Assessment of the Methods

Generally, measurement of the total petroleum hydrocarbon in an ecosystem is performed by the standard method (EPA 418.1) or some modification thereof. However, many other methods exist is which the data are also claimed to be representative of the total petroleum hydrocarbons in the ecosystem. In fact, many methods for determining total petroleum hydrocarbons are prone to the following  

Producing false negatives (reporting nondetected when considerable petroleum hydrocarbons were really present). 

Underestimating the extent of petroleum hydrocarbons present (true of virtually every total petroleum hydrocarbons methodology). 

Underestimating the overall risk from petroleum hydrocarbons due to missing significant amounts of some of the compounds of most concern (e.g., polynuclear aromatic hydrocarbons). 

Producing misleading data related to soil hot spots versus areas of less concern due to differing moisture concentrations of otherwise similar samples. 

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An assessment of the methods available for the design of condensers where the condensation is from a non-condensable gas is given by McNaught (1983). 

The selection of an analytical technique and the development of procedures and operating conditions are only one part of the process for achieving reliable measurements. Among the first steps of the validation figure the assessment of the method precision this parameter must be assessed between analysts and days. Appropriate precision, although necessary for reliable work, is not sufficient to guarantee accurate results Evaluation of sample matrix effect, development, and analysis of spiked samples, analysis of Certified Reference Materials (CRM) of similar composition for which the Pb concentration has been established by other laboratories and comparison of results between laboratories (proficiency testing) are equally important [13]. 

CRITICAL ASSESSMENT OF THE METHOD Locomotion tests estimate whether a test substance possesses psychostimulant or sedative activity, but... 

CRITICAL ASSESSMENT OF THE METHOD The Hot Plate Test is one of the most frequently employed screens for evaluating the nociceptive threshold. It is reliable and reproducible, and remains robust in the face of moderate environmental variations. Most known analgesic substances show... 

CRITICAL ASSESSMENT OF THE METHOD The Purkinje fiber is a non-contractile tissue, which facilitates electrode positioning and stability. In comparison to the papillary muscle or the monophasic action potential in the intact heart, drug-induced effects on the action potential duration are considerably larger. Whereas this is not necessarily a disadvantage, the model has been viewed as possibly being too sensitive for drug-induced effects on repolarization. 

CRITICAL ASSESSMENT OF THE METHOD Problems associated with the microsphere technique in rats are the hemodynamic effects of the solutions used to inject the microspheres and the effects of blood withdrawal after repeated determinations (Stanek et al. 1985). 

CRITICAL ASSESSEMENT OF THE METHOD The method has the clear advantage of simplicity but does not measure the true bile excretion since the outflow from the bile bladder during the test period is neglected. 

CRITICAL ASSESSEMENT OF THE METHOD Among other applications, the method is suited to study the enterohepatic circulation of compounds. There should be a close health monitoring of the chronically prepared rats, and only those in a very good health conditions should be used for the study to avoid any misinterpretations of the results. 

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