Testing for simple sugars: Benedict's Reagent

Left to right: Benedict's reagent (BnR), potato extract + BnR, onion extract + BnR, 5% glucose + BnR.

RESULTS: Aqua-blue to green = negative.
Yellow to orange = positive. Note: this test cannot detect the simple sugar sucrose.

Testing for starch: Lugol's Iodine

Left to right: Lugol's iodine (LI), starch solution, starch solution + LI.

RESULTS: Yellow-orange = negative.
Purple-black = positive.

Testing for proteins: Biuret's Reagent

Left to right: Biuret's reagent (BrR), water + BrR, egg albumin solution, egg albumin solution+ BrR.

RESULTS: Denim-blue = negative. Lavender = positive.

Terminology review: Controls

Water plus Biuret's reagent is a negative control for the protein test. It demonstrates a negative test result (no protein present).

Egg albumin plus Biuret's reagent is a positive control for the protein test. It demonstrates a positive test result (protein is present).

How would you set up similar controls for the other chemical tests?