Gmelin's test explained

Gmelin's test is a chemical test used for detecting the presence of bile pigments in urine. It is named after Leopold Gmelin, who introduced the test.^{[1] [2] [3]} Five millilitres of urine is slowly added to five millilitres of concentrated nitric acid in a test-tube. Different coloured rings between the two layers are visible if bile pigments are present as they are oxidised to various chemical products.^{[4] [5]} Nitric acid is used as the oxidising agent.^[6] Blue, green and violet rings are seen if bilirubin is present.^[7] Gmelin's test is not sensitive, so a positive result always indicates the presence of bile pigments, but a negative result does not exclude the presence of small quantities of bile pigments.^[8]

Notes and References

1. Book: Erwin Kuntz. Hans-Dieter Kuntz. Hepatology: Textbook and Atlas. 11 March 2009. Springer. 978-3-540-76839-5. 11.
2. Book: John Daintith. Derek Gjertsen. A Dictionary of Scientists. 4 March 1999. Oxford University Press. 978-0-19-280086-2. 216.
3. Book: John Daintith. Biographical Encyclopedia of Scientists, Third Edition. 12 December 2010. CRC Press. 978-1-4200-7272-3. 295.
4. Book: Srinivas B Rao. Practical Biochemistry for Medical Students. Academic Publishers. 56.
5. Book: Dandekar. Practicals And Viva In Medical Biochemistry. 1 January 2004. Elsevier India. 978-81-8147-025-6. 47.
6. Book: D M Vasudevan. Textbook of Biochemistry for Medical Students. 2013. JP Medical Ltd. 978-93-5090-530-2. 279.
7. Book: Malhotra. Practical Biochemistry for Students. 1 January 2003. Jaypee Brothers Publishers. 978-81-8061-109-4. 46.
8. Book: A.C. Croftan. Clinical Urinology. Рипол Классик. 978-1-275-01265-3. 123.