GCMS sampler LCTOF

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Research Equipment

 

 

photo of GC-MS/FIDAgilent 7890 capillary gas chromatograph is equipped with Agilent 7683 autosampler using programmed temperature vaporizing (PTV) injection port or an optional split/splitless injector. The GC can be interfaced to a flame ionization detector (FID), thermal conductivity detector (TCD), and Agilent 5975 MS detector. The MS operates in electron ionization (EI) mode. A microfluid 2-way splitter allows for simultaneous data acquisition using two different detectors. This instrument is dedicated to the ananlysis of biofuels.The system may be coupled with CDS 5200 pyroprobe allowing for online pyrolysis studies.

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Photo of Agilent GCMS 6890 with pyroprobe with For the analysis of partiuclate matter samples Agilent GC6890 is employed. This system is equipped with split/splitless and on-column injectors. Three detectors are available for analysis. This GC is interfaced into the Agilent MSD 5975C with inert source. The MS can be operated in hard (EI) or soft (CI) ionization mode. Two additional detectors, FID and FPD (flame-photometric detector), are available for analysis. A microfluid 2-way splitter allows for simultaneous data acquisition using two different detectors. Multipurpose Gerstel MPS2 autosampler installed on this system allows for automated liquid, headspace or SPME injections.

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Photo of GC-FID HP5890Our lab also maintains two Hewlett-Packard (HP) 5890 Series coupled to HP 5972 MS or HP 5971 MS both operating in EI mode. These instruments are used for advanced analytical classes and routinne organic measurements. For teaching purposes several GC/FID with split/splitless injection are available. The instruction guideline for the use of these instruments is provided in on the Instrument Policies link.

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Photo of HPLC-TOF Agilent G1969AOur research laboratory (Abbott Hall 110) houses Time-of-Flight MS G1969A Series 6200. This high resolution TOF MS allows distinguishing compounds with a 5 ppm mass accuracy with mass range up to 10,000 amu. This can be especially useful for characterization of complex matrices containing numerous compounds with similar molecular ions. Two types of atmospheric ionization sources, electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) allow for analysis of a wide range of analytes. The instruction guideline for the use of these instruments is provided in on the Instrument Policies link. This instrument can be coupdled with Agillent 1100 HPLC with in-line diode arrray detection (DAD) and/or evaporative light scattering detector detection (ELSD).

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Our group maintains departmental LC1100, which is equipped with the autosampler, DA detector and interfaced into the Bruker LC-Esquire ion trap MS. Two ionization sources, ESI and APCI, are available for the analysis. Ion trap MS allows for MS/MS experiments, which can be useful for compound identification.

In order to ensure proper quantification of any species from complex matrixces (environmental, biological samples) our work involves development of efficient extraction methods, preferentially using nontoxic solvents such as carbon dioxide and water. Thus besides trational soxhlet and ultrasound extraction our laboratory frequenly employes hot pressurized water extraction or pressurized fluid extraction.

Scheme of Extraction appratu for HPW and PFE

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Research in our lab involes atmopheric chemistry studies. For this we have joinly with chemical engineering acquired suite of instruments allowing for characterization of ambient atmospheric particualte matter (PM) samples as well as PM samples generated in atmopheric chamber and small flow reactors.

Air PM Samplers

Particle characterization

Reaction experiments

We have available several PM samplers. The high volume sampler for semivolatile organic species consists of a 92 LPM PM2.5 cyclone followed by a 600 mm 8-channel annular glass denuder, a two-stage 90 mm filter pack (all from URG Corp.), an Alicat Scientific mass flow controller and an Air Dimensions high speed pump. This sampler is capable of collecting gas phase as well as particulate phase.

Scheme of High volume PM sampler

Photo of BGI PQA200 Particulate samplersThe PQ200 Ambient Air Samplers (BGI Inc.) shared joinly SUNRISE program are designed to conform to the EPA PM2.5 reference method. The built-in pump pulls 16.7 L/min (1 m3/h) of air through the filter(s). These air PM samplers employ the use of a Very Sharp Cut Cyclone (VSCC) as the impactor, which allows only particles of size 2.5 µm and smaller to reach the filters. Two different filter set-ups can be employed with these samplers: a dual cassette filter holder (often used for speciation sampling) and a single cassette filter holder.

