Extraction of Gaseous VOCs Using Passive Needle Trap Samplers

Abstract

Gaseous toluene, ethylbenzene and o-xylene (TEX) were extracted by using the divinylbenzene (DVB) particle of 60-80 mesh as a sorbent packed in series of needle trap samplers (NTS). The feasibility of using this self-designed DVB-NTS as a diffusive time-weighted average (TWA) sampler for occupational hygiene applications was evaluated by examining extended sampling periods of 4-12 hr. Additionally, the NTS was compared in terms of extraction efficiency by simultaneously using the 75 μm Carboxen/polydimethylsiloxane-solid phase microextration (Carboxen/PDMS-SPME) fiber for sampling TEX. Experimental results indicated that, regardless of static (in a bulb) or dynamic samplings (in a flowing gas stream), the packed DVB-NTS achieved higher TEX extraction rates (ng VOCs/min) than those of 75 μm Carboxen/PDMS-SPME fiber. The decreasing rates of extracting TEX for SPME fiber were 24-34% and 28-36% as NTS performed during the sampling periods of 240 and 480 min, respectively. Typically, the maximum VOC adsorption capacities per mg DVB were measured as 5.692 μg toluene, 7.669 μg ethylbenzene and 5.199 μg o-xylene. During the sampling period of 12 hr, the DVB-NTS extracted 1600-1800 ng of individual TEX components from a continuously flowing air stream, in which the gas flow rate equals 200 mL/min. We recommend the badgelike or penlike NTS as an alternative passive sampler to the legal active sampling method 1501, National Institute of Occupational Safety and Health (NIOSH), owing to its small size and high extraction capacity of TEX.

Gaseous Products of Incense Coil Combustion Extracted by Passive Solid Phase Microextraction Samplers

“…The SPME fibers were also analyzed using the same procedures as those for the NTS. Notably, after analysis, no VOC carryovers were available for sample extraction by the NTS or SPME, which was verified by earlier examinations [10][11][12][13].…”

“…Since few studies have examined the uniformity of the packing phase in an NTS, the procedures by Cheng et al [10][11][12][13] were applied to examine all NTS in terms of desired sampling flow rates (mL/min) when drawn by an aspirating pump through the packing phase. When the RSD for three duplication tests of sampling flow rates did not exceed 5%, the materials filled in the NTS were assumed uniformly immobilized.…”

“…Cheng et al [10] extracted gaseous benzene, toluene, ethylbenzene and o-xylene (BTEX) using divinylbenzene (DVB) particles as sorbents packed in a self-fabricated SPME device, the novel needle trap samplers (NTS). Based on experimental results obtained by Cheng et al [10], indoor combustion sources including mosquito coils [11,12] and essential oils [13], were sampled successfully using an NTS, and they were then analyzed via GC/MS.…”

Extracting Emissions from Air Fresheners Using Solid Phase Microextraction Devices

“…According to the assembly of sampling chamber (Cheng et al, 2011(Cheng et al, , 2013(Cheng et al, , 2014aUhde and Schulz, 2015), 10 g of air freshener was placed in a circular glass chamber (with inner dimensions of a diameter of 30 cm, a height of 22 cm and a total volume of about 17.5 L) at 27°C. Air was then pumped into the chamber at a flow rate of 0.5 L min -1 as the freshener emitted the gaseous compounds.…”

“…2 presents that the NTS is composed of mainly a stainless steel needle that is packed with DVB particles (60-80 mesh). The procedures developed by Cheng et al (2011Cheng et al ( , 2013Cheng et al ( , 2014a were used to examine all NTS in terms of the desired sampling flow rates (mL min -1 ) when drawn by an aspirating pump through the packing phase to examine the uniformity of the packing phase in an NTS. When the relative standard deviations (RSD) in triplicate sampling flow rate tests did not exceed 5%, the filled materials in the NTS were considered to be uniformly immobilized.…”