Glass beads, preparation

Fig. 15 Optical images of DNA-based materials for environmental purpose, a DNA-alginic acid hybrid matrix coagulated by Ca2+, in fiber, film, and gel form, b DNA-immobilized porous glass beads prepared by UV-irradiation. c DNA-polyacrylamide hydrogel beads synthesized by inverse suspension polymerization...

CDs are effectively used for the removal of cholesterol fi-om animal products, such as eggs and dairy products with the need of nutrition properties. The immobilized /3-CD glass beads prepared by silanization and immobilization reaction can generate 41% of cholesterol removal in milk and a recycling efficiency of almost 100% [41]. It is also reported that the crosslinked fi-CD can obviously reduce the cholesterol and retain most of physicochemical and sensory properties of mayonnaise [42]. Another previous study has been carried out to estimate the functional properties of cholesterol-removed whipping cream by -CD, indicating that the cholesterol is almost eliminated and less time is needed for cream whipping, after the treatment of /3-CD [43]. 

Freshly opened bottles of diehloroacetyl chloride from Aldrich Chemical Company, Inc., were used. The acid chloride can also be prepared by the dropwiae addition of 1 volume of dichloroacetic acid to 2.5 volumes of phthaloyl chloride heated to 140°. After the addition is complete, the solution is vigorously heated and diehloroacetyl chloride, b.p. 106-108°, is distilled through a 30-cm. column packed with glass beads the yield is 85%. 

Ethylene Dibromide. Technical material was washed three times with concentrated sulfuric acid, rinsed with water, and dried over calcium chloride. It was then distilled through 1 foot of glass beads. The fraction boiling between 130.2° and 131.2° C. was used. Every third day an aqueous solution was prepared by weighing approximately 0.5000 gram of ethylene dibromide into 2000.0 grams of water. It was stored in a dark bottle to minimize light decomposition. 

Figure 23 Preparation and activity in Heck reaction of glass bead/palladium catalysts.

WCE is prepared by homogenizing the washed cells by rigorously vortexing with 4 mm diameter acid-washed glass beads (Thomas Scientific) corresponding to 1/2 of the total volume of resuspended cells for 30 s, followed by 1 min on ice, conducted 5 times. Cells were placed on ice for 1 min between each cycle of vortexing. 

Boylan and Tripp [76] determined hydrocarbons in seawater extracts of crude oil and crude oil fractions. Samples of polluted seawater and the aqueous phases of simulated samples (prepared by agitation of oil-kerosene mixtures and unpolluted seawater to various degrees) were extracted with pentane. Each extract was subjected to gas chromatography on a column (8 ft x 0.06 in) packed with 0.2% of Apiezon L on glass beads (80-100 mesh) and temperatures programmed from 60 °C to 220 °C at 4°C per minute. The components were identified by means of ultraviolet and mass spectra. Polar aromatic compounds in the samples were extracted with methanol-dichlorome-thane (1 3). 

Laser ablation ICP-MS (LA-ICP-MS) was established in the early 1990s as a potential routine tool for the measurement of trace and ultra-trace elements in silicate systems for geology. Early studies (Perkins et al. 1993) used sample preparation techniques identical to that used to prepare rock samples for WDXRF, i.e., either a pressed powder disk or a glass bead fusion method (see Appendix VIII). Such studies concluded that LA-ICP-MS had the potential to surpass XRF in terms of the limits of detection achieved and INAA in terms of the speed of analysis (Perkins et al. 1993 481). It has long been recognized that the main limit on the quantitative performance of LA-ICP-MS is the homogeneity at the trace and ultra-trace level of the solid calibration standards available. Subsequent work (e.g., Hollecher and Ruiz 1995, Norman et al. 1996) has demonstrated that some of the international... 

The high-throughput purification in a discovery environment and the removal of transition metals using adsorption on or crystallization in the presence of activated carbon, glass-bead sponges, polymeric fibers, or silica-bound scavengers and the preparative isolation of radiolabeled compounds are out of the scope of this contribution. 

SFE also would appear to have utility in sample preparation methods. Lopez-Avila et al. (1992) applied SFE to the recovery of a variety of analytes, including organophosphorus pesticides, from solid matrices. The unoptimized extraction from sand gave a recovery of 54% for diazinon. Supercritical trifluoromethane has been shown to extract diazinon from glass beads with a recovery of 86% (Hillmann and Bachmann 1995). Organophosphorus pesticides have also been recovered from Tenax-GC, an adsorbent used to collect diazinon during air sampling, and analyzed directly by GC (Raymer and Velez... 

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