按字母顺序筛选Active Directory用户

        String domain = Properties.Settings.Default.ADConn;
        String user = Properties.Settings.Default.ADAdmin;
        String pass = Properties.Settings.Default.ADPass;

        DirectoryEntry ADEntry = new DirectoryEntry(domain, user, pass);
        DirectorySearcher ADSearcher = new DirectorySearcher(ADEntry);
        ADSearcher.Filter = "(&(objectClass=user)(objectCategory=person))";                        
        SearchResultCollection allResults = ADSearcher.FindAll();            
        foreach (SearchResult result in allResults)
        {
            DirectoryEntry deUser = result.GetDirectoryEntry();

             //....Do stuff here

公司里有很多人,所以有人要求我按字母顺序分割用户,一次处理一个用户块。例如,更改用户[A-G],然后[H-N],然后[O-Z]的属性。我如何修改我的过滤器以提供用户X到Y?

ADSearcher.Filter = "(&(objectClass=user)(objectCategory=person)(sAMAccountName>=X)(sAMAccountName<=Y))";                        

非常感谢你的帮助。