Measurement Process

C14-SCAR measures solid, liquid and gaseous fuel samples, including diesel, gasoline, jet fuel, HVO, FAME, ethanol, bio-oils and feedstocks. Each sample is converted to CO₂, and its ¹⁴C content is measured automatically. Only 1.5–2 mg of carbon is needed per measurement.

1. Sample preparation and combustion

• A few milligrams of each sample are weighed into a tin capsule.
• The capsules are placed in the autosampler carousel of an elemental analyzer (EA), which holds up to 50 samples.
• The EA burns each sample completely, removes water and nitrogen oxides, and sends the resulting CO₂ to C14-SCAR in a helium stream. It also reports the carbon and nitrogen content of the sample.
• Because the result is measured on CO₂, it does not depend on the chemical composition of the fuel.

2. Trapping, purification and measurement

• C14-SCAR captures the CO₂ in its built-in sample trap, separates it from the helium and purifies it.
• Before each measurement, the instrument checks that there is enough gas, which protects your data from incomplete fills.
• The measurement cell is filled to the optimal pressure and the Saturated-absorption CAvity Ring-down (SCAR) scan starts automatically.
• While one sample is measured, the next one waits in the trap, so the instrument is never idle.

3. Result and reporting

• The ¹⁴C content is reported in percent Modern Carbon (pMC) with its uncertainty and converted to bio-based carbon content with the reference factor defined in the standards.
• Results are stored and can be synced to a network drive. The post-analysis software lets you build data sets, review calibrations and exclude outliers, and every step remains documented for audits.

Walk-away operation

In AutoCycle mode, C14-SCAR runs a full sequence on its own, from the EA carousel to the final result. With samples run in sequence it delivers a result at 1–2 pMC precision every 15 minutes, which is about 30 samples in an 8-hour working day. A full carousel can keep running unattended after hours.

Samples can be added to the carousel while a sequence is running. If something needs attention, the instrument pauses safely and raises an alarm.

Good practice for audit-ready results

• Representative sampling. Draw samples from the batch or consignment that the bio-content claim refers to, and record where and when each one was taken.
• Reference materials. Run certified reference materials, such as the NIST oxalic-acid standard, and fossil blanks with each sequence to document calibration and background.
• Sample retention. Retain a split of every sample. EU co-processing rules require samples to be kept for at least two years and made available to auditors.
• Traceable records. Keep the sample ID, batch, EA data and the pMC result with its uncertainty together, so any claim can be traced back to a measurement.

Measurement Performance

C14-SCAR combines close-to-AMS precision with laboratory-friendly throughput. Precision improves with averaging time, so you can choose between fast screening and high-precision verification.

¹ Best performance requires a lab temperature stability better than ±0.5 °C/day. Values for the standard C14-SCAR configuration (Datasheet Rev. 2026-10-01).

What this means for fuels

On a pMC scale where fossil carbon is 0 and modern biomass is about 100, 1 pMC corresponds to roughly one percentage point of bio-based carbon. In practice:

• Routine checks. A 15-minute measurement quickly shows whether a batch lies in the expected range, for example to confirm that a nominally 100 % renewable HVO contains no fossil carbon, or to follow a co-processing ratio from run to run.
• Verification of co-processed fuels. Longer averaging of 1–4 hours brings precision to 0.5 pMC typical and 0.3 pMC best. That is suited to comparing the measured bio-share with a mass-balance or yield calculation against the 1 % absolute deviation threshold used in EU co-processing rules.
• Low blend ratios. At very low co-processing ratios, precision matters most. Use longer averaging and repeat measurements, and plan for the uncertainty in how claims are set.

SCAR vs AMS vs LSC

Validated against AMS

• Fuel blends. Aviation-fuel blends and pyrolysis bio-oils measured by SCAR agreed with AMS and with gravimetric mixing ratios (Delli Santi et al., Advanced Photonics Research 2, 2000069, 2021, doi:10.1002/adpr.202000069 ).
• Repeatability. A two-week run on the NIST oxalic-acid standard (401 measurements) gave normally distributed results and an overall standard error of about 0.2 pMC, comparable to the best AMS results.
• Review. Laser spectroscopy as a versatile solution for radiocarbon analysis, including SCAR, is discussed in Guan et al., Radiocarbon 67, 565–577 (2025), Cambridge University Press, doi:10.1017/RDC.2025.10 .

