DETERMINATION OF FLUORIDE USING AN ION-SELECTIVE ELECTRODE
PURPOSE
This experiment is designed as a no-risk opportunity to demonstrate competence in calculations and performing the associated dilutions to create a calibration curve with high linearity and high accuracy (as determined by the slope of a linear regression between instrument response vs concentration).
You will then apply the L1NEST function in Excel to calculate the concentration of a sample with unknown concentration.
OUTCOME
This is an open opportunity to practice critical instrumental analytical skills at NO PENALTY.
You will provided with feedback on the composition of your tables and graphs (remember, these always require a caption to describe their contents), as well as your processing of the collected data.
You should strive to have approved calculations and corresponding calibration results before leaving the laboratory.
If you choose, you can complete the calculation of the concentration of the unknown samples along with its uncertainty, to ensure you are utilizing LINEST and the associated calculations correctly. Your write-up will be used to provide you with feedback on tasks you will need to perform in nearly ever) experiment in this course.
EXPERIMENTAL PROCEDURE
All solutions containing NaF should be transferred to plastic bottles and the volumetric flasks rinsed with water as soon as they are prepared. Think about and discuss why this is important with your TA and the Lab Technician.
STANDARDS
You are provided with a stock solution of 100 mg F-IL. Record the actual concentration of this solution and its en-or.
Prepare the 3 standards in 100 mL volumetric flasks using distilled water as diluent at concentrations of 1.0, 5.0, and 10.0 mg/L. Calculate the volumes needed to prepare them first.
Check with the TA or technician to verify these volumes before proceeding. When you are finished preparing the standards inform the TA or Technician. They will provide additional training on top of the instructions below on how to take the ion-selective electrode (mV) measurements.
FLUORIDE MEASUREMENTS
Before you start, please be aware that these electrodes are VERY DELICATE. Take extreme at all times when handling this electrode.
