GC-MS

Webinar Date/Time: Tue, Dec 13, 2022 11:00 AM EST

A simple method for extraction and concentration of trace organic compounds found in water for gas chromatography-mass spectrometry (GC-MS) analysis was developed. The method used 25 and 45 mL glass vials with a 5-10 µm thick polymer coatings for extraction of analytes from 20 and 40 mL water samples, respectively. Analytes were subsequently transferred from the polymer coating into an organic solvent, which was reduced in volume to 200-400 µL for analysis. A 10-20 µL sample from the vial was transferred to a tiny coiled stainless steel wire filament using a micro-syringe, or by dipping the coil into the sample. After air evaporation of the solvent, the coil was inserted into the heated injection port of a portable GC-MS system where the analytes were desorbed. Injection using the coiled wire filament eliminated sample discrimination of high boiling point compounds, and minimized system contamination caused by sample matrix residues. The GC-MS contained a new resistively heated column bundle that allowed elution of low-volatility compounds in less than 4 min. Analyses of organochlorine pesticides, polycyclic aromatic hydrocarbons, polychlorinated biphenyl congeners, pyrethroid insecticides, phthalate esters, and n-alkanes in water and wastewater samples were accomplished for low ppb concentrations in less than 10 min total analysis time.

This article investigates the use of gas chromatography–time-of-flight mass spectrometry (GC–TOF MS) to fragrance-profile three essential oils (ginger, wintergreen and rosemary). As well as considering the compositional differences between the oils, we will examine the use of peak deconvolution to identify closely-eluting compounds, and explore the use of soft electron ionization, assisted by comparison of ion ratios, to discriminate between isomeric monoterpenes that are difficult to identify at conventional 70 eV ionization energies due to their very similar mass spectra.

Compounds that are added as fragrances to personal care products (PCPs) can also be allergens or skin irritants for some consumers. Knowing whether these compounds are present in a product is important for both consumers with known allergies and for manufacturers in order to be compliant with various regulations related to allergens. Here, a GC-TOFMS method was developed to screen for and quantify regulated allergens in approximately 5 minutes. This method utilized a short and narrow chromatographic column along with mathematical deconvolution of the TOFMS data to separate the target allergens from each other in the standards and from matrix interference in samples. Calibration equations were compiled for standards from 1 ppb to 1 ppm (on-column) with excellent linearity and correlation coefficients. These were applied to various commercially-available perfume and cologne samples to determine quantitative information for the targeted allergens. The full-mass range data acquisition also provided for non-targeted characterization and comparisons to better understand the aroma profile of each sample. The reported method reduced analysis time for allergen screening while simultaneously increasing the acquired information about the PCP samples.

Water samples were obtained from the Tar River and a local water treatment plant in eastern North Carolina in spring 2013 and fall 2015 to monitor the presence of a panel of pharmaceutical and personal care products (PPCPs). Samples were extracted by solid phase extraction (SPE) or liquid-liquid extraction and analyzed for parent PPCPs and their metabolites by liquid chromatography-time of flight mass spectrometry (HPLC-TOFMS) and gas chromatography-mass spectrometry (GC-MS). Both extraction and detection methods were compared by their recoveries and detection limits for each compound. Many parent PPCPs and their metabolites were detected including: carbamazepine, iminostillbene, oxcarbazepine, epiandrosterone, loratadine, β-estradiol, triclosan, and others. Liquid-liquid extraction was found to give overall superior recoveries. Furthermore, HPLC-TOFMS gave lower detection limits than GC-MS. Library searching of additional peaks identified further compounds with biological activity. Additionally, the effectiveness of the treatment plant on the removal of the compounds of interest is discussed.

In this study we report on the use of a field-portable GC-MS with rapid sampling techniques such as solid-phase micro extraction, purge-and-trap, thermal desorption, and heated headspace to provide a fast response for in-field-SVOCs analyses for a wide variety of environmental-type samples including potable waters, tea, plants and road gravel. We will show that this field-portable approach can provide the required sensitivity, selectivity for the effective analysis of SVOCs with very high boiling points such as polycyclic aromatic hydrocarbon (PAHs), pesticides, phenolic compounds and phthalate esters in a number of different field-based samples, in less than 10 minutes.

The purpose of this study was the development of various analytical MS methods to investigate the chemical composition of e-liquids used in electronic cigarettes and characterize their quality. Low-quality nicotine (the main active compound), glycerol, propylene glycol (solvents), or flavors could greatly increase the toxicity. The search of alkaloid contaminants of nicotine was performed by LC–MS-MS after a deep study of fragmentation pathways by high resolution ESI-MS. A fully validated method for quantitation of organic polar impurities such as cotinine, anabasine, myosmine, nornicotine, and N-nitroso-nornicotine and nicotine itself was developed using MS coupled to UHPLC. To evaluate organic volatile toxicants, headspace from e-cigarette refill liquids was sampled by SPME to perform GC–MS analysis. Finally, heavy metal residues as inorganic toxicants were determined by ICP-MS after simple dilution. A number of cases of contamination by metals (mainly arsenic) was detected.

This work addresses two challenges: developing a technique capable of measuring ppb levels of hormones, and developing an SPLE technique capable of extracting contaminants and hormones from a single sample without additional cleanup steps.

This study focuses on United States Environmental Protection Agency (US EPA) Method 524.3 for volatile organic compounds (VOCs) in water using gas chromatography–mass spectrometry (GC–MS).

In most countries, herbal medicinal products (HMPs) are introduced into the market without proper scientific evaluation or enforced safety and toxicological studies.

Despite the advantages of soft ionization ion-source technologies for improving confidence in the identification of a range of challenging analytes, soft ionization remains a niche technique for gas chromatography–mass spectrometry (GC–MS).