Explanation of Reporting Limit for Paint Chips
By Jeffrey W. Siria, M.S., Ph.D., National Director of Inorganic Chemistry, EMSL Analytical, Inc.
Summary of Brief
This brief explains how the laboratory can achieve a reporting limit (RL) as low as 0.008% by weight (80 ppm) for lead in paint chips using FLAA or significantly lower by ICP-OES. The RL is the concentration that, below that limit, is not statistically quantifiable and thus is reported as less than (“<”). The RL is not the same as the method detection limit (MDL), a statistical limit of detection where the RL is a statistical limit of reliable quantitation.
The RL is inversely proportional to the sample weight. However, the quantity of sample submitted is outside the control of the laboratory. The following table provides example reporting limits for lead in paint chips as a function of sample weight for both FLAA and ICP-OES.
| Sample Weight | Lead Reporting limit, FLAA | Lead Reporting limit, ICP-OES |
|---|---|---|
| 0.25 grams (250 mg)* | 80 mg/kg (ppm), 0.008% by wt. | 4 mg/kg (ppm), 0.0004% by wt. |
| 0.10 grams (100 mg) | 200 mg/kg (ppm), 0.020% by wt. | 10 mg/kg (ppm), 0.0010% by wt. |
| 0.02 grams (20 mg)** | 1000 mg/kg (ppm), 0.10% by wt. | 50 mg/kg (ppm), 0.0050% by wt. |
* reporting limits will not be less with more than 250 mg of sample.
** 20 mg is the minimum acceptable weight for FLAA or ICP-OES analysis.
Similar calculations apply to other metals analyzed by ICP-OES (cadmium or chromium only if by FLAA), although the reporting limit may be higher or lower than that for lead depending upon the analyte.
English 
French 
Spanish 
Portuguese