A method for reducing cross contamination in an immunodiagnostic testing apparatus, the method comprising the steps of: estimating a time for using a sealed element having a puncturable seal in the performance of a specified test, using software; determining whether a previous use of a current disposable punch is compatible with the specified test based on stored data specifying past usage of the current disposable punch, wherein the disposable punch is determined as being not compatible if it has been used with a test or reagent that will introduce unacceptable risk of cross-contamination; if the previous use of the current disposable punch is compatible with the specified test: aligning the current disposable punch with the sealed element, wherein the current disposable punch is not used to aspirate fluids; punching an opening in the puncturable seal on the sealed element with the current disposable punch to enable a fluid-carrying tip of the immunodiagnostic testing apparatus to aspirate fluids therefrom or to dispense fluids therein without touching the puncturable seal; and if the previous use of the current disposable punch is not compatible with the specified test, evaluating whether an alternative disposable punch from an array of disposable punches is compatible with the specified test and using the alternative disposable punch to punch the opening in the puncturable seal if the alternative disposable punch is compatible with the specified test. estimating a time for using a sealed element having a puncturable seal in the performance of a specified test, using software; determining whether a previous use of a current disposable punch is compatible with the specified test based on stored data specifying past usage of the current disposable punch, wherein the disposable punch is determined as being not compatible if it has been used with a test or reagent that will introduce unacceptable risk of cross-contamination; if the previous use of the current disposable punch is compatible with the specified test: aligning the current disposable punch with the sealed element, wherein the current disposable punch is not used to aspirate fluids; punching an opening in the puncturable seal on the sealed element with the current disposable punch to enable a fluid-carrying tip of the immunodiagnostic testing apparatus to aspirate fluids therefrom or to dispense fluids therein without touching the puncturable seal; and if the previous use of the current disposable punch is not compatible with the specified test, evaluating whether an alternative disposable punch from an array of disposable punches is compatible with the specified test and using the alternative disposable punch to punch the opening in the puncturable seal if the alternative disposable punch is compatible with the specified test. aligning the current disposable punch with the sealed element, wherein the current disposable punch is not used to aspirate fluids; punching an opening in the puncturable seal on the sealed element with the current disposable punch to enable a fluid-carrying tip of the immunodiagnostic testing apparatus to aspirate fluids therefrom or to dispense fluids therein without touching the puncturable seal; and if the previous use of the current disposable punch is not compatible with the specified test, evaluating whether an alternative disposable punch from an array of disposable punches is compatible with the specified test and using the alternative disposable punch to punch the opening in the puncturable seal if the alternative disposable punch is compatible with the specified test.