The 30-year-old Somdev, who also came into the main draw of the event through Qualifiers, lost 1-6 6-3 4-6 to Donaldson, 12 years younger than the Indian.
After a sluggish start, Somdev came back well to force a decider but the young American cashed in on the lone break he got to make it to the second round of the USD 659,070 hard court event.
Somdev broke his rival only once in the match.
Somdev did not get any ranking point but pocketed USD 6050.