Quantitative Analysis of High-Concentration Samples without Dilution - Introducing the UV-2700i Plus

Importance of the Topic

The ability to measure high‐concentration samples without dilution streamlines workflows, reduces error sources, and expands the applicability of UV‐Vis spectroscopy in industrial QC, environmental testing, and research settings. By minimizing stray light and extending dynamic range, analysts can obtain accurate absorbance readings for samples that would otherwise require time‐consuming dilution.

Objectives and Study Overview

This application note evaluates the Shimadzu UV‐2700i Plus UV‐Vis spectrophotometer for quantitative analysis of potassium permanganate solutions up to 8 Abs without dilution. It also demonstrates the spectrum‐based quantitative analysis feature in LabSolutions UV‐Vis software, which records full absorbance spectra and enables wavelength optimization for improved calibration linearity.

Methodology and Instrumentation

• Instrument: UV‐2700i Plus with double monochromator and Lo-Ray-Ligh® low stray light diffraction gratings
• Accessories: high‐absorbance measurement kit; 4 Abs neutral density filter on reference side
• Software: LabSolutions UV‐Vis for standard and spectrum‐based quantitation
• Standard Quantitative Analysis Settings:
  
  • Wavelength: 525.0 nm
  • Integration time: 2.0 s
  • Slit width: 5.0 nm
• Spectrum Measurement Conditions:
  
  • Wavelength range: 400–650 nm
  • Data interval: 0.1 nm
  • Scan speed: low stray light mode
  • Slit width: 5.0 nm

Main Results and Discussion

• The standard quantitation feature yielded a calibration curve for KMnO₄ at 65–520 mg/L (1–8 Abs) with excellent linearity (r2 = 0.99999).
• Spectrum data identified absorbance saturation above 8 Abs; inclusion of 585 and 650 mg/L points at 525 nm reduced linearity (r2 = 0.99498).
• By selecting a shoulder wavelength at 565 nm via spectrum‐based analysis, linearity was maintained up to 650 mg/L, illustrating the advantage of flexible wavelength choice.

Benefits and Practical Applications

• No‐dilution measurement up to 8 Abs saves time and reduces pipetting errors.
• Spectrum‐based analysis enables identification of optimal wavelengths to avoid peak saturation and maintain calibration accuracy.
• Applicable to initial method development, contaminated or colored samples, and high‐throughput industrial QC.

Future Trends and Potential Applications

• Incorporation of machine learning for automated wavelength selection and interference correction.
• Advancements in stray light reduction to further extend dynamic range beyond 8 Abs.
• Application expansion to turbid, scattering, or highly colored matrices in pharmaceuticals and environmental monitoring.

Conclusion

The UV‐2700i Plus, with its double monochromator and low stray light gratings, reliably quantifies high‐concentration samples up to 8 Abs without dilution. Spectrum‐based quantitative analysis in LabSolutions UV‐Vis provides flexibility to choose measurement wavelengths that preserve calibration linearity across a broad concentration range.