The Laboratory Notebook
Answering important questions about quality.
By Robert Green
Q. I am about to start importing a lesser-known botanical raw material and I would like to test each lot to get some assurance of the material’s identity and to monitor lot-to-lot consistency. I have called several labs but none test this material. So now what do I do?
A. This is a common problem in the nutritional supplement industry; participants want to do the right thing by testing their products but at times there are many impediments to doing that. These problems arise because the products are diverse, complicated and continually changing. New products are introduced so frequently that the analytical testing community cannot keep up. It can be extremely frustrating trying to find a lab to conduct an analysis that may be new to them or at least not routine. It could be that the labs are unfamiliar with the product, but not necessarily an analyte in the product that could be tested, thereby making the process much easier.
Generally speaking, botanicals are identified and quantified by one or more selected analytes sometimes referred to as “marker compounds.” For example, ginger is not identified and quantified by measuring ginger as a whole, but by measuring gingerols, which are compound markers for ginger. While there are some marker compounds that are unique to a particular botanical, generally analytes are not. Anthocyanins, for example, are not specific to a single product. Anthocyanins are found in many berries like cherry, bilberry and blueberry, to name a few. If you have a relatively unknown berry and call up an analytical lab and request a test for it, that berry may not be on the list of routine analyses, so you may be told the lab does not test that material. However, if you know the berry contains anthocyanins and you provide that information, the lab may indeed be able to help you. From there you may want to talk to a member of the technical staff if the lab has not tested your berry before, but this is a lot easier than starting from scratch.
If you are starting from scratch, find an analytical lab with a little bit of entrepreneurial spirit that specializes in method development. There are several factors that contribute to a successfully executed method—paramount is research. Give your lab adequate time to research the product thoroughly as it will save you time and money. The first issue often considered is the analytical standard used to identify and quantify the product. The “standard” is a pure sample of the compound marker. When going into method development, it is most timely and cost-effective if that standard is commercially available. If not, then one would have to be prepared. This would involve the isolation and purification of the compound marker and may require LC-MS expertise.
Depending upon the structure of the compound marker, the instrumentation is selected and the instrument method is developed. For natural products, HPLC and GC are the most common instruments used for analysis. The “instrument method” refers to the settings of the various parameters that the instrument is capable of, i.e. the solvent gradient for HPLCs that is designed to maximize results based on the column (which separates the components of the sample) and the detector (which, as the name implies, detects the characteristics of the sample). Usually analytes require a customized instrument method.
Extraction experiments go hand in hand with instrument method development. Every time a sample is analyzed it is “prepped,” which generally means it undergoes one or more processes to separate the analyte(s) of interest from the product matrix. Usually this consists of dissolving the product in a solvent using a particular technique (i.e., sonication, soxhlet, Parr bomb, etc.) so that extraction of the compound marker is maximized. To find the best extraction procedure experiments are conducted using multiple solvents and multiple techniques; the goal is to determine the one that is consistently the most effective. Extraction procedures are usually matrix dependant, that is, what may work for a raw material may not work for a finished product (tablet, capsule, etc.).
Needless to say, this process takes some time. If there is a published analytical method the job may not be too daunting. While a lab may not always be able to successfully duplicate a published method the first time, the publication is a great starting point. If, however, the lab must start from scratch, it will probably be a significant project, both in terms of time and money. Although you may be anxious to get your product to market, it is well worth the wait for a good lab to develop a reliable method.
When choosing a lab for this kind of work make sure it values communication. The lab should keep you informed and alert you to any complications that arise as this process can become very costly and delayed if not closely monitored. Your lab should also be completely open to sharing chromatograms and other data generated by this process. You should also have an understanding with the lab as to whether or not you will be given the SOP detailing the entire procedure.
Method development is an expense, but with impending regulations and some peace of mind in this sometimes tumultuous industry it can be well worth it.NW