods of analysis. Many of the analytical methods used to detect lead in environmental samples are the methods approved by federal organizations such as EPA and the National Institute for Occupational Safety and Health (NIOSH). Other methods presented in this chapter are those that are approved by groups such as the Association of Official Analytical Chemists (AOAC) and the American Public Health Association (APHA). Additionally, analytical methods are included that refine previously used methods to obtain lower detection limits, and/or to improve accuracy, precision, and selectivity. 

The Environmental Health Laboratory Sciences Division of the National Center for Environmental Health, Centers for Disease Control and Prevention, is developing methods for the analysis of endrin and phenolic compounds in urine. These methods use high resolution GC and magnetic sector MS which gives detection limits in the low parts per trillion (ppt) range. 

Exposure Levels in Environmental Media. There were no quantitative data on current atmospheric levels of 3,3 -dichlorobenzidine emissions or on the chemical s potential to act as a surface eontaminant of soil environments. It is difficult to determine 3,3 -dichlorobenzidine levels in the aquatic environment because the concentrations tend to be at or below analytical detection limits. In general, it may only be possible to ascertain fully the environmental fate of 3,3 -dichlorobenzidine as analytical advances permit the routine determination of very low concentrations. Moreover, determination of the nature and environmental fate of breakdown products of 3,3 -dichlorobenzidine would be useful. 

During recent years, a great effort of development has been carried out to detect PFCs in environmental samples and biota and different reviews have been published [32, 33]. However, a limited number of works have reported the concentrations levels of PFCs in food. 

Trace level analysis using ISEs was considered impossible only a decade ago. With detection limits in micromolar levels and the discrimination of interfering ions by a factor of 103-104, researchers at the time did not see any possibility of serious advances in the area and the application of ISEs in new field such as trace metal analysis in environmental samples was regarded as impossible. The potential response of an ISE in the presence of interfering ions is described by the well-known... 

Polychlorinated biphenyls (PCBs) have been known for sometime as persistent pollutants, which can be readily bioaccumulated through the food chain causing well-documented toxic effects in number of species including humans [191]. Consequently, PCBs are commonly routinely monitored as potential industrial pollutants. Due to their environmental persistence and toxicity, detection limits in the ng ml-1 region are generally required. Consequently, such work has generally required solvent or solid extraction and concentration steps prior to separation by GC in conjunction with electron capture detection, or mass... 

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