An automated system for the collection of blood platelets with a reduced risk of bacterial contamination comprising: a) a disposable fluid circuit configured for the flow of whole blood and/or a separated blood component therethrough, said disposable fluid circuit comprising a blood separation chamber for separating whole blood into one or more components; b) a reusable hardware device configured to receive a portion of said disposable fluid circuit, said hardware device including a separator element, a pump for introducing a predetermined volume of whole blood into said fluid circuit, a pump for removing one or more blood components from said separation chamber, valves for selectively diverting and directing liquid flow, and a controller configured to: i) effect the introduction of said predetermined volume of whole blood from a donor into said fluid circuit; ii) selectively control said pumps to effect movement of blood and blood components through said disposable fluid circuit; iii) process said pre-determined volume of whole blood without collecting platelets; iv) effect the return of said predetermined volume of whole blood back to said donor before withdrawing said second volume of whole blood; v) introduce a second volume of whole blood into said fluid circuit; and vi) effect collection of platelets only from said second volume of whole blood. a) a disposable fluid circuit configured for the flow of whole blood and/or a separated blood component therethrough, said disposable fluid circuit comprising a blood separation chamber for separating whole blood into one or more components; b) a reusable hardware device configured to receive a portion of said disposable fluid circuit, said hardware device including a separator element, a pump for introducing a predetermined volume of whole blood into said fluid circuit, a pump for removing one or more blood components from said separation chamber, valves for selectively diverting and directing liquid flow, and a controller configured to: i) effect the introduction of said predetermined volume of whole blood from a donor into said fluid circuit; ii) selectively control said pumps to effect movement of blood and blood components through said disposable fluid circuit; iii) process said pre-determined volume of whole blood without collecting platelets; iv) effect the return of said predetermined volume of whole blood back to said donor before withdrawing said second volume of whole blood; v) introduce a second volume of whole blood into said fluid circuit; and vi) effect collection of platelets only from said second volume of whole blood. i) effect the introduction of said predetermined volume of whole blood from a donor into said fluid circuit; ii) selectively control said pumps to effect movement of blood and blood components through said disposable fluid circuit; iii) process said pre-determined volume of whole blood without collecting platelets; iv) effect the return of said predetermined volume of whole blood back to said donor before withdrawing said second volume of whole blood; v) introduce a second volume of whole blood into said fluid circuit; and vi) effect collection of platelets only from said second volume of whole blood.