Among various spiral disks tested in the past, the mixer-settler spiral disk previously reported showed the best resolution of proteins with polymer phase systems. Based on the results of the previous experiment, a multiple disk assembly consisting of 8 units has been constructed and the performance tested with 5 standard protein samples,cytochrome c, lysozyme , ovalbumin, myoglobin , and trypsinogen using a polymer phase system composed of 12.5%(ww) PEG1000 and 12.5%(ww) dibasic potassium phosphate. Based on these results, a new spiral disk assembly made from polyethylene by injection molding was purchased from CCBiotech for separation of single wall carbon nanotubes (SWNTs) with a polymer phase system composed of 6.15% (w/w)PEG8000 and 6.15% (w/w) dextran 70000 in water adding two detergent additives of sodium deoxycholate and sodium dodecyl sulfate as follows: 1 Apparatus: The type-J coil planet centrifuge which holds a separation column assembly and the counterweight symmetrically at a distance of 10 cm from the central axis of the centrifuge. 2. Column. The barricaded spiral disks are made from polyethylene by injection molding. Each disk has 4 interwoven spiral grooves (each 1 m long, 2.6 mm wide and 2 mm deep) divided by multiple sections (each 6 mm long) with barricades where glass beads (1 mm diameter) are inserted each at every 4th sections. Five disks are sealed with a viton membrane and sandwiched between a pair of aluminum flanges tightly with a number of bolts. The total capacity is 90 ml. 3. Solvent system: It is composed of two polymers, PEG8000 and dextran 70000 each at 6.15% (w/w) in water. A detergent sodium deoxycholate is added at 0.02% to distribute the SWNTs in the lower dextran-rich stationary phase while sodium dodecyl sulfate is added to PEG-rich mobile phase in a linear gradient mode from 0% to 07% to elute the SWNTs according to their partition coefficients. 4. Sample: SWNTs are supplied by the National Institutes of Standards and Technology (NIST), Gaithersburg, MD (Dr. Ming Zheng et al.). About 1 ml of dispersed SWCTs suspension containing ca 0.5 g of SWCTs is charged in each experiment. 5. Separation procedure: The column is first entirely filled with the lower phase followed by the sample solution (1 ml composed of equal volumes of upper and lower phases). Then, the column is rotated at 1000 rpm which the mobile phase is eluted through the column in a linear gradient mode of sodium dodecyl sulfate from 0 to 0.7% at a flow rate of 0.5 ml/mi. The effluent from the outlet of the column is collected in test tubes at 2 ml/tube. 6. Analysis: The CCC fractions are analyzed by a spectrophotometer at the NIST from 350 to 1200 nm to construct the 2-dimensional chromatogram. 7. Results: In a single run several chirality species of SWNTs are purified including (9,4), (7,5), (7,6), (8,3) and (6,5). In addition most other fractions contain no more than 2-3 major species. We also observe strong (n, m) dependent elution peak width, most likely due to enantiomer-resolved partition. These results demonstrate CCC as an effective way to obtain high purity (n, m) species, and suggest the potential of CCC as an analytical tool for chirality distribution mapping of synthetic mixtures. Report Bibliography 1. Y. Ito, R. Clary, F. Sharpnak, H. Metger, J. Powell, Mixer-settler counter-current chromatography with multiple-spiral-disk assembly, J. Chromatogr. A 1172, 151-159, 2007. 2. Y. Ito, L. Qi., J. Powell, F. Sharpnak, H. Metger, J. Yost, , X.-Y. Cao, L.-S. Dong, L.-S. Huo, X.-P. Zhu, T. Li, J. Chromatogr. A 1151, 108-114, 2007. 3. Y. Ito, F.-Q. Yang, P.E. Fitze, J. Powell, D. Ide, J. Chromatogr. A 1017, 71-81, 2003. 4. Y. Ito, F.-Q. Yang, P.E. Fitze, J.S. Sullivan, J. Liq. Chromatogr. Rel. Technol. 26, 1355-1372, 2003. 5. M. Zhang, C. Y. Khripin, J. A. Fagen, Y. Ito, M. Zheng, Single-step total fractionation of single-wall carbon nanotubes by countercurrent chromatography, Nano Letter, pending. .
