### How is biuret assay calculated?

## How is biuret assay calculated?

A more accurate method is to perform a linear regression analysis on the standard curve which will yield the equation for a straight line: y = mx+b. With this equation you can calculate the concentration by entering the absorbance value of each unknown into the equation as the y value and then solve for x.

**How do you calculate protein using biuret method?**

Aim: To estimate the protein using Biuret method.

- Principle: The –CO-NH- bond (peptide) in polypeptide chain reacts with copper sulphate in.
- Pipette out 0.0, 0.2, 0.4, 0.6, 0.8 and 1 ml of working standard in to the series of labeled.
- Make up the volume to 1 ml in all the test tubes.

**How do you calculate protein concentration from absorbance 280?**

Concentration (mg/ml) = Absorbance at 280 nm divided by path length (cm.) Pure protein of known absorbance coefficient. Use the following formula for a path length of 1 cm. Concentration is in mg/ml, %, or molarity depending on which type coefficient is used.

### How do you calculate standard protein concentration?

Plotting a graph with the absorbance value as the dependent variable (Y-axis) and concentration as the independent variable (X-axis), results in an equation formatted as follows: y = ax2 + bx + c, where solving for x determines the protein concentration of the sample.

**What is biuret assay method?**

The biuret method is a colorimetric technique specific for proteins and peptides. Copper salts in alkaline solution form a purple complex with substances containing two or more peptide bonds. Thus, the biuret reaction with proteins is suitable for the determination of total protein by spectrophotometry (at 540–560 nm).

**Why is biuret assay not used?**

The disadvantages include low sensitivity, and that ammonium sulfate can often interfere with color development or generate colored complexes within the sample. This can be minimized by analyzing protein precipitates prior to performing the test.

#### What is the principle of biuret test?

PRINCIPLE: Proteins, in an alkaline medium, bind with the cupric ions present in the biuret reagent to form a blue-violet coloured complex. The intensity of the colour formed is directly proportional to the amount of proteins present in the sample. Total Protein + Cu Violet complex.

**What wavelength do proteins absorb?**

between 275 and 280 nm

Proteins usually show absorption maxima between 275 and 280 nm (Figure 1), which are caused by the absorbance of the two aromatic amino acids tryptophan (Trp) and tyrosine (Tyr) and, to a small extent, by the absorbance of cystine (i.e. of disulfide bonds).

**How do you calculate standard curve?**

Standard Curves To calculate the sample concentration based on the standard curve, first you find the concentration for each sample absorbance on the standard curve; then you multiply the concentration by the dilution factor for each sample.

## What is the Colour of biuret solution?

Reagents and food testing

Food sample | Reagent | Initial colour |
---|---|---|

Reducing sugar | Benedict’s | Blue |

Starch | Iodine | Yellow-brown |

Protein/amino acids | Biuret (a mixture of sodium hydroxide and copper sulfate). | Blue |

Fat | Ethanol | Colourless |

**What is the formula for metric BMI?**

With the metric system, the formula for BMI is weight in kilograms divided by height in meters squared. Since height is commonly measured in centimeters, an alternate calculation formula, dividing the weight in kilograms by the height in centimeters squared, and then multiplying the result by 10,000, can be used.

**How is the body mass index ( BMI ) calculated?**

Body mass index (BMI) is a measure of body fat based on height and weight that applies to adult men and women. Enter your weight and height using standard or metric measures. Select “Compute BMI” and your BMI will appear below.

### How to calculate BMI using a handheld calculator?

When using a handheld calculator, if your calculator has a square function, divide weight (lb) by height (in) squared, multiply by 703, and round to one decimal place. If your calculator does not have a square function, divide weight by height twice, as shown in the calculation above, multiply by 703, and round to one decimal place.

**How to make 1000ml of biuret reagent at home?**

Following are the steps to yield 1000mL of Biuret reagent. Take distilled water (500 ml) and dissolve pentavalent copper sulphate (1.5gm) and sodium potassium tartrate (6gm). Sodium potassium tartrate, a chelating substance that stabilises the copper ions. Now take a volumetric flask and mix two solutions.

How is biuret assay calculated? A more accurate method is to perform a linear regression analysis on the standard curve which will yield the equation for a straight line: y = mx+b. With this equation you can calculate the concentration by entering the absorbance value of each unknown into the equation as the y value…