Dimethyl sulfoxide chromatograms

A fluorodensitometric assay was developed by Montague and co-workers 140) to analyze cultures from Ochrosia elliptica for ellipticine (1), 9-methoxy-ellipticine (2), and 9-hydroxyellipticine (3) by thin-layer chromatography (TLC) without the need for prior purification. Using silica gel impregnated with dimethyl sulfoxide and a mobile phase of EtOAc-water-l-octanol (17 2 2), these workers were able to achieve good separation of these alkaloids and to assay the resulting chromatograms by fluorodensitometry (40-300 fmol detection limits of alkaloid). 

In an effort to reduce the use of toxic mobile phases such as methanol and ACN, dimethyl sulfoxide (DMSO)-modified HPLW was used as the mobile phase for the reversed-phase separation of a four-PAH mixture. A typical 25-cm ODS column was employed as the stationary phase and temperature was increased from ambient to 125°C as DMSO content in the mobile phase was decreased from 80 to 66%. PAHs have been separated on a 25-cm Zorbax ODS column using HPLW modihed with methanol as the mobile phase. NAP, PHN, PYR, CHY, and B[a]P were separated in 20 min at 140°C in 62% methanol with reasonable column stability reported. An increase of 4 to 5°C was equivalent to a 1% increase in the methanol content of the mobile phase. The quality of the chromatograms also improved with heating. 

Fig. 5. Chromatogram of an isomerate resulting from irradiation for 56 h of methyl aW-tranS retinoate in (A) dimethyl sulfoxide and (B) heptane. Column, Partisil lO-ODS-2 (10 xm) mobile phase, methanohwater (85 15) flow rate, 0.7 ml/min peak (0) 13-m-(photocyclized) methyl retinoate peak (1)9,11,13-tri-cw-methyl retinoate peak (2) 11,13-di-cw-methyl retinoate peak (2A) 7,13-di-cis-methyl retinoate peak (3) 13-cw-methyl retinoate peak (4) 9,13-di-d5-methyl retinoate peak (5) 11-cw-methyl retinoate peak (6) 9-c -methyl retinoate peak (6A) 7-c/5-methyl retinoate peak (7) all-tra/i5-methyl retinoate. (Reprinted with permission from Halley and Nelson, 1979.)...

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