A side-by-side comparison for biogenic analysis instruments is available as a download: C14-SCAR Competitor Comparison Sheet .

Regulations and Standards

Renewable-fuel schemes in Europe and North America rely on ¹⁴C analysis to prove the biogenic share of fuels, especially fuels produced by co-processing. This page summarizes the main requirements and the standards behind them, and explains where SCAR fits.

Status as of November 2026. This overview is for information only. Always check the current legal texts and the requirements of your certification scheme.

SCAR in the revised EN 16640

EN 16640 is the European standard for determining the bio-based carbon content of products with the radiocarbon method. CEN/TC 411 is revising it, and the draft prEN 16640 specifies three ¹⁴C measurement methods:

• Method A: Liquid Scintillation Counting (LSC)
• Method B: Accelerator Mass Spectrometry (AMS)
• Method C: Saturated-absorption Cavity Ring-down (SCAR) spectroscopy

This is the first time a laser-based method has been included in the standard, which places SCAR alongside the established techniques. The draft completed the CEN public enquiry in early 2026. Once published, the revised standard will supersede EN 16640:2017, which covered LSC, beta ionization and AMS. Publication is currently foreseen for 2027.

What this means in practice. Some regulations name the ¹⁴C techniques directly instead of referring to EN 16640. The EU co-processing regulation, for example, specifies AMS and LSC (see below). For compliance testing, follow the methods your regulation or scheme currently names until it recognizes SCAR. In the meantime, C14-SCAR delivers the same ¹⁴C measurement in-house for process control, verification between mandatory tests, pre-screening and audit preparation, so your laboratory is ready as the revised standard is adopted.

European Union

Renewable Energy Directive (RED III)

Directive (EU) 2023/2413 (RED III) requires Member States, by 2030, either to reach a 29% share of renewable energy in transport or to achieve a 14.5% reduction in the greenhouse-gas intensity of transport fuels. A combined sub-target of 5.5% for advanced biofuels and renewable fuels of non-biological origin applies, with at least 1% from RFNBOs. Compliance of biofuels counted towards these targets is typically certified through recognized voluntary schemes such as ISCC EU or RSB.

Co-processing: Delegated Regulation (EU) 2023/1640

When biomass is processed together with fossil feedstock in a refinery, the biogenic share of each output must be determined with an approved methodology. Commission Delegated Regulation (EU) 2023/1640 sets the rules:

• Main methods. The biogenic share may be determined by mass or energy balance, by yield methods, or by radiocarbon (¹⁴C) testing.
• ¹⁴C verification is mandatory. Where the main method is not ¹⁴C-based, ¹⁴C testing must be used to verify it, for all outputs claiming a carbon-based bio-content.
• Frequency. ¹⁴C testing must be carried out at least once every 4 months, and again whenever feedstock, process or product composition changes by more than 5% compared with the baseline conditions.
• Deviation threshold. A deviation of more than 1% in absolute terms between the ¹⁴C result and the main method must be reviewed (3% during the first year). Deviations found by auditors are treated as major non-conformities and can lead to suspension of the certificate.
• Sample retention. Operators must keep samples for at least two years and give certification bodies and auditors full access to them.

Voluntary schemes such as ISCC EU and RSB implement these rules in their co-processing requirements, and auditors check them during certification.

ReFuelEU Aviation

Regulation (EU) 2023/2405 obliges fuel suppliers at EU airports to blend sustainable aviation fuel: 2% from 2025, 6% from 2030 and 20% from 2035, rising to 70% in 2050. SAF made by co-processing or blending must have its renewable share documented, which increases demand for reliable ¹⁴C analysis of jet fuel.

North America

• US Renewable Fuel Standard (EPA). The RFS references ASTM D6866 for the renewable content of partially renewable and co-processed fuels. Method B (AMS) is the default, and Method C (LSC) may be used in some cases where the renewable content is at least 10%.
• California Low Carbon Fuel Standard (CARB). The LCFS requires the ¹⁴C method (ASTM D6866) to determine the biogenic content of co-processed fuels. Alternative methods may be considered where ¹⁴C testing is impractical, for example at very low co-processing ratios.

Key standards

Talk to us

Planning ¹⁴C testing for co-processing, preparing for an audit, or evaluating SCAR for your laboratory? Contact us to discuss your application, or request a test measurement through our biofuel testing services .

Want to see C14-SCAR results on your own fuels first? Send us samples through our biofuel testing service , or rent an instrument for a trial period in your laboratory.