If you are one of the millions of people who take botanical dietary supplements, perhaps you would prefer not to know what’s in them. Dietary supplements have become a multi-billion-dollar business, as a bewildering range of products become available in the supermarket and on the internet. But these high-value products are vulnerable to adulteration and fraud. How does the consumer know which dietary supplements are authentic, whether they work, and more importantly, whether they’re safe?
Characterizing Dietary Supplements
Fortunately, there is growing interest in developing analytical methods to characterize dietary supplements, not only to verify the declared ingredients, but also to reveal the presence of any contaminants, residues, and adulterants, including the non-declared, unapproved addition of active pharmaceutical compounds. At least, that was evident from the poster presentations at the conference on Recent Advances in Food Analysis (RAFA 2015) (link to conference page). The various poster presentations covered the analysis of numerous substances, including pesticides, mycotoxins, hydrolysed collagen, anabolic-androgenic steroids, and phosphodiesterase type 5 (PDE5) inhibitors.
Detection Using Mass Spectrometry
The detection, identification, and quantification of such a diverse array of chemicals in such a variable matrix –no two samples are the same- is a tough challenge. Fortunately, Dr. Katerina Mastovska, (link to LinkedIn) Associate Scientific Director of Nutritional Chemistry and Food Safety at Covance Laboratories, recently gave some insight into the development of a combined targeted and non-targeted approach. Her approach uses a Q-Exactive Orbitrap mass spectrometer (link to case study) operated in full-scan acquisition with data dependent MS/MS alternating with all ions fragmentation (AIF). Dr. Mastovska highlighted the benefits of high resolving power, wide dynamic range, and excellent mass accuracy (< 1 ppm) for full-scan data and MS/MS fragments.
Distinguishing between analytes and matrix
Distinguishing milligram-level adulterants from trace-level contaminants
Correct identification of contaminants and adulterants for which standards are available
Risk of Side Effects
Sexual enhancement supplements are among the most adulterated products, most often by addition of drugs used to treat erectile dysfunction and pulmonary hypertension. These not only include approved prescription drugs such as sildenafil and tadalafil, but also a growing list of more than 50 illegitimate designer analogues (modifications of the drugs approved for medical use). These compounds are classed as phosphodiesterase type 5 (PDE5) inhibitor compounds because they inhibit specific enzymes, allowing blood vessels to relax, which in turn enables increased blood flow. However, adulteration with these drugs, often at high concentration or as a cocktail, is a serious problem. PDE5 inhibitors have a long list of potentially adverse, even lethal side effects, including heart attacks. Another issue is the fact that the fraudsters are continually engineering small modifications to the molecules to create new previously ‘unkown’ compounds in an attempt stay one step ahead of the analysts to avoid detection. In response to these concerns, the AOAC International is establishing voluntary consensus standards under contract with the National Institutes of Health-Office of Dietary Supplements (link to announcement). The method developed and validated by Dr. Mastovska and colleagues met the Fitness for purpose statements by AOAC International:
To be able to screen and identify known and unknown (unexpected) PDE5 inhibitors in various dietary supplement matrices
To be able to combine targeted and non-targeted approaches, with the ability to quantitate PDE5 inhibitors for which reference standards are available
The method has been approved by an AOAC International Expert Review Panel as the AOAC First Action Method for screening, identification and quantification of PDE5 inhibitors in dietary ingredients and supplements. Another step towards ensuring the safety of dietary supplements!
Determination of Other Substances
Using the same mass spectrometry technology, the FDA developed and validated a method for the simultaneous determination of 96 pharmaceuticals, plant toxins and other plant secondary metabolites in herbal dietary supplements (link to article). Additionally, Shuyin et al developed a method for the rapid detection and confirmation of illegal adulterated sedative-hypnotics in dietary supplements using liquid chromatography coupled to high-resolution quadrupole-Orbitrap mass spectrometry (link to article).
There is also interest in the use of novel technologies that require minimal sample preparation, enabling high throughput rapid screening of dietary supplements. A good example is the novel use of Direct Analysis ID-CUBE coupled to a mass spectrometer for the rapid screening and fingerprint characterization of omega fatty acid dietary supplements derived from marines and flaxseed oils. This approach uses the Direct Analysis in Real Time (DART ®) ionization source and requires minimal sample preparation (link to application note).
Visit these additional resources if you’re interested in the analysis of dietary supplements.