DETERMINATION OF TRACE AMOUNT OF ALUMINUM IN WATER SAMPLES BY A FLUORESCENT MICROSCOPIC SELF-ORDERED RING TECHNIQUE

ABSTRACT

When a droplet of solution was spotted onto a hydrophobic substrate, a self-ordered ring (SOR) can be formed along the perimeter of the spotted droplet if its contact line can be pinned and the solvent can be evaporated. This phenomenon was applied herein for the determination of trace amounts of aluminum in water samples. When a 0.20 μL droplet of the fluorescent complex of Al(III)–Acid chrome dark blue (ACDB) was spotted to the surface of dimethyl dichlorosilane (DMCS) pretreated glass slide, a SOR with the outer diameter of 1.04 mm and the ring line width of 32 μm can be obtained. Linear response was observed between maximum fluorescence intensity (I _max) of the SOR with the content of aluminum in the range of 20–320 fmol (or 1.0–16 × 10⁻⁷ M), and the limit of determination is 0.41 fmol (or 2.05 × 10⁻⁹ M) with three folds of signal to noise. Water samples including mineral drink water and river water were determined satisfactorily.

Keywords:

• Self-ordered ring (SOR) technique
• Acid chrome dark blue (ACDB)
• Aluminum
• Fluorescent microscopic analysis

ACKNOWLEDGMENTS

This research was supported by the National Natural Science Foundation of China (NSFC, 20175017) and the University Key Teachers Program directed under the Ministry of Education of PRC [2000] 65 = 2804.