Isotope Mass Spectrometry Analysis

Sample ¹³C/¹²C ratio VPDB standard ratio

Measured δ¹³C (‰) Pure C3 reference (‰) Pure C4 reference (‰)

Measured δ¹³C (‰) Acceptable limit (‰, from the less-negative side)

Enter your own limit — verify the exact figures for your specific regulation separately.

Measured (D/H)ᵢ — methyl (ppm)

Reference ranges: grape 101.5–106.0; apple/pear 99.0–103.0; beet 90.5–94.5; cane 108.0–112.0 ppm (see Theory, Section 6).

δ¹³C—

Likely origin—

C3 range ≈-24 to -34 ‰; C4 range ≈-9 to -17 ‰ (indicative).

Estimated C4 fraction—

Interpretation—

An approximate linear mixing model — not laboratory-certifiable proof. See the warning in Theory.

Status—

Margin from limit—

Best fit—

Interpretation—

δ¹³C alone cannot distinguish C3 sources from each other (grape vs. beet vs. apple) — D/H exists precisely for this. See Theory, Sections 6-7.