Rapid on-site detection of ephedrine and its analogues used as adulterants in slimming dietary supplements by TLC-SERS

Abstract

Ephedrine and its analogues are in the list of prohibited substance in adulteration to botanical dietary supplements (BDS) for their uncontrollable stimulating side effects. However, they were always adulterated illegally in BDS to promote losing weight. In order to avoid detection, various kinds of ephedrine analogues were added rather than ephedrine itself. This has brought about great difficulties in authentication of BDS. In this study, we put forward for the first time a method which combined thin-layer chromatography (TLC) and surface-enhanced Raman scattering (SERS) to directly identify trace adulterant. Ephedrine, pseudoephedrine, methylephedrine, and norephedrine were mixed and used in this method to develop an analytical model. As a result, the four analogues were separated efficiently in TLC analysis, and trace-components and low-background SERS detection was realized. The limit of detection (LOD) of the four analogues was 0.01 mg/mL. Eight common Raman peaks (△υ = 620, 1003, 1030, 1159, 1181, 1205, 1454, 1603 cm(-1)) were extracted experimentally and statistically to characterize the common feature of ephedrine analogues. A TLC-SERS method coupled with common-peak model was adopted to examine nine practical samples, two of which were found to be adulterated with ephedrine analogues. Identification results were then confirmed by UPLC-QTOF/MS analysis. The proposed method was simple, rapid, and accurate and can also be employed to trace adulterant identification even when there are no available reference derivatives on-site or unknown types of ephedrine analogues are adulterated.

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“…Results prove that the TLC-SERS technique proposed by Lv et al [97] is able to quickly and reliably detect the four ephedrine analogues as adulterants in HMPs or botanical products in trace amounts with no reference materials available. This technique was applied to nine samples of weight-loss HMPs provided by the Shandong Institute for Food and Drug Control.…”

Two‐dimensional correlation infrared spectroscopy applied to the identification of ephedrine and pseudoephedrine in illegally adulterated slimming herbal products

“…[20] Here, DFT was applied to calculate the IR spectra of Ep and Ps to identify their different IR vibrational modes. [20] Here, DFT was applied to calculate the IR spectra of Ep and Ps to identify their different IR vibrational modes.…”

“…[13] Therefore, to prevent this occurrence, a rule has been issued by the Food and Drug Administration that prohibits the adulteration of SHPs with Ep alkaloids. [20] In recent years, there have been many applications of Fourier transform infrared spectroscopy (FTIR) in pharmaceutical analysis such as identification, quality control and forecasting stability of drugs. [15][16][17][18][19] Although these methods are accurate, reliable, and amenable to high-throughput analysis, the ability to carry out rapid on-site detection is becoming increasingly important.…”

Screening and Confirmation of Different Synthetic Adulterants in Slimming Products

“…Natural anti-obesity products have been always considered as attractive alternatives to synthetic products as they are publically advertised as products containing purely natural ingredients with lacking specific side effects [8,9]. The truth is that such herbal products seem to be weaker than synthetic slimming products and it could be nearly impossible to achieve rapid short-term effects, therefore some manufacturers often illegally add synthetic pharmaceutical drugs to the natural product to improve their efficacy and achieve huge profits, while the presence of these ingredients could not be discriminated due to misleading packaging [10][11][12][13]. Unfortunately, continuous consumption of chemical slimming products, which are illegally adulterated with synthetic materials, may cause severe harms to patients and could be considered as a threat to individual's health and even a reason for mortality [14].…”