The PocketChem BA PA-4140 is a handheld meter with separate printer unit and you can determine ammonium from whole blood in a simple way.
Requires 20 ?l of whole blood.
Dimensions: 124 (W) x 85 (D) x 38 (H) mm and 150 g weight.
You can test anywhere using 2 AA batteries and/or AC adapter.
Uses reactive strips without any pretreatment.