Teflon caps

Additional reports on olefination reactions have appeared [64] including the preparation of several phosphonium salts using a domestic MW oven wherein the reaction of neat triphenylphosphine and organic halide shows remarkable rate enhancement in a pressure tube with a threaded Teflon cap [65]. 

When human skin was treated in vitro with 0.0013-0.0027 mg/cm2 [14C]-labeled phenol and left unoccluded, 20% of the radioactivity was absorbed when analyzed 72 hours later, while 7% remained on the skin surface (Hotchkiss et al. 1992). Covering the skin with a teflon cap resulted in the absorption of 47%, with 3% recovered in the skin. When rat skin was subjected to the same exposure regime in this study, 72 hours later 24% of the radioactivity was absorbed with 22% recovered in the skin when the skin was unoccluded, and 36% was absorbed with 3-4% recovered in the skin when the skin was occluded. 

Place 50 (xl of sample or cells in a 2 ml eppendorf or 13x100mm screw-capped, borosilicate glass test tubes with Teflon caps. 

Resin Elution Concentration. The first three ethyl ether elutions were combined into a 500-mL glass bottle with a Teflon cap liner. The bottles and all the laboratory glassware used in the sample analysis were cleaned with 6.0 N HC1, acetone, and hexane and then baked at 200 °C to remove the solvent. The combined elutions were brought to the laboratory for evaporative concentration and analysis. 

Recover the upper organic layer containing the FAME. Place the organic layer in a 1.5 ml GC sample vial (Teflon cap) containing a 1 mm-deep layer of anhydrous sodium sulfate on the bottom. Properly dispose of the lower layer that contains methanol. 

N-EVAP model 112 nitrogen evaporator (Organomation) with moisture trap in line from N2 source 50°C heating block Test tube shaker Tabletop centrifuge GC sample vials with Teflon caps... 

Reconstitute the FAME in a volume of hexane appropriate for the conditions of GC analysis (see Critical Parameters) and FAME concentration. Transfer to GC sample vials with Teflon caps and perform GC analysis. 

The diamine 2 was added to an etherial solution of an acyl chloride 1 in a Teflon-capped vial. Salt precipitaion was instant. The solvent was removed by filtration, where the Teflon cap served as the filter. Lawesson s reagent (1.0-1.5 equiv.) was added to the salt 3 and the resulting mixture of solids was mixed thoroughly and thereafter irradiated for 8 min in a domestic microwave oven (900 W, Whirlpool M401). Solid-phase extraction afforded the thioamides 4 in adequate purities and yields. 

In order to determine the initial TCE concentrations prior to initiation of EO, samples of the contaminated slurry were collected at the same time they were loaded into individual EC. A 5 g slurry sample was loaded into a previously weighed, teflon-capped borosilicate vial. After reweighing to obtain the actual sample weight, the vial was opened and reagent grade methanol added to the top of the vial and the teflon cap replaced without headspace in the vial. The vial was again re-weighed to obtain the amount of methanol added. A second slurry sample was taken in the same manner. 

As an example, tablet samples for a product were prepared in an 85% organic medium and transferred into HPLC vials. An impurity peak was observed in some, but not all, of the tablet samples, blanks and standards. It was suspected that the solution in some of the vials may have come in contact with the HPLC Teflon caps and extracted a component from the cap. To evaluate this possibility, dissolving solvent was transferred into similar HPLC vials. These vials were capped with the Teflon caps and were kept inverted overnight to allow maximum contact of the solvent with the vial caps. A set of control samples were also prepared in which the vials were only filled halfway with dissolving solvent and care was taken not to allow the dissolving solvent to come into contact with the vial caps. These samples were analyzed by HPLC and, as shown in Fig. 10.3, confirmed the origin of the peak in question as being from the vial caps. In addition, the UV spectral analyses of the... 

Figure 6 Four separated compartments cell for isolation of electrolysis products of non-aqueous solutions (1) working electrode, (2) counterelectrode, (3) reference electrode, (4) luggin capillary, (5) glass frits, (6) Teflon caps [15]. (Reprinted with copyright from Elsevier Science Ltd.)... 

Figure 1 displays the solid-state NMR spectrum characteristic of Ceo- The sharp peak with a chemical shift of 143.7 ppm is consistent with Ceo, and the broad feature at approximately 110 ppm is simply due to the Teflon cap sealing the NMR rotor. 

Fig. 10.8 Thin-layer electrochemical cell used in SNIFTIR studies and reflection optics (a) Teflon cap (b) N2 inlet (c) glass tube (d) Teflon cell body (e) port for reference electrode (f) ceramic tube (g) Pt wire counter electrode (h) single crystal working electrode (i) hemispherical ZnSe window (k) focal plane for reflection optics (m) instrument focal plane and (n) folding mirrors (From reference 16, with permission.)...

NH3 vapor neutralization apparatus (Figure 10.2), a side-arm gas scrubbing tube and vented Teflon cap are connected to the sample cell and an anhydrous NH3 tank with a needle valve for fine-flow adjustment. 

In a glass vial with a teflon cap and using glass Hamilton syringes, mix 22.5 mmol of DOPC with 2.5 mmol of DOGS-NiNTA (ratio 10 1) in chloroform. (This will produce 10 mM lipid solution after reconstitution with 5 mL.). 

Before analysis, the bacterial cultures should be transferred into standard 20 ml headspace vials and sealed with PTFE-lined Teflon caps to equilibrate the headspace. Sample handling is a critical step affecting the analysis by E-nose. The quality of the analysis can be improved by adopting an appropriate sampling technique. To introduce the volatile compounds present in the headspace (HS) of the sample into the E-nose s detection system, several headspace sampling techniques have been used in E-nose. Typically, the methods of headspace sampling (Ayoko, 2004) include static headspace (SHS) technique, purge and trap (P T) technique, stir bar sorptive extraction (SBSE) technique, inside-needle dynamic... 

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