Solution 96-Well Format

Antimony trioxide is insoluble in organic solvents and only very slightly soluble in water. The compound does form a number of hydrates of indefinite composition which are related to the hypothetical antimonic(III) acid (antimonous acid). In acidic solution antimony trioxide dissolves to form a complex series of polyantimonic(III) acids freshly precipitated antimony trioxide dissolves in strongly basic solutions with the formation of the antimonate ion [29872-00-2] Sb(OH) , as well as more complex species. Addition of suitable metal ions to these solutions permits formation of salts. Other derivatives are made by heating antimony trioxide with appropriate metal oxides or carbonates. 

The advantages of this screen filter, as cited by the authors, consist of its reusability, its standard 96-well format size, and its ability to be used whenever sample transfer or pipetting is needed. After usage, the screen filter can be easily cleaned by rinsing with water and methanol and additionally, by ultrasonication in water or methanol or other appropriate solution. The filter can be inserted into a plasma storage plate before sample transfer by the Tomtec Quadra used by the authors for automation. 

Based on the 96-well format, OCT-PAMPA was proposed and has proved its ability to determine (indirectly) log Poet [87]. PAM PA is a method, first developed for permeability measurements, where a filter supports an artificial membrane (an organic solvent or phospholipids) [88, 89]. With this method, the apparent permeability coefficient (log P ) of the neutral form of tested compounds is derived from the measurement of the diffusion between two aqueous phases separated by 1-octanol layer (immobilized on a filter). A bilinear correlation was found between log Pa and log Poct> therefore log Poet of unknown compounds can be determined from log Pa using a calibration curve. Depending on the detection method used a range oflog P within —2 to +5 (with UV detection) and within —2 to +8 (with LC-MS detection) was successfully explored. This method requires low compound amounts (300 pi of 0.04 mM test compound) and, as for the previous method, samples can be prepared in DM SO stock solutions. For these experiments, an incubation time of 4h was determined as the best compromise in term of discrimination. The limitation of the technique lies in the lower accuracy values... 

Dibromo-tetrammino-cobaltic Sulphate, [Co(NH3)4Br2]2S04, may be obtained, as well as the aeid sulphate.1 All the salts and their derivatives are green in colour, and all decompose in solution with formation of aquo- and diaquo-salts. 

A more reliable means of providing a reference of -OH in a biological system maybe by means of irradiation with ionizing radiation (von Sonntag et al. 2000). The action of ionizing radiation on an aqueous medium gives rise to OH whose yield/dose relationship (G value) is known (Chap. 2). Apart from this, since biological media are concentrated solutions the formation of the indicator product, e.g., a phenol (ArOH), via the direct effect [expressions (69) and (70)] must in principle be taken into account as well. It can be shown that with k4i [probe]/ k42 [cellular components] above 10 4 the direct effect contributes less than 10%... 

Apparently, aromatic amines such as pyridine and imidazole react more strongly than do aliphatic amines, but even so, the reaction is weak. Although its formation is not highly favored, a well-defined pyridine complex of VL2 stoichiometry is observed at high pyridine concentrations in aqueous solution, its formation constant... 

Abstract Polyelectrolyte block copolymers form micelles and vesicles in aqueous solutions. Micelle formation and micellar structure depends on various parameters like block lengths, salt concentration, pH, and solvent quality. The synthesis and properties of more complicated block and micellar architectures such as triblock- and graft copolymers, Janus micelles, and core-shell cylinder brushes are reviewed as well. Investigations reveal details of the interactions of polyelectrolyte layers and electro-steric stabilization forces. 

Procedure. Follow the proportions in Table II. Mix and pour into a sealed gel former immediately. Leave room for a short upper stacking gel. With a fine pipette, layer a small amount of 0.1% SDS solution on top of the unpolymerized gel to give a flat surface and to remove bubbles. As the gel polymerizes the water interface will become indistinct and then will reappear as the gel sets. Pour off the water and add the upper gel. Immediately insert the comb for well formation. Upper stacking gels usually shrink slightly as they polymerize. Mount the gel in a vertical apparatus. Make sure the running buffer contacts both upper and lower surfaces of the gel. 

Ammonium hypobromite.—Bromine is said to react with a well-cooled ammonium-hydroxide solution, with formation of an unstable solution of the hypobromite.8... 

Due to the fact that in most companies the sample storage and retrieval facilities are centralized, the test samples have to be transferred to the screening groups at various locations. Therefore, logistics such as bar-coding, data transfer, and delivery are crucial points. Delivery of the samples is performed usually in 96-well format after sealing with removable films in solution (e.g. on dry ice in DMSO), or as neat-films. Workstations able to seal microplates, label with bar-codes, and remove organic solvents in order to prepare neat-films are commercially available. 

Many approaches to determine thermodynamic solubility in drug discovery have focused on miniaturizing the classic shake-flask method with solid samples manually weighed and dispensed into 96-well plates or 96-vial arrays [32-34]. The 96-well format enables the use of liquid handling robots to improve throughput. As with the standard shake-flask method, aqueous buffer is added and the solution is agitated for a minimum of 24 h prior to plate filtration or centrifugation to remove the supernatant, which is then analyzed by HPLC-UV or direct UV. 

High throughput in-well sonication has been applied to dissolve compounds that are insoluble in DMSO in 96, 384, and 1536 well formats (Oldenburg et ah, 2005). Compounds that precipitated from DMSO stocks, due to either water uptake that reduced solubility or low instrinsic solubility that promoted crystallization, can be re-dissolved by low energ) sonication. Sonication can accelerate compound dissolution in seconds and, in some cases, drive the solution to super saturation, due to energy input and elevated temperature. This process can bring many precipitates back into solution and has no effect on compound stability. Sonication of DMSO stocks or concentrated aqueous solutions can improve HTS hit rates and enhance biological assay results. 

Simultaneous, contact transfer of fixed volumes (10, 25, 50 nL) of compound DMSO solutions with slotted stainless steel pins in 384- or 1,536-well formats... 

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