Evaluation of the turbidity and thin layer chromatographic tests for detection of castor oil

Detection procedures for castor oil in genuine and treated groundnut oils were screened and false turbidity was noticed when ammonium molybdate/sulfuric acid reagents were added to rancid groundnut oil. Successively bleached and neutralized rancid groundnut oil samples do not respond to the tests. Turbidity did not appear for groundnut oils containing 10 and 20% castor oil and even for pure castor oil sample. Thin layer chromatography (TLC) was found to be quite effective for most of the treated, adulterated, genuine, old and fresh oil and fat samples, but showed a streaking, when applied to rancid groundnut oil. However, streaking could be greatly reduced and TLC could be successfully performed with bleached and neutralized, rancid groundnut oil samples.