Essay About Benzoic Acid Cas And Retention Time

Instrumental Analysis
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HPLC By: Steven Parra, Lab Partner: Leo Garbar.Completed on 11/15/10, Due 11/29/10.Introduction:High performance liquid chromatography is a useful analytical tool that allows for the separation, identification, and quantification of many different organic compounds. A HPLC system consists of a column that is filled with a stationary phase that can be ether polar or non-polar.  This stationary phase is attractive to what is being passed through the column in the mobile phase. The retention time is the amount of time it takes the sample to run through the column, different compounds will have different retention times and therefore the identity of the compound of can be determined. Changes to the mobile phase as well as stationary phase will allow the separation of compounds even if they elute at the same times. Objective:To determine the amount of additives in diet soda and energy drinks by HPLC. To determine the amount of caffine in teas. To determine the parameters that affects the separation of compounds by HPLC. To use propagation of error to determine accuracy of prepared standards.Equipment: ThermoFisher Modular Spectra HPLC system, ChromeQuest 5.0 software to control instrument, Rheodyne Injection valve with 20-L loop, Xterra RP 18 column.Reagents:Methanol CAS #: 67-56-1Caffine CAS #: 58-08-2Benzoic acid CAS #: 65-85-0Acetaminophen CAS #: 103-90-2Acetic acid CAS #: 64-19-7Acetylsalicylic acid CAS #: 50-78-2I have read and understand the MSDS sheets for these compounds.Chemical Reactions: None.Data:Chromatograph for Black tea[pic 1]Chromatograph for green tea[pic 2]Chromatograph for Energy drink [pic 3]Chromatograph for Diet Soda[pic 4]Table of data for runs. Sample Retention time for caffeine  (min)Retention time for benzoic acid (min)Peak area caffeine Peak area Benzoic acid W(1/2) Caffine W(1/2)Benzoic acidEnergy drink 2.247.4590601014014653294782438Diet soda 2.237.4212649311474130744077867135Green tea 2.297.47125788826037399341531Black tea2.257.39193071047758113571128092Table of values for sample runs standardRetention time Peak areaCapacity factor (k)Height of plates (H)Number of plates (N)Selectivity factor (α)Caffeine 2.2525009421.0091.13×10131.29×10-113.33Benzoic acid7.503694115.692.27×10106.59×10-9.3[pic 5]Graph of benzoic acid standard.   [pic 6][pic 7]Graphs provided courtesy of Dr. Hall. Diet soda sampleSample name Caffeine Conc. (ppm)Caffeine Conc. (mg/L)Benzoic acid Conc. (ppm)Benzoic acid Conc. (mg/L)Coca-Cola brand: Diet Coke 125.73125.73437.00437.00Energy drink sampleSample name Caffeine Conc. (ppm)Caffeine Conc. (mg/L)Benzoic acid Conc. (ppm)Benzoic acid Conc. (mg/L)FRS Healthy energy 89.8189.8136.4536.45Amount of caffeine in the green and black teasSample Caffeine Conc. (ppm)Total mass of caffeine per tea bag (%)Nestlé green tea 249.332.05Lipton black tea192.311.26Caffeine and Benzoic acids formula and interactions when being passed through the HPLC column.