Detection of formaldehyde in urine samples
View Patent ↗A method for rapidly detecting the presence of formaldehyde in a urine sample (e.g., urine or a urinary material associated therewith, such as headspace gas located associated with urine) is provided. The method includes contacting the urine sample with a substrate on which is disposed a colorant that is capable of undergoing a detectable color change in the presence of formaldehyde. Without intending to be limited by theory, it is believed that oxidation of the colorant by formaldehyde induces either a shift of the absorption maxima towards the red end of the spectrum (“bathochromic shift”) or towards the blue end of the spectrum (“hypsochromic shift”). The absorption shift provides a color difference that is detectable, either visually or through instrumentation, to indicate the presence of formaldehyde within the urine sample. For example, prior to contact with a urine sample, the colorant may be colorless or it may possess a certain color. However, after contacting the urine sample and reacting with formaldehyde, the colorant exhibits a color that is different than its initial color. The color change may thus be readily correlated to the presence of formaldehyde in the urine sample.
1. A method for detecting formaldehyde in a urine sample, the method comprising:
catching a flow of urine from an individual in an absorbent article, the absorbent article comprising a device that contains a substrate, the substrate defining a sample application zone for receiving the urine and a discrete detection zone located downstream from the sample application zone and within which is located a colorant, wherein the urine contacts the sample application zone of the substrate and flows therethrough to reach the colorant within the detection zone, and wherein the colorant reacts directly with formaldehyde to produce a visible spectral response; and
visually detecting the spectral response.
2. The method of claim 1 , wherein the colorant includes a triarylmethane.
3. The method of claim 2 , wherein the triarylmethane includes pararosanilin or an analog thereof.
4. The method of claim 2 , wherein the colorant includes basic fuchsin.
5. The method of claim 2 , wherein the triarylmethane is pre-reacted with a sulfur-containing compound.
6. The method of claim 1 , wherein the colorant comprises an aromatic azo compound.
7. The method of claim 6 , wherein the aromatic azo compound comprises chrysoidin.
8. The method of claim 1 , wherein the substrate is a chromatographic medium of a lateral flow device.
9. The method of claim 1 , wherein the spectral response is detected and compared to a control colorant.
10. The method of claim 1 , wherein the spectral response is correlated to the presence of formaldehyde at a concentration of about 10 parts per billion or more.
11. The method of claim 1 , wherein the spectral response is produced in about 5 minutes or less after the substrate is contacted with the urine.
12. The method of claim 1 , wherein the sample application zone is located adjacent to or is part of an absorbent core of the absorbent article.
13. The method of claim 1 , wherein the substrate is positioned between a substantially liquid impermeable layer and an absorbent core of the absorbent article.
14. The method of claim 1 , wherein the substrate is positioned between a liquid permeable layer and an absorbent core of the absorbent article.
15. The method of claim 1 , wherein the substrate is adhered to the absorbent core.
16. The method of claim 1 , wherein the detection zone is in the shape of a stripe, band, dot, or a combination thereof.
17. The method of claim 1 , wherein the spectral response is correlated to the presence of formaldehyde.
18. The method of claim 1 , wherein the substrate is in the form of a strip and the detection zone is in the form of a band that extends along a width of the strip.
19. The method of claim 1 , wherein the sample application zone is in fluid communication with an absorbent core of the absorbent article.
20. The method of claim 1 , wherein the absorbent article is a personal care absorbent article.
21. The method of claim 20 , wherein the personal care absorbent article is a diaper, training pants, absorbent underpants, incontinence article, feminine hygiene product, swim wear, or a baby wipe.
22. The method of claim 20 , wherein the absorbent article is a medical article, food service wiper, or a clothing article.