To determine the concentration of caffeine in a freshly brewed cup of coffee, we will use liquid chromatography LC to analyze the composition of the coffee sample. Here's a step-by-step process:1. Prepare the coffee sample: Collect a sample of freshly brewed coffee and filter it to remove any solid particles. Dilute the sample if necessary.2. Prepare a caffeine standard: Create a series of caffeine standards with known concentrations e.g., 10, 50, 100, 200, and 500 ppm by dissolving pure caffeine in a suitable solvent.3. Perform liquid chromatography: Inject the coffee sample and caffeine standards into the LC system. The LC system will separate the components of the coffee sample and the caffeine standards based on their chemical properties.4. Analyze the chromatograms: Examine the chromatograms generated by the LC system for both the coffee sample and the caffeine standards. Identify the peak corresponding to caffeine in each chromatogram.5. Determine the peak area: Measure the area under the caffeine peak for both the coffee sample and the caffeine standards.6. Create a calibration curve: Plot the peak area of the caffeine standards against their known concentrations. Fit a linear regression line to the data points.7. Calculate the concentration of caffeine in the coffee sample: Use the peak area of the caffeine peak in the coffee sample and the calibration curve to determine the concentration of caffeine in the coffee sample.The concentration of caffeine in a freshly brewed cup of coffee can vary depending on the type of coffee beans, brewing method, and serving size. On average, an 8-ounce 240-milliliter cup of coffee contains approximately 80 to 100 milligrams of caffeine. However, this value can range from 30 to 200 milligrams per cup.