Pressure-programming of a binary, on-line mixed mobile phase for capillary column SFC using a packed column SFC pumping system

1988 ◽  
Vol 26 (1) ◽  
pp. 224-228 ◽  
Author(s):  
K. Anton ◽  
N. Periclès ◽  
S. M. Fields ◽  
H. M. Widmer
Keyword(s):  
Mobile Phase ◽  
Capillary Column ◽  
Packed Column ◽  
Pumping System ◽  
On Line ◽  
Pressure Programming

Determination of Phytosterols in Butter Samples by Using Capillary Column Gas Chromatography

1987 ◽  
Vol 70 (5) ◽  
pp. 912-915 ◽  
Author(s):  
Randall L Smith ◽  
Darryl M Sullivan ◽  
Earl F Richter
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Retention Time ◽  
Capillary Column ◽  
Limit Of Detection ◽  
Packed Column ◽  
Gas Chromatography Mass Spectrometry ◽  
Positive Bias ◽  
Capillary Column Gas Chromatography

Abstract A positive bias in the gas chromatographic (GC) analysis of butter for β-sitosterol was discovered when attempting to confirm values by gas chromatography/mass spectrometry (GC/MS). The source of the problem was traced to an interfering material that was not effectively separated by packed column GC. Because capillary columns are known to provide superior separation, they were substituted for packed columns in the assay, and instrument parameters were modified accordingly. A compound with a similar retention time, identified by GC/MS as lanosterol, was separated from β-sitosterol by the capillary column. The capillary column technique was applied to over 300 butter samples. The results indicate that the method can accurately quantitate β-sitosterol in butter with no known interferences. The limit of detection for this method is 1 mg/100 g. Recoveries at a level of 3 mg/100 g averaged 98% with a coefficient of variation of 3.45%

Gas Chromatographic Analysis of Amino Acids as the jV-Heptafluorobutyryl Isobutyl Esters

1987 ◽  
Vol 70 (1) ◽  
pp. 151-160 ◽  
Author(s):  
Samuel L MacKenzie
Keyword(s):  
Amino Acids ◽  
Capillary Column ◽  
Packed Column ◽  
Complex Mixture ◽  
Amino Acid Profile ◽  
Reaction Sequence ◽  
Maximum Resolution ◽  
Acid Catalyzed ◽  
Derivatives Of ◽  
Heptafluorobutyric Anhydride

Abstract The N-heptafluoroburyryl isobutyl derivatives of proteic amino acids are well resolved by gas chromatography and form the basis of a convenient, rapid assay. The derivatives are prepared by acid-catalyzed esterification at 120°C for 20 min in 3N HCl-isobutanol followed by acylation with heptafluorobutyric anhydride at 150°C for 10 min. The reaction sequence is performed without any transfers or extractions and thus is compatible with microscale analysis. A complete proteic amino acid profile can be completed in less than 20 min by using a packed column or less than 10 min by using a capillary column in combination with an elevated oven temperature program rate. Physiological sample matrixes, which frequently contain a complex mixture of components, and thus require maximum resolution, can be assayed in less than 1 h using a program rate of 4°C/min. A capillary column is recommended for this application. Capillary column chromatography, in combination with a nitrogenspecific detector, is useful for identifying and assaying nonproteic amino acids in physiological sample matrixes. Frequently, a prior cleanup of the sample can be avoided.

Liquid-chromatographic separation and on-line bioluminescence detection of creatine kinase isoenzymes.

