Chemical spot test for lead in paint and other media

• US 20030203496A1
• Filed: 05/14/2003
• Published: 10/30/2003
• Est. Priority Date: 12/03/1998
• Status: Active Grant

• Current Assignee: Sandra Lynn Cole
• Original Assignee: Sandra Lynn Cole
• Inventors: Cole, Sandra Lynn
• Granted Patent: US 6,800,485 B2
• Time in Patent Office: Days
• US Class Current: 436/77
• CPC Class Codes: G01N 31/22 using chemical indicators G01N31/02 takes precedence
• CPC Class Codes: G01N 33/32 Paints; inks investigating resistance to the weather, to corrosion, to light G01N17/00

Abstract

A one-step chemical spot test for the qualitative determination of lead in lead-based paint and other media. This test is based upon the reaction of lead with sodium rhodizonate under strong acid conditions to develop an intense purple colored complex. The acid preferred is dilute hydrochloric acid. The test is performed in one step using a dropper, plastic cylinders, or like apparatus.

Claims

1. A method of detecting a metal in a media which comprises the steps of:

(a) exposing the media to a strong acid;

(b) exposing the media to a rhodizonate; and

,

(c) monitoring the media for a visible color change.

2. The method of claim 1 wherein the color change of step (c) is a purple to blue tint.

3. The method of claim 2 wherein the purple to blue tint is an indicator of the presence of lead.

4. The method of claim 1 wherein the rhodizonate is formed from a rhodizonic acid salt and water.

5. The method of claim 1 wherein the rhodizonate is formed from rhodizonic acid, disodium salt, and water.

6. The method of claim 5 wherein the rhodizonate formed is sodium rhodizonate of a concentration that appears as a yellow/brown color.

7. The method of claim 1 wherein the acid is dilute hydrochloric acid.

8. The method of claim 7 wherein the dilute hydrochloric acid comprises a concentration of approximately 5%. volume to volume.

9. The method of claim 1 further comprising the steps of:

(d) comparing the color change to a color chart.

10. The method of claim 9 wherein the color chart contains a range of colors indicating the positive or negative detection of lead.

11. The method of claim 9 wherein the color chart contains a range of colors in which the positive colors arc correlated to a detected lead concentration.

12. A method of detecting a metal in a media which comprises the steps of:

(a) abrading the media;

(b) exposing the media to a strong acid;

(c) exposing the media to a rhodizonate; and

,

(d) monitoring the media for a visible color change.

13. The method of claim 12 wherein the color change of step (d) is a purple to blue tint.

14. The method of claim 13 wherein the purple to blue tint is an indicator of the presence of lead.

15. The method of claim 12 wherein the rhodizonate is formed from a rhodizonic acid salt and water.

16. The method of claim 12 wherein the rhodizonate is formed from rhodizonic acid, disodium salt, and distilled water.

17. The method of claim 16 wherein the rhodizonate formed is sodium rhodizonate in a concentration that appears as a yellow/brown color.

18. The method of claim 12 wherein the acid is dilute hydrochloric acid.

19. The method of claim 18 wherein the dilute hydrochloric acid comprises a concentration of approximately 5%. volume to volume.

20. The method of claim 12 wherein the color change of step (d) is further compared to a color chart.

21. The method of claim 20 wherein the color chart contains a range of colors indicating the positive or negative detection of lead.

22. The method of claim 20 wherein the color chart contains a range of colors in which the positive colors are correlated to a detected lead concentration.