Muneo Saito

New double-stage separation analysis method : Directly coupled laboratory-scale supercritical fluid extraction—supercritical fluid chromatography, monitored with a multiwavelength ultraviolet detector

Abstract Instrumentation and applications of a new double-stage separation analysis method are described. The new method incorporates supercritical fluid extraction as the first separation step and supercritical fluid chromatography as the second separation step. The extraction section of the instrument was tested by caffeine extraction from roasted coffee beans with carbon dioxide, and the effects of extraction parameters on the extracted amounts of caffeine were examined by high-performance liquid chromatography. Then, directly coupled supercritical fluid extraction—supercritical fluid chromatography, monitored with a highly sensitive multiwavelength detector, was performed on the powdered coffee beans, and separation was successfully carried out without any special pretreatment. The obtained data were graphically presented by a data processor, as three-dimensional plots of supercritical fluid chromatograms, at 250 and 270 nm, and a spectrum at 9.60 min, which showed clear characteristics of the caffeine spectrum.

Carbon dioxide supercritical fluid chromatography on a chiral diamide stationary phase for the resolution of D- and L-amino acid derivatives

Abstract A super critical carbon dioxide mobile phase, used in conjunction with polar modifiers, brought about the rapid optical resolution of racemic N-acetylamino acid tert. ≈butyl esters on chiral (N-formyl- l -valylamino)propylsilica without a loss of enantioselectivity The time of analysis of the solute enantiomers was less than 4 min. Methanol, acetonitrile and diethyl ether were used as polar modifiers and their influence on the enantiomer resolution is discussed.

Simple microscale supercritical fluid extraction system and its application to gas chromatography-mass spectrometry of lemon peel oil

Abstract The instrumentation and applications of a simple microscale supercritical fluid extraction system are described. The system consisted of an high-performance liquid chromatography pump with a pump-head cooling jacket, an extraction vessel made from a short empty column, 35 mm × 4.6 mm I.D., and a capillary restrictor. Lemon peel oil was extracted with sub- and supercritical carbon dioxide at various pressures and temperatures and collected in a micro-vial. The extract was analyzed by gas chromatography-mass spectrometry and the results were compared to those for a cold-pressed lemon oil.

Enrichment of eicosapentaenoic acid and docosahexaenoic acid esters from esterified fish oil by programmed extraction-elution with supercritical carbon dioxide

Abstract Methyl esters of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in esterified fish oil were extracted by supercritical fluid extraction with carbon dioxide and directly introduced into a silica gel column coated with silver nitrate. Supercritical fluid chromatography with carbon dioxide was then performed by changing stepwise the pressure of the column outlet. The EPA and DHA methyl esters thus separated were fractionated by reducing the pressure of column effluent to atmospheric. In this way, EPA and DHA methyl esters were enriched from 12% to 93% and from 13% to 82%, respectively.

Application of photodiode array ultraviolet detector to unresolved peak analysis

Abstract Poorly resolved chromatographic peaks have been mathematically resolved to give all component peaks of a multicomponent sample, using a newly developed 32-channel multiwavelength spectrophotometric UV detector and its data processor. In order to isolate poorly resolved peaks quantitatively, three-dimensional chromatographic data were stored on a floppy disk and computed by a data processor. A mathematical method of simultaneous multicomponent analysis for UV spectra was applied to all the points along the time axis. The results obtained have been compared with those by conventional perpendicular-dropping and tangential-skimming methods for known amounts of components. Recoveries obtained by the new method were 100.7 and 101.1%, while those by the conventional methods wer 89.9 and 110.1%, and 126.8 and 26.4%, respectively, by perpendicular dropping and tangential skimming. The detection of a hidden component in a chromatogram and determination of its UV spectrum was also investigated.

Enantiomer resolution of d- and l-α-amino acid derivatives by supercritical fluid chromatography on novel chiral diamide phases with carbon dioxide

The rapid resolution of racemic N-4-nitrobenzoylamino acid isopropyl esters was accomplished without the loss of enantioselectivity by supercritical fluid chromatography (SFC) on novel chiral valine-diamide phases with carbon dioxide and a polar methanol modifier. In each stationary phase, a chiral moiety was anchored to the silica gel surface by a long decamethylene spacer. The enantioselectivity in SFC was comparable to that in liquid chromatography using 2-propanol-n-hexane. The time required for analysis was less than 5 min, and the range of enantiomer resolution (Rs) was 10.8-1.25. On using 2-propanol in place of methanol the separation was improved, but was accompanied by a decrease in column efficiency. The end-capping effect of the remaining surface silanols on enantiomer resolution is discussed.

Supercritical fluid chromatography with micro packed columns and carbon dioxide as a mobile phase

Abstract Supercritical fluid chromatography with micro packed fused-silica columns and carbon dioxide is investigated. The instruments were carefully constructed to operate under high pressures with minimum dead volume. Polynuclear aromatic hydrocarbons and styrene oligomers are rapidly separated on a micro column of 150 × 0.34 mm I.D.

A high-speed liquid chromatograph with a flow-spectrofluorimetric detector and the ultramicro-determination of aromatic compounds

Abstract A high-speed liquid chromatograph has been used with new spectrofluorimetric detector, which is more sensitive than a normal ultraviolet absorption or spectrophotometric detector for fluorescent compounds. The spectrofluorimeter is equipped with double-beam optics and with a flow-cell, 3 μl in volume, and is used to record the emission and excitation spectra of the separated components during the chromatographic separation by stopping the elution at peak maxima. This technique enables both qualitative identification and quantitative determination of the separated components. Selective recording of chromatograms is possible by varying the wavelengths for emission and excitation. The technique is demonstrated using mixtures of vitamins B 2 , B 3 and B 6 , and of naphtalene, anthracene, pyrene, benz( a )anthracene, benz( a )pyrene and benz( e )pyrene have been separated and identified.

Quantitative deconvolution of heavily fused chromatographic peaks of biological components using a multiwavelength uv detector

Quantitative deconvolution of a chromatographic peak with extremely low UV absorption (less than 0.005 A.U.) is demonstrated for the analysis of an anaesthetic (ketamine) in rabbit serum. One ketamine metabolite, nor-ketamine, was deconvoluted from a completely fused peak in the three-dimensional chromatogram by using a highly sensitive multi-wavelength UV detector. After injection of ketamine, the nor-ketamine level in the serum increased to 3 micrograms/ml, calculated as ketamine, in 120 min.