A sample holder system for an automated sample analyzer, comprising: at least a first well strip and a second well strip, wherein each well strip comprises, a first end, a second end, a longitudinal axis extending from said first end to said second end, first and second side walls (121, 124), each of said walls extending parallel to said longitudinal axis, a plurality of wells extending along said longitudinal axis, a first engagement piece disposed on said first side wall and a second engagement piece disposed on said first side wall, another first engagement piece disposed on the second side wall and another second engagement piece disposed on said second side wall, characterized in that said first and second well strips are reversibly interlockable with each other to form the sample holder system by horizontal sliding of the first well strip parallel to said longitudinal axis of said second well strip such that, in one orientation, said first engagement piece of said first well strip cooperates with said another second engagement piece of said second well strip and said second engagement piece of said first well strip cooperates with said another first engagement piece of said second well strip to reversibly attach said first well strip with said second well strip to form said sample holder system, and, in a second orientation, said first engagement piece of said first well strip cooperates with said second engagement piece of said second well strip and said second engagement piece of said first well strip cooperates with said first engagement piece of said second well strip to reversibly attach said first well strip with said second well strip to form said sample holder system. at least a first well strip and a second well strip, wherein each well strip comprises, a first end, a second end, a longitudinal axis extending from said first end to said second end, first and second side walls (121, 124), each of said walls extending parallel to said longitudinal axis, a plurality of wells extending along said longitudinal axis, a first engagement piece disposed on said first side wall and a second engagement piece disposed on said first side wall, another first engagement piece disposed on the second side wall and another second engagement piece disposed on said second side wall, characterized in that said first and second well strips are reversibly interlockable with each other to form the sample holder system by horizontal sliding of the first well strip parallel to said longitudinal axis of said second well strip such that, in one orientation, said first engagement piece of said first well strip cooperates with said another second engagement piece of said second well strip and said second engagement piece of said first well strip cooperates with said another first engagement piece of said second well strip to reversibly attach said first well strip with said second well strip to form said sample holder system, and, in a second orientation, said first engagement piece of said first well strip cooperates with said second engagement piece of said second well strip and said second engagement piece of said first well strip cooperates with said first engagement piece of said second well strip to reversibly attach said first well strip with said second well strip to form said sample holder system. a first end, a second end, a longitudinal axis extending from said first end to said second end, first and second side walls (121, 124), each of said walls extending parallel to said longitudinal axis, a plurality of wells extending along said longitudinal axis, a first engagement piece disposed on said first side wall and a second engagement piece disposed on said first side wall, another first engagement piece disposed on the second side wall and another second engagement piece disposed on said second side wall, characterized in that said first and second well strips are reversibly interlockable with each other to form the sample holder system by horizontal sliding of the first well strip parallel to said longitudinal axis of said second well strip such that, in one orientation, said first engagement piece of said first well strip cooperates with said another second engagement piece of said second well strip and said second engagement piece of said first well strip cooperates with said another first engagement piece of said second well strip to reversibly attach said first well strip with said second well strip to form said sample holder system, and, in a second orientation, said first engagement piece of said first well strip cooperates with said second engagement piece of said second well strip and said second engagement piece of said first well strip cooperates with said first engagement piece of said second well strip to reversibly attach said first well strip with said second well strip to form said sample holder system.