Carpets for office use are nowadays in most cases applied with water-based adhesives. During the last decade the complaints about odors and emission of volatile organic compounds from these fitted carpets have increased dramatically, causing a major problem for indoor air quality. In a series of investigations it has been established that in many cases…
The TOPAS / TDS D system combines the advantages of the passive sampling of badge-type passive samplers with thermal desorption for sample transfer to the gas chromatography system. The large surface and the sampler’s short diffusion path permit high sampling rates. Use of thermal desorption as a sample transfer technique avoids the necessity for time…
A variety of volatile organometalloid species finds application in industrial processes. Among these are e.g. the fumigation of tobacco leaves or flour with phosphine (PH3) for elimination of insects, or the use of sulfurhexafl uoride (SF6) as arc extinguishing media in electrical circuits. The occurrence of volatile metal(loid) species was also proved in emissions of…
The analysis of airborne aldehydes and ketones first involves collection of the analytes by passing air through a cartridge containing 2,4-dinitrophenylhydrazine (DNPH). As the air passes through the cartridge, the analytes react with the DNPH to form hydrazones which are immobilized on the cartridge. The cartridges are then eluted with solvent and the DNPH derivatives…
The analysis of airborne aldehydes and ketones first involves collection of the analytes by passing air through a cartridge containing 2,4-dinitrophenylhydrazine (DNPH). As the air passes through the cartridge, the analytes react with the DNPH to form hydrazones which are immobilized on the cartridge. The cartridges are then eluted with solvent and the DNPH derivatives…
Direct thermal extraction (DTE) is a thermal desorption technique in which a small amount of sample, typically 10-50 mg, is placed in an empty fritted thermal desorption tube or into a small vial (μ-vial) within an empty thermal desorption tube. The sample is then heated in a thermal desorption unit under a flow of inert…
In this study, different food and beverage samples were analysed without chromatographic separation by direct transfer of their analytes into a mass spectrometer or by disregarding chromatographic separation. Three different sample introduction techniques – Headspace, Solid Phase MicroExtraction (SPME) [1], and HeadSpace Sorptive Extraction (HSSE) – were used. Mass spectral fingerprints were compared using pattern…
A multi-residue method to determine five groups of 85 pesticides – chlorinated, carbamate, phosphorous, pyrethroid and others – in vegetables, fruits and green tea has been developed using stir bar sorptive extraction (SBSE) coupled to thermal desorption and retention time locked (RTL) GC-MS. Pre-extraction with methanol and dilution with water prior to SBSE (60 min)…
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.…
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…
Disposable Pipette Extraction (DPX) has been shown to be a rapid, efficient and reproducible method for performing solid-phase extraction (SPE) of pesticides from fruits and vegetables. DPX is a unique SPE method because the solid phase sorbent is contained inside a disposable pipette tip and is mixed with sample solutions. This mixing allows for the…
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…
Fruit and vegetable extracts that are produced following the well established QuEChERS method [1,2] typically contain a signifi cant amount of involatile matrix material. After several injections of such extracts into the GC, sufficient matrix residue will be present in the GC inlet liner to lower or sometimes even increase the response of certain pesticide…
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…
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…
Packaging materials for foodstuffs or consumer usage must not alter the flavor or odor of the substance being packaged. Examples of packaging materials include the paper used to wrap cigarettes, the paper cartons used in orange juice or milk and the Polyethylene (PE) often used for caps to seal soft drink bottles. Sometimes, due to…
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 (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…