Overview
ISO/TR 18105:2014 - Soil quality: Detection of water soluble chromium(VI) using a ready-to-use test-kit method - provides a practical screening procedure to detect water-soluble Cr(VI) (chromium(VI)) in soil using commercially available ready-to-use test-kits. The method follows a water extraction approach (liquid-to-solid ratio 10 L/kg) and is intended for rapid field or laboratory screening to indicate concentration levels from mg/kg to percent (%) using colour charts or a photometer.
Key topics and technical requirements
- Principle: Chromium(VI) reacts with 1,5-diphenylcarbazide (or equivalent reagents) to form a red‑violet complex; detection by visual comparison or spectrophotometry at 540 nm.
- Sampling & extraction:
- Typical test: 1 g soil + 10 mL de‑ionized water, shake 1 min, then filter through 0.45 µm membrane.
- Dilute filtrate as needed (e.g., 1 mL to 10 mL) if concentration exceeds colour chart range.
- Measurement:
- Use a hand‑held/portable photometer (10 mm path length) or the supplied colour chart.
- Calibration: photometer users prepare blank and spiked working standards; colour‑chart users may not require photometer calibration.
- Reagents & apparatus: de‑ionized water, test‑kit reagent (1,5‑diphenylcarbazide), non‑metal sampling spoon, tubes/vials.
- Interferences: arsenic, cobalt, iron(II/III), tin, vanadium, lead, phenol and reducing agents (e.g., iron(II), ascorbic acid) can alter colour or reduce Cr(VI), affecting results.
- Quality assurance / QC:
- Implement soil/equipment blanks, spikes, duplicates and periodic recalibration (recommended at least daily).
- Estimate measurement uncertainty using ISO/IEC Guide 98 principles.
- Limitations: Designed as a screening technique. Confirm a subset of positive/negative results near regulatory action levels with laboratory methods.
Practical applications
- Rapid site screening for Cr(VI) at potentially contaminated land, brownfields and industrial sites.
- Field surveys where fast, cost‑effective screening of many spots is needed before targeted laboratory analysis.
- Preliminary risk assessment and mapping of Cr(VI) distribution to prioritize remediation or detailed sampling.
- Useful when laboratory capacity, time or budget is limited and when water‑soluble Cr(VI) fraction is the monitoring target.
Who would use this standard
- Environmental consultants and site investigators
- Remediation contractors and field technicians
- Regulatory agencies performing screening assessments
- Laboratories conducting rapid on-site screening or method validation
Related standards
Keywords: ISO/TR 18105, soil quality, chromium(VI), Cr(VI) detection, test-kit, 1,5-diphenylcarbazide, water extraction, field screening, photometer, colour chart.