Chromatography

 

background [prelab assignment (10 points); due at the beginning of the lab]

brief description on the applications of chromatography

MSDS data on isopropyl alcohol

purpose

recording experimental observations

analyze dyes in Cool-Aid Grape drink mix

materials

Sep-pak C-18 cartridge ("cartridge")

syringe (1 & 10 mL); microwell plate (to collect output from cartridge = sample); pipets

Cool-Aid Grape drink mix; water (or 5 drops red food dye + 7 drops blue food dye in 100 mL water)

70 % isopropyl alcohol (i.e. rubbing alcohol);  red, blue, & purple pencils  (supply your own pencils)

methods

using 10 mL syringe, rinse cartridge with ~ 5 mL 70 % isopropyl alcohol, followed by ~ 5 mL water then ~ 10 mL air

using 1 mL syringe, load ~1 mL Cool-Aid Grape solution onto the chromatography column

do experiments: to remove the dyes from the chromatography column, use a 10 mL syringe with ~ 10 mL eluent (i.e. 0%, 15%, or 70% isopropyl alcohol) at a rate of ~ 1 drop / second, collect ~5 drop samples into the microwell plate, and record your observations (use color pencils) until no changes are seen in the chromatography column or eluate.

at the end of each experiment, using 10 mL syringe, rinse cartridge with ~5 mL 70 % isopropyl alcohol, followed by ~5 mL water then ~ 10 mL air

experiment 1: 70% isoproply alcohol as eluent

as experiment 3, but use 70% isoproply alcohol

experiment 2: water as eluent

as experiment 3, but use water

experiment 3: 15% isopropyl alcohol as eluent

prepare 15 % isopropyl alcohol, i.e. mix 2.2 mL 70 % isopropyl alcohol + 7.8 mL water

 

Content of lab report [45 points; no lab report revision]

results   [10 points]

draw / describe the color of the eluant  AND  cartridge as a function of the fraction number

discussion   [20 points]

rationalize your observations

using concepts involving intermolecular forces

hints: 

C18 cartridge

(source:  stationary phase's surface)

isoproply alcohol

(source:  isopropyl alcohol - mobile phase)

 

blue dye

(source:  blue dye)

red dye

(source:  red dye)

reflection [15 points]

use a two-column table fomat to address this prompt, where one column is the NGSS / ELA standard and the other column is the coresponding aspect of the lab / lab report meeting this / these standard(s). More than one standard can be met a single aspect of the lab / lab report. select & identify two standards per section for a total of six standards.

NGSS standards

ELA / writing; e.g. std 8 & std 2

ELA / science; e.g. std 7 & std 10

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