Good day!

It is possible to quantify protein using a **Nanodrop** or **Biodrop**; however, the buffer you are using, particularly the presence of **bromophenol blue**, could interfere with accurate quantification.

Here are some considerations:

### 1. **Using Nanodrop for Protein Quantification**:

- The **Nanodrop** can measure protein concentration at **280 nm**, which detects the absorbance of aromatic amino acids (tryptophan, tyrosine, and phenylalanine).

- If your buffer contains bromophenol blue or other interfering components (like detergents, reducing agents), this may absorb at the same wavelength or cause light scattering, leading to inaccurate readings.

### 2. **Impact of Bromophenol Blue**:

- **Bromophenol blue** absorbs strongly at wavelengths below 600 nm, especially around 590 nm. Although it doesn’t absorb directly at 280 nm, it can still interfere with the measurement by affecting the baseline or creating background noise.

- To overcome this, you can run a blank measurement with the same buffer (containing bromophenol blue) to try and subtract its absorbance, but this may not completely solve the issue.

### 3. **Alternative Quantification Methods**:

- **Bradford Assay**: This method uses **Coomassie Brilliant Blue** to bind to proteins, and it’s less sensitive to bromophenol blue interference. It can give you more accurate results with such buffers.

- **BCA Assay**: This is another colorimetric assay where you can measure absorbance at 562 nm. The BCA assay is less affected by bromophenol blue, though components in your buffer may still cause interference.

- **Lowry Assay**: A more sensitive method that might give accurate readings depending on buffer components.

### Recommendations:

- If bromophenol blue is necessary in your buffer, consider **dialyzing** the protein sample to remove interfering components before using the Nanodrop for quantification.

- Alternatively, you could switch to a buffer without bromophenol blue or use a protein quantification method less affected by the buffer, like the **Bradford** or **BCA** assays.

Thank you Raghad Mouhamad

you would need a colorimeter not calorimeter, but a host of background data and calibration curves.

so, prepare a serial dilution for the calibration curve and measure it via colorimeter or even refractive index. you will have very little signal for UV.