Isolation and concentration techniques for capillary column gas chromatographic analysis

Determination of Volatile Terpenes in Coriander Cold Pressed Oil by Vacuum Assisted Sorbent Extraction (VASE)

Cold-pressed plant oils are of high interest to consumers due to their unique and interesting flavors. As they are usually only pressed at low temperatures and filtered, without further processing stages (as refining), they preserve their character that originates from the plant the oil was extracted from. Coriander cold pressed oil is gaining popularity as a novel product, obtained from its fruits/seeds; due to the high amount of terpenes, it has very characteristic flavor. A novel, vacuum-assisted sorbent extraction (VASE) method was used to extract terpenes from coriander cold pressed oil. Optimal parameters were determined. The profile of compounds extracted using VASE was compared with that of classic hydrodistillation method. Moreover, 17 monoterpene hydrocarbons and alcohols were identified with β-linalool as the main compound, followed by α-pinene, γ-terpinene, camphor, sylvestrene, β-pinene, and o-cymene. Differences were noted between profiles of terpenes after hydrodistillation and VASE extraction. For 8 out of 17 terpenes, VASE was used for their quantitative analysis. Regarding simplicity of the method, small sample requirement (200 mg) and short extraction time (5 min), VASE combined with GC/MS is well suited for characterization of terpenes in such matrix as plant oils.

Quantification of residual solvents in antibody drug conjugates using gas chromatography

The detection and quantification of residual solvents present in clinical and commercial pharmaceutical products is necessary from both patient safety and regulatory perspectives. Head-space gas chromatography is routinely used for quantitation of residual solvents for small molecule APIs produced through synthetic processes; however residual solvent analysis is generally not needed for protein based pharmaceuticals produced through cultured cell lines where solvents are not introduced. In contrast, antibody drug conjugates and other protein conjugates where a drug or other molecule is covalently bound to a protein typically use solvents such as N,N-dimethylacetamide (DMA), N,N‑dimethylformamide (DMF), dimethyl sulfoxide (DMSO), or propylene glycol (PG) to dissolve the hydrophobic small molecule drug for conjugation to the protein. The levels of the solvent remaining following the conjugation step are therefore important to patient safety as these parental drug products are introduced directly into the patients bloodstream. We have developed a rapid sample preparation followed by a gas chromatography separation for the detection and quantification of several solvents typically used in these conjugation reactions. This generic method has been validated and can be easily implemented for use in quality control testing for clinical or commercial bioconjugated products.

Development of a headspace gas chromatographic test for the quantification of 1- and 2-bromopropane in human urine

A test procedure was developed for the detection and quantification of 1- and 2-bromopropane in human urine. 1-Bromopropane (1-BP) is a commonly used industrial solvent, and 2-bromopropane (2-BP) is often found as an impurity component in industrial grade 1-BP. Both compounds are a health concern for exposed workers due to their chronic toxicity. Bromopropanes have been associated with neurological disorders in both animals and humans. Sample preparation consisted of diluting urine with water and fortification with 1-bromobutane (1-BB), which was used as an internal standard; then each sample was sealed in a headspace vial. A static-headspace sampler (Teledyne-Tekmar Model 7000) was used to heat each sample at 75 degrees C for a 35-min equilibrium time. Quantification was by means of a gas chromatograph (GC) equipped with an electron capture detector (ECD) and a dimethylpolysiloxane (DB-1) capillary column. A recovery study using fortified urine samples at multiple concentrations (0.5-8 microg/ml) demonstrated full recovery; 104-121% recovery was obtained. Precision ranged from 5 to 17% for the 15-20 spiked samples used at each concentration, which were analyzed over multiple experimental trial days. The limit of detection (LOD) for this test procedure was approximately 2 ng/ml 1-BP and 7 ng/ml 2-BP in urine. A recovery study of 1- and 2-BP from fortified urine stored in vials appropriate for field collection was also completed. These results and other factors of the development and validation of this test procedure will be discussed.

Environmental applications of membrane introduction mass spectrometry

The purpose of this review is to highlight the versatility of membrane introduction mass spectrometry (MIMS) in environmental applications, summarize the measurements of environmental volatile organic compounds (VOCs) accomplished using MIMS, present developments in the detection of semi-volatile organic compounds (SVOCs) and forecast possible future directions of MIMS in environmental applications.

Determination of urinary mevalonic acid using isotope dilution technique

A simplified and highly accurate, stable isotope dilution method using gas chromatograph/mass spectrometry (GC/MS) with deuterated (2H7) or (2H7) or (2H3)mevalonic acid (MVA) as internal standard was developed for the measurement of MVA in urine samples. MVA was converted to its lactone (MVL) and transferred with the total water of the sample (100 microliters) to a mixture of acetone/methyl t-butyl ether (MTBE). This solution was concentrated and dried by azeotropic removal of MTBE/water in special vessels (used for volume reduction under partial reflux for solutions containing volatile compounds). After producing MVA by adding NaOH followed by azeotropic drying, MVA was converted to its tris-t-butyldimethylsilyl (tri-TBDMS) derivative. GC/MS selected ion monitoring measurements at m/z 317, m/z 320 and m/z 324 were performed in the electron impact ionization (EI) mode. Overall recoveries of about 70% were obtained as shown by following the procedure with (14C)MVL, (2H7)- and (2H3)MVL as external and/or internal standards. Six replicate analyses of one urine sample revealed a coefficient of variation of 3.3%. Based on this experience we developed two other methods. The second method was based on a fluid/fluid extraction and the third one on an extraction with total water transfer. Both methods are combined with azeotropic drying and showed improved precision, handling and speed.