CHROMIUM VI TEST

Abstract

The present invention is in the field of chromium VI test, a chromium VI tester, a test kit comprising said chromium VI tester, and in particular to identify low amounts of chromium VI, such as in coatings and paints, which low amounts may form a health risk and may be toxic.

Claims

1. A chromium VI-tester comprising a volume of fluid absorbing material, in the fluid absorbing material, a pH-indicator, wherein the pH-indicator has a color in neutral form, and no color under acidic conditions, and in the fluid absorbing material, a chromium VI-indicator, wherein the chromium VI-indicator has a color in the presence of chromium VI, and no color in absence of chromium VI.

2. The chromium VI-tester according to claim 1, wherein the fluid absorbing material is selected from cotton, paper, cellulose comprising material, polymer comprising material, including acrylate polymers, sponge, fluff pulp, starch, polysaccharides, proteins, and combinations thereof.

3. The chromium VI-tester according to claim 1, wherein the fluid absorbing material is provided on a carrier.

4. The chromium VI-tester according to claim 1, wherein the volume of fluid absorbing material is 1-1000 mm.sup.3.

5. The chromium VI-tester according to claim 1, wherein the pH-indicator is provided in an amount of 0.01-10 mg/cm.sup.3.

6. The chromium VI-tester according to claim 1, wherein the pH-indicator is selected from organic indicators, including indicators with structural formula ##STR00002## wherein each of R1, R2, and R3, each independently comprise at least one aromatic hydrocarbon moiety, and wherein each of R1, R2, and R3, each independently, comprise 0-2 sulfonate groups, and each independently, comprise 0-2 tertiary ammine groups, wherein R1 and R2 comprise 0-1 sulfonate groups and wherein R2 comprise 1-2 sulfonate groups, including E131, E133, E142, ethyl violet, methyl violet, malachite green, bromophenol blue, and methyl thymol blue, wherein R4 is selected from a C.sub.1-C.sub.5 alkane, H, or is absent, in which latter case a double bond is present, and from sulfur comprising silicates Si.sub.nO.sub.4nS.sub.j.sup.m−, wherein n∈[5-8], j∈[3-6], and m∈[5-20], and from quinaldine red, and wherein the pH-indicator has an absorbance of <10%.

7. The chromium VI-tester according to claim 6, wherein the chromium VI-indicator is provided in an amount of 0.01-200 mg/cm.sup.3.

8. The chromium VI-tester according to claim 1, wherein the chromium VI-indicator is selected from 1,5-Diphenylcarbazide, pentamethylene-bis triphenylphosphonium, triphenylterazolium chloride and nitrobluetetrazolon chloride.

9. At least one chromium VI-tester according to claim 1, the at least one chromium VI-tester comprising a volume of fluid absorbing material, in the fluid absorbing material, a pH-indicator, wherein the pH-indicator has a color in neutral form, and no color under acidic conditions, and in the fluid absorbing material, a chromium VI-indicator, wherein the chromium VI-indicator has a color in the presence of chromium VI, and no color in absence of chromium VI, further comprising a container for providing fluid drops of acid, wherein the acid is in pure or diluted form, wherein the acid has a pH<3.

10. The at least one chromium VI-tester according to claim 9, wherein the container comprises 0.1-20 ml of acid, and wherein the at least one chromium VI-tester is more than two chromium VI-testers.

11. A method of testing presence or absence of chromium VI comprising, providing a surface potentially comprising chromium VI, such as wherein the surface is a coating surface or a paint surface, providing at least one drop of acid to the chromium VI-tester according to claim 1, preferably lowering the pH to <3, rubbing the acidic chromium VI-tester over the surface, and determining coloration of the tester thereby identifying presence or absence of chromium VI.

12. A method of producing a chromium VI-tester according to claim 1, comprising providing a volume of the fluid absorbing material, providing the pH-indicator dissolved in a first solvent, adding pH-indicator dissolved in the first solvent to the fluid absorbing material, and providing the chromium VI-indicator dissolved in a second solvent, adding chromium VI-indicator dissolved in the second solvent to the fluid absorbing material, and removing the first and second solvent.

13. The method according to claim 12, wherein 0.1-3 ml of the first solvent is added, and wherein 1-10 ml of the second solvent is added, and wherein the first solvent comprises 0.01-10 mg pH-indicator/cm.sup.3 first solvent, and wherein the second solvent comprises 0.01-200 mg chromium VI-indicator per cm.sup.3 second solvent, and wherein the first and second solvent are each individually selected from alcohols and from water.

Description

SUMMARY OF FIGURES

[0035] FIG. 1 shows a chromium VI test.

[0036] FIGS. 2a-i show exemplary pH indicators and FIG. 2j a general chemical structural formula thereof.

[0037] FIGS. 3a-i show exemplary Cr-VI indicators

DETAILED DESCRIPTION OF THE FIGURES

[0038] FIG. 1 shows a chromium VI test. FIG. 1A: cotton swab (or cotton bud) with blue dye and indicator. B: moistened head of cotton wool with an acid, causing the color of the pH-indicator to fade. C: Moistened swab rubbed on a surface where chromium-6 was present, causing the head to turn purple, as the chromium VI indicator changes color.

