Chloride of which ion is present in Hartmann's solution but absent in Darrow's solution?

• A. Sodium
• B. Potassium
• C. Calcium
• D. Magnesium

Answer: (C)

In intravenous fluid formulations, the specific salts included determine which ion chlorides appear. Hartmann's solution (Ringer’s lactate) includes calcium chloride, so calcium chloride contributes chloride ions associated with calcium. Darrow's solution is formulated without calcium salts, so there is no chloride of calcium in it. Therefore, the chloride of the calcium ion is present in Hartmann's solution but absent in Darrow's solution. Sodium and potassium chlorides are common to many IV fluids as well, and magnesium is not the distinguishing difference here, so the key distinction is calcium.