Analysis of Caffeine in Coffee Kate Penrod, Nikki DeLuca, Christina Robinson, and Jess Bases

Analysis of Caffeine in Coffee

Kate Penrod, Nikki DeLuca, Christina Robinson, and Jess Bases

Purpose

• Quantify caffeine in brewed coffee– Varying strengths

• Extract caffeine from grounds

• Maxwell House: Regular and Decaf.

Background

• Caffeine in food/drink• CNS stimulant• Schedule V drug• High levels– Restlessness– Irritability– Headaches– Heart complications

Methods

• HPLC– Liquid

• Separation– Liquid

• IR– Solid and liquid

• SFE – Solid

• UV/Vis– Disabled

HPLC

• Hypothesis• Samples– 10-50ppm caffeine standards– Strong caffeinated/decaffeinated– Regular caffeinated/decaffeinated– Weak caffeinated/decaffeinated

• Dilution of coffee samples

Sample Conc [ppm] Retention Time Area

Standard 10 2.346 1026491

Standard 20 2.323 1360973

Standard 30 2.314 1612710

Standard 40 2.305 1915989

Standard 50 2.302 2330806

Weak DC 1:2 46.55369153 2.266 1436697

Reg DC 1:5 77.88165933 2.293 1193080

Str DC 1:5 227.381635 2.283 2139010

Weak C 1:5 180.6469498 2.294 1843306

Reg C 1:10 321.8074968 2.313 1718385

Str C 1:25 548.2456002 2.310 1394082

Organic Separation• Sample Preparation (Dr. Peterman’s Coffeemaker) – Regular Caffeinated/ Decaffeinated

• 1 Tbsp. grounds, ¾ cup water

– Strong Caffeinated/ Decaffeinated• 3/2 Tbsp. grounds, ¾ cup water

– Weak Caffeinated/ Decaffeinated • ½ Tbsp. grounds, ¾ cup water

Organic Separation• First Method– Adapted from Dr. Halligan’s Organic I Lab Manual– Extraction of Caffeine using

Dichloromethane– Large emulsion layer,

not a clear separation

Organic Separation• Revised Method– Added Na2CO3 which increased

caffeine’s solubility in aqueous layer– Separation layer more pronounced– Dried with Anhydrous MgSO4

– Vacuum under reduced pressure

Mass QuantificationAppearance Mass of Product

Regular Caffeinated Yellow/brown liquid 0.2753g

Weak Caffeinated Light brown liquid 0.2731g

Strong Caffeinated Yellow/ brown solid, black spots

0.2892 g

Regular Decaffeinated Yellow/brown liquid 0.2006 g

Weak Decaffeinated Light brown liquid 0.2001g

Strong Decaffeinated Yellow/ brown liquid 0.2296 g

Extracted Caffeine IR Characterization

Substituted Alkene

Extracted Caffeine IR Characterization

Strong DecaffRegular Decaff

Weak Decaff

C = N

C = O

O – H stretchC = N

C = O

Substituted Alkene

Substituted Alkene

C = O

C = N

O – H stretch

CH3C - N

Substituted Alkene

Extracted Caffeine IR Characterization

Strong Caffeinated Regular Caffeinated

C = O

C = N

O – H stretch

CH3C - N

Substituted Alkene

C = O

C = N

O – H stretch

CH3

C - N

Substituted Alkene

Substituted Alkene

C - NCH3

C = NO – H stretch

Weak Caffeinated

The Devil’s Instrument a.k.a. SFE

The Devil’s Instrument a.k.a. SFE

• 4 Samples– “Pure” coffee grounds– Post brewing coffee grounds

• 1 gram of each sample• 10 minute runs• End mass indications• IR results

SFE DataSample Percent Yield

Pure Caffeinated 5.186 %

Pure Decaf. 6.286 %

Brewed Caffeinated 1.185 %

Brewed Decaf. 3.576 %

SFE Extraction IR Analysis

UV/Vis

• Attempted to use the DRA-600– Solid Analysis

• Missing part!• Call EVERYONE– Manufacturer– Distributor– Delivery Guy

• Piece was backordered until May 20th

• Put on hold INDEFINITELY.

Sources of Error

• Organic Method– Impure caffeine for mass quanitification– Transfer between different glassware– Incomplete drying in extraction (O-H stretch peak)

• HPLC– Day 1: Low pressure, purge lines– Day 2: Invalid date/time error, inconsistent– Day 3: Consistent results, ran all samples

Sources of Error (Part 2)

• SFE– Leaks in the line– Issues with the amount of sample– Needed constant supervision

• UV/Vis– Missing part– Phone tag– Wasted 2 whole lab periods

Sources of Error (Part 3)

Jerry Sainsbury – Sales RepresentativeThermo Fisher Scientific

Conclusions• HPLC:

• Strong decaf. was comparable to weak caf.• Weak and regular brews – 4:1 caf. vs. decaf.• Strong brew – 5:2 caf. vs. decaf.

• Organic Method:• Qualitative data• Erroneous quantitative data• Masses very similar

• SFE:• Low percent yields• Higher yield from decaf

• Did not extract pure caffeine• May be caffeine plus side products

• If UV/Vis hadn’t been in the initial method, further research would have been conducted

Further Research

• Organic Method– Develop a new or revised method to extract pure

caffeine in its solid form as was done in Dr. Halligan’s Organic I Lab

• IR– Analyze liquid only– Create calibration curve

• HPLC– Compare different coffee makers and brands

Further Research (Part 2)

• SFE– Brew remaining grounds, analyze with HPLC– Determine other components of extracted

grounds• UV/Vis– Obtain calibration disc and sample holder– Develop SOP for DRA-600