Chemistry: analytical and immunological testing – Peptide – protein or amino acid
Reexamination Certificate
2000-03-22
2004-03-09
Warden, Jill (Department: 1743)
Chemistry: analytical and immunological testing
Peptide, protein or amino acid
C422S028000, C422S119000, C134S018000
Reexamination Certificate
active
06703243
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of detecting protein present on the surface of a sample wherein substances present on a portion of said surface are transferred to a sampling means and wherein, subsequently, these substances are contacted with a reagent capable of forming or changing colour upon reaction with protein. The invention also relates to a kit for detecting protein using this method.
BACKGROUND OF THE INVENTION
Soil (i.e. dirt or contamination) of mainly organic origin, and typically comprising protein, carbohydrate and/or fat, may be present on the surface of objects which come into contact with foodstuffs. This type of soil is generally associated with bacterial or microbial contamination which may present a risk to health. In order to visualize said soil it is convenient to use a reagent, such as certain dyes, which binds protein. By disclosing protein-containing soil, the location of the contamination can be indirectly visualised and can be targeted for effective cleaning. Consequently, methods for easily detecting protein have been developed in the past.
In most of the known methods for detection of protein, the surface of a sample is directly contacted by a reagent capable of forming colour upon reaction with protein. These known methods are less desirable because the colored material formed remains on the surface of the sample and can often hardly be removed with water.
As a result, the subject portion of the sample may be easily contaminated. Another problem associated with these known methods is that they generally require a long detection time.
In order to overcome these drawbacks, EP-A-738,891 (Konica) discloses a method to detect the presence of protein by transferring a substance to be detected from the surface of a sample to a water-absorbable portion of a sampling means (said portion comprising a water-insoluble synthetic polymer). This method solves the problem of contamination of the sample. Furthermore, the detection time for performing a good analysis could be expedited using this method. It is explicitly mentioned in this prior art document that the water-absorbable portion of the sampling means used in the method disclosed therein contains a synthetic polymer.
The method disclosed by EP-A-738,891 further includes the steps of contacting the transferred substances with a reagent capable of forming colour upon reaction with protein, and of measuring colour formed by this reaction so as to determine the presence of protein in the substance concerned.
When applying this method for hygiene monitoring, it has been found that it gives generally good results using any of the various protein detection methods described in EP-A-738,891. However, when this hygiene monitoring method was applied using the Coomassie protein detection dye method for monitoring the cleanliness of surfaces treated with quaternary ammonium compounds, it was found that residues of these compounds may negatively influence the detection method. Reason is that these compounds may react with the colour-forming reagent, resulting in a strong colour formation even in the absence of protein.
This effect is called false positive reading caused by the quaternary ammonium compounds.
Furthermore, the prior art contains various documents which refer to colourant containing compositions, test devices and methods for determining the presence or concentration of proteins, such as albumin, in body fluids, such as urine.
For instance, EP-A-545,128 discloses a method, wherein a composition containing a colourant, a buffer and a hydrophobic polymeric compound is applied for measuring the presence of protein in urine. It is mentioned in this document that the number of false positive readings due to the presence of quaternary ammonium compounds, such as peptides, amino acids and creatinine, is reduced when using this composition.
In addition, DE-A-25 10 633 discloses a method for detecting proteins in urine, wherein a composition including an octahalogenated sulphophthalein, as colourant, is applied. This composition further contains a water-immiscible polypropylene glycol in order to overcome interference with N-containing compounds present in the urine sample tested and to reduce false positive reactions. It is noted that the prior art documents relating to methods for determining the presence of protein in urine samples, do not disclose anything about the negative influence caused by disinfectant-type quaternary ammonium compounds on the detection method for determining the presence of protein on a previously cleaned surface.
In view of the foregoing, it is an object of the present invention to eliminate, or at least reduce, this negative effect resulting in false positive readings and caused by residues of the disinfectant-type quaternary ammonium compounds on the results of this detection method, as disclosed by EP-A-738,891 (Konica).
In this connection, these effective disinfectant-type (or antimicrobial) quaternary ammonium compounds may be generally defined to be quaternary ammonium compounds having the formula (R
1
) (R
2
) (R
3
) (R
4
) N
+
X
−
wherein R
1
, R
2
, R
3
, and R
4
are independently a C
1
-C
24
aliphatic group, a C
1
-C
4
hydroxyaliphatic group, benzyl, C
1
-C
24
alkyl benzyl, or halo benzyl, and X
−
represents an anion capable of imparting water solubility or dispersibility to the compound such as chloride, bromide, iodide, sulphate, methylsulphate, and others.
We have surprisingly found that this object can be achieved when contacting the substances transferred onto the sampling means with a nonionic or zwitterionic surfactant as specified in claim
1
.
We have also found that this detection method can be advantageously carried out when applying a sampling means having a water-absorbable portion comprising a water-insoluble polymer. This polymer can be a synthetic polymer or a non-synthetic polymer. Cellulose is preferably used as non-synthetic polymer.
DEFINITION OF THE INVENTION
Accordingly, in one aspect the present invention provides a method for detecting protein present on the surface of a sample comprising the steps of:
transferring substances present on a subject portion of said surface to a sampling means which comprises a water absorbable portion comprising a water-insoluble polymer;
contacting the substances transferred onto said sampling means with a reagent capable of forming or changing colour upon reaction with protein;
visually determining color formed by the reaction of said reagent with protein,
wherein the substances transferred onto the sampling means are also contacted with a zwitterionic surfactant or a nonionic surfactant selected from the group consisting of
(i) condensates of aliphatic carboxylic acids having about 8 to about 18 carbon atoms in an aliphatic chain and incorporating from about 2 to about 50 ethylene oxide and/or propylene oxide and/or butylene units,
(ii) condensates of aliphatic alcohols having from about 6 to about 24 carbon atoms and incorporating from about 2 to about 50 ethylene oxide and/or propylene oxide and/or butylene oxide units,
(iii) condensates of alkyl phenols having about 6 to 12 carbon atoms and incorporating from about 2 to 25 moles of ethylene oxide and/or propylene and/or butylene oxide,
(iv) polyoxyethylene derivatives of sorbitan mono-, di- and tri-fatty acid esters wherein the fatty acid component has between 12 and 24 carbon atoms and the polyethylene chains contain between about 4 and 30 ethylene oxide units,
(v) polyoxyethylene-polyoxypropylene block copolymers having the formula:
HO(CH
2
CH
2
O)
a
(CH(CH
3
)CH
2
O)
b
(CH
2
CH
2
O)
c
H or
HO(CH(CH
3
)CH
2
O)
d
(CH
2
CH
2
O)
e
(CH(CH
3
)CH
2
O)
f
H
wherein a, b, c, d, e, and f are integers from 1 to 350 reflecting the respective polyethylene oxide and polypropylene oxide blocks of said polymer, wherein the polyoxyethylene component of the block polymer is at least about 10% of the block polymer,
(vi) alkyl glycosides having formula:
R
4
O(R
5
O)
n
(Z
1
)
p
wherein R
4
is a monovalent organic radi
Baars Edwin
Linxweiler Winfried
Van den Brom Guido Clemens
Bovee Warren R.
Cole Monique T.
Hamilton Neil E.
JohnsonDiversey, Inc.
Rymarz Renee J.
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