To determine the concentration of caffeine in a given sample of coffee extract using liquid chromatography, you will need to follow these steps:1. Prepare a series of standard solutions with known concentrations of caffeine. These solutions will be used to create a calibration curve.2. Inject each standard solution into the liquid chromatograph and record the peak area or height for each concentration.3. Plot the peak area or height against the concentration of caffeine in each standard solution. This will create a calibration curve.4. Inject the coffee extract sample into the liquid chromatograph and record the peak area or height for caffeine.5. Use the calibration curve to determine the concentration of caffeine in the coffee extract sample. Locate the peak area or height of the sample on the y-axis, and find the corresponding concentration on the x-axis.6. Convert the concentration to parts per million ppm if necessary. To do this, use the formula:ppm = concentration in mg/L 1,000 Without specific data on the peak areas or heights and the calibration curve, it is impossible to provide an exact concentration of caffeine in the coffee extract sample. However, by following these steps, you can determine the concentration of caffeine in your sample using liquid chromatography.