Even as some experts raised eyebrows over the efficacy of the nitric acid test in detecting argemone presence in mustard oil, the government insisted on Wednesday that it continues to be a "fairly dependable and handy" guide for testing the quality of mustard oil. Delhi government officials, in the wake of reports on vanaspati samples testing positive for argemone oil in the nitric acid test, had said on Tuesday the test had its limitations and was not conclusive, especially for testing vanaspati.