Separation and Identification of Organics from an Aqueous/Organic Environment through Physical Manipulation

Separation and Identification of Organics from an Aqueous/Organic Environment through Physical Manipulation
Date Lab Performed: Nov. 11/2013
Date Lab Submitted: Nov. 18/2013

Introduction
We conducted this experiment to investigate the technique of liquid / liquid extraction, the miscibility of organics and water and the effect of a mixture of compounds in methylene chloride versus pure compounds retention time as introduced to a Gas chromatograph. From this information, the identity of the compounds can be determined.
GC delivery psi: 60
Carrier Gas 1: 3.5 kg/cm2
Carrier Gas 2: 0.75 kg/cm2
Porapak Q 80/100 6’X1/855 79434 10.21.88 Supelco

Method
We rinsed a separatory funnel with tap and then deionized water, then poured our unknown sample into the top (ensuring that the stopcock was closed). We rinsed the beaker with methylene chloride and poured the rinsing into the separatory funnel. We added 10 mL of methylene chloride to the separatory funnel from a graduated cylinder. We greased the ground glass stopper with silicone grease and stoppered the separatory funnel. We then inverted it, swirling gently and venting often by opening the stopcock towards a fumehood. We repeated this process several times until the amount of gas escaping had diminished. We placed the separatory funnel into an iron ring we had attached to a retort stand on the benchtop and allowed the aqueous and organic layers to separate. (Unlike in typical aqueous/organic separations, our organic layer was on the bottom of the separatory funnel.) We cleaned and dried an Erlenmeyer flask, and drained the organic layer into the Erlenmeyer by opening the stopcock. We stoppered the Erlenmeyer with a rubber stopper between draining. We repeated the adding of methylene chloride, swirling, venting, settling and draining the organic layer three times. Into the Erlenmeyer, we added a scoop of drying agent and swirled until clumps formed. We stoppered the Erlenmeyer and allowed it to sit for five minutes with the drying agent in the liquid. We started up the GC according to the protocol and began by injecting the series of single standards before injecting the mixture.
Deviation from protocol: Rotary evaporation of the concentrated mixture was not performed as it was determined that the process took to long. Attenuation was set to 64 for all single standards and changed to 16 for mixture.

Refer to “Gradient HPLC Laboratory” (Analytical Instrumentation Lab Manual CHEM 3003, Version 1, 2013) for complete procedure.

Results
Table 1. Comparison of retention times of single compounds (Atten. 64) versus unknown mixture (Atten. 16).
Standard
Retention Time (min)
Retention Time of Compounds in Extract (min)
Methanol
0.523
0.625
Ethanol
1.017
--------------
Acetone
1.512
--------------
Methylene Chloride
1.433
1.465
2 - Propanol
1.658
--------------
1 - Propanol
2.257
2.567
Methyl Ethyl Ketone
3.24
--------------
Ethyl Acetate
3.348
--------------
2 – Butanol
3.692
--------------
Hexane
3.21
--------------
Cyclohexane
4.062
4.397
1 – Butanol
5.24
--------------

Table 2. Possible contaminants of unknown mixture which would contribute to longer retention times.
Name
Structure
Miscibility / solubility in Water
Miscibility / solubility in Methylene Chloride
Boiling Point ()C)
Methanol

Miscible
Miscible
65
Ethanol

Miscible
Miscible
78
Acetone

Miscible
Miscible
57
Methylene Chloride

Immiscible
Miscible
39
2 - Propanol

Miscible
Miscible
82
1 - Propanol

Miscible
Miscible
97
Methyl Ethyl Ketone

Immiscible
Miscible
80
Ethyl Acetate

Immiscible
Miscible
77
2 – Butanol

Immiscible
Miscible
100
Hexane

Immiscible
Miscible
69
Cyclohexane

Immiscible
Miscible
81
1 - Butanol

Immiscible
Miscible
100

Discussion
When looking at the miscibility of our standards in methylene chloride (see table 2.) it is clear that all the standards are soluble in methylene chloride (our organic layer). This suggests that no one contaminant can be pinpointed as the source of extended retention times for the unknown mixture. It is likely there was some incomplete separation while in the separatory funnel contributing to the addition of water to the Erlenmeyer that was not completely absorbed by the drying agent. The components of our unknown mixture (as compared to the data in Table 1.) were determined to be methanol, methylene chloride, 1 – propanol and cyclohexane.

References
Mandeville, T. (2013). Liquid/Liquid Extraction with Identification by GC. Analytical Instrumentation Lab Book, pgs. 41 – 44. Belleville, ON; Loyalist College.
Kramp, K. (2012). Liquid/Liquid Extraction with Identification by GC. Analytical Instrumentation Lab Manual CHEM 3003, Version 3, pgs. 1 – 5. Belleville, ON; Loyalist College.
Phenomonex. (2013). Solvent Miscibility Chart. Retrieved from: http://www.erowid.org/archive/rhodium/pdf/solvent.miscibility.pdf
Webmaster. (2013). Methanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=methanol
Webmaster. (2013). Ethanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=ethanol
Webmaster. (2013). Acetone. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=acetone
Webmaster. (2013). Methylene Chloride. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=methylene+chloride
Webmaster. (2013). 2 - Propanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=2-propanol
Webmaster. (2013). 1 - Propanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=1-propanol
Webmaster. (2013). Methyl Ethyl Ketone. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=methyl+ethyl+ketone
Webmaster. (2013). Ethyl Acetate. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=ethyl+acetate
Webmaster. (2013). 2 - Butanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=2-butanol
Webmaster. (2013). Hexane. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=hexane
Webmaster. (2013). Cyclohexane. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=cyclohexane
Webmaster. (2013). 2-Butanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=2-butanol
Sigma-Aldrich. (2013). Miscibility Immiscibility: Dichloromethane. Retrieved from: http://www.sigmaaldrich.com/chemistry/solvents/dichloromethane-center/miscibility-immiscibility.html

References: Mandeville, T. (2013). Liquid/Liquid Extraction with Identification by GC. Analytical Instrumentation Lab Book, pgs. 41 – 44. Belleville, ON; Loyalist College. Kramp, K. (2012). Liquid/Liquid Extraction with Identification by GC. Analytical Instrumentation Lab Manual CHEM 3003, Version 3, pgs. 1 – 5. Belleville, ON; Loyalist College. Phenomonex. (2013). Solvent Miscibility Chart. Retrieved from: http://www.erowid.org/archive/rhodium/pdf/solvent.miscibility.pdf Webmaster Webmaster. (2013). Ethanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=ethanol Webmaster Webmaster. (2013). Methylene Chloride. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=methylene+chloride Webmaster Webmaster. (2013). 1 - Propanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=1-propanol Webmaster Webmaster. (2013). Ethyl Acetate. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=ethyl+acetate Webmaster Webmaster. (2013). Hexane. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=hexane Webmaster Webmaster. (2013). 2-Butanol. Retrieved from: http://www.stenutz.eu/chem/solv6.php?name=2-butanol Sigma-Aldrich