Flash Chromatographic Separation and Electronic Absorption Spectra of Carotenoids: A Project for a Problem-Oriented Laboratory Course

Abstract

Procedure for separating beta-carotene and lycopene from carrots and tomatoes to illustrate the operation and versatility of flash chromatography.

Separation of the Carotenoid Bixin from Annatto Seeds Using Thin-Layer and Column Chromatography

“…In the few cases where pigment molecules are isolated, barely detectable quantities are obtained. For example, usually only 0.5 mg of lycopene can be isolated from 3 g of tomato paste (8). In the present experiment, this problem is circumvented because bixin exists in much higher quantities in the plant materials used (typically 4 to 5% by mass) and is significantly more chemically stable than other carotenoids (13,14).…”

“…The separation of colored plant pigments to demonstrate the principles of TLC and column chromatography has long been a classic experiment in the organic chemistry lab. Typical examples include the separation of chlorophyll from spinach or other plant leaves, the isolation of β-carotene from carrot baby food, and the isolation of lycopene from tomato paste (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12). This type of experiment is popular because the compounds are brightly colored and students can actually see the separation process as it occurs.…”

“…Despite their popularity, previous plant pigment separation experiments have several weak points. In previous experiments, the compounds being isolated are found in very small quantities in the plant sources being used and tend to be chemically unstable when isolated (1,3,8). Therefore, the separation of these pigments works well as a TLC experiment where the goal is to observe the separation of different pigments, but poorly as a column chromatography experiment where the goal is to isolate significant quantities of the pigments.…”

The State of Organic Teaching Laboratories

“…Modernization of the organic laboratory has not been limited to the technological and pedagogical changes described above. Modern techniques such as flash chromatography (6,19,63,161,(204)(205)(206)(207)(208)(209)(210)(211)(212)(213)(214)(215)(216)(217)(218), combinatorial chemistry (136)(137)(138)(139)(140)(219)(220)(221), and green chemistry (21, 219,[222][223][224][225][226][227][228][229][230][231][232][233][234][235][236], including microwave synthesis (35,200,219,(236)(237)(238)…”

Thermodynamic and Kinetic Controlled Enolates: A Project for a Problem-Oriented Laboratory Course

“…Here we report an open-ended project that allows a great deal of flexibility. This project, undertaken by SUNY Oswego and University of California, Irvine, students who had previous involvement in project-oriented laboratories (1)(2)(3)(4)(5)(6)(7), can be readily adapted to the microscale organic laboratory (8,9). The overall synthetic pathway is presented below.…”