Solubility plate method

Liu, D. Chau, Z.K. Dutka, B.J. Rapid toxicity assessment of water-soluble and water-insoluble chemicals using a modified agar plate method. Water Res. 1989, 23, 333-339. 

Some of the commonly used techniques for measuring contact angle [215, 216, 217] are the sessile drop method, captive bubble method and Wilhelmy plate method. These techniques have been extensively used and well documented for characterisation of modified PE surfaces [218, 219, 220, 221, 222, 223, 224, 225, 226, 227, 228, 229, 230] for various applications. Whitesides et al. [231 ] studied the wetting of flame-treated polyethylene film having ionisable organic acids and bases at the polymer-water interface. The effect of the size of substituted alkyl groups in amide and ester moieties on the surface hydrophilicity was also studied [232]. The biocompatibility of the polyethylene film surface modified with various water-soluble polymers was evaluated using the same technique [233]. The surface properties of hy-perbranched polymers have been very recently reported [234]. 

The solubility enhancement method is the most straightforward static technique in which the apparent solubility (S w) of a HOC is measured in the presence of increasing amounts of DOM (Chiou et al., 1986, 1987 Chin et al., 1997 Uhle et al., 1999). Briefly, the analyte is added in excess (10-100 times the reported aqueous solubility) to glass reactors by plating the solute out from a stock solution. Buffered DOM solutions at various concentrations are added to each tube along with a control reactor containing... 

Liu, D., Kwasniewska, K., Chau, Y. and Dutka, B. (1991) A four-hour agar plate method for rapid toxicity assessment of water-soluble and water-insoluble chemicals, Environmental Toxicology and Water Quality 6, 437-444. 

Figure 12 Filter plate method for solubility testing. (1) Add compound dissolved in organic solvent to aqueous buffer. (2) Shake for 90 minutes to allow insoluble compound to precipitate. (3) Apply vacuum to filter solution into collection plate. Precipitates remain on membrane. Analyze filtrate in collection plate to quantify the amount of the compound still in the solution. Source Courtesy of Millipore Corporation, Billerica, Massachusetts, U.S.A.

Figure 4.12 Filter plate method for solubility testing.

Surface activity of these PAMAMOS dendrimers was determined by the Wilhelmy plate method for the water soluble dendrimers and by the Langmuir trough technique for the insoluble ones. Some preliminary data on water soluble PAMAMOS have already been published (5,42), It was shown that the best of these materials lower the surface tension of water to just below 30 mN/m at 5 wt. %, with no break to a constant surface tension that would indicate micelle formation. Thus, these PAMAMOS behave more like considerably surface active water soluble polymers than surfactants. However, it is probable that their homologues with longer siloxane dendrons than the trimethylsilyl- groups studied so far will have considerably more surfactant-like behavior. 

The advantages of the capillary assay are its simplicity, quantitative nature, and high sensitivity. Alternative methods for studying chemotaxis such as the swarm plate method of Adler (1966) require that the chemoattractant be metabolized. This is not necessary in the standard capillary assay. In addition, due to the small size of the chemotaxis chamber, only small amounts of compound are required to perform the experiments. The main disadvantage of this method is that the compound tested must be soluble in the chemotaxis medium. 

Bevan, C. D., Uoyd, R. S. A high-throughput screening method for the determination of aqueous drug solubility using laser nephelometry in microtiter plates. Anal. Chem. 2000, 72,1781-1787. 

Lipinski et al. [12] and Pan et al. [463] compared several commonly used methods of solubility measurement in early discovery, where samples are often introduced as 10 mM DMSO solutions. Turbidity-based and UV plate scanner-based detections systems were found to be useful. The methods most often used in discovery and in preformulation will be briefly summarized below. 

A high-throughput method using a 96-well microtiter plate format and plate UV spectrophotometry has been described [26]. Solubilities at a single pH, or at <12 pH values can be determined, using one of two methods. 

The method constitutes a simple preparation of ethanol-in-soluble cinnamic acids, of a high degree of purity when compared with the Perkin reaction 6 or the usual procedure for the Doebner reaction,6 which uses a large excess of pyridine. A useful modification of this reaction is to warm the reactants on a steam plate in the absence of alcohol.7 8... 

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