A composition and an assay solution for the determination of dissolved borate concentration comprising a catechol dye, a solubilizing agent, and a buffer are described. The composition and assay solution may further comprise a solubilizing agent. The catechol dye acts as a chemical borate sensor. The chemical borate sensor changes its optical properties upon binding to borate. The multivalent cation chelator binds multivalent cations present in a sample being analyzed. The buffer prevents changes in pH. The solubilizing agent aids in solubilizing the catechol dye, multivalent cation chelator, and/or the buffer.

A composition and an assay solution for the determination of dissolved borate concentration comprising a catechol dye, a solubilizing agent, and a buffer are described. The composition and assay solution may further comprise a solubilizing agent. The catechol dye acts as a chemical borate sensor. The chemical borate sensor changes its optical properties upon binding to borate. The multivalent cation chelator binds multivalent cations present in a sample being analyzed. The buffer prevents changes in pH. The solubilizing agent aids in solubilizing the catechol dye, multivalent cation chelator, and/or the buffer.

A composition and an assay solution for the determination of dissolved borate concentration comprising a catechol dye, a solubilizing agent, and a buffer are described. The composition and assay solution may further comprise a solubilizing agent. The catechol dye acts as a chemical borate sensor. The chemical borate sensor changes its optical properties upon binding to borate. The multivalent cation chelator binds multivalent cations present in a sample being analyzed. The buffer prevents changes in pH. The solubilizing agent aids in solubilizing the catechol dye, multivalent cation chelator, and/or the buffer.

Provided is a cathode active material containing a Ni-based lithium mixed transition metal oxide. More specifically, the cathode active material comprises the lithium mixed transition metal oxide having a composition represented by Formula I of Li.sub.xM.sub.yO.sub.2 wherein M, x and y are as defined in the specification, which is prepared by a solid-state reaction of Li.sub.2CO.sub.3 with a mixed transition metal precursor under an oxygen-deficient atmosphere, and has a Li.sub.2CO.sub.3 content of less than 0.07% by weight of the cathode active material as determined by pH titration. The cathode active material in accordance with the present invention and substantially free of water-soluble bases such as lithium carbonates and lithium sulfates and therefore has excellent high-temperature and storage stabilities and a stable crystal structure. A secondary battery comprising such a cathode active material exhibits a high capacity and excellent characteristics, and can be produced by an environmentally friendly method with low production costs and high production efficiency.

A composition and an assay solution for the determination of dissolved borate concentration comprising a catechol dye, a solubilizing agent, and a buffer are described. The composition and assay solution may further comprise a solubilizing agent. The catechol dye acts as a chemical borate sensor. The chemical borate sensor changes its optical properties upon binding to borate. The multivalent cation chelator binds multivalent cations present in a sample being analyzed. The buffer prevents changes in pH. The solubilizing agent aids in solubilizing the catechol dye, multivalent cation chelator, and/or the buffer.

A method for preparing hydrophobic gold nanoparticles includes adding 1,2-dichlorobenzene as a solvent to gold precursor and using oleylamine and oleic acid with volume ratio of 7.5:2.5 to 5:5 as surfactants. The size of the prepared gold nanoparticles can be controlled over a broad range and may be utilized in various fields such as bio-imaging, photonic crystallization, sensors, organic catalysts, surface enhanced raman spectrum, electronic devices, etc. Further, a method for colorimetric detection of a strong acid uses hydrophilic nanoparticles that are phase transited from the prepared hydrophobic gold nanoparticles. Up to 5 ppm of low content hydrochloric acid can be detected utilizing phase transited hydrophilic nanoparticles in the colorimetric detection method, and the gold nanoparticles that were used in the detection of strong acid can be reused without loss of activity through neutralization with bases.