ISO 14869-2:2002

Overview

ISO 14869-2:2002 - "Soil quality - Dissolution for the determination of total element content - Part 2: Dissolution by alkaline fusion" - defines an alkaline-fusion procedure to dissolve soils for measurement of total element content. The method is intended for elements such as Na, K, Mg, Ca, Ti, Mn, Fe, Al, Si, and other elements provided they are not lost during fusion and meet the detection/precision requirement w > (3·d·V/m). The procedure uses a lithium tetraborate / lithium metaborate flux and produces a high-salt nitric acid solution suitable for instrumental analysis.

Key topics and technical requirements

• Sample pre‑treatment
  • Dry and grind soil per ISO 11464; determine moisture per ISO 11465.
  • Calcine the dried, ground sample at 450 °C (to avoid reduction of metal oxides).
• Test portion and flux
  • Typical test portion ≈ 0.200 g (±0.002 g).
  • Flux composition: Li2B4O7 (tetraborate) and LiBO2 (metaborate) - commonly used ratio: 0.200 g tetraborate + 0.800 g metaborate added to the calcined sample.
• Fusion conditions
  • Heat with suitable furnace (induction, muffle, or air‑propane Mecker burner) to about 1000–1100 °C until the borate flux melts and the sample dissolves (typically 10–30 min).
  • Use corrosion‑resistant crucibles (preferably platinum:gold 95:5 alloy or glassy carbon) to avoid loss and contamination.
• Dissolution and dilution
  • Pour molten mass into 200 ml dilute HNO3 (0.5 mol/L), agitate (magnetic stirrer) until solids dissolve (≈15–20 min).
  • Transfer and dilute to a volumetric flask (250, 500 or 1000 ml) depending on required analytical concentrations.
• Analytical limits and checks
  • Ensure element mass w satisfies w > (3·d·V/m) where d = analytical detection limit (mg/L), V = final solution volume (L), m = test portion mass (kg).
  • Run blank/fusion control for each batch; analyze solution within 3 days to avoid hydrolysis/polymerization.

Applications and users

• Routine laboratory method for soil quality assessment, environmental monitoring, agricultural soil testing, geochemistry, and regulatory compliance.
• Primary users: environmental and agricultural testing laboratories, research institutions, contract analytical labs, and agencies requiring reliable total element determinations where alkaline fusion is preferable to HF digestion.

Related standards

• ISO 14869-1 (acid dissolution using hydrofluoric + perchloric acids)
• ISO 3696 (laboratory water quality)
• ISO 11464 (sample pre‑treatment)
• ISO 11465 (moisture/dry matter determination)

Keywords: ISO 14869-2, soil quality, alkaline fusion, dissolution, total element content, lithium tetraborate, lithium metaborate, soil sample preparation, analytical chemistry.