Development and Validation of a Method for Trace Level Zinc Quantification in Pharmaceutical Zinc Supplements Using a Carboxyl Functional Group Packed Column and Refractive Index Detector.

Background: Zinc helps with cell division, growth, wound healing, and carbohydrate breakdown. Humanbeings have to obtain zinc from food or supplements because our bodies do not produce it naturally. In view of the greater advantages (such as low cost, time of analysis, and stability-indicating) compared to other quantification methods (titration, ion chromatography, Atomic absorption spectroscopy) proposed in the literature, a refractive index detector coupled with HPLC has been used in quantification of zinc.

Objective: The goal of this research is to develop and validate a sensitive, low-cost, high-resolution, and stability- indicating method for detecting and quantifying zinc levels in zinc supplement pharmaceutical products (injectables, tablets, and capsules).

Methods: A novel isocratic reverse-phase HPLC method with a refractive index detector (with sensitivity 64, detector temperature 35°C, and positive polarity) was developed using a carboxyl functional group packed column and 0.8% (v/v) formic acid as the mobile phase to detect and quantify zinc content.

Results: The reported method has a good optimal sensitivity (LOQ: 0.006 mg/mL and LOD: 0.002 mg/mL). The correlation coefficient (r) obtained from the zinc calibration plot was greater than 0.998, indicating that the method was linear and that there was a strong correlation between zinc concentration (0.006 mg/mL to 0.375 mg/mL) and peak response. The accuracy at LOQ level was found to be 95-105% and 97-103% at the remaining levels (50, 100, and 150%).

Conclusion: The proposed method was successfully developed and validated as per International council for harmonisation (ICH) guidelines. Therefore, this method can be used for the quantitative testing of zinc in the QC laboratory.

Highlights: A novel method was developed for zinc levels determination in pharmaceutical products using HPLC with a refractive index detector. The present approach has a quick run time of 10 min and is inexpensive.