Detecting arsenic in krill oil: US researchers improve identification method

14 Nov 2019 --- Researchers at dietary supplements manufacturing company NOW have developed an identification method testing for the presence of inorganic arsenic in krill oil. Although a natural element, arsenic compounds are potent poisons and are classified as a Group-A carcinogen. The NOW research team’s new method improves on Food Chemicals Codex’s (FCC) monograph from 2017 and contributes to a more accurate risk assessment analysis regarding consumption of krill oil supplements.

“We determined that available test methods did not go far enough in ensuring that the krill oil we were sourcing for our supplements met our purity and safety standards. We published the method in keeping with NOW’s long standing practice of sharing test methods we develop with the industry,” says Aaron Secrist, NOW’s Vice President of Quality and Regulatory Affairs and one of the study’s authors. The full method has been published in the journal Spectroscopy. 

Research parameters
The study chromatographically separated five arsenic species: arsenobetaine (AsB), dimethylarsinic acid (DMA), arsenite (AsIII), monomethylarsonic acid (MMA) and arsenate (AsV). The high performance liquid chromatography (HPLC) used an anion exchange column and strongly basic carbonate eluent, a commonly used process that separates substances based on their charges. The content of total arsenic in the krill oil was detected by inductively coupled plasma mass spectrometry (ICP-MS). 

The most abundant arsenic species identified in krill oil samples appeared to be DMA, the study noted. The average percent mass balance from replicate preparations of krill oil samples was 95 percent, and the recovery of fortified analytical portion (FAP) of all five species met the acceptance criteria of 95 to 105 percent. The researchers note that this procedure can prove useful when quantitating inorganic arsenic species in marine oils.

The study faced certain limitations. The researchers note that due to the lack of a certified reference material for arsenic speciation in a matrix similar to krill oil, it could not verify the trueness of its method.

Potent poison
Arsenic and many of its compounds are especially potent poisons. Elemental arsenic and arsenic sulfate and trioxide compounds are classified as “toxic” and “dangerous for the environment,” according to an EU Directive. The existing scientific literature on arsenic identifies AsB as the predominant organic arsenic form present in marine organisms. 

The most abundant arsenic species found in krill oil samples appeared to be DMA, highly toxic when ingested, inhaled or in contact with skin.

Health benefits
Krill (Euphausia superba) is a small crustacean commonly found in ocean waters around the world. In recent years, krill has gained more popularity in the natural product industry and krill oil has become a promising dietary supplement due to its high content of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and other health promoting compounds, such as astaxanthin, regarded as one of nature’s most potent antioxidants.

Still requiring further research to confirm health claims, krill oil’s health benefits potentially include heart health improvement, inflammation and arthritic pain reduction, cancer prevention and diabetes treatment, the study notes. NOW offers krill oil dietary supplements in soft gel applications, touting their support for cardiovascular and joint health. 

Pioneering other health benefit areas, Aker BioMarine and Lupus Research Alliance partnered to launch a new clinical study investigating how krill oil can benefit people with lupus, with the aim to lessen the severity of symptoms associated with the disease. 

Edited by Anni Schleicher