Sonic probes

This technique is used mainly for nonpolar compounds. Typically a small aliquot of soil (10-30 g) is dried by mixing with sodium sulfate prior to extraction. Next, the sample is extracted with a solvent for 10-20 min using a sonicator probe. The choice of solvent depends on the polarity of the parent compound. The ultrasonic power supply converts a 50/60-Hz voltage to high-frequency 20-kHz electric energy that is ultimately converted into mechanical vibrations. The vibrations are intensified by a sonic horn (probe) and thereby disrupt the soil matrix. The residues are released from soil and dissolved in the solvent. 

On a laboratory scale, generally an ultrasonic probe (horn) and an ultrasonic cleaner are used. The ultrasonic field in an ultrasonic cleaner is not homogeneous. Sonication extraction uses ultrasonic frequencies to disrupt or detach the target analyte from the matrix. Horn type sonic probes operate at pulsed powers of 400-600 W in the sample solvent container. Ultrasonic extraction works by agitating the solution and producing cavitation in the... 

Quickly wash beads 2 times with coupling buffer using centrifugation and resuspend using a sonic probe in 5 ml of the same buffer. 

Wash particles with coupling buffer at least 3 times using centrifugation and resuspend in the same buffer using a sonic probe to disperse fully the particles. 

Sanz, E., R. Munos-Olivas, and C. Camara. 2005. Evaluation of a focused sonication probe for arsenic speciation in environmental and biological samples. J. Chromatogr. A 1097 1-8. 

Oily materials may adsorb strongly on plastic surfaces, and such samples are usually collected in glass bottles. Oil that remains on the bottle walls should be removed by rinsing with a solvent and be returned to the sample. A sonic probe can be used to emulsify oily samples to form a uniform suspension before removal for analysis. 

In order to prepare liposomes, the lipid preparation is dried at low temperature under an inert gas atmosphere (protect the lipid from oxidation). The lipid film is swollen with water or buffered aqueous solution and several freeze-thaw cycles are carried out to get optimal rehydration of the lipid. The rehydrated lipid preparation is filtered using membrane filters with defined pore size. After repeated filtration steps (extrusion) an unilamellar liposome preparation with a defined size distribution is obtained. Large unilamellar vesicles (LUV) are produced in this way. LUV s are about 100 nm in size the thickness of the lipid bilayer is about 4 nm. Even smaller liposomes can be derived from sonication (sonication probe or ultra-sonication bath). Separation of the prepared liposomes... 

To study enzymic reactions, cell extracts were prepared by Hughes press or sonic probe (7), and activity was assayed in a Warburg flask which was closed with a rubber serum stopper. A hydrogen atmosphere was added to the flask, and after isolation of the flask, the substrate was tipped into the main compartment of the flask. Samples of the gas atmosphere were removed with a hypodermic syringe and were injected into a gas chromatograph which contained a silica gel column (7). 

Sonicate for 15 s, using a sonic probe to release formazan products from the matrix. 

The fundamental basis of the sonoelectrochemical technique to form nanoparticles is massive nucleation using a high current density electrodeposition pulse (ca. 150-300 mA cm ), followed by removal of the deposit from the sonoelectrode by the sonic pulse. Removal of the particles from the electrode before the next current pulse prevents crystal growth. Overall there are many experimental variables involved in sonoelectrochemical deposition electrolyte composition and temperature, electrodeposition conditions including current density (le), pulse-on time (te(on)) and ratio between pulse-on time and pulse-off time (te(off)) (the duty cyde) sonic probe conditions sonic power (Is), sonic pulse parameters, fs(on) and ts(off). 

The container should be small enough so that the sonicator probe can immerse deeply (1-2 cm) in the sample but large enough so that the probe does not touch the sides or bottom of the container. 50 ml plastic tubes with round bottoms are used. 

Another concern is shedding. The sonication probe tip, normally made of titanium, can suffer from pitting and erosion during use. One commercial solution to this problem is to use a secondary fluid to carry the ultrasonic waves to the product slurry container, as occurs with, for example, glass or metal containers in an ultrasonic bath. 

Hydrogen peroxide Tap, lake, rain, purified waters Ultrasound-assisted luminol-H202-Co(II) reaction CL 1.0 x 1(T9 mol L 1 Flow injection system coiled reactor [147] immersed in a water bath inside which the sonication probe is inserted... 

Preparation of the Cab-O-Sil fumed silica, a multi-stepped procedure, was as follows. The fumed silica powder (25-125 mg) was weighed into a 10-mL vial and then suspended in 5 ml. of a 0.0016 M NaOH solution. After an initial 10-s vortex stage, the sample vial and a sonic probe were both immersed in a small water bath. Sonication was carried out for 5 min at 200 W. (The recommended procedure called for 2-min sonication at 480 W with a microtip inserted directly into the sample solution. This procedure was modified because we did not have a microtip.) Immediately before each injection the sample was vortexed for 10 s. 

Large-scale batch sonochemical reactors can be designed on the basis of the performance of conventional laboratory sonicators if it is assumed that there are no serious scale-up factors. These are the cleaning bath reactors (indirect sonication) and reactors with immersible transducers or sonic probes (direct sonication). Continuous reactors use either wall-mounted transducers (indirect sonication) or sonic probes (direct sonication). 

Several designs are shown in Figure 22.12 (a) common batch cleaning bath reactor with wall mounted transducers (b) batch reactor with immersible transducers (c) batch reactor with sonic probe (d) continuous flow tubular reactor with wall-mounted transducers (e) the Harwell sonochemical reactor and (f) a shell-and-tube reactor. A number of other designs are discussed by Thompson and Doraiswamy (1999b). 

Now let us consider the sonic probe reactor (Figure 22.12c). Here, only the probe is inserted, not the entire assembly with the transducer. The probe generates a high intensity field around its tip and can be inserted easily into the liquid... 

The largest available sonic probe has a rating of 2.S kW from a 5-cm diameter probe tip. Thus the ultrasonic intensity is... 

In the synthesis of the alkaloid vindolinine from 9-iodotabersonine (Eq. 58),266 the critical annulation step, a conjugate addition on an a,p-unsaturated ester, was achieved with sodium. High-energy sonication (probe) gave a high conversion yield accompanied by the formation of four stereoisomers. Reducing the probe energy lowered the conversion to 50%, but only two stereoisomers were formed. 

There is no great need to measure levels in the plant, but merely to have an indication of whether a tank or hopper is empty, full, or in between. This is achieved by conductivity, or sonic, probes. They are fitted to the two polymer tanks, to initiate a new batch make-up, and to actuate transfer before the polymer supply tank empties. Probes could be employed in the polymer powder hopper to guard against running out during operation. Smaller plants will not use powder probes, and rely on a system using several days supply. 

Electromechanical extensometers include sonic probes that allow for up to 20 permanent anchors up to a 6-m (20-ft) height. The probes have the added benefit of being remotely read by portable devices or by connection to a data acquisition system. Recently, NIOSH introduced an easy to fabricate and install extensometer called the Remote Monitoring Safety S5rs-tem (RMSS). This instrument can be read remotely with a multimeter or can be connected directly to a data acquisition S5rstem. 

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