Novel polymethyl methacrylate (PMMA) chip has been designed and fabricated in our laboratory with the purpose to minimize the reagent consumption and waste generation. The low-cost chip was fabricated by CO₂ laser (with 225 μm wide) and thermal bonding to use in conjunction with a reverse flow injection system. A fiber optic probe was fixed in a PMMA cover plate as the optical sensor opposite to light emitting diode (LED) as light source for detection with mini-spectrometer. The fabricated analyzer has been applied for determination of Fe(III) in water samples with a sampling rate of 40 h⁻¹. The method was based on the reaction of Fe(III), eriochrome cyanine R (ECR) and cetyltrimethylammonium bromide (CTAB), yielding a blue colored complex in an acetate buffer medium (pH 4.5) with absorption maximum at 610 nm. The linearity of this analysis was studied in the range of 0.03-0.70 mg L^-1. The limit of detection (LOD, defined as 3σ) was 0.015  mg L⁻¹. The percentage relative standard deviation for 10-replicate injections for analyte was less than 2. Results obtained were in good agreement with those obtained by the official FAAS method at the 95% confidence level. The method is simple, rapid, precise, economical and could be classified as a greener analytical method.

Keywords: microfluidic, iron, ECR, water samples