Choice of an Appropriate Method

For sterile products, particular attention should be paid to the choice of an appropriate method of sterilization. Wherever possible a terminal sterilization process should be applied to the product in its final container-closure system, as suggested in the Ph Eur. The preferred options include steam sterilization, dry heat sterilization, and irradiation using the Ph Eur listed conditions (saturated steam at 121°C for 15 minutes dry heat at 160°C for 120 minutes irradiation with an absorbed dose of not less than 25 kGy). Where these cannot be used, the application must include justification for the alternative procedure adopted on the understanding that the highest achievable sterility assurance level should be achieved in conjunction with the lowest practicable level of presterilization bioburden. There is guidance in the form of decision trees as to the preferred options for sterilization method to be applied ... 

A further point for the choice of an appropriate method is, whether the final model needs to be interpreted. In this case, and especially in case of many original regressor variables, the interpretation is in general easier if only a few regressor variables are used for the final model. This can be achieved by variable selection (Section 4.5), Lasso regression (Section 4.8.2), or regression trees (Section 4.8.3.3). Also PCR (Section 4.6) or PLS (Section 4.7) can lead to components that can be interpreted if they summarize the information of thematically related x-variables. 

The types of reactions that are sequenced and the order in which they occur often dictate the choice of an appropriate method. Thus, sequential radical reactions are classified by transformation, and they are presented below in roughly increasing order of difficulty. With careful substrate design and selection of an appropriate method and reaction conditions, a diverse collection of tandem radical reactions has been executed. Yet the known reactions only begin to show the potential of such radical sequences for the rapid assemblage of complex molecules. 

Of course, another central question regarding fitness is whether a particular type of measurement is a suitable one for the purpose at all. This is, however, a matter of professional judgement addressed by the choice of an appropriate method. 

Some techniques are known to provide higher variability than others. The choice of an appropriate method at the outset can improve precision. For example, a volume of less than 20 mL can be measured more accurately and precisely with a syringe than with a pipette. Large volumes are amenable to precise handling but result in dilution that lowers sensitivity. The goal should be to choose a combination of sample preparation and analytical instrumentation that reduces both the number of sample preparative steps and the RSD. Automated techniques with less manual handling tend to have higher precision. 

The four methods described in this chapter provide some different advantages and disadvantages. Choice of an appropriate method will depend on factors including available equipment, screening capacity required, and whether further detailed kinetic analysis will be needed. The following notes describe some of the differences in the methods and the problems that may be encountered when using these methods. 

However, it is not always possible or useful to follow these procedures. In that case, ISO 14044 recommends a step-wise approach for the choice of an appropriate method of allocation. In the first place, the division of flows between the respective... 

The European Commission has mandated the European Committee for Standardization to establish a validated method of analysis for the determination of OMLs and SMLs. If a product complies with the compositional requirements of the directives, i.e., it is produced from authorized monomers and additives, then it may be tested for any desired application. If it meets the migration requirements, it is acceptable for use in cases covered by that test method. Typical food simulants used in the tests are hot water, acetic acid, ethyl alcohol and olive oil. The choice of an appropriate simulant depends on the type of food expected to come into contact with the packaging. 

This is not an exhaustive list, but it illustrates the fact that the choice of an appropriate naming method is a function of the substance to be named, and that there may be more than one way of deriving a correct name. 

The tables given at the end of the book, as well as the hardness testing results by various methods included in the text itself, are meant to serve as a rough guide in the choice of an appropriate test method, whilst simultaneously providing the reader with reference details. 

The starting point of every computer simulation in biology, chemistry or physics is the choice of an appropriate structural and computational model. Depending on the question of interest, simulations can consider only a part of the real-world system, although progress in computational methods allows one to treat increasingly realistic models. 

---