Development of second-generation sample enrichment probe for improved sorptive analysis of volatile organic compounds

Abstract

The sample enrichment probe (SEP) has recently been introduced as a user-friendly and cost-effective method for the sorptive extraction of volatile organic analytes from gaseous and aqueous samples for GC and GC-MS analyses. In a further development of the SEP technique, thinner polydimethylsiloxane (PDMS) tubing on polyimide-coated fused silica, instead of stainless steel rods or stalks, were used to produce the second-generation SEPs. The new SEP does not require widening of the needle-guiding orifice of the septum cap and analytes are desorbed at a faster rate from the thinner sleeve, which reduces the risk of carry-over. The flowless period that was previously recommended for analyses of highly volatile analytes is made redundant by the faster desorption from the thinner sorptive medium. It was found that differences in the thermal histories of SEPs are not the cause of the high relative standard deviations (RSDs) reported in our first paper on the technique. Excellent reproducibility can be attained by careful handling and storing of loaded SEPs and by rigorously following a standardised analytical protocol.

Olfactory Cue Mediated Neonatal Recognition in Sheep, Ovis aries

“…Because of its high sensitivity and simplicity, the SEP technique (Burger et al, 2006(Burger et al, , 2011 eventually was used for sample enrichment of the wool VOCs. The recently introduced term "enrichment" has gained wide acceptance, and is now preferred for sampling techniques in which the constituents of a gas sample, or the headspace of solids or liquids, are concentrated in the sample preparation step prior to introduction of the sample into the injector of the analytical instrument.…”

“…A second generation SEP50 sample enrichment probe (MasChrom Analisetegniek, Stellenbosch, South Africa), consisting of a fused silica stalk, or shaft, carrying a 50 mm sleeve (47 mg) of polydimethylsiloxane (PDMS) tubing (Burger et al, 2006(Burger et al, , 2011, was used to trap VOCs from wool samples for GC and GC-MS analyses. The Teflon face of a septum was pierced centrally with the sharpened back end of the SEP, and the septum positioned on the stalk so as to enable headspace sampling from an 8-ml vial.…”

Characterization of Volatiles and Aroma-Active Compounds in Honeybush (Cyclopia subternata) by GC-MS and GC-O Analysis

“…For each low-resolution GC-MS (GC-LRMS) analysis, 50 mL of filtrate was transferred to a 100 mL glass bottle with adapted cap,(7) sealed, and incubated at 50 °C for 30 min, after which the headspace volatiles of the filtrate were enriched at 50 °C for 5 h using a SEP30 (MasChrom Analisetegniek, Stellenbosch, South Africa), which contains 30 mm polydimethylsiloxane (PDMS) tubing, equivalent to 28 mg of PDMS. (7,8) Longer enrichment periods of 17 h and a SEP60 (56 mg of PDMS) were used for GC-O and high-resolution GC-MS (GC-HRMS) analyses.…”

“…The sample enrichment probe (SEP) (7,8) was developed specifically to fill a niche that exists for a moderately priced, high-capacity sampling method that can be used in applications that do not require automated, high-throughput sample handling.…”

Acrolein Dimer as a Marker for Direct Detection of Acrolein in Wine

“…The amount of available phase conversely limits the mass of analyte extracted. Recent developments in the high-capacity sample enrichment probe (SEP) circumvent this problem (Burger et al, 1990(Burger et al, , 2006(Burger et al, , 2011. An SEP consists of a thin probe of inert material that is provided at one end with a short sleeve of silicone rubber for analyte sorption.…”