Browse Prior Art Database

DEVICE FOR MONITORING pH

IP.com Disclosure Number: IPCOM000043115D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 3 page(s) / 64K

Publishing Venue

IBM

Related People

Studebaker, JF: AUTHOR

Abstract

This article relates generally to devices for monitoring pH and more particularly to pH monitoring devices useful with columns for treating blood plasma. "Affinity Chromatography," a powerful method of purifying proteins and other molecules of biological origin, has been used for over twelve years in research laboratories and in some industrial processes [1]. It is now being applied to "on-line" extraction of pathological molecules from patients' blood plasma, which is first separated from the blood cells on a separator like the IBM 2997 (Fig. 1) [2,3]. The high cost of the column-packing materials makes it attractive to use two or more columns, which are used one-by-one until saturated, regenerated with appropriate solutions, and used again (Fig. 2).

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DEVICE FOR MONITORING pH

This article relates generally to devices for monitoring pH and more particularly to pH monitoring devices useful with columns for treating blood plasma. "Affinity Chromatography," a powerful method of purifying proteins and other molecules of biological origin, has been used for over twelve years in research laboratories and in some industrial processes [1]. It is now being applied to "on-line" extraction of pathological molecules from patients' blood plasma, which is first separated from the blood cells on a separator like the IBM 2997 (Fig. 1) [2,3]. The high cost of the column-packing materials makes it attractive to use two or more columns, which are used one-by-one until saturated, regenerated with appropriate solutions, and used again (Fig. 2). Antibodies to the pathological molecules are often the molecules covalently bound to the column packing, and they may be freed of the associated pathological molecules by washing with glycine-HCL solutions which have pH's around 3.0. In order to return the bound antibodies to their active form and to avoid bringing the patient's plasma in contact with an acidic column, it is necessary to raise the pH up to about 7.0. Thus, it is important to have some means of insuring that the pH has returned to a value near 7.0. A method based on a glass electrode like that used in standard pH meters could be used, but the cost and reliability of the electrode and the associated electronics are problems. Because one is concerned only that the pH has been raised to a suitable range, rather than with a continuous measurement of pH, polymeric beads incorporating a pH-sensitive dye with the proper transition may be used for following pH at lower cost and with greater reliability than with a method based on electrodes. Greater reliability is obtained because the operator can see directly the change in the color of the beads as the pH moves into the desired range. Recent work by Peterson et al has led to the development of polymer-bound phenol red, brilliant yellow C.I. #24890, and rosolic acid [4,5]. None of these dyes, the only ones tried by Peterson et al [5], are suitable for the present application because their transition ranges (6.0-8.2, 6.5-7.5, and 6.0-8.0) are too high. The three dyes investigated by Peterson et al have the common characteristic that the two indicator rings have no substituents at the positions ortho to the hydroxyl groups. It seems likely that the acrylamide attacks those positions in the process described by Peterson et al because...