[0039] FIGS. 2a-e show exemplary pH indicators and FIG. 2f a general chemical structural formula thereof. FIG. 2a shows E131 en E131 lake Patent blue V (CAS Number 3536-49-0), FIG. 2b shows E133

Brilliant Blue FCF (Blue 1) (CAS 3844-45-9), FIG. 2c shows E142 (CAS 3087-16-9), FIG. 2d shows Bromophenol Blue (CAS 115-39-9), FIG. 2e shows Methyl thymol blue (CAS 3778-22-1), FIG. 2f shows pigment blue 29 (CAS 57455-37-5), FIG. 2g shows malachite green (CAS number 569-64-2, chlorite salt), FIG. 2h shows ethyl violet, analogue to methyl violet (CAS 8004-87-3), which may comprise, each individually, an alkane moiety on each N-end-group, and FIG. 2i shows quinaldine red (CAS 117-92-0). FIG. 2j shows generic pH-indicators, wherein each of R1, R2, and R3, each independently comprise at least one aromatic hydrocarbon moiety, such as benzene and naphthalene, and wherein each of R1, R2, and R3, each independently, comprise 0-2 sulfonate groups, and/or, each independently, comprise 0-2 tertiary ammine groups, preferably wherein R1 and R2 comprise 0-1 sulfonate groups and wherein R2 comprise 1-2 sulfonate groups, such as E131, E133, E142, ethyl violet, methyl violet, malachite green, bromophenol blue, and methyl thymol blue. R4 may be selected from a C.sub.1-C.sub.5 alkane, H, or may be absent, in which latter case a double bond is present (dashed line).

Examples/Experiments

[0040] The invention although described in detailed explanatory context may be best understood in conjunction with the accompanying examples and figures.

Experimental

[0041] Background chromium-6 (or chrome-VI) test, such as for paints, coatings, and surfaces.

[0042] Test rods, such as the cotton swabs above, can be produced by adding an indicator in the cotton head of a cotton swab. This swab can then be used to detect chromium-6; the swab head is moistened with an acid, such as diluted sulphuric acid, and then rubbed over a layer of paint or another surface that may contain chromium-6. A chromium-6 indicator in combination with an acid reacts with the dissolved chromium-6 leading to a purple discoloration.

[0043] So in the present chromium VI tester a use of an additional dye in addition to a chromium VI indicator (for the swab head of the wadding rods) that fades or discolors (to a light color or no color at all) when the cotton swabs are moistened (dripped) with an acid, such as sulphuric acid. The fading may be due to the fact, for example, that the dye is (intentionally) not stable, and therefore breaks down at high acidity. But these can also be dyes that don't give a color, or a lighter color when the pH changes (i.e. a pH indicator).

[0044] Treatment of the cotton swabs with ‘fading’ dyes has several advantages:

(1) During production, the color of the cotton swabs allows us to clearly see which cotton wool rods have been treated. This prevents mistakes: the white untreated cotton wool rods cannot be confused with the treated rods. Such is also subject to government regulations.
(2) Cosmetic products, such as cotton swabs, may not legally be treated with chemicals without this being clearly visible.
(3) A customer can clearly see that the cotton wool bars have been treated. She will therefore not think that she can use untreated cotton swabs (white cotton swabs) for the test.
(4) A customer can clearly see if a cotton swab is sufficiently moistened with sulphuric acid: only in this case the blue color will disappear.
(5) After moistening with e.g. sulphuric acid, the color becomes light (i.e. no longer blue) so that any purple discoloration due to presence of chromium-6 becomes clearly visible during the test. This will result in a lower detection limit compared to a cotton swab treated with a dye that does not fade. The detection limit (just visible coloration by bare eye) is at present about 100 ppm (0.01 weight % chromium VI in a paint layer) for a swab size of ap-proximately 0.2 cm.sup.3. At this detection limit approximately 0.1 μg chromium VI is dissolved. With smaller swab sizes lower amounts of chromium VI can be detected, such as 10 ppm.
(6) The color of the cotton swab may camouflage the light-purple discoloration that occurs over time when cotton wool rods are stored longer in a bag. With the blue discolored cotton wool rods this (innocent) discoloration will not/less stand out and therefore will not cause discussion. The shelf life can therefore be extended.

[0045] Examples of Dyes

These are typically pH-indicators. The chemical (acid-base) reaction involved can be represented by:

HInd+H.sub.2OH3O.sup.++Ind.sup.−

[0046] Wherein HInd has a different color than Ind.sup.− (the conjugated form). In the present application HInd has a light color or is colorless. This is obtained with the acid (moist) state of the cotton bud. For the present application, the Ind form preferably has the basic color of the not moistened cotton wool bar (neutral).

[0047] A few examples of successful pH indicators are given in FIGS. 2a-i, whereas FIG. 2j represents a generic chemical structure.

[0048] FIG. 3a shows benzidine (CAS 92-87-5), 3b 2,7-diaminodiphenylene oxide, 3c o-Dianisidine (CAS 119-90-4), 3d pyrrole (CAS 109-97-7), 3e strychnine (CAS 57-24-9), 3f Leuco xylene cyanole FF (CAS 303-373-0), 3g tetrazolium chloride (CAS 298-96-4).