Advanced Isotope Ratio Calculator

Calculate isotope ratios (R) and delta values (δ in ‰) between isotopes of an element using natural abundances. Supports multiple isotopes for pairwise ratios, reference standards for delta notation, and comparative analysis for isotopic fractionation studies.

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Add Comparison Element (Optional) ▼

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Calculation Details

Isotope Ratio Comparison

Formulas

Isotope Ratio Calculation

The isotope ratio R (heavy/light) is calculated from fractional abundances:

R = (abundance_heavy / 100) / (abundance_light / 100) = abundance_heavy / abundance_light

For delta notation relative to a standard:

δ (‰) = [(R_sample / R_standard) – 1] × 1000

Where:

  • abundanceₙ: Percentage abundance of the nth isotope.
  • R_standard: Known reference ratio (e.g., 0.0112372 for δ13C VPDB).
  • Base isotope (Isotope 1) is the denominator for ratios.

Usage Notes:

  • Abundances must sum to approximately 100%.
  • Masses are optional but useful for identification.
  • Results rounded to 6 decimal places for R, 2 for δ.
  • Comparison element enables relative isotopic analysis.

How to Use the Isotope Ratio Calculator

  1. Enter Element Details: Provide the element name and isotopes’ masses (optional) and abundances (%).
  2. Specify Reference Ratio (Optional): Input the standard ratio for delta (δ) calculations (e.g., VPDB for carbon).
  3. Add Comparison Element (Optional): Include isotopes for another element to compare ratios or deltas.
  4. Choose Display Mode: Select standard, step-by-step, or chart view.
  5. Calculate: Click “Calculate” to compute ratios and deltas.
  6. Export Results (Optional): Download as JSON for reports or further analysis.
  7. Reset Data: Click “Reset” to clear fields.

FAQs (Frequently Asked Questions)

What is an isotope ratio?

An isotope ratio is the relative abundance of one isotope to another in an element, expressed as R = heavy/light. Used in stable isotope analysis for tracing processes in geochemistry, biology, and forensics.

How is delta notation (δ) calculated in isotope ratios?

Delta (δ) measures deviation from a standard: δ (‰) = [(R_sample / R_standard) – 1] × 1000. Positive δ indicates enrichment in heavy isotope relative to standard.

Why use isotope ratios in geochemistry?

Isotope ratios help study fractionation, source tracing, and paleoclimate reconstruction. For example, δ18O in water indicates temperature changes over time.

What are common reference standards for isotope ratios?

Standards include VPDB for carbon, VSMOW for oxygen and hydrogen, and AIR for nitrogen. Values like 0.0112372 for 13C/12C VPDB are internationally accepted.

Where can I find natural isotope abundances?

Natural abundances are available from IUPAC, NIST Atomic Spectra Database, or periodic tables. For example, 13C is 1.07% in carbon.