Headspace sampler, determination

Suitable PLOT columns for the determination of vinyl chloride monomer in PVC include 15.00 m, 0.53 mm bonded polystyrene-divinyl benzene and 30 m, 0.53 mm porous divinyl benzene homopolymer types. Typical responses for vinyl chloride monomer standards (0.06, 0.19 and 0.31 mg/1) in N,N-d imethylaceta-mide expressed as mg/kg vinyl chloride (PVC sample) using the 30 m homopolymer column and flame ionisation detection are shown in Figure 38. An automatic static headspace sampler was employed. 

Bicchi and Bertolino [193] analyzed a variety of pharmaceuticals for residual solvents. Samples were equilibrated directly or dissolved in a suitable solvent with a boiling point higher than that of the residual solvent to be determined. Equilibration conditions were 90 or 100°C for 20 min. A Perkin-Elmer HS-6 headspace sampler was used. The chromatographic phase chosen was a 6 x Vs in. column packed with Carbopack coated with 0.1% SP 1000. Residual ethanol in phenobarbital sodium was determined by a direct desorption method. An internal standard, /-butanol, was used. Typically, 0.44% of ethanol was detected (compared to a detection limit of 0.02 ppm). The standard deviation of six determinations was 0.026. Pharmaceutical preparations which were analyzed by the solution method included lidocaine hydrochloride, calcium pantothenate, methyl nicotinate, sodium ascorbate, nicotinamide, and phenylbutazone. Acetone, ethanol, and isopropanol were determined with typical concentrations ranging from 14 ppm for ethanol to 0.27% for acetone. Detection limits were as low as 0.03 ppm (methanol in methyl nicotinate). 

Boyer and Probecker [191] determined organic solvents in several pharmaceutical forms using a Perkin-Elmer HS-6 headspace sampler. Typically, the samples were heated at 90°C for 10 min to establish equilibrium. Head-space samples were injected onto a Chromosorb 102 column. Ten injections of a mixed ethanol-acetone standard using methanol as the internal standard gave better precision than manual injections as measured by the relative standard deviation 1.63% and 2.48% for ethanol and acetone, respectively, using the sampler as compared to 4.77% and 3.93% by manual injection, respectively. Methods were reported for acetone and ethanol in dry forms such as tablets and microgranules, ethanol of crystallization in raw materials, and ethanol in syrups. Denaturants such as n-butanol and isopropanol in ethyl alcohol were determined using ethyl acetate as the internal standard. 

Monomers are either gaseous or relatively volatile liquids and so GC and GC-MS based techniques are used to determine them in both the rubber compound and the food simulant/food product. To simplify the analysis, a static headspace sampler is often used to isolate the monomer from the sample matrix an extraction procedure often presenting chromatographic problems with the extraction solvent obscuring the analyte. 

Summary Polydimethylsiloxanes (PDMS) were cleaved using boron trifluoride etherate under defined conditions in a headspace sampler, and the resulting fluorosilanes were quantified by gas chromatography. The method makes it possible to determine traces of mono- and trifunctional organosiloxy groups in PDMS in concentrations down to... 

A spectrophotometric technique has been used for quantifying pg/mL levels of free and acid-labile (chemically bound) carbon disulfide in the blood of rats (Lam and DiStefano 1982, 1983). This technique is based on measuring the absorbance at 430 nm of a yellow cupric diethyldithiocarbamate complex that is formed by reacting carbon disulfide in blood with Viles reagent in the presence of acid and heat. A headspace sampler connected to GC equipped with a sulfur-specific flame photometric detector (FPD) has been developed for measuring low levels of free and acid-labile carbon disulfide in the blood of shift workers exposed to carbon disulfide (Campbell et al. 1985). A detection limit of 15.2 pg of carbon disulfide/L of blood was achieved. Concentrations of free and acid-labile carbon disulfide have also been determined by GS/MS (Brugnone et al. 1993, 1994 Perbellini et al. 1994). 

Amino acids. Sugars and Organic Acids were analysed as previously described (4). Total Volatiles determination. Volatiles composition and concentration in the samples of melon flesh were determined using a headspace sampler (HP 19393) coupled to a gas chromatograph (HP 5890). Approximately 5g of flesh was obtained by using a cork borer to remove a number of cores from around the equator of the fhiit. This was immediately sealed in a headspace vial, placed in the headspace sampler at a bath temperature of 100 C, equilibrated for 15min before analysis on an HP 5890 GC equipped with an FID detector and fitted with a 30m x 0.32mm i.d. OVl fused silica colunm. 

Headspace and thermal desorption are thermal extraction methods which can be directly connected to gas chromatography and do not need additional sample preparation. Usually both methods are applied for the determination of volatile compounds in air and water. Only few applications are known for the direct treatment of soil samples. The investigations for analysis of phenylarsenic compounds were carried out with an Headspace Sampler HS40 (Perkin-Elmer Inc.) and a Thermal desorption system TDS 2 (Gerstel GmbH, Germany). 

Gadelle and co-workers [13,14] used a Hewlett Packard headspace sampler (HP-19395A) connected to a Hewlett Packard gas chromatograph (HP5890) equipped with a capillary column and a flame ionisation detector to determine benzene, chlorobenzene, toluene and xylene in ethylene oxide propylene oxide tri block copolymers. The headspace sampler consists of a valve and loop system to inject a vapour sample of a known volume (1 pi) into the gas chromatograph. Peak areas are then determined by a Hewlett Packard integrator (HP 3393A). 

Elke, K., Jermann, E., Begerow, J., and Dunemann, L., Determination of benzene, toluene, ethylbenzene and xylenes in indoor air at environmental levels using diffusive samplers in combination with headspace solid-phase microextraction and high-resolution gas chromatography-flame ionization detection, J. Chromatogr. A, 826(2), 191-200, 1998. 

Solid-phase microextraction (SPME) devices can be employed with solid samples as passive samplers, but this approach must be conducted in headspace mode and so it is limited to the more volatile PAHs [269], Furthermore, it appears that SPME is a better approach to extract primarily PAHs present in sediment porewater rather than in the colloidal phase [270], EPA method 8272 describes the determination of parent and alkyl polycyclic aromatics in sediment pore water by SPME-GC-MS. In a similar way, SPMDs have been mainly used for the determination of PAHs contained in sediment porewater [271],... 

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