Determination of isopropanol (isopropyl alcohol)

Isopropanol (C ₃ H ₇ OH, isopropyl alcohol) is used in industry and clinical laboratory diagnostics as a solvent. It is less toxic than methanol and ethylene glycol.

Isopropanol poisoning is not often observed in clinical practice. When ingested, isopropanol is quickly absorbed and metabolized by alcohol dehydrogenase to form acetone, CO ₂ and water. The half-life of isopropanol is approximately 3 hours, a lethal dose is considered to be 250 ml. The clinical picture of poisoning is manifested by dizziness, slurred speech, headache, nausea, vomiting, abdominal pain, hemorrhagic gastritis, diarrhea, ataxia, arterial hypotension, stupor and coma. Bradycardia, rhabdomyolysis and hemolysis then develop. The concentration of isopropanol in the blood above 40 mg% is regarded as severe intoxication, at a concentration above 100 mg% coma develops, a concentration above 350 mg% is considered lethal. Severe metabolic acidosis and a high anion gap often accompany isopropanol poisoning, but are not specific. Lactic acidosis and high acetone concentrations in the blood and urine are characteristic. The presence of acetone in the blood and urine, especially in high concentrations, in comatose patients suggests isopropanol poisoning.

Methanol, ethylene glycol, and isopropanol are metabolized similarly to ethanol and also cause metabolic acidosis, although the actual metabolic products of these alcohols are different.

Characteristics of the toxic effects of various alcohols

Alcohol	Metabolites	Acidosis	Ketosis	Clinical manifestations
Ethanol Ethylene glycol Methanol Isopropanol	Acetaldehyde Glycolaldehyde Glyoxal Formaldehyde Formate Acetone	+++ ++-	+ - - ++	Alcoholic ketoacidosis Renal failure Blindness Hemorrhagic tracheobronchitis, gastritis

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