The present invention provides a fluorescent dye HPTS-lipo for monitoring two-dimensional pH value, a fluorescent sensing film, and use thereof, belonging to the field of two-dimensional pH value monitoring. The fluorescence sensing film for monitoring two-dimensional pH is prepared from the fluorescent dye HPTS-lipo, and HPTS-lipo is embedded by hydrogel D4 in a preparation process. The fluorescent dye HPTS-lipo is prepared by ligating alkylamine into sulfonic acid groups of the fluorescent dye HPTS. Compared with the fluorescent dye HPTS, the pKa value of the modified fluorescent dye HPTS-lipo is significantly varied, so that the fluorescent sensing film is suitable for monitoring different pH values and meets different experimental requirements; and the fluorescent dye HPTS-lipo has better hydrophobicity, can be kept for longer time in environment, and further solves the problem of dye leakage after being embedded by the hydrogel.

The present invention relates to a novel thieno[3,2-b]pyridine-5(4H)-one derivative compound, a preparation method thereof, and a use thereof. The novel thieno[3,2-b]pyridine-5(4H)-one derivative compound according to the present invention is synthesized via an aza-[3+3] cyclization addition reaction using BOP, wherein the compound is obtained by synthesizing a 4-arylthiophen-3-amine in which aryl groups such as 4-piperidyl-C6H4, 4-pyrrolidyl-C6H4, 4-MeOC6H4, 3,4,5-(MeO)3C6H4, C6H5, 4-C6H5C6H4, and 4-F3COC6H4 are introduced via a synthesis process by a bromination reaction, a hydrolysis reaction, a decarboxylation reaction, and a Suzuki coupling reaction of methyl 3-aminothiophene carboxylate, and by synthesizing 4-arylthiophen-3-amine and mono-methyl fumarate via a formal aza-[3+3] cyclization addition reaction using BOP and conjugation. Accordingly, novel thieno[3,2-b]pyridine-5(4H)-one derivative compounds according to the present invention have fluorescence properties with a wide range of emission wavelengths and thus may be utilized in various industrial fields such as physics, chemistry, and biomedical research.

A method for determining whether a syrup contains a preservative at a needed level is provided. The method includes measuring a conductivity of the syrup, determining whether the measured conductivity is below a predetermined conductivity value determined based on a target syrup according to a syrup recipe, and determining whether the preservative is below the needed level in response to the measured conductivity being below the predetermined conductivity value.

Disclosed herein are a hydrogel bead, a chemical sensor including the same, and an electronic product including the chemical sensor. The hydrogel bead includes at least one type of polysaccharide physically crosslinked with a cation or an anion, and a pH indicator dye.

Disclosed are a method for synthesizing a thieno[3,2-b]pyridine-5(4H)-one derivative by using a gold catalyst and a use of the derivative compound, wherein the novel thieno[3,2-b]pyridine-5(4H)-one derivative of the present disclosure, which is a compound synthesized using gold as a catalyst, has fluorescence characteristics with a wide range of emission wavelengths and thus can be helpfully used in various industrial fields, such as physics, chemistry, and biomedicine research.

Fluorescent pH sensors are provided. The fluorescent pH sensor comprises a copolymer for sensing pH and a polymerized form of N-(2-hydroxypropyl)methacrylamide (HPMA) or 2-hydroxyethyl methacrylate (HEMA). The probe for sensing pH has formula (I): ##STR00001##
wherein R.sub.1 and R.sub.2 are as defined herein. The fluorescent pH sensors may be used in determining the pH of a sample and detecting extracellular pH in a sample. Methods for preparing the fluorescent pH sensors and the probe for sensing pH are also provided.

A pyrogallarene solution and a method for using a calixarene as an indicator are disclosed. The calixarene may be a pyrogallarene, and the pyrogallarene may be a pyrogallol[4]arene. The pyroallol[4]arene may be C-alkyl pyrogallol[4]arene. The calixarene indicator having a dynamic chromophore may be used to assess pH, metal content, or water content.

A method for detecting cancer involved lymph nodes. The method includes placing a pH-sensing paper inside a needle of an injection syringe, filling the injection syringe with a buffer solution, putting the pH-sensing paper in contact with lymphatic fluid of a lymph node by inserting the needle of the injection syringe inside the lymph node, putting the lymphatic fluid in interaction with the buffer solution by injecting the buffer solution into the lymph node utilizing the injection syringe, and detecting that the lymph node as a cancer involved lymph node if color of the pH-sensing paper is changed to an acidic-range pH color.

A process of toilet training a subject to encourage urination in a toilet. Urease and color changing first pH indicator are introduced into water a toilet bowl of the toilet. In the presence of urine in the water the urease reacts with the urine to create a by-product that causes the color changing first pH indicator to change to a first color at a first pH thereby encouraging the subject to urinate in the toilet. A composition is provided that includes urease, color changing first pH indicator an excipient comprising citric acid, a binder, or a combination thereof. A kit is provided for the composition, a container for the composition, and instructions for using the composition during toilet training.

A composition and method for the photometric determination of a film-forming amine in liquid by adding an indicator reagent to an aqueous system that is pH dependent, combining a water soluble non-ionic polymer to modify the physical properties of the aqueous system, and adding an acidic buffer to said aqueous system to lower pH and activate said indicator, said water soluble polymer keeping the filming amine/indicator complex in solution despite the acidic buffer and preventing it from precipitating out.