Patent ID: 6579434
Filing Date: 2003-06-17
Classification: G01N

Abstract:
A free-fluoride-ion-sensitive electrode comprising:(A) a substantially liquid-impermeable solid fluoride-sensing crystal that is constituted of one or more fluoride-ion-sensitive solid, crystalline, substantially water-insoluble fluorides; (B) first and second solid elastomeric gaskets that form a sealing array with the fluoride-sensing crystal; (C) a primary container body constituted of electrically insulating material and having walls surrounding a central cavity that extends completely through the primary container body, thereby forming a first and second end of said central cavity, said central cavity having a size and a shape such that a sealing array among the primary container body, the fluoride-sensing crystal, and said first and second elastomeric gaskets is formed; (D) means for maintaining the sealing array among the fluoride-sensing crystal, the first and second elastomeric gaskets, and the primary container body when they are jointly rotated, said means not including use of any cement or adhesive or any incorporation of the fluoride-sensing crystal into a cohesive unitary solid from which it can not be removed intact without dividing all parts of the unitary solid that do not consist of the fluoride-sensing crystal into at least two separate pieces; (E) means for dividing the central cavity of the primary container body so as to constitute jointly with the primary container body, the fluoride-sensing crystal and at least one of the first and second elastomeric gaskets, boundaries of a liquid- and vapor-tight portion of the central cavity of the primary container body; (F) a volume of a first liquid ionic solution of known composition and concentration confined within said substantially liquid- and vapor-tight portion of the central cavity of the primary container body and in physical contact with the fluoride-sensing crystal; (G) a first reference electrode enclosed within said substantially liquid- and vapor-tight portion of the central cavity of the primary container body, said first reference electrode including a metallic electrical conductor that is in physical contact with the first liquid ionic solution but is not in physical contact with the fluoride-sensing crystal; and (H) an electrically conducted lead component that is in physical contact with both the metallic electrical conductor part of the first reference electrode and a point outside said substantially liquid- and vapor-tight portion of the central cavity of the primary container body but is not in physical contact with the fluoride-sensing crystal or with the first ionic solution, wherein: the central cavity of the primary container body has a central portion that is cylindrical; a first end portion of the central cavity of the primary container body has a shape of a cylinder that is concentric with but has a larger diameter than the cylindrical central portion of the central cavity, so that the primary container body in said first end portion has a bounding wall surface that consists of two concentric cylinders joined by an annular disk with a circular center hole, the disk and center hole both being concentric with said concentric cylinders; and a solid portion of said annular disc and an end portion of the walls of the primary container body surrounding the central cavity bound a space in which the sealing array of said fluoride-sensing crystal and said first and second elastomeric gaskets is retained.