Measurement of urinary calcium using AT89C51RD2 microcontroller.

Area of Science:

• Biomedical Engineering
• Analytical Chemistry
• Clinical Diagnostics

Background:

• Accurate calcium ion determination in urine is crucial for diagnosing various health conditions.
• Existing methods can be complex, expensive, or require large sample volumes.
• Development of a simple, cost-effective, and sensitive assay is needed.

Purpose of the Study:

• To develop and validate a simple, inexpensive absorption technique for quantifying calcium ions in urine samples.
• To assess the system's performance, including linearity, detection limit, and interference effects.
• To compare the developed method with a standard clinical spectrophotometric technique.

Main Methods:

• Utilized a light emitting diode (650 nm) as a light source and a photodiode as a detector, controlled by an AT89C51RD2 microcontroller.
• Developed custom software for sample processing monitoring and results display on an LCD screen.
• Investigated interferences from monovalent and divalent cations and determined absorption changes across a pH range of 3-12.

Main Results:

• Achieved a linear output for calcium concentrations in the range of 2.5-7.5 mM using a small sample volume (15 microliters).
• Established a low detection limit of 0.06 mM for calcium ions.
• Demonstrated successful application in successive urine sample assays, showing good agreement with clinical spectrophotometric methods (95% confidence level).

Conclusions:

• The developed absorption technique provides a simple, inexpensive, and accurate method for urine calcium determination.
• The system exhibits a low detection limit and minimal interference, making it suitable for clinical applications.
• This method offers a viable alternative to current clinical spectrophotometry for routine calcium analysis in urine.