Biomedical subjects

J A Koziel

Publications and source records attributed to J A Koziel.

5 recordsLinked to original sources

PubMed2001

Sampling and Raman confocal microspectroscopic analysis of airborne particulate matter using poly(dimethylsiloxane) solid-phase microextraction fibers.

Commercial poly(dimethylsiloxane) (PDMS) 7-microm solid-phase microextraction (SPME) fibers were used for sampling and Raman spectroscopic analysis of a tailpipe diesel exhaust, candle smoke, cigarette smoke, and asbestos dust. Samples were collected via direct exposure of the SPME fiber to contaminated air. The mass loading for SPME fibers was varied by changing the sampling time. Results indicate that PDMS-coated fibers provide a simple, fast, reusable, and cost-effective air sampling tool for airborne particulates. The PDMS coating was stable; Raman bands of the PDMS coating were observed exactly at the same wavenumber positions before and after air sampling. Raman spectroscopic analysis resulted in identification of several characteristic bands allowing chemical speciation of particulates. The advantage of the SPME fiber is the open bed geometry allowing for application of various spectroscopic methods of particulate analysis. This paper describes the first-ever combined application of SPME technology with Raman confocal microspectroscopy for sampling and analysis of airborne particulates. Advantages of the combination of solid-phase microextraction and Raman microspectroscopy for airborne particulate analysis are discussed. Challenges associated with combined SPME sampling and Raman analysis of single particles are also described.

Journal Article↗

PubMed2001

Field sampling and determination of formaldehyde in indoor air with solid-phase microextraction and on-fiber derivatization.

A new sampling and analysis method for formaldehyde in indoor air was tested in several indoor air surveys. The method was based on the use of solid-phase microextraction (SPME) poly(dimethylsiloxane)/divinylbenzene,65-microm fiber and gas chromatography. Indoor air surveys included grab and time-weighted average (TWA) sampling and were completed at six locations using (a) the SPME method employing on-fiber formaldehyde derivatization with o-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine hydrochloride and (b)the conventional National Institute for Occupational Safety and Health (NIOSH) 2451 method. Sampling time for SPME fiber ranged from 10 min for grab sampling to 8 h for TWA sampling. Sampling locations included a residential house, a rental apartment, an office building, and industrial workplaces. The air concentrations measured by SPME ranged from 10 to 380 ppbv and correlated well with those estimated by the NIOSH method. Results also indicated thatin some cases the formaldehyde concentrations measured in residential air could be much higher than those allowed in occupational settings. The SPME method proved to be accurate, fast, sensitive, and cost-efficient in field sampling applications. This research should be of interest to research, industrial, and regulatory agencies as well as to the general public concerned with indoor air quality.

Air Pollution, Indoor↗

PubMed2001

Sampling and analysis of airborne particulate matter and aerosols using in-needle trap and SPME fiber devices.

A needle trap device (NTD) and commercial poly(dimethylsiloxane) (PDMS) 7-microm film thickness solid-phase microextraction (SPME) fibers were used for the sampling and analysis of aerosols and airborne particulate matter (PM) from an inhaler-administered drug, spray insect repellant, and tailpipe diesel exhaust. The NTD consisted of a 0.53-mm o.d. stainless steel needle having 5 mm of quartz wool packing section near the needle tip. Samples were collected by drawing air across the NTD with a Luertip syringe or via direct exposure of the SPME fiber. The mass loading of PM was varied by adjusting the volume of air pulled through the NTD or by varying the sampling time for the SPME fiber. The air volumes ranged from 0.1 to 50 mL, and sampling times varied from 10 s to 16 min. Particulates were either trapped on the needle packing or sorbed onto the SPME fiber. The devices were introduced to a chromatograph/mass spectrometer (GC/MS) injector for 5 min desorption. In the case of the NTD, 10 microL of clean air was delivered by a gas-tight syringe to aid the introduction of desorbed analytes. The compounds sorbed onto particles extracted by the SPME fiber or trapped in the needle device were desorbed in the injector and no carry-over was observed. Both devices performed well in extracting airborne polycyclic aromatic hydrocarbons (PAHs) in diesel exhaust, triamcinolone acetonide in a dose of asthma drug and DEET in a dose of insect repellant spray. Results suggest that the NTDs and PDMS 7-microm fibers can be used for airborne particulate sampling and analysis, providing a simple, fast, reusable, and cost-effective screening tool. The advantage of the SPME fiber is the open-bed geometry allowing spectroscopic investigations of particulates; for example, with Raman microspectroscopy.

Journal Article↗

PubMed2001

Air sampling and analysis of volatile organic compounds with solid phase microextraction.

Solid phase microextraction (SPME) presents many advantages over conventional analytical methods by combining sampling, preconcentration, and direct transfer of the analytes into a standard gas chromatograph (GC). Since its commercial introduction in the early 1990s, SPME has been successfully applied to the sampling and analysis of environmental samples. This paper presents an overview of the current methods for air sampling and analysis with SPME using both grab and time-weighted average (TWA) modes. Methods include total volatile organic compounds (TVOCs), formaldehyde, and several target volatile organic compounds (VOCs). Field sampling data obtained with these methods in indoor air were validated with conventional methods based on sorbent tubes. The advantages and challenges associated with SPME for air sampling are also discussed. SPME is accurate, fast, sensitive, versatile, and cost-efficient, and could serve as a powerful alternative to conventional methods used by the research, industrial, regulatory, and academic communities.

Air Pollutants↗

PubMed2000

Kinetics of solid-phase extraction and solid-phase microextraction in thin adsorbent layer with saturation sorption isotherm.

The effects of sorbent saturation in thin adsorbent layers have been much overlooked in earlier research and should be taken into account in both the theory and practice of solid-phase extraction (SPE) and solid-phase microextraction (SPME). The adsorption kinetics of a single analyte into a thin adsorptive layer was modeled for several cases of agitation conditions in the analyzed volume. The extraction process in the adsorbent layer was modeled using a Langmuir isotherm approximated by the linear isotherm at low concentrations and by a saturation plateau at concentrations exceeding the critical saturation concentration. Laplace transformations were used to estimate the equilibration time and adsorbed analyte concentration profile for no agitation, practical and perfect agitation in the analyzed volume. The equilibration time may be significantly reduced at high degrees of oversaturation and/or agitation in the analyzed volume. The resulting models indicated that the adsorbent layer becomes saturated at some critical value of the oversaturation degree parameter. The critical value of the oversaturation parameter is affected by both the concentration of the analyte in the analyzed volume and the sorbent characteristics. It was also shown that the adsorption process is carried out via the propagation of the saturation adsorption boundary toward the inner boundary of the adsorbent layer. These new adsorption models should serve as "stepping stones" for the development of competitive adsorption kinetic models for both SPE and SPME, particularly in cases where fast sampling is used.

Chromatography, Liquid↗