Question

In our lab using a bradford assay to determine the protein content of a milk sample, we made a standard curve using 25, 100, 250, and 500 ug/ml bsa and we had a linear equation y=0.0038x-0.0172 (y is adjusted ab 595 nm reading, x is the concentration ) to fit the curve with r2=0.9997. we then tested our diluted milk sample (100 dilution) in triplicates. the uv595 nm reading of our milk sample were 0.238, 0.245, 0.236, and the average absorption reading of total blank was 0.061. what is average protein content in our milk sample in mg/ml (4points)? what is confidence interval for our protein data at 95% certainty? (t value=4.30 at degree of freedom of 2 and 95% certainty)

Answer 1

The average protein content in the milk sample is calculated using the standard curve equation, with an adjustment for the blank's absorbance. The 95% confidence interval is computed using the average protein concentration, the standard deviation, the t-value, and the number of replicates.

Step-by-step explanation:

The average protein content in the milk sample can be calculated using the given linear equation of the standard curve (y=0.0038x-0.0172), where y represents the adjusted absorbance at 595 nm, and x represents the concentration of the protein. To determine the average protein concentration, we first calculate the average absorbance of the milk sample by subtracting the average absorbance reading of the total blank from each of the milk sample readings, then averaging the adjusted results. Once we have the average adjusted absorbance, we can insert it into the standard curve equation to solve for x (the protein concentration in µg/ml). After calculating the concentration for the diluted sample, we multiply by the dilution factor (100) to find the concentration in the original milk sample.

To find the 95% confidence interval for our protein data, we utilize the average protein concentration, the standard deviation of the adjusted absorbance readings, the t-value (4.30 for a degree of freedom of 2), and the sample size (number of triplicates). The confidence interval provides a range in which the true protein concentration of the sample is likely to fall with 95% certainty. The confidence interval is calculated by taking the average protein concentration and adding and subtracting the value of the t-value multiplied by the standard deviation divided by the square root of the sample size.