A method of, and apparatus for, determining properties relating to multi-phase systems are provided. In the method, an array of sample tubes each containing a sample of a multi-phase system is formed. An iterative process is used to generate at least two data sets of transmitted and/or backscattered values for each sample and the data sets for each sample are processed to determine at least one property of the sample. The apparatus has a support on which an array of sample tubes each containing a sample of a multi-phase system may be assembled. It also has a wave source and at least one wave detector for detecting transmitted and/or backscattered values for each sample and computer means for iteratively operating said wave source and said at least one detector to generate data sets of transmitted and/or backscattered values for each sample and for processing the data sets for each sample to determine at least one property of the sample.