Single drop method

There are many classical methods to investigate the chemical reaction and kinetics at the liquid-liquid interface, which include a Lewis cell, a single drop method, and rotating disc method [22]. All of these methods however could not measure both the extraction rate and interfacial concentration of extractant, simultaneously. Modern experimental methods of interfacial reaction can determine the interfacial species, interfacial concentration, and interfacial chirality of an extractant or complex as a function of time. 

Ligor, T., Buszewski, B. Extraction of trace organic pollutants from aqueous samples by a single drop method. Chromatographia 51, S279-S282 (2000)... 

The schematic and Bode plot for the single-pole method of compensation are given in Figure B-16. At dc it exhibits the full open-loop gain of the op amp, and its gain drops at -20dB/decade from dc. It also has a constant -270 degree phase shift. Any phase shift contributed by the control-to-output characteristic... 

Fig. 5.18 Potentiostatic methods (A) single-pulse method, (B), (C) double-pulse methods (B for an electrocrystallization study and C for the study of products of electrolysis during the first pulse), (D) potential-sweep voltammetry, (E) triangular pulse voltammetry, (F) a series of pulses for electrode preparation, (G) cyclic voltammetry (the last pulse is recorded), (H) d.c. polarography (the electrode potential during the drop-time is considered constant this fact is expressed by the step function of time—actually the potential increases continuously), (I) a.c. polarography and (J) pulse polarography...

The fractional dispersed phase holdup h is normally correlated on the basis of a characteristic velocity equation, which is based on the concept of a slip velocity for the drops vsiip, which then can be related to the free rise velocity of single drops, using some correctional functional dependence on holdup f(h). The normal method of correlating dispersed phase holdup is normally of the form... 

Both AC and DC potential-drop methods are well-established techniques for monitoring subcritical crack growth. A combined AC/DC potential-drop measuring technique can, in some cases, help in obtaining more information from a single test, in particular for the onset of stable crack growth.172... 

Acidity Transfer about 25 g of sample, accurately weighed, into a 125-mL conical flask add 50 mL of toluene and 2 drops of thymol blue TS and titrate rapidly with 0.02 M sodium methoxide in toluene. Swirl the flask continuously until the yellow color changes to a dark color, and then continue the titration without stopping but slowing the addition of titrant until a single drop changes the solution to a clear blue color. The endpoint is stable for about 8 to 15 s. Not more than 1.0 mL of 0.02 M sodium methoxide is required. Lead Determine as directed for Method I in the Atomic Absorption Spectrophotometric Graphite Furnace Method under Lead Limit Test, Appendix IIIB. 

Single-Reference Methods for Excited States in Molecules and Polymers 53 where we have dropped the e-im -lEcl factor and used... 

The most useful method for solvent residue analysis is GC. It can be performed by direct injection technique, or by headspace, solid phase microextraction (SPME), or single-drop microextraction (SOME) techniques [96]. GC has high selectivity, good specificity, is easy to perform, and involves simple sample preparation. Modem capillary GC allows separation of many compounds, together with their identification and quantification [96]. GC uses different detector systems, which are presented in Table 8.7. 

In 1978, Karlberg and Thelander [5] described the flow injection extraction (FIE) technique, and in 1979 Murray [6] improved the microextraction, reducing the amount of solvent to 200 pL. The main disadvantage of these methods was the necessity to use complicated equipment. Jeannot and Cantwell [7] and, independently, Hee and Lee [8] introduced a simpler kind of microextraction in which a solvent drop is applied, single drop microextraction (SOME). They designed a microreactor with 8 pL of -octane in a Teflon tube (Fig. 14.3) [7]. The authors performed measurements of diffusion coefficients and the kinetics of the system, which suggested a mass transfer model. 

Fernandes, V.C., Subramanian, V., Mateus, N., Domingues, V.F., Deleme-Matos, C. The development and optimization of a modified single-drop microextraction method for organo-chlorine pesticides determination by gas chromatography-tandem mass spectrometry. Microchim. Acta 178, 195-202 (2012)... 

Enteshari, M., Mohammadi, A., Nayebzadeh, K., Azadniya, E. Optimization of headspace single-drop microextraction coupled with gas chromatography-mass spectrometry for determining volatile oxidation compounds in mayonnaise by response surface methodology. Food Anal. Methods 7,438-448 (2014)... 

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