 

 

Several instruments are employed for characterization of PM. Online instruments include SMPS and TEOM, for chacterization of carbonaceous species thermal optical analyzer (TOA) is employed. Further characterization may be performed upon extraction and using chromatography/mass spectrometric techniques decribed above.

 

Photo of TEOM particulate monitorThe Tapered Element Oscillating Microbalance (TEOM 1405 Ambient Particulate Monitor, Thermo Scientific) is a gravimetric instrument providing real-time mass concentrations in µg/m3. The total air flow pumped through the system is 16.7 L/min. The tapered element is a hollow tube which has a small filter positioned on the end which oscillates at a certain frequency; ambient air is pumped through the filter, depositing PM on the filter. As PM accumulates, the frequency of oscillations of the tapered element changes; the measurement of these changes allows the TEOM to detect mass changes. A computer built into the TEOM then calculates mass concentration averages for various time periods using a sliding scale.

 

 

Photo of SMPSThe Scanning Mobility Particle Sizer (SMPS, TSI Inc.) provides information on mass concentrations, size distributions, and number of particles. The SMPS is composed of an Electrostatic Classifier, which includes a Differential Mobility Analyzer (DMA), and a Condensation Particle Counter (CPC). The air sample is pumped through an impactor, allowing only particles within a specific size range (as determined by the diameter of the impactor and the flow rates through the system) to enter the instrument. As the particles enter, their charge becomes neutralized by a radiation source before they move into the DMA. The DMA classifies the particles based on their mobility (size dependent). Within the DMA, there is a negatively charged rod in the center of a larger tube; through this tube there is the sample flow and the "sheath" flow, which are usually a 1:10 ratio. The sheath flow ensures that the sample flow containing particles has laminar flow. The negatively charged rod scans through a range of voltages; at each voltage, only particles of a specific size have the correct mobility to exit the DMA. After the particles leave the DMA, they go to the CPC which tallies the number of particles that enter; by scanning a range of voltages in the DMA, the CPC is able to provide full size distribution.

 

Photo of OCEC analyzerThe thermal optical analyzer (TOA, Sunset Laboratories) is used for determining total carbon content (TC), organic carbon (OC) and elemental carbon (EC) from aerosol samples. Carbonaceous samples are submitted into a quartz oven on a 1.5 cm2 quartz filter punch. The carbon is then volatilized with increasing temperature in an inert helium atmosphere followed by a mixture of helium and oxygen evolving organic carbon and elemental carbon respectively. The evolved carbon is oxidized over a MnO2 catalyst to CO2 and subsequently reduced to methane which is then detected by a flame ionization detector (FID). During the analysis, portion of EC pyrolyses prematurely. In order to determine the split point between OC and EC, this instrument employs a correction by either laser transmittance or reflectance.

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Photo of Aerosol smog chamber enclosureFor small scale preliminary experiments we have setup a smal flow Teflon reactor. At the same time for atmospherically relevant studies we are in process of setting up 20 m3 atmospheric chamber. We have built, the main enclosure structure of the chamber including a power panel including supply for the instrumentation, space heaters, black lights, and two air-conditioning units. The light fixtures for the 25 black lights (350 blacklight, 40W Sylvania) were installed with individual switches for each light. To prevent overheating and to control the chamber temperature, two space heaters and air-conditioning units were installed. The interior part of the enclosure was covered with 5 mil mirror sheeting (Nielsen Enterprises, Kent, WA) to maximize the light intensity. To provide dry, purified air clear of hydrocarbons and particles, the system was connected to compressed house air passing through the adsorbent and particulate filters, a refrigeration drier (Parker Zander ASD25), and a zero air generator (Model 767-14A Webster Assoc.) providing high flow rates of 0-100 LPM including a methane reactor and heat indicating system.

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Last updated February 2012 | Chemistry Department | University of North Dakota |