Penentuan Kadar Fosfat dengan metode Spektrofotometri Visibel

Introduction

This tutorial provides a step-by-step guide on determining phosphate levels using the visible spectrophotometry method. This technique is essential in various fields, including environmental monitoring and water quality assessment, making it a valuable skill for researchers and technicians.

Step 1: Prepare the Samples

• Collect water samples that need to be analyzed for phosphate concentration.
• If necessary, filter the samples to remove any particulate matter that may interfere with the measurements.
• Prepare standard phosphate solutions to create a calibration curve.

Step 2: Create Calibration Standards

• Prepare a series of phosphate standards with known concentrations. This can be achieved by diluting a stock solution of phosphate.
• Ensure you have at least five different concentrations to establish a reliable calibration curve.
• Label each standard clearly for easy identification during measurement.

Step 3: Measure Absorbance Using Spectrophotometer

• Turn on the spectrophotometer and allow it to warm up as per the manufacturer's instructions.
• Set the wavelength to the appropriate value for phosphate analysis, typically around 880 nm.
• Measure the absorbance of each standard solution one by one:
  • Rinse the cuvette with the standard solution and fill it.
  • Place the cuvette in the spectrophotometer and record the absorbance.
• Repeat this process for all standard solutions.

Step 4: Plot the Calibration Curve

• Using the absorbance data obtained from the standards, plot a graph with concentration on the x-axis and absorbance on the y-axis.
• Draw a best-fit line through the data points; this line will be used to determine the concentration of phosphate in your sample.

Step 5: Analyze Sample Absorbance

• Measure the absorbance of your prepared water sample using the same method as the standards.
• Ensure that the cuvette is clean and free from scratches, as these can affect readings.

Step 6: Determine Phosphate Concentration

• Use the calibration curve to find the concentration of phosphate in your sample:
  • Locate the absorbance value of your sample on the y-axis.
  • Draw a horizontal line until it meets the calibration curve, then drop down to read the corresponding concentration on the x-axis.
• Record the phosphate concentration.

Conclusion

In this tutorial, you learned how to determine phosphate levels using visible spectrophotometry. Key steps include preparing samples, creating calibration standards, measuring absorbance, and using a calibration curve to find concentrations. This method is widely applicable in environmental analysis, making it a valuable technique for ensuring water quality. Consider practicing these steps with real samples to gain confidence and precision in your measurements.