Teflon liner

Pumps for Corrosive or Toxic Applications. For some appHcations, pumpage is not only severely corrosive but also toxic, so that the pumpage must be contained with 2ero leakage (see Waste tee atment, hazardous wastes). One possibiHty is to employ a magnetically driven pump having a nonmetaUic, usually Teflon, liner at the Hquid end. 

Residual pendimethalin in various crops was determined as follows." A 10-20-g amount of fruits or vegetables was extracted by blending twice with 200 mL of methanol. Grasses and mint were extracted with 200 mL of methanol-water (1 1, v/v). Nuts were extracted with 200 mL of n-hexane-2-propanol (3 1, v/v). For the residue analysis of the dinitroaniline herbicides butralin, dinitramine, ethalfluralin, pendimethalin, and trifluralin, a tomato sample (5 g) was extracted twice with 20 mL of methanol in a Sorvall homogenizer and filtered through filter paper. Benfluralin and trifluralin residues in the sample (10 g) were extracted with 100 mL of acetonitrile-water (99 1, v/v) in 250-mL screw-cap jars with Teflon liners rotated for 1 h on an end-over-end shaker (40 rpm). ... 

Inorganic and organic materials can be dissolved rapidly in Parr acid digestion bombs with Teflon liners and using strong mineral acids, usually nitric and/or aqua regia and, occasionally, hydrofluoric acid. Perchloric acid must not be used in these bombs due to the high risk of explosion. 

Collect and label 4-ml standard glass tubes equipped with screw caps and Teflon liner (Alltech). 

Collect and label clean 4-ml glass vials including screw caps and Teflon liners (Alltech). 

Steel autoclave Fluoropolymer vessel Teflon liner Titanium rack... 

Add 1 ml dichloromethane (DCM) to extract the alditol acetates. Vortex to mix (do not cap the tubes, as the glue holding Teflon liners may be soluble in DCM). Allow the phases to separate and transfer the lower DCM phase to a clean borosilicate glass tube using a Pasteur pipet. 

All efforts need to be made to reduce the likelihood of plasticizers (Henry et al., 1983) and other contaminants getting into one s samples. Avoid DCM making contact with the glue that attaches Teflon liners to caps, as this glue can give rise to peaks in the chromatogram. 

The surface of the sample container may interact with the analyte. The surfaces can provide catalysts (e.g., metals) for reactions or just sites for irreversible adsorption. For example, metals can adsorb irreversibly on glass surfaces, so plastic containers are chosen for holding water samples to be analyzed for their metal content. These samples are also acidified with HNO3 to help keep the metal ions in solution. Organic molecules may also interact with polymeric container materials. Plasticizers such as phthalate esters can diffuse from the plastic into the sample, and the plastic can serve as a sorbent (or a membrane) for the organic molecules. Consequently, glass containers are suitable for organic analytes. Bottle caps should have Teflon liners to preclude contamination from the plastic caps. 

Glass vial with screw cap, Teflon liner, 8 ml (approximately)... 

Identification Place about 150 mg of melted sample into a 16- x 125-mm tube equipped with a screw cap having a Teflon liner, and add 4 mL of absolute methanol, 4 drops of a 25% sodium methoxide solution in absolute methanol, and a boiling chip. Cap the tube, reflux for 15 min, and cool to room temperature. Extract as follows Add 8 drops of a 15% potassium acid sulfate solution, 4 mL of water, and 4 mL of n-hexane cap the tube shake for 1 min and centrifuge for 30 to 60 s. Decant and discard the M-hexane layer, and repeat the extraction with three additional 4-mL portions of M-hexane, discarding each extract. Transfer the aqueous alcoholic phase from the tube into a 50-mL round-bottom, glass-stoppered flask place the flask in a water bath at 50° to 55° and evaporate to near dryness (about 0.5 mL of residue) in a rotary film evaporator under full water aspirator vacuum. 

Apparatus For sample digestion, use a microwave oven (CEM Model MDS-2100, or equivalent) equipped with advanced composite vessels with 100-mL Teflon liners. Use rupture membranes to vent vessels should the pressure exceed 125 psi. The vessels fit into a turntable, and each vessel can be vented into an overflow container. Equip the microwave oven with an exhaust tube to ventilate fumes. 

Osmium tetroxide was supplied by Matthey-Bishop, Inc. in 1-g amounts in sealed glass ampuls. The procedure that we describe below should be followed to prepare the osmium tetroxide catalyst solution. Work in a well-ventilated hood. One ampul is scored in the middle, broken open, and the two halves are dropped into a clean, brown bottle containing 39.8 mL of reagent grade terf-butyl alcohol and 0.20 mL of 70 or 90% terf-butyl hydroperoxide (Aldrich). The bottle is capped (use caps with Teflon liners) and then swirled to ensure dissolution of the Os04. These solutions are stored in the hood at room temperature and seem to be very stable. 

Insert the Teflon liner about 3A of the way into the nipple. Make sure the liner edges are abutting and even. 

Remove the Teflon liner from the pipe nipple. 

Insert and position the Teflon liner back into the nipple. The threaded rod will now protrude through the holes in the liner when it is positioned correctly. 

Procedure Place 10 mg (ca. 0.04 0.08 mmole) of sulfur-containing amino acid and 10 mg of phenanthrene (as internal standard) in a 16 X 76 mm culture tube (screw cap with Teflon liner). Add 0.5 ml (ca. 2.6 mmoles) of BSA (or 0.5 ml ca. 3 mmoles, of BSTFA) and 1.5 ml of acetonitrile. Screw the cap on the tube and immerse just to the top of the liquid level in an oil bath at 150° for 5 minutes. Allow to cool and inject 5 JU.1 into the gas chromatograph. The chromatograms shown in Figs. 22 and 23 illustrate the results obtained by this procedure. The authors claim that the minimum detectable limit at a 2 1 signal-to-noise ratio with respect to the flame ionization detector is about 5 ng of sulfur-containing amino acid injected on the column. 

The oxidation of phenol solution was performed in a IL SS316 autoclave (Parr Instrument Co.)batch reactor equipped with a teflon liner and a gas entrainment impeller having a... 

The production of NS-Ti02 by the hydrothermal method is usually carried out in small autoclaves of Morey type [101-103], provided with Teflon liners. The operating conditions selected for the production of NS-TiOz particles are at a temperature less than, or equal to 200°C and at a pressure less than 100 bars. Such pressure-temperature conditions only require the use of autoclaves of simple design. 

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