Comparative analysis of EPA and DHA in fish oil nutritional capsules by GC-MS

Abstract

BackgroundFish oil is a popular nutritional product consumed in Hong Kong. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are the two main bioactive components responsible for the health benefits of fish oil. Market survey in Hong Kong demonstrated that various fish oil capsules with different origins and prices are sold simultaneously. However, these capsules are labelled with same ingredient levels, namely EPA 180 mg/g and DHA 120 mg/g. This situation makes the consumers very confused. To evaluate the quality of various fish oil capsules, a comparative analysis of the contents of EPA and DHA in fish oil is crucial.MethodsA gas chromatography–mass spectrometry (GC-MS) method was developed for identification and determination of EPA and DHA in fish oil capsules. A comprehensive validation of the developed method was conducted. Ten batches of fish oil capsules samples purchased from drugstores of Hong Kong were analyzed by using the developed method.ResultsThe present method presented good sensitivity, precision and accuracy. The limits of detection (LOD) for EPA and DHA were 0.08 ng and 0.21 ng, respectively. The relative standard deviation (RSD) values of EPA and DHA for repeatability tests were both less than 1.05%; and the recovery for accuracy test of EPA and DHA were 100.50% and 103.83%, respectively. In ten fish oil samples, the contents of EPA ranged from 39.52 mg/g to 509.16 mg/g, and the contents of DHA ranged from 35.14 mg/g to 645.70 mg/g.ConclusionThe present method is suitable for the quantitative analysis of EPA and DHA in fish oil capsules. There is a significant variation in the contents of the quantified components in fish oil samples, and there is not a linear relationship between price and contents of EPA and DHA. Strict supervision of the labelling of the fish oil capsules is urgently needed.Electronic supplementary materialThe online version of this article (doi:10.1186/1476-511X-13-190) contains supplementary material, which is available to authorized users.

Microwave‐Assisted, Base‐Catalyzed Synthesis of Fatty Acid Methyl Esters from Seeds and Fish Oil Supplements

“…Several publications have studied the correctness of the manufacturers' information in fish oil supplements (Opperman et al, ; Osadnik and Jaworska, ; Yi et al, ). For example, Osadnik et al found that, for the majority of their tested products in the Polish market, there was consistency in the total amount of DHA and EPA claimed on the label, while Opperman's group reported that the n‐3 supplements available in the South African market contained ≤89% of the stated content.…”

“…For example, in their extraction and derivatization of the FA, they follow multistep procedures and/or involve long heating times (among others, Opperman et al, ), high temperatures (Rincón‐Cervera et al, ), costly automated instrumentation (Roberts, et al, ; Stuff and Whitecavage, ), high‐resolution equipment (Osadnik and Jaworska, ), or special analysis software (Kanable et al, ). Many of them have been conducted in other countries and only concentrate in supplements obtained in local markets (Opperman et al, ; Osadnik and Jaworska, ; Yi et al, ).…”

Analysis of Seaweeds from South West England as a Biorefinery Feedstock

“…Seaweed could provide a viable alternative source where, for example, in Palmaria palmata, despite having a lipid content of just 2.3% at the time of sampling, 50% (11.6 mg/g biomass) of this lipid was in the form of EPA (20:5). Given that the EPA content of commercially available fish oil supplements range between~40-500 mg/g [20], it is clear that seaweeds could make a big impact as a substitute feed stock for the production of high-value omega-3 animal feed supplements, nutraceuticals, pharmaceuticals and cosmetics. Indeed, the recommended dietary ratio of ω-6: ω-3 PUFA is less than 10 [16] and with all of the seaweeds analysed here having a ratio of between 0.15 and 2, so offering a significant advantage to the food and feed industries.…”

Cardiovascular disease and omega-3s: Prescription products and fish oil dietary supplements are not the same

“…Furthermore, multiple publications have raised concerns regarding the variability of omega‐3 content in dietary supplements as well as the quality and purity of these products (Kleiner, Cladis, & Santerre, ; Mason & Sherratt, ; Shim, Santerre, Burgess, & Deardorff, ; Truong, Johnson, & Gabriel, ; Tur, Bibiloni, Sureda, & Pons, ; Weitz, Weintraub, Fisher, & Schwartzbard, ; Zargar & Ito, ). For example, studies have shown that the actual concentrations of DHA and/or EPA in omega‐3 supplements may be far below or far in excess of the labeled amounts (Albert et al., ; Kleiner et al., ; Shim et al., ; Yi et al., ). In addition, omega‐3 dietary supplements are not “pure” and may contain contaminants and/or harmful/unwanted ingredients such as high concentrations of cholesterol, saturated fats, lipid peroxides, and oxidation products (Albert et al., ; Jackowski et al., ; Mason & Sherratt, ; Ritter, Budge, & Jovica, ; Truong et al., ; Tur et al., ; Weitz et al., ; Zargar & Ito, ).…”