The question is whether blood levels can be determined by urine test strips, correct?
Frankly, I don't see how. Vitamin C only "spills" into the urine when blood levels exceed 1.5 mg/dl, otherwise there is a kidney pump that recirculates vitamin C.
We have found that certain glucose meters can measure vitamin C levels in the blood, at least very high levels that occur with "mega doses" of vitamin C.
Owen R. Fonorow, Orthomolecular Naturopath