If a protein has a MW of about 25,000 daltons, how many drops should it elute in? our lab was MW cut off of 150,000 daltons. How do I determine this????

To determine the number of drops in which a protein elutes, you need to estimate the volume of each drop. Here's how you can calculate it:

1. Convert the molecular weight (MW) of the protein from daltons to grams.
- In this case, the protein has a MW of 25,000 daltons.

2. Determine the molecular weight of the MW cutoff.
- In this case, the MW cutoff is 150,000 daltons.

3. Calculate the volume of solution that would contain the MW cutoff amount of protein.
- Divide the MW cutoff by the MW of the protein: 150,000 daltons / 25,000 daltons = 6.

However, we need to be cautious in applying this calculation directly to determine the number of drops because there are other factors that can influence the elution volume, such as the specific chromatography column being used, the buffer composition, and the flow rate.

Here is an alternative method to estimate the elution volume:

1. Determine the ratio of the protein's MW to the MW cutoff.
- In this case, 25,000 daltons / 150,000 daltons = 0.1667.

2. It is reasonable to assume that the elution volume will be around 6 times the column bed volume. We can use this assumption as a rough estimate.

3. Calculate the elution volume by multiplying the column bed volume by the ratio calculated in step 1.
- Let's assume the column bed volume is 1 mL. Therefore, the elution volume would be approximately: 1 mL * 0.1667 = 0.1667 mL.

Now, to determine the number of drops that corresponds to the elution volume, you need to know the volume of each drop. Usually, the number of drops per milliliter is provided by the manufacturer, and it can vary depending on the size of the dropper or pipette used. Suppose you have this information—let's say there are 20 drops per milliliter.

4. Multiply the elution volume by the number of drops per milliliter to estimate the number of drops.
- In this case, 0.1667 mL * 20 drops/mL = 3.33 drops.

Since you cannot have a fraction of a drop, you would round this number up to 4 drops.

Remember, these calculations are rough estimates and may vary depending on the specific experimental conditions.