Using UV-1900i Plus to Evaluate Raw Materials for Chemical Products Based on the Hazen Color Scale

Importance of the topic

Color measurement of transparent liquid raw materials is a fundamental quality control parameter in chemical production. The Hazen (platinum-cobalt) scale is widely adopted in ISO, JIS and ASTM standards to quantify slight chromatic changes that are not discernible by eye. Implementing a robust spectrophotometric method ensures reproducible, objective evaluation of product appearance.

Objectives and study overview

This study demonstrates how to use the Shimadzu UV-1900i Plus UV-Vis spectrophotometer, coupled with LabSolutions UV-Vis Color software, to determine Hazen unit values of glycerin and acetylacetone. The goal is to show compliance with ISO 6271:2015, JIS K0071-1:2017, JIS K3351:2009 and JIS K8027:2020 criteria and to highlight the method’s precision in distinguishing low-color samples.

Methodology and instrumentation

Measurements were performed using:

• Shimadzu UV-1900i Plus UV-Vis Spectrophotometer
• Long-path (50 mm) rectangular cell holder
• 50 mm quartz cell

Analytical conditions:

• Wavelength range: 380–780 nm
• Sampling interval: 1.0 nm
• Slit width: 1 nm
• Scanning speed: fast
• Baseline correction: pure water in 50 mm cell

LabSolutions UV-Vis Color software, preloaded with a calibration curve from 24 platinum-cobalt standards (0–500 Hazen units), automated the calculation of Hazen values and pass/fail judgments.

Main results and discussion

Transmittance spectra revealed:

• Glycerin: high transmittance (380–780 nm), Hazen unit = 1.649
• Acetylacetone: slight absorption below 500 nm, Hazen unit = 16.980
• Apparent transmittance >100% at 700–780 nm due to pure water reference with its own absorption features

Both samples met their respective appearance criteria: glycerin ≤20 Hazen units (JIS K3351:2009) and acetylacetone ≤100 Hazen units (JIS K8027:2020). The quantitative Hazen values confirmed a subtle color difference between the two nearly colorless liquids.

Benefits and practical applications

The described approach offers:

• Rapid, objective color quantification without visual comparison
• Elimination of manual standard preparation by using built-in calibration
• High reproducibility across laboratories
• Compliance with multiple international standards

Applications include routine QA/QC in glycerin, solvents, reagents and other clear liquids in pharmaceutical, polymer and fine-chemical industries.

Future trends and possibilities

Advances may include:

• Integration with process analytical technology (PAT) and inline monitoring
• Expansion to fluorescence or multi-angle color metrics
• Use of chemometric algorithms for enhanced color prediction
• Automated LIMS interfacing for real-time quality assurance

Further adoption of Hazen-based protocols in emerging standards and digital reporting is anticipated.

Conclusion

The UV-1900i Plus spectrophotometer, combined with LabSolutions UV-Vis Color, provides a turnkey solution for precise Hazen unit determination. The method satisfies ISO, JIS and ASTM criteria and enables sensitive differentiation of low-color liquid samples, streamlining quality control workflows.

Reference

1. ISO 6271:2015 Clear liquids – Estimation of colour by the platinum-cobalt colour scale
2. JIS K0071-1:2017 Test methods for colour of chemical products—Part 1: Estimation of colour in Hazen units (platinum-cobalt colour scale)
3. JIS K3351:2009 Glycerines for industrial use
4. JIS K8027:2020 Acetylacetone (Reagent)
5. ASTM D1209-05(2019) Standard Test Method for Color of Clear Liquids (Platinum-Cobalt Scale)