An automated large volume on-column injection technique for capillary gas chromatography

Automated large volume (25-200 μl) on-column injections into a gas chromatograph with a capillary column were successfully performed by coupling a retention gap technique with an air actuated rotary valve. The linearity, injection precision, and carryover were evaluated. Slight boiling point discrimination was observed. This technique is compatible with commonly used chromatographic detectors (FID, ECD, MS) and conditions, while requiring very little instrument modification. The work is directed at the eventual reduction of manpower and turnaround time for sample collection and extraction, and Kuderna-Danish concentration when dealing with methods similar to EPA 625.     

Programmed-temperture split-splitless injection of triglycerides: Comparison to cold on-column injection

The performance of split and splitless programmed-temperature (PTV) injection is compared to cold on-column and hot (classical) split injection for the analysis of triglycerides on an apolar capillary gas chromatographic column. Quantitative accuracy and precision of PTV injection are determined for a synthetic mixture of triglycerides relative to cold on-column injection.     

Gas chromatographic separation of sugars by on-column injection on glass capillary columns

Sugars were separated gas chromatographically on short apolar glass capillary columns by using cold, on-column injection (OCI) techniques. After silylation, oligomers up to the hexasaccharides could be efficiently separated in resonable retention times. Response factors of silylated sugars were determined as a function of varying sample amounts and concentrations. The optimum injection amount was found to be 1 μl in heptane as solvent.     

Determination of the calcium entry blocker verapamil in plasma by capillary gas chromatography with on-column injection

A specific, sensitive, and accurate assay for quantitation of verapamil has been developed. The method involves a single extraction step with n-heptane, followed by evaporation at room temperature under nitrogen. 0.1 μl of the extract was injected into a capillary column coated with crosslinked 5% phenylmethylsilicone. The column separated verapamil, norverapamil, and its internal standard within 15 minutes using temperature programming from 90 to 290°C. The lower limit of detection was 1 ng/ml for verapamil. The calibration curve was linear in the concentration range (5–300 ng/ml). Plasma concentration data from dogs receiving intravenous verapamil infusion are presented.     

Modified capillary GC/MS system enabling dynamic headspace sampling with on-line cryofocusing and cold on-column injection of liquid samples

The paper describes a capillary GC/MS hardware arrangement allowong either:

• (a) on-line injection of sample of gases and vapors coming from dynamic headspace or purg & trap samplers and their subsequent cryofocusing/thermal desorption prior to the analytical capillary column (first column):
• (b) direct injection of liquid samples through a cold on-column injector into a second analytical column (counted in series with the first).

Chromatographic profiles of acacia honey aromas provide condirmation of the suitability of this system.