Direct and simultaneous detection of organic and inorganic ingredients in herbal powder preparations by Fourier transform infrared microspectroscopic imaging

Trends in digital detection for the quality and safety of herbs using infrared and Raman spectroscopy

Herbs have been used as natural remedies for disease treatment, prevention, and health care. Some herbs with functional properties are also used as food or food additives for culinary purposes. The quality and safety inspection of herbs are influenced by various factors, which need to be assessed in each operation across the whole process of herb production. Traditional analysis methods are time-consuming and laborious, without quick response, which limits industry development and digital detection. Considering the efficiency and accuracy, faster, cheaper, and more environment-friendly techniques are highly needed to complement or replace the conventional chemical analysis methods. Infrared (IR) and Raman spectroscopy techniques have been applied to the quality control and safety inspection of herbs during the last several decades. In this paper, we generalize the current application using IR and Raman spectroscopy techniques across the whole process, from raw materials to patent herbal products. The challenges and remarks were proposed in the end, which serve as references for improving herb detection based on IR and Raman spectroscopy techniques. Meanwhile, make a path to driving intelligence and automation of herb products factories.

Recent Development of Quality Control Methods for Herbal Derived Drug Preparations

Pharmaceutical industries should apply rigorous QC (quality control) to ensure the consistency, safety, and efficacy of their herbal derived drug-preparations. QC must be performed at every stage of the production line i.e. incoming raw materials, extractions, in-process control, finished products and keeping samples. Due to the complex nature of the chemical content of herbal drugs, two approaches to QC should be taken, that is quantitative determination of the selected marker(s) compound(s), and metabolite profiling. Contamination of herbal medicines by heavy metals, pesticides, toxic metabolites, microbial toxins, pathogenic microorganisms and other foreign matter should also be evaluated. A combination of chemical profiling and multivariate analysis (MVA) is recommended as the QC tool for the botanical identification method (BIM) of herbs, extracts, herb materials, and herbal drug preparations. Microscopic methods, DNA profiling or chemical marker(s) are not recommended for use as the sole BIM due to the lack of specificity. Only markers that meet certain criteria i.e. quality active (QA) markers can be utilized as a QC tool. The limit specification range of markers used as QC tools should be described in the analytical target profile (ATP). To gain reliable results of any analysis that has been performed at any QC laboratory, the analysis method must be validated according to the newest guidance. Sample detection limit of any toxic compound(s) should be lower than its cut-off value and MPL. The reliability of any results of analysis of a QC laboratory must be evaluated by using QC-samples for each series of measurements.

Rapid and Integrated Quality Assessment of Organic-Inorganic Composite Herbs by FTIR Spectroscopy-Global Chemical Fingerprints Identification and Multiple Marker Components Quantification of Indigo Naturalis (Qing Dai)

This research aimed to develop an FTIR-based method for rapid and low-cost integrated quality assessment of organic-inorganic composite herbs, which are kinds of herbs composed of both organic and inorganic active ingredients or matrix components. A two-step quality assessment route was designed and verified using the example of Indigo Naturalis (Qing Dai). First, the FTIR spectra were used as global chemical fingerprints to identify the true and fake samples. Next, the contents of the organic and inorganic marker components were estimated by FTIR quantification models to assess the quality of the true samples. Using the above approaches, all the 56 true samples and five fake samples of Indigo Naturalis could be identified correctly by the correlation threshold of the FTIR chemical fingerprints. Furthermore, the FTIR calibration models provided an accurate estimation of the contents of marker components with respect to HPLC and inductively coupled plasma optical emission spectrometry (ICP-OES). The coefficients of determination (R²) for the independent validation of indigo, indirubin, and calcium were 0.977, 0.983, and 0.971, respectively. Meanwhile, the mean relative errors (MRE) for the independent validation of indigo, indirubin, and calcium were 2.2%, 2.4%, and 1.8%, respectively. In conclusion, this research shows the potential of FTIR spectroscopy for the rapid and integrated quality assessment of organic-inorganic composite herbs in both chemical fingerprints identification and marker components quantification.

Direct and model-free detection of carbohydrate excipients in traditional Chinese medicine formula granules by ATR-FTIR microspectroscopic imaging

A formula granule is a traditional Chinese medicine preparation made from the decoction of a single herbal medicinal. Because of the flexibility for combination and the convenience for utilization, formula granules are becoming popular in clinical applications. However, the efficacy and safety of commercial formula granules often suffer from the improper addition of carbohydrate excipients. Therefore, the detection of carbohydrate excipients is indispensable for the quality control of formula granules. FTIR spectroscopy has been used for the detection of carbohydrate excipients in formula granules. But the overlapped absorption signals limit the sensitivity and specificity of detection. Besides, a large number of multivariate calibration models are needed for quantitative determination. To overcome the above disadvantages, this research utilizes FTIR microspectroscopy for the model-free and universal detection of carbohydrate excipients in formula granules. Using ATR-FTIR imaging, excipient particles and herbal extract particles in formula granules can be measured individually, which resolves the absorption signals of excipients and herbal extract spatially and thus improves the sensitivity and specificity of detection. The content of excipients can be estimated directly from the number of excipient particles, which is robust to the variations of herb extracts and free of calibration models. The case study of Gardeniae Fructus formula granules shows the potential of FTIR microspectroscopy in the direct and rapid detection of carbohydrate excipients in formula granules. Graphical Abstract Excipient particles in TCM formula granules can be measured and recognized individually by FTIR microspectroscopy.