i-DReC (Intelligent Dynamic Range Extension Calculator), a New Photodiode Array Detector Function; Impurity Analysis Application

Importance of the Topic

Analytical methods in HPLC for high concentration samples suffer from signal saturation which affects accurate quantification of major components and trace impurities. The i DReC function extends dynamic range by using spectrum similarity and sensitivity correction allowing single-run analysis of samples with components outside the linear range. Accurate impurity profiling in pharmaceuticals is essential for safety and regulatory compliance.

Objectives and Study Overview

demonstrate principle of i DReC dynamic range extension function using PDA detector explain workflow for correcting saturated peaks apply method to determine impurity content in ofloxacin drug substance compare results with conventional two run approach

Methodology and Instrumentation

The method uses a PDA detector with the i DReC data analysis function installed on a Nexera X2 HPLC system. Shim pack XR ODS column and mobile phase as per Japanese Pharmacopoeia are employed at 40 C and 0.5 mL min flow. Detector SPD M30A is set at 294 nm sampling rate 240 ms. Key steps

• Acquire spectra of saturated peak region at primary wavelength λa
• Automatically select correction wavelength λb where absorbance is within linear range
• Integrate target peak in chromatogram at λb
• Extract spectrum on shoulder of saturated peak to calculate sensitivity coefficient k as ratio Ia Ib at λa λb
• Correct peak area and height by multiplying integrated value by k

Key Results and Discussion

Linearity correction experiments show extension of linear response up to high concentrations matching low concentration calibration. In impurity analysis of ofloxacin trace impurities around 0.02 to 0.15 percent are quantified in a single high concentration injection. Comparison indicates impurity content with i DReC match conventional two analysis results within 0.01 percent. Method halves number of injections and sample preparations.

Benefits and Practical Applications

Single injection quantification of both major and trace components reduces analysis time and solvent consumption. Improves throughput in pharmaceutical QA QC Simplifies impurity profiling in regulatory method development Reduces risk of sample handling errors

Future Trends and Opportunities

Integration of dynamic range extension with advanced chromatography techniques such as UHPLC and mass detection Adaptive real time wavelength selection could further automate correction functions Application to biodegradation studies and environmental monitoring High throughput screening with automated impurity confirmation in synthesis workflow

Conclusion

The i DReC function enables reliable quantification of saturated peaks in HPLC PDA detection by extending dynamic range through spectrum based sensitivity correction. Its application to ofloxacin impurity analysis demonstrates accuracy equivalent to traditional methods with half the experimental load. This approach enhances efficiency and data quality in pharmaceutical and industrial analytics.

Reference

Shimadzu Application News LAAN A LC E229 First Edition August 2013