My Iphone 4 will not sync to itunes because "iTunes cannot sync apps installed to the iPhone because the apps installed on the Iphone could not be determined"
had a look around for you and came across this
try restarting ther phone
To restart iPhone, first turn iPhone off by pressing and holding the Sleep/Wake button until a red slider appears. Slide your finger across the slider and iPhone will turn off after a few moments.
Next, turn iPhone on by pressing and holding the Sleep/Wake button until the Apple logo appears
the only other suggestion was turning icloud backup off