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CHEM 370

UV-visible Spectroscopy (UV-vis)

Table of Contents
  1. Summary
  2. Introduction
  3. Prelab
  4. Safety
  5. Reference

Summary

Objective: Precisely determine the concentration of quinine in tonic water using fluorescence spectroscopy.

Turn in:

  • Your complete lab notebook as a .jl file, functioning with no errors.
  • You complete lab notebook as a static .html file.
  • Your data files.

Student Learning Outcomes:

  • Recall methods of creating standards and standard curves from Quantitative Analysis.
  • Determine the concentration of quinine in an unknown sample, including the 95% confidence interval.
  • Calculate the limits of detection limits of quantitation from a blank sample.
  • Employ a quality control sample to check the accuracy of results.
  • Utilize Pluto (with Markdown) as an electronic lab notebook.
  • Utilize Julia functions to analyze spectroscopic data.

Introduction

This lab will use Vernier SpectroVis Plus UV-visible/fluorescence spectrometers to quantify the amount of quinine in tonic water. You will be given a sample of store-bought tonic water and a concentrated stock solution of quinine. You will then dilute the stock solution to create a standard curve and determine the concentration of quinine in (1) a commercial tonic water sample of unknown concentration and (2) a quality-control sample of known concentration to test the accuracy of your curve. Samples will be measured in triplicate so that you can determine the mean concentration and the 95% confidence interval. The limit of quantitation (LOQ) will be determined from a blank sample. You must get an $R^2$ of >0.9990 for your calibration curve.

Students should work in pairs for the lab activity but turn in independent lab notebooks.

Watch Dr. Fischer teardown a SpectroVis and find out what’s inside!

Prelab

Do the following before coming to lab:

  • Open the lab notebook template and write your title and introduction. (The template can be found in the prelab section of this lab.)
  • Install Vernier Spectral Analysis on your computer.

Safety

  • This lab uses 0.05 M sulfuric acid (SDS). Wear goggles and gloves.
  • Tonic water contains quinine hydrochloride and the stock solution contains quinine sulfate.
  • Although samples are over-the-counter products, you should avoid ingesting and/or contacting them with your skin.

Reference

Lawson-Wood, Kathryn, and Kieran Evans. “Determination of Quinine in Tonic Water Using Fluorescence Spectroscopy,” (Application Note: Fluorescence Spectroscopy) Link

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