Sampling from fluid mixtures under high pressure: Review, case study and evaluation

All analysis tools, techniques and diagnostic processes are worthless if the sample fails to effectively represent the actual composition of the mixture to be analyzed. Therefore, correct sampling is indispensable to get meaningful results whereby it is a difficult operation which requires the greatest care in terms of the choice of the sampling point, the way of sampling like sampling by pressure drop or isobaric sampling, the subsequent sample preparation and analysis steps as well as the back coupling of the sampling on the remaining system. In this contribution the focus is set on sampling related to the determination of high-pressure phase equilibria. Thereby the sub-steps and the magnitudes of influence of the sampling procedure on the sample itself as well as on the remaining system, which was investigated on basis of a case study, are discussed in detail. For illustration, many examples from the literature are given.