Wp_Nav_Menu – Identify the last menu item

I’m have a horizontal top menu with a solid border on the right hand side.

<?php wp_nav_menu( array('theme_location' => 'primary', 'container' => '', 'menu_class' => 'nav', 'fallback_cb' => '') ); ?> 

My CSS looks like this:

body > header .nav li a {
                background: none;
                text-decoration: none;
                font-family: 'Open Sans', sans-serif;
                font-size: 13px;
                color: #000000;
                text-shadow: none;
                text-transform: uppercase;
                border-right: solid 1px #000000;
            }

Now, this works fine but as expected it creates a border on the right hand side of the my last menu item. This does not look good, is there anyway to specifically identify the last item in the menu so I can put a ‘border: none’ style on it.

Regards,
Stephen