Wayeal HPLC with Nuopu HS-5A-Cr Column Determines Hexavalent Chromium in Dyes per GB/T 47088-2026

Customer Background

A dye manufacturer and its third-party testing partner needed to bring their hexavalent chromium testing in line with the newly issued Chinese standard GB/T 47088-2026. Dyestuffs are used throughout textile dyeing, home textiles and apparel, so any Cr(VI) residue travels with the finished product to consumers and into wastewater streams. The laboratory required a validated HPLC method that could handle complex dye matrices, reach trace detection limits and still deliver recoveries inside the standard's acceptance window.

Why Hexavalent Chromium Control Matters

• Health risk: Cr(VI) is highly toxic, carcinogenic and bio-accumulative. Skin contact with dyed garments or household articles can trigger skin ulcers and respiratory disorders, and long-term exposure is linked to cancer.
• Production safety: Over-limit Cr(VI) contaminates the dyeing workshop environment and endangers operators.
• Environmental impact: Effluent carrying excess Cr(VI) damages aquatic and soil ecosystems, inhibiting microbial activity and affecting plant and animal growth.

Rigorous determination is therefore a compliance, product-quality and public-health necessity, not merely a paperwork exercise.

Analytical Solution

The method pairs a Wayeal high performance liquid chromatograph with UV detection and a Nuopu New Materials anion exchange column HS-5A-Cr (4.0 × 250 mm), protected by an HS-5AG guard column (4 × 30 mm). The chromatographic conditions were set as follows:

Sample Preparation

1. Extraction: weigh 1.0 g of dye (to 0.0001 g) into a 100 mL stoppered conical flask, add exactly 50.0 mL phosphate buffer (22.8 g dipotassium hydrogen phosphate per litre, adjusted to pH 8.0 ± 0.1 and degassed), and ultrasonicate for 20 minutes. Filter through a syringe filter; if the sample dissolves completely, filtration can be omitted.
2. Clean-up: condition a C18 SPE cartridge (5 g / 20 mL) with 20 mL methanol, 40 mL water and 40 mL phosphate buffer. Load exactly 10.0 mL of extract, elute with 30 mL phosphate buffer, collect the eluate and make up to 50 mL.

Buffer preparation follows a strict shelf-life rule: prepare fresh, or store at 0-4 °C for no more than seven days, returning to room temperature and re-degassing before use.

Method Performance

• Calibration: a five-level working series prepared from a 1 mg/L Cr(VI) intermediate solution showed excellent linearity across the tested range.
• Detection limit: a 0.004 mg/L Cr(VI) concentration point was injected and confirmed as a reliable theoretical detection limit for the system.
• Blank samples: three dye samples were carried through the full preparation procedure and all returned not detected - no false positives from matrix or reagents.
• Spike recovery: samples fortified at 2.5 mg/kg gave recoveries of 95.8% - 96.8%, fully compliant with the standard's requirement.
• Repeatability: seven consecutive injections of the spiked sample confirmed stable retention time and peak response.

Conclusion

The combination of the Nuopu HS-5A-Cr anion exchange column (4 × 250 mm) and the Wayeal HPLC-UV system delivers a robust method for GB/T 47088-2026. Linearity is excellent, the detection limit is well below the regulatory threshold, and spike recoveries of 95.8%-96.8% at 2.5 mg/kg satisfy the standard's criteria. Dye producers and testing laboratories can therefore adopt this configuration to screen raw materials, verify finished goods and document compliance with confidence.

About the Suppliers

Wayeal (Anhui Wayeal Technology, Hefei, China) supplies the HPLC platform and application support; Nuopu New Materials supplies the dedicated HS-5A-Cr anion exchange column and matching guard column. Further application notes are available at www.wayeal.com.cn.