A unit is provided comprising an array (2) of sample containers (1), said containers, being connected together and arranged in a planar configuration, each container having multiple optically transparent windows arranged such that the sample contained therein can be interrogated using simultaneous multiple optical analytical techniques, the array of containers being configured so as to allow optical access to the windows of each container in the array. Also provided is an apparatus comprising such a unit, a system comprising a combination of such an apparatus and unit and a method of analyzing multiple samples by introducing each individual sample into an individual container of such an apparatus, illuminating the samples and detecting and analyzing light emerging therefrom.