Cellulose ester membrane filter

MCEF Mixed cellulose ester membranes filter... 

The method developed for sodium fluoroacetate is based on collection of the sample with cellulose ester filters especially low in extractables (Toyo-cel cellulosic ester membrane filters from Nuclepore were used). The samples were extracted with water and analyzed by ion chromatography. Other MCE filters contained high levels of extractables Cfrom wetting agents, surfactants) that... 

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. 

Air drawn through a 0.8 to 1.2 mm cellulose ester membrane filter, asbestos fibers counted by positive phase contrast microscopy technique sample prepared by acetone/triacetin method (NIOSH Method 7400, 1985). 

A measured volume of air drawn through a 0.8-mm cellulose ester membrane filter the particulates of hydroquinone extracted with 1% acetic acid in water ... 

Air (total chromium) Sample collected on cellulose ester membrane filter dissolved in acid mixtures ICP-AES 1 pg/sample 98% at 2.5 pg/filter NIOSH 1994d (Method 7300)... 

An employee s exposure to asbestos is evaluated by collection of asbestos fibers on a cellulose ester membrane filter. A Gel-lman G N-4 ( J, millipore AA (7J or other cellulose ester membrane which clarifies well in the mounting medium is commonly used. 

Cyanogen may be analyzed by GC by direct injection of air. Alternatively, air is passed through a cellulose ester membrane filter, extracted with KOH solution, and analyzed for cyanide by ion-specific electrode. It can also be analyzed by GC/MS technique. 

Collection Procedure A known volume of air is drawn through a 37-mm diameter filter cassette containing a 0.8-tim mixed cellulose ester membrane filter (MCEF). 

This method describes the colledion of airborne elemental cadmium and cadmium compounds on 0.8- m mixed cellulose ester membrane filters and their subsequent analysis by either flame atomic absorption spectroscopy (AAS) or flameless atomic absorption spectroscopy using a heated graphite furnace atomizer (AAS-HGA). It is applicable for both TWA and Action Level TWA Permissible Exposure Level (PEL) measurements. The two atomic absorption analytical techniques included in the method do not differentiate between cadmium fume and cadmium dust samples. They also do not differentiate between elemental cadmium and its compounds. 

Airborne elemental cadmium and cadmium compounds are collected on a 0.8- i.m mixed cellulose ester membrane filter (MCEF). The air filter samples are digested with concentrated nitric acid to destroy the organic matrix and dissolve the cadmium analytes. After digestion, a small amount of concentrated hydrochloric add is added to help dissolve other metals which may be present. The samples are diluted to volume with deionized water and then aspirated into the oxidizing air/acetylene flame of an atomic absorption spectrophotometer for analysis of elemental cadmium. 

Previously, two OSHA sampling and analytical methods for cadmium were used concurrently (5.3., 5.4.). Both of these methods also required 0.8- xm mixed cellulose ester membrane filters for the collection of air samples. These cadmium air filter samples were analyzed by either flame atomic absorption spectroscopy (5.3.) or inductively coupled plasma/atomic emission spectroscopy (ICP-AES) (5.4.). Neither of these two analytical methods have adequate sensitivity for measuring workplace exposure to airborne cadmium at the new lower TWA and Action Level TWA PEL levels when consecutive samples are taken on one employee and the sample results need to be averaged with other samples to determine a single TWA. 

Filter cassette unit for air sampling A 37-mm diameter mixed cellulose ester membrane filter with a pore size of 0.8-nm contained in a 37-mm polystyrene two- or three-piece cassette filter holder (part no. MAWP 037 AO, Millipore Corp., Bedford, MA). The filter is supported with a cellulose backup pad. The cassette is sealed prior to use with a shrinkable gel band. 

Collection efficiencies of metallic fume and dust atmospheres on 0.8- i.m mixed cellulose ester membrane filters are well documented and have been shown to be excellent (5.11.). Since elemental cadmium and the cadmium component of cadmium compounds are nonvola-... 

EDXA) and crystal structure by diffraction pattern analysis. TEM samples caii be taken on mixed cellulose ester membrane filters, but require special preparation. (See Baron, 1993.)... 

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