1980 ◽  
Vol 26 (6) ◽  
pp. 712-717
Author(s):  
W D Bostick ◽  
M S Denton ◽  
S R Dinsmore
Keyword(s):  
Creatine Kinase ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Pumping System ◽  
Side Stream ◽  
Peristaltic Pumping ◽  
Bioluminescence Assay ◽  
On Line ◽  
External Light Source ◽  
Liquid Chromatographic

Abstract We separated isoenzymes of creatine kinase by anion-exchange chromatography, with use of an elution of gradient containing lithium acetate (0.1 to 0.6 mol/L). A stream splitter was used to divert a 5% side stream of column effluent, which was subsequently mixed with the reagents necessary for bioluminescence assay of the separated isoenzymes. The use of the stream splitter greatly decreased the rate of consumption of reagent and, when combined with a peristaltic pumping system, permitted independent control of the side-stream flow rate. Thus both the residence interval in a delay coil in which the ATP reaction product is formed and the bioluminescence response could be increased. Bioluminescence emission was monitored in a flow-through fluorometer without use of an external light source or filters. Separation and detection of the isoenzymes of creative kinase were rapid, sensitive, and highly selective. The incremental decrease of bioluminescence response owing to inhibition by the ions in the eluent was less than 31% across the entire gradient.

Determination of N-(4-Chlorophenyl)-N´-(2,6-difluorobenzoyl)-urea in Milk by High-Speed Liquid Chromatography

1974 ◽  
Vol 57 (6) ◽  
pp. 1269-1271
Author(s):  
Calvin Corley ◽  
Richard W Miller ◽  
Kenneth R Hill
Keyword(s):  
Liquid Chromatography ◽  
Mobile Phase ◽  
High Speed ◽  
Packed Column ◽  
Sampling Interval ◽  
Detectable Level ◽  
Liquid Chromatograph ◽  
Whole Milk ◽  
Sensitive Method

Abstract A rapid and sensitive method of analysis in which high-speed liquid chromatography was used with ultraviolet absorption detection was developed for determining residues of Thompson- Hayward TH 6040 (N-(4-chlorophenyl)-N'- (2,6-dinuorobenzoyl)urea) in cows' milk. The larvicide is extracted from whole milk with ethyl acetate, and the lipids are removed by partitioning between hexane and acetonitrile. After evaporation of the acetonitrile, the residue is dissolved in ethanol, and aliquots are injected into a liquid chromatograph, using methanol-water (1+1) as the mobile phase in a packed column. Recovery of TH 6040 from cows' milk is essentially quantitative, and no interfering substances appear on the chromatogram. The lowest detectable level was 10 ng. Milk from a cow fed 1 mg larvicide/kg body weight daily in the diet was analyzed by this procedure, and no detectable residues (<0.1 ppm) were found over a 15 week sampling interval.

Supercritical argon as a mobile phase for the flame photometric detection of sulfur

2003 ◽  
Vol 81 (10) ◽  
pp. 1051-1056 ◽  
Author(s):  
Kevin B Thurbide ◽  
Brad W Cooke
Keyword(s):  
Carbon Dioxide ◽  
Supercritical Carbon Dioxide ◽  
Supercritical Fluid ◽  
Supercritical Fluid Chromatography ◽  
Mobile Phase ◽  
Packed Column ◽  
Flow Rates ◽  
Photometric Detection ◽  
Flame Photometric Detection ◽  
Background Emission

The background emission properties of supercritical argon and supercritical carbon dioxide mobile phases in packed column supercritical fluid chromatography (pSFC) with flame photometric detection (FPD) were compared. As column flow rates were increased toward common values used in pSFC, the carbon dioxide background emission grew enormously. The resulting emission spectrum displayed dominant features at wavelengths between 325 and 525 nm, consisting of a complex series of overlapping molecular emission band systems partly attributed to CO* and CH*. By comparison, when using the same flow rates with a supercritical argon mobile phase, the background emission was identical to that of the FPD flame without column effluent. In terms of intensity, when using a column flow rate of 2 mL/min, supercritical carbon dioxide contributes a background emission in the FPD that is about 3 × 105 times larger than that produced by supercritical argon. This difference leads to an improvement of two orders of magnitude in the pSFC-FPD signal-to-noise ratio for sulfur when a supercritical argon mobile phase is used. Results indicate that supercritical argon could also be advantageous for the pSFC-FPD analysis of other elements.Key words: supercritical fluid chromatography, packed column, flame photometric detection, supercritical argon.

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