Multi-Residue Method for the Determination of Five Groups of Pesticides in Non-Fatty Food Samples by Dual Stir Bar Sorptive Extraction (Dual SBSE) and Thermal Desorption GC-MS*

A multi-residue method for determination of five groups of 85 pesticides – organochlorine, carbamate, organophosphorous, pyrethroid and others – in non-fatty food, e.g. vegetables, fruits and green tea is described. The method is based on stir bar sorptive extraction (SBSE) coupled to thermal desorption (TD) and retention time locked (RTL) GC-MS in the scan mode.…

Elimination of Non-Volatile Sample Matrix Components After GC Injection using a Thermal Desorber and Microvial Inserts

GC analysis of complex sample types containing non-volatile materials normally requires extensive sample preparation and cleanup prior to injection to eliminate the interference from non-volatile components. Accumulation of nonvolatile matrix components in the inlet and at the head of the GC column can lead to generation of active sites, analyte degradation, poor quantitation due to…

Automation of Solid Phase Extraction Methods using a Robotic X-Y-Z Coordinate Autosampler with Software Control

Solid phase extraction (SPE) is one of the sample preparation methods most widely used by chromatographers, as demonstrated by the numerous published SPE methods found in the literature. Typically, a liquid sample is passed across an adsorbent bed to retain and concentrate target analytes and eliminate interference from the sample matrix. Alternatively, the adsorbent can…

Automated QuEChERS Extraction for the Determination of Pesticide Residues in Foods using Gas Chromatography/Mass Spectrometry

One of the most important aspects of reducing pesticide exposure is monitoring of pesticide residues in foods. A number of analytical methods have been developed, many of them based on traditional liquid-liquid extraction in combination with GC-MS or LC-MS. The QuEChERS (quick, easy, cheap, effective, rugged, and safe) sample preparation methods have been developed to…

Quantitative Analysis of Residual Pesticides in Hemp Oil Extract by Direct Liquid Injection Gas Chromatography/Mass Spectrometry

The number of cannabis containing products, such as extracts, tinctures, edibles, waxes and oils, available in the United States have increased significantly due to changes in state law and the 2018 Farm Bill. Cannabis concentrates are legally manufactured for both medicinal and recreational use and are quickly becoming the most commonly used products by consumers…

Application of Stir Bar Sorptive Extraction (SBSE) Coupled to Thermal Desorption GC-MS for Determination of Ultra-Trace Level Compounds in Aqueous Samples

During the past decade, miniaturized and solvent-less sample preparation techniques based on sorptive extraction, e.g. solid phase micro-extraction (SPME), have proven to be simple, fast and environmentally friendly alternatives to LLE while maintaining or even improving sensitivity. In 1999, a new extraction technique known as stir bar sorptive extraction (SBSE) using stir bars coated with…

Low Thermal Mass Technology, a New Approach to Accelerated Gas Chromatography that Provides More Efficient Dual Column Confirmation

Low Thermal Mass (LTM) technology was developed by RVM Scientific and is now offered as a retrofit to existing Agilent 5890 and 6890 GCs by GERSTEL as the Modular Accelerated Column Heater (MACH). The technology involves combining any length standard capillary GC column, a Resistance Temperature Detector (RTD) based thermal measurement system, and a precision…

Accelerating Single or Dual Column Environmental Methods using Low Thermal Mass Column Technology and Software-Controlled Independent Module Heating

Routine analytical methods employing mass spectral analysis on a gas chromatograph are often plagued with long run times in order to achieve acceptable separations. The Modular Accelerated Column Heater (MACH) System from GERSTEL is easily retrofitted to the Agilent 6890 GC with Mass Selective Detection. MACH is based on Low Thermal Mass (LTM) technology, that…

Ultra-Fast Determination of the Hydrocarbon Oil Index by Gas Chromatography using a Modular Accelerated Column Heater (MACH)

Ultra-fast gas chromatographic methods for determination of the hydrocarbon oil index according to ISO 9377-2 were developed using a modular accelerated column heater (MACH). The column heater consists of a module that enables very fast and controlled heating of the capillary column. The speed of analysis for the hydrocarbon group eluting between C10 and C40…

Fast Screening of Pesticide Multiresidues in Aqueous Samples by Dual Stir Bar Sorptive Extraction (Dual SBSE) and Thermal Desorption – Fast GC/MS using a Modular Accelerated Column Heater (MACH)

A method for fast screening of pesticide multiresidues in aqueous samples using dual stir bar sorptive extraction (dual SBSE) – thermal desorption (TD) – fast GC/MS has been developed. Recovery of 82 pesticides – organochlorine, carbamate, organophosphorous, pyrethroid and others – for the SBSE was evaluated as a function of octanolwater distribution coeffi cients (log…

Characterization of Organic Compounds in Atmospheric Nanoparticles by Thermal Extraction – Comprehensive Two-Dimensional Gas Chromatography (GC x GC) in Combination with Selective Detection, Mass Spectrometry and Accurate Mass Detection

A method for characterization of airborne particles including the nanoparticles fraction with a diameter of 29-58 nm in roadside atmosphere has been described. The method consists of thermal extraction (TE) and comprehensive two-dimensional gas chromatography (GC x GC) with novel detection capabilities, including high resolution time-of-flight mass spectrometry (HRTOF-MS), and simultaneous selective and mass spectrometric…

Automated Dynamic Headspace Sampling of Aqueous Samples Using Replaceable Adsorbent Traps

Static (equilibrium) headspace sampling is commonly used for GC determination of volatiles in solid and liquid samples. Since this technique relies on the analyte partitioning between the sample and headspace and uses a fixed injection volume it may not provide adequate detection limits, particularly for higher molecular weight, higher boiling analytes, and for polar analytes…

Automated Dynamic Headspace Sampling of Aqueous Samples using Replaceable Adsorben Traps, Part II

Static (equilibrium) headspace sampling is commonly used for GC determination of volatiles in solid and liquid samples. Since this technique relies on the analyte partitioning between the sample and headspace and uses a small injection volume it may not provide adequate detection limits, particularly for higher molecular weight, higher boiling analytes and for polar analytes…

A Novel Extraction Precedure for Stir Bar Sorptive Extraction (SBSE): Sequential SBSE for Uniform Enrichment of Organic Pollutants in Water Samples

A novel stir bar sorptive extraction (SBSE) procedure termed sequential SBSE was developed. Compared to conventional SBSE, sequential SBSE provides more uniform enrichment over the entire polarity/volatility range for organic pollutants at ultra-trace levels in water. Sequential SBSE consists of a SBSE performed sequentially on a 5-mL sample first without modifier using one stir bar,…