A method of determining an inventory of test elements (20, 30) of multiple types stored in a clinical analyzer comprising: positioning groups of test elements in a container disposed in a drawer of the clinical analyzer, wherein the container is a sleeve, a rack or support with positioning guides for test elements and in which each test element is independently accessible; further wherein the container comprises slots for holding the test elements, each of the test elements comprising an immunohematology test card or cassette and a top side surface, and each having, on its top side surface, a protective sealing cover, wherein the positioning comprises positioning all the test elements of a single type into consecutive slots of the container and providing a gap between each group of test elements by leaving at least one slot empty between each group of test elements, wherein the protective sealing cover is of measurably different reflectance than the gap, using an optical sensor bar disposed within the clinical analyzer, scanning the test elements positioned within the drawer upon closure of the drawer and also upon powering on of the clinical analyzer, wherein the scanning comprises detecting locations of the groups of test elements within the container containing multiple groups of test elements, wherein the gap is capable of being detected by the optical sensor bar by detection of the reflective difference between the protective sealing cover and the gap; determining the type of test element (20, 30) in an entire group, after the gaps have been detected, by picking up the first test element of each group with a gripper arm and placing it before illumination means, whereby a bar code affixed on the single test element is read by the imaging subsystem, whereby the bar code includes the information about the type of test element; by using a processing subsystem generating inventory data for the test elements of each type, based on the test element capacity of the container and the detection of at least one gap by the optical sensor bar; using said data generated by the processing subsystem to provide an inventory of the multiple test elements in the clinical analyzer. positioning groups of test elements in a container disposed in a drawer of the clinical analyzer, wherein the container is a sleeve, a rack or support with positioning guides for test elements and in which each test element is independently accessible; further wherein the container comprises slots for holding the test elements, each of the test elements comprising an immunohematology test card or cassette and a top side surface, and each having, on its top side surface, a protective sealing cover, wherein the positioning comprises positioning all the test elements of a single type into consecutive slots of the container and providing a gap between each group of test elements by leaving at least one slot empty between each group of test elements, wherein the protective sealing cover is of measurably different reflectance than the gap, using an optical sensor bar disposed within the clinical analyzer, scanning the test elements positioned within the drawer upon closure of the drawer and also upon powering on of the clinical analyzer, wherein the scanning comprises detecting locations of the groups of test elements within the container containing multiple groups of test elements, wherein the gap is capable of being detected by the optical sensor bar by detection of the reflective difference between the protective sealing cover and the gap; determining the type of test element (20, 30) in an entire group, after the gaps have been detected, by picking up the first test element of each group with a gripper arm and placing it before illumination means, whereby a bar code affixed on the single test element is read by the imaging subsystem, whereby the bar code includes the information about the type of test element; by using a processing subsystem generating inventory data for the test elements of each type, based on the test element capacity of the container and the detection of at least one gap by the optical sensor bar; using said data generated by the processing subsystem to provide an inventory of the multiple test elements in the clinical analyzer.