Urinalysis - The Carter Center

Trace - Ring is just perceptible against a black background
1+ - Ring is distinct against a black background, can barely be
seen when held up to the light.
2+ - Ring is very definite against light, fairly visible when viewed
from above
3+ - Ring is heavy against light, distinct cloudiness when viewed
from above.
4+ - Ring is thick and dense against light, opaque when viewed
from above.
The reading is interpreted as in the case of non-ring precipitation
test.
A. Robert's Test
Principle
The principle of this test is based on the precipitation of protein and
formation of white compact ring using concentrated Nitric acid
(HNO 3 ) .
Procedure
1. Place 3-5 ml of clear urine in a test tube.
2. Place the tip of a 5 or 10 ml pipette containing Robert's Reagent to
the bottom of the tube and allow 3 ml of the reagent to lay beneath
the urine.
3. If several tests are being done, wipe off the tip of the pipette before
inserting it into the next tube.
4. A white ring at the zone of contact indicates a positive test.
5. The ring must be read within 3 minutes after adding the reagent,
and with the eyes on the level of the contact ring.
Rings that are 1-2 mm above the zone of contact are due to mucin
and nucleaoalbumin; rings 1-2 cm above the zone of contact are
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