Design and Fabrication of Low-Cost Home-made All-in-set Colorimetric Detector with PC-interface Embed for the Determination of Tetracycline Antibiotics

Abstract

A low-cost home-made all-in-set colorimetric detector with PC-interface embed was
designed and fabricated. Light emitting diodes (LEDs) are the most energy-efficient means of
producing monochromatic light, and provide a concentrated small cool emitter ideal for miniature
analytical devices in the FIA system. A small blue LED and a light dependent resistor (LDR) were
used as a light source and a sensor. The detector???s electronic components, including a signal
amplifier and an A/D converter, were integrated on one small board connected to a personal
computer for measuring the signals.
The proposed device was used as a basis to develop a FIA-spectrophotometric method for
the determination of tetracycline antibiotics by forming orange-red complexes with uranyl acetate.
These complexes show the maximum absorption at 410, 415, 409 and 410 nm for tetracycline
hydrochloride (TCH), chlotetracycline hydrochloride (CTCH), oxytetracycline hydrochloride
(OTCH) and doxycycline hydrochloride (DCH), respectively. The detection limits were found to be
2.85, 2.89, 3.60 and 3.88 mg/L for TCH, CTCH, OTCH and DCH, respectively. The linear range of
calibration graph for each drug was obtained at 10-150 mg/L. This method was successfully applied
to the determination of tetratycline in the bulk drugs and pharmaceutical formulations.

Keywords : Tetracycline antibiotics, FIA-Colorimetry, Home-made FIA system