Improving Reliability in MOSH/MOAH Analysis: Addressing False Positives in LC-GC-FID

As global food safety standards continue to evolve, Mineral Oil Hydrocarbons (MOH) contamination has become a top priority for regulators and testing laboratories worldwide. Following the European Union’s draft update published in March 2026, maximum limits for Mineral Oil Aromatic Hydrocarbons (MOAH) are expected to take effect on January 1, 2027. This shift reflects a broader industry trend toward tighter analytical requirements and higher expectations for data accuracy.

For food manufacturers, third-party testing laboratories, and QA/QC managers, adopting the standard LC-GC-FID (Liquid Chromatography-Gas Chromatography-Flame Ionization Detection) hyphenated technique is becoming essential to meet regulatory expectations. However, compliance alone is no longer sufficient. Laboratories are increasingly expected to deliver results that are not only accurate, but also consistent, reproducible, and defensible across markets.

One of the most persistent challenges in MOSH and MOAH analysis is controlling background contamination, commonly referred to as blank values. Elevated blank values can significantly affect baseline stability, introduce uncertainty in quantification, and, in some cases, lead to false positive results.

Understanding Elevated Blank Values in MOH Analysis

Mineral oil compounds are ubiquitous in laboratory environments and are commonly found in plastics, cleaning agents, and packaging materials. As a result, the risk of secondary contamination is exceptionally high. Under highly sensitive LC-GC-FID detection, even minor oversights in your consumables can introduce background noise and lead to false positive results.

To achieve reproducible results and accurate baseline integration, optimizing key consumables such as your solid-phase extraction (SPE) cartridges, gas chromatography (GC) columns, and autosampler vials is essential.

The following considerations highlight key factors for improving analytical reliability across the workflow.

Key Considerations for Reducing Background Contamination

SPE Cartridges: Eliminate Matrix Interference Without Adding Impurities

Food matrices, particularly vegetable oils, dairy, and animal fats, contain high levels of natural lipids and squalene that can overlap with MOSH/MOAH peaks if not effectively removed during pre-treatment. In addition, low-quality plastic housings or sorbents in standard SPE cartridges may introduce mineral oil into your sample.

Careful selection of SPE cartridges is therefore critical. MOH-optimized SPE Cartridges, such as specialized Silver Nitrate (Ag^+) Silica or Aluminum Oxide columns, are designed to support effective matrix cleanup while minimizing the risk of background interference. The use of high-purity sorbents and solvent-resistant housings helps ensure clean lipid retention while introducing zero mineral oil artifacts into your eluent.

GC Capillary Columns: Maintaining Baseline Stability

MOAH analysis requires high-temperature baking and prolonged separation profiles. Under these conditions, GC Columns with insufficient thermal stability may exhibit “column bleed” at high temperatures. The FID detector interprets this bleed as MOAH fractions, elevating your baseline and distorting integration zones.

Switching to next-generation low-bleed GC Capillary Columns engineered for high-temperature and high-sensitivity applications can help maintain a stable baseline even during rigorous temperature programming, ensuring accurate quantification of complex MOAH humps.

High-Purity Autosampler Vials and Septa: Preventing Last-Mile Contamination

Laboratories often overlook the impact of sample vials and caps. Standard plastic caps or lower-quality PTFE/Silicone septa can swell or degrade when exposed to aggressive extraction solvents like n-hexane or dichloromethane. Once punctured, they may release trace plasticizers or oligomers directly into the prepared sample.

This can be addressed through the use of certified high-purity glass vial kits. Septa that are free from mineral oil-releasing raw materials and designed for solvent resistance offer reliable resealing performance, helping maintain sample integrity and support zero cross-contamination while samples wait in the autosampler queue.

Final Thoughts

In trace-level mineral oil analysis, small variations in method execution can have a significant impact on results. As regulatory frameworks continue to evolve, laboratories need to take a more holistic view that considers both analytical methodology and the quality of supporting consumables.

A structured and consistent approach across the analytical workflow will be essential to maintaining reliable outcomes. Laboratories that act early to strengthen their processes will be better positioned to meet upcoming regulatory requirements while maintaining confidence in their data.

As a global distribution and strategic solutions partner, DKSH Technology supports manufacturers and laboratories with high-quality specialty chemicals, ingredients, and technical expertise. With capabilities spanning regulatory support, innovation, and application expertise, DKSH enables organizations to strengthen analytical workflows and adapt to evolving MOH testing requirements across markets.

A full range of MOSH/MOAH consumables is available for evaluation. Laboratories interested in exploring these solutions further may contact us to request additional information or discuss specific technical requirements.

Sources:

1. Chromatography Online. A Review of MOSH and MOAH Analysis in Food. Available at: https://www.chromatographyonline.com/view/a-review-of-mosh-and-moah-analysis-in-food
2. European Commission Joint Research Centre (JRC). JRC133174. Available at: https://publications.jrc.ec.europa.eu/repository/handle/JRC133174
3. European Food Safety Authority (EFSA). Scientific Opinion on Mineral Oil Hydrocarbons in Food. EFSA Journal, 2023. Available at: https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2023.8215
4. European Commission. Contaminants Catalogue — Chemical Safety. Available at: https://food.ec.europa.eu/food-safety/chemical-safety/contaminants/catalogue_en