Millipore Fluoropore

The fine particle airstream from the cyclone was sampled by two total filters in parallel. A Millipore Fluoropore 47 mm diameter Teflon filter with a 1 pm pore size was used for the first seven samples. Subsequent samples were obtained with a 0.4 pm pore size 47 mm Nuclepore polycarbonate filter because particle absorption measurements and elemental analysis by particle induced X-ray emission (PIXE) were easier and more accurate using the Nuclepore filters. In parallel with the Nuclepore filter, a TWOMASS tape sampler collected aerosol using a Pallflex Tissuequartz tape. The aerosol deposit area was 9.62 cm on the Nuclepore and Millipore filters and 0.317 cm on the Tissuequartz tape. The flow rate was 16-20 1pm through the Nuclepore and Millipore filters and 10 1pm through the Tissuequartz tape. Each Millipore or Nuclepore filter was placed in a labeled plastic container immediately after collected, sealed with Parafilm, enclosed in a ziplock bag, and placed in a refrigerator in the trailer. The tape in the TWOMASS sampler was advanced between samples. The tape sample was removed about once every 8-10 weeks and stored similarly to the Nuclepore filters. The TWOMASS was cleaned at that time. All samples were stored in an ice chest during the return trip to Caltech. Field blanks were handled identically to the samples. Of approximately 100 filter samples collected in 1979, 61 were selected for analysis. The 61 were chosen to span the variation in bjp and to obtain representative seasonal and diurnal samples. Sample times varied from 6 to 72 hours, with an average of 20.1 hours. 

Sierra Radial Slit Jet Millipore Fluoropore filters 10.2... 

Materials. Unless otherwise stated, all chemicals and solvents were analytical grade materials (Fluka and B.D.H.), and were used as received. The water used for washing and preparation of aqueous electrolyte solutions was deionized and freshly double-distilled in a fused-silica still. All liquids are filtered (0.22 pm Millipore or Fluoropore filters) prior to introduction into the glass cell. The mica used throughout was Best Quality FS/GS grade 2 Muscovite Ruby mica, mined in Kenya (Mica and Micanite Ltd., U.K.). 

All solutions were filtered through a 0.5 ym Fluoropore poly(tetrafluorethylene) filter (FHUP, Millipore Corp.). The solvents trichlorobenzene (TCB), o-dichlorobenzene (ODCB) and a-chloronapthalene (aCN) were used as received without further purification. 

Refractive Index Detector (Knauer). The KMX-6 scattering intensity was measured with the 6-7 degree forward-scattering annulus. A series of Zorbax PSM columns (DuPont) was used PSM 60, PSM 1000, PSM 1000, PSM 60, PSM 1000. Tetrahydrofuran (THF) from Baker was filtered through a 0.22 micrometer Fluoropore filter (Millipore Corp.) before use in chromatography, and a flow rate of 0.7 ml/min was used. 

Three filtering media commercially available from Millipore Corporation were evaluated for the collection of airborne particulates of the organoarsenical compounds. These were (l) cellulose ester membranes (2) Fluoropore and (3) Mitex. The cellulose ester membrane filters (0.8 ym pore size) are the standard Millipore filters used for aerosol sampling and consist of a mixture of cellulose nitrate and cellulose acetate. The Fluoropore filters are made of Teflon (PTFE) and are bonded to a polyethylene net. Fluoropore filters with a pore size of 1.0 ym were selected for this study. 

Methodology. Teflon filters exhibit the lowest HN03 retention of those in common use (12). Fluoropore (Millipore Corporation) and Zefluor PTFE filters (Gelman Sciences) of 0.5- to 2- xm pore size, are frequently used as prefilters in the filter pack method (FPM). With 47-mm-diameter filters, flow rates with the FPM from 10 to 20 L/min are typical. The 2- xm pore size Zefluor filter exhibited 97% efficiency for 0.035- xm particles at a face velocity of 33 cm/s, with a pressure drop of 1.0 cm Hg (1.3 kPa) (33). 

Soot from an 02-propane flame was produced in a 5 cm diameter 1-meter flow tube, with a total flow rate (N2 carrier gas) of 3.5 liter min. 1 0.2 pm pore size Fluoropore filters (Millipore Corp.) were used for mass evaluation. 

It consists of a 25-mm-diameter Deldrin filter holder (Gelman product No. 1109) with one of the nylon hose nipples removed. The filter used is a 25-mm-diameter, 0.5-pm pore size Fluoropore membrane filter (Millipore catalogue No. FHLP 025 00). An auto sampler cup cap is used to seal the apparatus, both before and after use. In use, the filter holder is attached to an Edwards E2 M12 vacuum pump. 

Note The purpose of the in line 1-pm filter is to retain any inorganic particles removed from the swab by the organic extraction. The filter and filter holder are an integral part of a subsequent concentration/cleanup procedure for inorganic FDR as outlined in reference 220. The filter unit consists of a 13-mm-diameter Swinnex disposable filter holder containing a 13-mm-diam-eter, 1-pm pore size, fluoropore membrane filter (Millipore FALP 01300). 

The membranes used were all from Millipore, with thickness and porosity as shown MF Cellulose (150 jun, 0.75), Fluoropore (60 p.m, 0.85) and Durapore (125 p.m, 0.75). Viscosity values were obtained from previous papers [16] and standard literature sources, giving vifg = 0.153 at 15 °C, and v = 0.102 at 15 °C. 

Analytical GPC. Size measurements were made on an analytical GPC system using %-in. o.d. /x-Styragel columns (Waters Associates) with 1 ft 104 A porosity, 2 ft 500 A porosity, and 1 ft 100 A porosity. The samples were run as 0.1% tetrahydrofuran solutions prefiltered through a 0.5-/1 Fluoropore filter (Millipore Corporation) with THF at 2 mL/min as the mobile phase. 

With air-gap electrodes an additional 0.1% of a non-ionic wetting agent is added (such as Victarwet (Stauffer Chemical Cor.) [167]) ) such as Fluoropore with 1 ju pore size and a polyethylene backing (Millipore) [171]... 

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