MALODOUR SAMPLING METHOD

Abstract

A method of sampling volatile malodorous materials, said method comprising the topical application of a patch comprising an absorbent hydrogel layer and a backing sheet adhering to it, the volatile malodourous materials being absorbed into the hydrogel layer and subsequently extracted from it.

Claims

1. A method of sampling volatile malodorous materials from the human skin, said method comprising the topical application of a patch comprising an absorbent hydrogel layer and a backing sheet adhered to the hydrogel layer, the volatile malodourous materials being absorbed into the hydrogel layer and subsequently being extracted from the hydrogel layer.

2. A method according to claim 1, wherein the hydrogel layer comprises a hydrophilic polymer.

3. A method according to claim 2, wherein the hydrophilic polymer is poly(2-hydroxyethylmethacrylate) or a metal salt of poly(2-acrylo-2-methyl-1-propanesulfonic acid).

4. A method according to claim 3, wherein the hydrophilic polymer is a metal salt of poly(2-acrylo-2-methyl-1-propanesulfonic acid) crosslinked with poly(ethylene glycol) diacrylate.

5. A method according to claim 1, wherein the backing sheet comprises a pressure sensitive adhesive.

6. A method according to claim 5, wherein the pressure sensitive adhesive comprises an acrylic polymer or a triblock copolymer of styrene with butadiene or isoprene, the block copolymer being formulated with oil.

7. A method according to claim 1, wherein the hydrogel layer or pressure sensitive adhesive comprises a tackifier.

8. A method according to claim 1, wherein the absorbent hydrogel layer is separated from direct contact with the skin by a permeable membrane.

9. A method according to claim 1, wherein the extraction of the volatile materials from the hydrogel layer is performed using supercritical fluid technology.

10. A method according to claim 1, wherein the volatile malodourous materials are volatile fatty acids.

11. A patch for sampling volatile malodourous materials from the human skin comprising an absorbent hydrogel layer, a backing sheet adhered to the hydrogel layer and a permeable inner membrane, which is held between the hydrogel layer and the skin when the patch is in use, wherein hydrogel layer comprises poly(2-hydroxyethylmethacrylate) or a metal salt of poly(2-acrylo-2-methyl-1-propanesulfonic acid).

12. A patch according to claim 11, wherein the hydrogel layer comprises a metal salt of poly(2-acrylo-2-methyl-1-propanesulfonic acid) crosslinked with poly(ethylene glycol) diacrylate.

13. A patch according to claim 11, wherein the backing sheet comprises a pressure sensitive adhesive.

14. A patch according to claim 11, wherein patch comprises a tackifier.

15. A patch according to claim 11, wherein all components of the patch are permeable to air.

Description

EXAMPLES

[0089] The following examples are provided to better illustrate the invention and are not to be considered limiting.

[0090] FIG. 1 shows a cross-section through a patch (1) suitable for use in accordance with the invention.

[0091] FIG. 2 shows how a patch may be located in the underarm region (axilla) and shows a top view of the patch (1).

[0092] FIG. 1 shows that the patch (1) comprises a hydrogel layer (2) sandwiched between a backing layer (3) and a permeable inner membrane (4) that contacts the skin (5). In this embodiment, each of the components is sufficiently flexible to allow the patch (1) as a whole to flex with the movement of the skin of the body to which it is attached.

[0093] FIG. 1 further illustrates the backing layer (3) overlapping the hydrogel layer (2) and making contact with the skin (5) around the periphery of the hydrogel layer (2). The backing layer (3) adheres to the skin (5) in this peripheral region by means of a pressure sensitive adhesive (6) applied on the inner surface of the backing layer (3) around its periphery.

[0094] In FIG. 2, the top view of the patch (1) illustrates a central region (7) and a peripheral region (8) of the patch. In the central region (7), the permeable inner membrane (4), hydrogel layer (2) and backing layer (3) lie one or top of the other. In the peripheral region (8), the backing layer (3) is stuck to the skin (5) by the pressure sensitive adhesive (6).

EXPERIMENTS

[0095] PolyAMPS hydrogel samples were synthesised using the following method. A batch of reaction mixture was prepared from 2-acrylamido-2-methylpropane sulfonic acid sodium salt (NaAMPS, 50% by weight in water, 46.4 g in total), poly(ethylene glycol) diacrylate (PEGDA, M.sub.n 575 g mol.sup.1, 0.1077 g), water (30.53 g) and the photo-initiator Irgacure 1173 (2-hydroxy-2-methylpropiophenone, 0.1 ml of a 10% aqueous solution). 3 ml samples were transferred to individual moulds and then photo-cured using high intensity UV radiation from a Light Hammer from Fusion UV Systems Corp.

[0096] In a first experiment, an artificial sweat sample comprising variety of malodourous volatile aliphatic acids (as often found in human perspiration) was applied to the surface of polyAMPS hydrogel samples (as prepared above). 0.5 ml of the artificial sweat sample (comprising the aliphatic acids at 1 to 3 mmol dm.sup.3) was applied and the samples placed on storage in heat-sealed aluminium pouches in an incubator at 25 C. Samples were removed at weekly intervals for analysis by Gas Chromatography (GC) using a Shimadzu GC2014 G C. The results are presented in Table 1 and are expressed as the average of 3 or 4 measurements for each of the indicated aliphatic acids vs. the amount originally applied. The results illustrate the excellent ability of the hydrogel to retain the volatile malodourous acids.

TABLE-US-00001 TABLE 1 Average Recovery (%) after . . . Volatile acid added 1 week 2 weeks 3 weeks 4 weeks Acetic acid 33.4 32.3 28.6 33.8 Isobutyric acid 89.1 89.6 81.1 72.1 Butyric acid 86.8 79.2 70.2 73.4 Valeric acid 71.3 65.2 71.6 58.0 4-methylvaleric acid 49.2 41.5 39.7 32.3

[0097] In a second experiment, sweat patches according to the invention (comprising a polyAMPS hydrogel layer) were applied to the underarms of human volunteers. Following vigorous sporting activity, the patches were collected and extracted. Analysis of the extracts was by GC using a Shimadzu GC2014 G C. The retention time of the peaks in the worn sample were identified and compared with known retention times of volatile compounds tested. Linear regression analysis was used to determine the concentration based on pre-prepared calibration curves. GC analysis of the extracts revealed significant levels of acetic acid and propionic acidboth known malodourous components of human perspiration as typically exuded from the underarm regions. This is good evidence for the effectiveness of the method of the invention.