Short Note a) Test for uric acid b) Test for redusing sugars c) Benzidine test

• Uric acid blood test, also known as a serum uric acid measurement, determines how much uric acid is present in your blood.
• Uric acid is a chemical produced when your body breaks down foods that contain organic compounds called purines.
• The uric acid blood test is used to detect high levels of this compound in the blood in order to help diagnose gout.
• The test can help determine how well your body produces and removes uric acid.
• A uric acid test is most often used to:

1. Help diagnose gout
2. Help find the cause of frequent kidney stones
3. Monitor the uric acid level of people undergoing certain cancer treatments.
4. Chemotherapy and radiation therapy can cause high levels of uric acid to go into the blood.

• A uric acid test can be done as a blood test or a urine test.

1. During a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial.
2. For a uric acid urine test, you'll need to collect all urine passed in a 24-hour period. This is called a 24-hour urine sample test. Your health care provider or a laboratory professional will give you a container to collect your urine and instructions on how to collect and store your samples.

• Non-reducing sugars are sugars whichdo not have an aldehyde functional group- the reducing species. As non-reducing sugars do not have the aldehyde group, they cannot reduce copper (I) (blue) to the copper(II) (red).
• Principle of Benedict's Test is:The monosaccharide products of hydrolysis are reducing sugars i.e. have the aldehyde functional group and can reduce copper in the presence of alkali  producing the colour changes.
• Benedict's reagent is  to test for  reducing sugar: glucose. Benedict's reagent starts out aqua-blue. As it is heated in the presence of reducing sugars, it turns yellow to orange. The "hotter" the final color of the reagent, the higher the concentration of reducing sugar.
• Benzidine Test:
  
• It is a sensitivetestfor the presence of blood (as in urine or feces) based on the production of a blue color upon contact with a solution of benzidine, hydrogen peroxide, and glacial acetic acid.

Hey!

Test for uric acid :-

This test measures the amount of uric acid in your blood or urine. Uric acid is a normal waste product that's made when the body breaks down chemicals called purines. Purines are substances found in your own cells and also in some foods. Foods with high levels of purines include liver, anchovies, sardines, dried beans, and beer.

Most uric acid dissolves in your blood, then goes to the kidneys. From there, it leaves the body through your urine. If your body makes too much uric acid or doesn't release enough into your urine, it can make crystals that form in your joints. This condition is known as gout. Gout is a form of arthritis that causes painful inflammation in and around the joints. High uric acid levels can also cause other disorders, including kidney stones and kidney failure.

Other names: serum urate, uric acid: serum and urine.

Test for redusing sugar:-

Benedict’s Test is used to test for simple carbohydrates. The Benedict’s test identifies reducing sugars (monosaccharide’s and some disaccharides), which have free ketone or aldehyde functional groups. Benedict’s solution can be used to test for the presence of glucose in urine.

Some sugars such as glucose are called reducing sugars because they are capable of transferring hydrogens (electrons) to other compounds, a process called reduction. When reducing sugars are mixed with Benedicts reagent and heated, a reduction reaction causes the Benedicts reagent to change color. The color varies from green to dark red (brick) or rusty-brown, depending on the amount of and type of sugar.

Benedict's Test

Benedict’s quantitative reagent contains potassium thiocyanate and is used to determine how much reducing sugar is present. This solution forms a copper thiocyanate precipitate which is white and can be used in a titration. The titration should be repeated with 1% glucose solution instead of the sample for calibration.

Principle of Benedict’s Test

When Benedict’s solution and simple carbohydrates are heated, the solution changes to orange red/ brick red. This reaction is caused by the reducing property of simple carbohydrates. The copper (II) ions in the Benedict’s solution are reduced to Copper (I) ions, which causes the color change.

The red copper(I) oxide formed is insoluble in water and is precipitated out of solution. This accounts for the precipitate formed. As the concentration of reducing sugar increases, the nearer the final colour is to brick-red and the greater the precipitate formed. Sometimes a brick red solid, copper oxide, precipitates out of the solution and collects at the bottom of the test tube.

Sodium carbonate provides the alkaline conditions which are required for the redox reaction. Sodium citrate complexes with the copper (II) ions so that they do not deteriorate to copper(I) ions during storage.

Complex carbohydrates such as starches DO NOT react positive with the Benedict’s test unless they are broken down through heating or digestion (try chewing crackers and then doing the test). Table sugar (disaccharide) is a non-reducing sugar and does also not react with the iodine or with the Benedict Reagent. Sugar needs to be decomposed into its components glucose and fructose then the glucose test would be positive but the starch test would still be negative.

Benzidine test :-

Benzidine (trivial name), also called 1,1'-biphenyl-4,4'-diamine (systematic name), is an organic compound with the formula (C6H4NH2)2. It is an aromatic amine. It is a component of a test for cyanide. Related derivatives are used in the production of dyes. Benzidine has been linked to bladder and pancreatic cancer. Benzidine is prepared in a two step process from nitrobenzene. First, the nitrobenzene is converted to 1,2-diphenylhydrazine, usually using iron powder as the reducing agent. Treatment of this hydrazine with mineral acids induces a rearrangement reaction to 4,4'-benzidine. Smaller amounts of other isomers are also formed.The benzidine rearrangement, which proceeds intramolecularly, is a classic mechanistic puzzle in organic chemistry.

The conversion is described as a [5,5]sigmatropic reaction.

In terms of its physical properties, 4,4'-benzidine is poorly soluble in cold water but can be recrystallized from hot water, where it crystallises as the monohydrate. It is dibasic, the deprotonated species has Ka values of 9.3 × 10−10 and 5.6 × 10−11. Its solutions react with oxidizing agents to give deeply coloured quinone-related derivatives.

Conversion of benzidine to the bis(diazonium) salt was once an integral step in the preparation of direct dyes (requiring no mordant). Treatment of this bis(diazonium) salt with 1-aminonaphthalene-4-sulfonic acid gives the once popular congo red dye. In the past, benzidine was used to test for blood. An enzyme in blood causes the oxidation of benzidine to a distinctively blue-coloured derivative. The test for cyanide relies on similar reactivity. Such applications have largely been replaced by methods using phenolphthalein/hydrogen peroxide and luminol.

Good luck!