HunterLab Platinum-Cobalt (Pt-Co/Hazen/APHA) Standard Solution, 500 APHA Units

Overview

The HunterLab Platinum-Cobalt (Pt-Co/Hazen/APHA) Standard Solution, 500 APHA Units is a traceable, NIST-traceable liquid color reference material engineered for daily performance verification of spectrophotometric color measurement instruments. It is formulated in strict accordance with the platinum-cobalt scale defined in ASTM D1209 and ISO 6271, where one APHA unit corresponds to the color intensity produced by 1 mg/L of platinum (as chloroplatinic acid) and 0.5 mg/L of cobalt (as cobaltous chloride). This standard solution provides a stable, reproducible reference point at the upper end of the conventional Pt-Co scale (0–500 APHA), enabling laboratories to validate instrument linearity, photometric stability, and baseline drift across the visible spectrum (400–700 nm). Its use supports routine instrument qualification under GLP and GMP frameworks, particularly in water quality analysis, pharmaceutical excipient testing, chemical manufacturing, and polymer processing—where color consistency directly correlates with product purity, oxidation state, or degradation kinetics.

Key Features

• Traceable calibration: Certified against primary standards with documented uncertainty; batch-specific certificate of analysis includes absorbance values at key wavelengths (e.g., 430 nm, 465 nm, 510 nm)
• Stability-optimized formulation: Proprietary chelation and pH stabilization ensure shelf life ≥24 months when stored unopened at ≤30 °C, protected from light and thermal cycling
• Compatibility with 8°/diffuse optical geometry: Designed for use with HunterLab’s UltraScan VIS, ColorFlex EZ, and other spectrophotometers employing d/8° or 8°/d illumination
• Consistent spectral profile: Engineered to replicate the characteristic absorption peak near 430 nm typical of Pt-Co solutions, enabling accurate validation of UV–vis photometric response
• Ready-to-use format: Supplied in 500 mL amber glass bottles with tamper-evident seal; no dilution or preparation required prior to use

Sample Compatibility & Compliance

This standard is intended exclusively for instrument performance verification—not for direct sample analysis. It is compatible with all spectrophotometers configured for transmission color measurement in transparent liquids, including those compliant with ASTM D1209 (Platinum-Cobalt Scale), ISO 6271 (Water Quality — Determination of Colour), USP (Color), and Chinese national standards GB/T 605-2006 and GB 3143. Each lot undergoes independent verification per ISO/IEC 17025-accredited procedures. The solution meets requirements for audit readiness under FDA 21 CFR Part 11 when used within validated workflows that include electronic record retention and user access control.

Software & Data Management

When used with HunterLab’s EasyMatch QC software, the 500 APHA standard integrates into automated verification protocols. Users can configure pass/fail limits for L*, a*, b*, YI E313, and APHA index deviations; generate PDF reports with instrument ID, operator signature, timestamp, and deviation history; and export CSV logs for trend analysis in LIMS or statistical process control (SPC) platforms. Audit trails capture all parameter changes, result approvals, and calibration events—fully compliant with ALCOA+ principles (Attributable, Legible, Contemporaneous, Original, Accurate) for regulated environments.

Applications

• Verification of spectrophotometer photometric accuracy and wavelength calibration stability before daily water quality testing (e.g., drinking water, wastewater effluent, boiler feedwater)
• Performance qualification of color measurement systems in pharmaceutical manufacturing, especially for APIs and liquid dosage forms subject to USP
• Linearity assessment across the full Pt-Co range (0–500) during instrument commissioning or requalification
• Supporting ISO/IEC 17025 accreditation audits through documented evidence of ongoing instrument fitness-for-purpose
• Reference material for internal method validation studies evaluating inter-instrument agreement or operator-to-operator reproducibility

FAQ

How often should the 500 APHA standard be used for instrument verification?

Daily verification is recommended for high-throughput or regulated environments; weekly use may suffice for low-frequency applications—always aligned with your laboratory’s SOPs and risk-based validation strategy.
Can this standard be reused after opening?

Yes, provided it is stored in its original container at ≤30 °C, protected from light, and handled using clean, dedicated pipettes to avoid contamination; discard if turbidity, precipitation, or color shift is observed.
Does this product comply with FDA 21 CFR Part 11 requirements?

The standard itself is not software—but its use within validated workflows employing compliant software (e.g., EasyMatch QC v5.0+) satisfies electronic record and signature requirements when combined with appropriate access controls and audit trail configuration.
What is the uncertainty associated with this standard?

Certified uncertainty is ±2 APHA units (k=2) as stated on the accompanying Certificate of Analysis, determined via comparative spectrophotometry against NIST SRM 2105.
Is there a lower-range counterpart available for routine calibration?

Yes—HunterLab offers certified Pt-Co standards at 10, 50, 100, 200, and 300 APHA units; the EasyCert Verification Kit includes multiple points for comprehensive linearity assessment.