Is It Possible Approve PO/Req using mobile device (SmartPhones and Tablets)

Hi Everybody,

For some years our Executives had approved the PO and Reqs using email notifications inside our LAN environment.  But in the last days most of them not using pc or laptops any more, but smartphone and tablets.

I would like to know if there are some apps which allow to approve these notifications from emails using this kind of mobile devices.

Thanks in advance for your help.

JorSan