The benefits of spectrophotometric quantitative analysis and the small sample requirements of a spot test have been merged in this new methodology for metal analysis at the sub-micro level. A 1 µL sample is transferred to a suitable medium (TLC plate) with subsequent application of reagent(s) at the same spot; the color density of the resulting spot is then measured using a flatbed color scanner connected to a PC running specially developed software. Calibration data was collected for As, Hg, and Pb in 1-5 ppb range with a correlation co-efficient better than 0.9962. The method is especially suitable for precipitation systems where absorption spectroscopy fails.