Viewed as one of the most significant tools in analytical chemistry, the Nuclear Magnetic Resonance (NMR) is a spectroscopy tool often used by chemists to determine the molecular profile – quality and quantity of the major components - of any given organic substance. Operating on basis of spectroscopy (study of the interaction between matter and radiated energy - Harris), the NMR can be either a one (1H NMR) or two (1H/13C NMR) dimensional spectral analysis that can be used identify and quantify the major components of a given substance by examining spectral patterns that derive from excitation of matter with radiated energy in the form of radio waves. In this experiment we will examine the spectral patterns derived from NMR scans of Red Bull and sugar-free Red Bull energy drinks. By examining the spectral splitting patterns of the major substance components as derived from experimental NMR scans against predicted spectrums, we will be able to identify both the quality and quantity of many of the major components of Red Bull and sugar-free Red Bull. As will be seen, some of the components of the two energy drinks will be identified with minimal difficulty. The experimental concentrations of DMSO, Caffeine and Sodium Citrate were 0.0014 M, 0.0021 M and 0.0017M respectfully for Red Bull and 0.0014 M, 0.0018 M and 0.0019 M, respectfully for Sugar Free Red Bull. The concentrations of the other major components of Red Bull and Sugar Free Red Bull were not obtained because analysis of those compounds required a higher degree of expertise than can be offered for this lab and will be identified by process of comparison, elimination and two dimensional spectral analysis where both protons and carbon 13 are examined to identify and quantify a compound that does not show up on a one dimensional NMR spectrum. This experiment will allow students to gain a better understanding of a Nuclear Magnetic Resonance, including spectra analysis as well as how to use predictive software to predict and confirm the outcome of future NMR scans. Introduction
As with all organic substances, Red Bull and sugar-free Red Bull are made up of certain quantities of unique ingredients. While the exact chemical formula of the “billion dollar” drinks are proprietary and held in secret, an NMR spectral analysis of samples of Red Bull and sugar-free Red Bull can allow us to determine both the identities and quantities of the major components contained in the two drinks. As will be seen in today’s lab the major components of Red Bull energy drink are: Sodium Citrate, Caffeine, Taurine, Glucose and Sucrose. In sugar-free RedBull, the glucose and sucrose are replaced with Aspartame and Acesulfame Potassium.
Before beginning the lab, my lab partner and I discussed the lab with Dana and Amjad. The conversation was extremely helpful as my partner and I experienced little difficulty in setting up the experiment, running and reading the NMR spectra proved to be more challenging that either of us expected. Prior to making the NMR samples the predicted NMR spectra of the major components of Red Bull, sugar free Red Bull and the internal standard of DMSO were obtained from nmrdb.org (Figures 1-8). Figure 1 below details the predicted NMR spectra for Sodium Citrate (Na3C6H5O7). According to the spectra, Sodium Citrate has two major peaks; both with singlet peak patterns, each with an integral of 2.00, indicating that there are a total of 4 1H protons in the Sodium Citrate compound. As indicated by this predicted NMR spectra, the chemical shifts for the peaks should be ~2.92 and ~ 3.00. Figure 1. Predicted NMR Spectra of Sodium Citrate.
Figure 2 below details the predicted NMR spectra for Sodium Caffeine (C8H10N4O2). According to the spectra, Caffeine has three major peaks all having singlet peak patterns. One peak appears at 3.29 ppm and has an integral of 6 which indicates that...