A Rapid Colorimetric Method for Determining Calcium, Inorganic Phosphorus, and Zinc in Human Milk Using Clinical...

Area of Science:

• Clinical Chemistry
• Nutritional Biochemistry
• Infant Nutrition

Background:

• Human milk is vital for infant growth, containing essential minerals like calcium (Ca), inorganic phosphorus (IP), and zinc (Zn).
• Conventional methods for mineral analysis in human milk, such as ICP-AES, are time-consuming and labor-intensive.
• Accurate and efficient mineral quantification is crucial for preparing safe donor human milk (DHM).

Purpose of the Study:

• To develop and validate a rapid, simple, and accurate colorimetric assay for quantifying Ca, IP, and Zn in human milk.
• To compare the performance of the colorimetric assay with the established ICP-AES method.

Main Methods:

• 71 pooled donor human milk (DHM) samples were analyzed after Holder pasteurization.
• Samples underwent a simple 5-fold dilution pretreatment.
• Ca, IP, and Zn concentrations were determined using an automated analyzer with clinical laboratory reagents and a colorimetric assay.

Main Results:

• The colorimetric assay demonstrated excellent intra-assay precision with coefficients of variation ranging from 0.7% to 7.4% for Ca, IP, and Zn.
• Recovery rates were high, ranging from 94.5% to 104.9% across different concentrations.
• Significant correlations were observed between the colorimetric assay results and ICP-AES measurements for Ca (r=0.944), IP (r=0.463), and Zn (r=0.949), all with p < 0.001.

Conclusions:

• The colorimetric assay using clinical laboratory reagents is precise and accurate for determining Ca, IP, and Zn in human milk.
• This method offers a practical alternative to traditional techniques, facilitating faster analysis.
• The assay can support the timely and appropriate provision of DHM to vulnerable preterm infants.