Field trials application phase

Application of the test substance to the test system is without doubt the most critical step of the residue field trial. Under-application may be corrected, if possible and if approved by the Study Director, by making a follow-up application if the error becomes known shortly after the application has been made. Over-application errors can usually only be corrected by starting the trial again. The Study Director must be contacted as soon as an error of this nature is detected. Immediate communication allows for the most feasible options to be considered in resolving the error. If application errors are not detected at the time of the application, the samples from such a trial can easily become the source of undesirable variability when the final analysis results are known. Because the application is critical, the PI must calculate and verify the data that will constitute the application information for the trial. If the test substance weight, the spray volume, the delivery rate, the size of the plot, and the travel speed for the application are carefully determined and then validated prior to the application, problems will seldom arise. With the advent of new tools such as computers and hand-held calculators, the errors traditionally associated with applications to small plot trials should be minimized in the future. The following paragraphs outline some of the important considerations for each of the phases of the application. 

There are many crucial activities which must be completed during or in parallel to each of these phases, such as application testing, HSE studies, product registration and customer, clinical or field trials, these are discussed in greater detail in subsequent sections. If all the steps were carried out in a sequential manner, the time from start to finish would be inordinately long. This is never the case, most of the steps overlap and the big issue of the management of time in the overall project is covered in Section D, 2.3. 

The approaches outlined in this brief review are however of great application with respect to decontamination of lead and arsenic streams and the results of field trials [78] and related environmental issues [79] continue to be aired in the literature. It is anticipated that further thermodynamic data for some of the phases that can not at present be modelled satisfactorily will be forthcoming as a result of the importance of the problems that have been mentioned. These are of particular importance with respect to long-term environmental modelling and wiU have to be viewed in conjunction with related kinetic studies, areas which have received much less attention that equilibrium approaches [80]. 

The successful testing of DDM method for structure refinement purposes allows us to predict its applicability in other fields of powder diffraction, such as the analysis of microstructure and quantitative phase analysis (QPA). Trial runs of DDM for the XRD data supplied by the International Union of Crystallography Commission on Powder Diffraction for the Size-Strain and QPA round-robins gave encouraging results. Respective examples are included in the DDM program package. In particular, the biases in the phase contents determined by DDM refinement for the QPA round-robin samples from the weighted amounts were less than 1 wt.%. 

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