Provenance determination, general requirements

The goals and the final quantities to be obtained determine the method to be used. As a first approach, it is always worth checking if a documented and proven method exists. Standardized methods are often the best. They are developed by experts in the field and are usually of a high quality and are well documented. Frequently no standards can be applied and generally known methods have to be relied on. Sometimes situations occur when the whole of the measurement procedure has to be tailored for the specific situation. This is a very demanding task and considerable experience is required. 

The most common measure of polarity used by chemists in general is that of dielectric constant. It has been measured for most molecular liquids and is widely available in reference texts. However, direct measurement, which requires a nonconducting medium, is not available for ionic liquids. Other methods to determine the polarities of ionic liquids have been used and are the subject of this chapter. However, these are early days and little has been reported on ionic liquids themselves. I have therefore included the literature on higher melting point organic salts, which has proven to be very informative. 

More difficult to estimate are the amounts required annually for modifications and repairs to the experimental plant. These depend very much on whether new or already proven technologies are being used. The development costs determined in this way do not contain any contributions arising from personnel not directly involved in development, such as management or patent spedahsts. Nor is account taken of unsuccessful developments. It nevertheless seems reasonable to apportion the direct development costs to the product and to allow for the other research and development costs in some other way, for example by means of a general cost provision (see Chapter 6). Although this method only accounts for the costs of successfid development projects, the financial burdens on the product will be relatively high if it must bear all the development costs of the first plant. 

Obviously, other spectroscopic time-resolved methods have been applied, although less general. Most often, EPR has been used for triplets and radicals (see for instance [29, 30]). Time-correlated single-photon counting, on the other hand, has proven to be a sensitive and informative method for mechanistic smdies of singlet reactions [31, 32], besides than a technique useful for analytic applications, e.g. for determining the composition of mixmres of aromatics, when both lifetime and spectrum shape were required for obtaining a reasonable picture. 

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