Chemistry: analytical and immunological testing – Tracers or tags
Reexamination Certificate
1999-02-05
2001-06-26
Lipman, Bernard (Department: 1713)
Chemistry: analytical and immunological testing
Tracers or tags
C436S085000, C436S163000, C436S166000, C436S172000, C252S408100, C525S929000, C525S379000
Reexamination Certificate
active
06251680
ABSTRACT:
BACKGROUND
The present invention is directed to detectable polymers and methods for detecting polymers in aqueous systems. In particular, the present invention concerns water-soluble polymers containing a pendant amine group capable of reacting with amine-reactive labels.
Water-soluble polymers are used in many aqueous systems, for example, as mineral dispersants, as water-treatment additives for boiler waters, cooling towers, reverse osmosis applications, sugar refining, paper production, geothermal processes and oil wells, and as detergent additives acting as builders, anti-filming agents, dispersants, sequestering agents and encrustation inhibitors. In many of these aqueous systems it is desirable to know the level of polymer in the system. However, the level of active polymer is not simply a function of how much polymer has been added. The polymer may have adhered to a surface or may have flocculated out with sediment, or the polymer itself may have decomposed. Because polymers generally add cost to processes employing them, it is desirable to be able to use them efficiently.
One of the problems associated with detecting polymers in aqueous systems is that the polymers are generally present at very low levels, from 500 down to less than 5 parts per million (ppm). Another problem associated with detecting polymers in aqueous solutions is that the detection methods frequently lack selectivity and may give false results for components of the aqueous system other than polymers.
One attempt at overcoming these problems has been to use, in conjunction with the polymer, a tracer compound. The assumption behind this approach is that the tracer compound will be present in the aqueous system at a level proportional to the level of the polymer. However, this assumption is undermined by the fact that the fate of the tracer compound and the fate of the polymer in the aqueous system may differ.
Another approach to overcoming these problems is to incorporate into the polymer a detectable moiety. This has been accomplished, for example, by using a fluorescent monomer in preparing the polymer. This approach has the drawback of additional processing steps in preparing the fluorescent monomer. Also, the presence of the fluorescent moiety, which is usually a fairly bulky, hydrophilic group, may interfere with the performance characteristics of the resulting polymer. For example, many water treatment polymers have molecular weights below 10,000; the attachment of a fluorescent moiety can be a significant percentage of that, which can affect the function of the polymer.
U.S. Pat. No. 5,171,450 attempted to overcome these problems by recognizing that amine-containing dyes and amine-containing fluorescent compounds can be used with conventional water-treatment polymers which contain functional groups of carboxylic acids or amides. The amine-containing dyes or fluorescent compounds can be attached to these polymers via a transamidation reaction to create labeled or “tagged” polymers. These tagged polymers can be used and detected in aqueous systems. The drawbacks to this approach are that (1) the attachment of the fluorescent label may not be quantitative and (2) the presence of the label may interfere with the functioning of the polymer in the aqueous system.
The present invention overcomes the above problems by providing on the polymer not a detectable label but instead a site for the attachment of one, the label being attached during a reaction involving just a sample of the polymer removed for analysis. In this way the label is never attached to any polymer actually residing in the aqueous system in which it is being used.
STATEMENT OF INVENTION
Thus the present invention provides in a first aspect a polymer capable of detection by colorimetric or fluorimetric techniques, comprising at least one moiety containing a pendant amine group to which is attached an amine-reactive detectable label.
In a further aspect the invention provides a method for detecting a polymer in an aqueous system, comprising
i) prior to addition to the aqueous system, reacting the polymer so that it comprises at least one moiety containing a pendant amine group;
ii) removing a sample of the aqueous system containing the polymer and adding a detectable label reactive with amines;
iii) maintaining the sample under such conditions that the detectable label reacts with the pendant amine group to become attached to the polymer; and
iv) detecting the label.
Another aspect of the invention comprises the use of an amine-reactive detectable label which is attached to a pendant amine group on a polymer sample after removal of said sample from the polymer, to provide colorimetric or fluorimetric detectability to the polymer.
Thus it is pendant amine functionality that provides the site to which can be attached the label during analysis. The pendant amine moiety is not required on every monomer unit in the polymer: the molar ratio of moiety containing a pendant amine group to other monomer in the polymer (excluding the detectable label) may range from 1:3 to 1:300, more usually from 1:5 to 1:100.
DETAILED DESCRIPTION
A suitable method for imparting a pendant amine functionality to a polymer is to use a monomer containing a pendant amine functionality. Suitable monomers containing a pendant amine functionality include 2-aminoethylacrylate, 2-aminoethylmethacrylate, 2-aminoethylacrylamide, 2-aminoethylmethacrylamide, and homologues such as aminopropyl(meth)acrylamide. Latent amines such as vinylformamide may also be used. When a monomer containing a pendant amine functionality is used, the resulting polymer may contain one or more pendant amine groups.
Preferably, the pendant amine functionality which is imparted to the polymer is a terminal pendant amine functionality. Terminal pendant amine functionality can be imparted to a polymer by using one or more compounds which, when they function as a chain transfer agent, have a pendant amine group. Preferred compounds for imparting terminal amine functionality are amine-thiols.
Amine-thiols are compounds which contain, or those which under the conditions of the polymerization will contain: one or more amine groups (—NR
1
R
2
) wherein R
1
and R
2
are each independently selected from hydrogen and alkyl groups having from one to four carbon atoms; and one or more thiol groups (—SH). Preferably, the amine group is a primary amine (—NH
2
). The amine-thiols suitable for the present invention are capable of functioning as a chain transfer agent for aqueous addition polymerizations; thereby imparting an amine-sulfide terminal moiety to the polymer chain. The amine-sulfide moiety is the residue of the amine-thiol resulting from the attachment of the sulfur group of the amine-thiol to the polymer chain.
Amine-thiols suitable for imparting terminal amine functionality include: amino acids containing one or more amines and one or more thiols; derivatives, peptides and polypeptides of amino acids containing one or more amines and one or more thiols; derivatives, peptides and polypeptides of amino acids containing one or more thiols and one or more protected amines wherein the protecting group is capable of being removed; and aminoalkyl thiols. A suitable amino acid is, for example, cysteine (“Cys”). Suitable derivatives of amino acids containing one or more amines and one or more thiols are, for example, N-alkyl and N,N-dialkyl substituted amino acids wherein the alkyl groups each contain from one to four carbon atoms. A suitable polypeptide of an amino acid containing one or more amines and one or more thiols is, for example, glutathione (“Glu”). A suitable derivative of an amino acid containing one or more thiols and one or more protected amines wherein the protecting group is capable of being removed is, for example, N-acyl cysteine (“N—Ac”). In addition, cystine may be used in the present invention under polymerization conditions which cause the cystine to cleave at the sulfur-sulfur bond to form at least one cysteine molecule. Suitable aminoalkyl thiols are, for example, as small as aminoeth
Fu Zhenwen
Keller Lorraine Holowach
Weinstein Barry
Howell Thomas J.
Lipman Bernard
Rohm and Haas Company
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