Why Test for Ketones?
In recent years, ketosis has become a familiar term due to the low carb Ketogenic diet, but ketones have been known by healthcare professionals and those with diabetes well before this diet was widely recognized. Ketones are water-soluble molecules produced by the liver and formed by fatty acids when the body cannot produce enough insulin to convert glucose to energy your body needs. Essentially, ketones are an alternative fuel source, when there is not enough sugar or glucose, that breaks down fat to support your metabolism and muscle functions.
For those with diabetes, especially Type 1, ketone testing is vital for the individual’s health and safety since the body cannot properly regulate insulin, glucagon, and other hormones. This can lead to dehydration and change the chemical balance of one’s blood making it more acidic which can induce a coma or death. Measuring ketone production can be accomplished through a urine test or blood meter, which is considered the gold standard for testing.
Why Test for Aldehydes?
Aldehydes can be found in both natural and anthropogenic sources and are used in a variety of everyday materials for preserving, flavoring, embalming as well as germicides, fungicides, and insecticides used to protect plants and vegetables. When under acidic conditions, the aldehyde is oxidized into a carboxylic acid, but when oxidized under alkaline conditions, a salt of carboxylic acid can form.
It is important to test for aldehydes as they are generally considered toxic to humans and can be harmful to physiological processes leading to DNA damage, protein modification, and enzyme inactivation.
What is the Difference Between Aldehydes and Ketones?
Aldehydes are similar to ketones, except this compound is readily oxidized since a hydrogen atom is present in the double carbon-oxygen bond making it a strong reducing agent. If there is not at least one hydrogen atom present, the compound is known as a ketone. A common way to distinguish between an aldehyde and a ketone is known as the 2,4- dinitrophenylhydrazine test to achieve qualitative organic analysis.
How is the 2,4-Dinitrophenylhydrazine Test used to Identify Aldehydes and Ketones?
2,4-Dinitrophenylhydrazine has a benzene ring, a hydrazine group and two nitro groups. Testing to identify aldehydes or ketones with 2,4- dinitrophenylhydrazine (DNPH), or also known as Brady’s reagent, is a convenient way to separate mixture components between aldehydes and ketones. DNPH is used to detect any carbonyl group(-CO) present in the organic compound.
If an aldehyde or ketone is present a yellow, an orange or reddish-orange precipitate of the dinitrophenylhydrazine appears. When these compounds are brought to their melting point, this confirms the carbonyl compound.
How to Prepare Brady’s Reagent Used In The Test for Aldehydes and Ketones?
Brady’s reagent is a red to orange solid of DNPH, methanol, and sulfuric acid that reacts with carbonyl compounds such as aldehydes and ketones and produces coloured precipitate. It is very sensitive to friction and shock, so it is usually supplied wet to avoid the risk of explosion. A positive test is signaled by a yellow precipitate, for aliphatic carbonyls, or red to orange precipitate, for aromatic carbonyls. The sharp melting point of these precipitates indicates the presence of carbonyl compounds.
How can you Identify a Specific Unknown Aldehyde or Ketone?
When looking to identify an unknown aldehyde or ketone, one should examine its physical properties, perform a functional group test like DNPH and check the compound’s melting points against other known compounds.
How can Chem Service help in your testing for ketones and aldehydes?
Chem Service provides analytical standards which can be used in tests for ketone and aldehydes. DNHP is on sale the entire month of June 2021. For more information on all Chem Service testing options give us a call at 1-800-452-9994 to discuss your aldehyde or ketone analytical standards needs with our seasoned staff.
Sources:
- Admin. “2,4 DNP Test (2,4-Dinitrophenylhydrazine).” BYJUS, BYJU’S, 26 Mar. 2021, byjus.com/chemistry/2-4-dinitrophenylhydrazine/.
- Brown, William H. “Aldehyde.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 2008, www.britannica.com/science/aldehyde/Other-carbonyl-compounds-of-industrial-use.
- Clark, Jim. “Oxidation of Aldehydes and Ketones.” Chemistry LibreTexts, Libretexts, 13 Sept. 2020, chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Aldehydes_and_Ketones/Reactivity_of_Aldehydes_and_Ketones/Oxidation_of_Aldehydes_and_Ketones.
- “Identification of an Unknown: Alcohols, Aldehydes, and Ketones.” People.chem.umass.edu, University of Massachusetts, people.chem.umass.edu/mcdaniel/chem269/experiments/aak/procedure.pdf.
- “Identification of Unknown Aldehydes and Ketones.” Jove, Jove, www.jove.com/science-education/11222/identification-of-unknown-aldehydes-and-ketones#:~:text=When%20a%20non%2Daromatic%20ketone,react%20with%20alcohols%20or%20esters.
- “Ketones.” Diabetes Education Online, dtc.ucsf.edu/types-of-diabetes/type2/understanding-type-2-diabetes/how-the-body-processes-sugar/ketones/.
- Libretexts. “Nomenclature of Aldehydes & Ketones.” Chemistry LibreTexts, Libretexts, 16 Dec. 2020, chem.libretexts.org/Bookshelves/Organic_Chemistry/Supplemental_Modules_(Organic_Chemistry)/Aldehydes_and_Ketones/Nomenclature_of_Aldehydes_and_Ketones.
- O’Brien, Peter & Siraki, Arno & Shangari, Nandita. (2005). Aldehyde Sources, Metabolism, Molecular Toxicity Mechanisms, and Possible Effects on Human Health. Critical reviews in toxicology. 35. 609-62. 10.1080/10408440591002183.
- SingleCare Team Apr. “What Are Ketones, and Why Are They Dangerous?” Single Care, 17 Apr. 2020, www.singlecare.com/blog/what-are-ketones/.
- Simek, William. “Identification of an Unknown Aldehyde or Ketone.” Blogs.nvcc.edu, Northern Virginia Community College, blogs.nvcc.edu/wp-content/blogs.dir/683/files/2016/05/46_unknown_carb.pdf.
