Protocols, sampling

In this section we will consider some precautions necessary for the sampling of various materials before analysis. In general, samples should be representative of the bulk samples from which they were taken. 

It is shown that the variation associated with field sampling is 5 to 10 times greater than that associated with laboratory procedure. It would therefore be better to increase the number of core samples taken from the field than try to improve the accuracy of the analytical methods if the precision of the results from our field experiments is to be improved. 

Galvanized sampling tools should not be used for trace element analysis. Usually from 20 to 25 cores are taken in a W pattern across the whole area. An alternative approach is to traverse the whole area in a zig-zag manner, sampling at random along different sections of the area (Scott et ai, 1971). The cores should be broken up and mixed well in a bucket, then about 200 g retained in a labelled polythene bag. 

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The type of plate, chamber system, composition of mobile phase, running time and detection reagent used must naturally all be recorded The sample protocol illustrated in Figure 62 can be employed... 

Wallace JC, Hites RA. 1996. Diurnal variations in atmospheric concentrations of poychlorinated biphenyls and endosulfan implications for sampling protocols. Environ Sci Technol 30(2) 444-446. 

The results of environmental monitoring exercises will be influenced by a variety of variables including the objectives of the study, the sampling regime, the technical methods adopted, the calibre of staff involved, etc. Detailed advice about sampling protocols (e.g. where and when to sample, the volume and number of samples to collect, the use of replicates, controls, statistical interpretation of data, etc.) and of individual analytical techniques are beyond the scope of this book. Some basic considerations include the following, with examples of application for employee exposure and incident investigation. 

Mason, B. J. Preparation of Soil Sampling Protocol Techniques and Strategies, Report EPA-60014-83-020, U.S. Environmental Protection Agency, 1983. 

Obtaining a representative sample is an important part of any analysis, since errors or faults in the sampling protocol cannot be corrected at any later point in the analysis [15-21]. 

Radhakrishnan, R. Schlick, T., Biomolecular free energy profiles by a shoot-ing/umbrella sampling protocol, BOLAS , J. Chem. Phys. 2004,121, 2436-2444... 

Smith, D.B., Woodruff, L.G., O Leary, R.M., Cannon, W.F., Garrett, R.G., Kilburn, J.E., Goldhaber, M. B. 2009. Pilot studies for the North American Soil Geochemical Landscapes Project - site selection, sampling protocols, analytical methods, and quality control. Applied Geochemistry, in press. 

Sampling Methods From the outset of the high density lake sampling program in 1987, the application of a robust and consistent sampling protocol was considered paramount and this is still the case. Lake sediment and water sampling is performed by 2-person teams primarily from float-equipped Bell 206B helicopters. 

There are many recommended sampling protocols (Table 6.2). The sampling methods used for petroleum hydrocarbons are generally thought of as methods for determination of the total petroleum hydrocarbons. In part due to the complexity of the components of the total petroleum hydrocarbons fractions, little is known about their potential for health or environmental impacts. As gross measures of petroleum contamination, the total petroleum hydrocarbons data simply show that petroleum hydrocarbons are present in the sampled media. Measured total petroleum hydrocarbons values suggest the relative potential for human exposure and therefore the relative potential for human health effects. 

Thus, the importance of correct sampling of any sample destined for analysis should always be overemphasized. Incorrect sampling protocols can lead to erroneous analytical data, from which decisions about regulatory issues cannot be made accurately. In addition, adequate records of the circumstances and conditions during sampling have to be made for example, in sampling from storage tanks, the temperatures and pressures of the separation plant and the atmospheric temperature would be noted. 

Table 6.2. Sampling Protocols Recommended by the Environmental Protection Agency... 

R82103 Sampling Protocols for Collecting Surface Water, Bed Sediment, Bivalves, and Fish for Priority Pollutant Analysis Pinal Report 823R92006 Sediment Classification Methods Compendium... 

Because of the nature of sampling protocols and the location of the sites from which samples are taken, it should be assumed that no two samples are identical. Factors such as (1) depth from which the sample is taken, (2) distance of the sampling point from the initial location of the spill, and (3) ambient conditions... 

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