Rapid and comprehensive quality evaluation of Huang-qin from different origins by FT-IR and NIR spectroscopy combined with chemometrics.

INTRODUCTION: Quality evaluation of Huang-qin is significant to ensure its clinical efficacy. OBJECTIVE: This study aims to establish an accurate, rapid and comprehensive Huang-qin quality evaluation method to overcome the time-consuming and laborious shortcomings of traditional herbal medicine quality assessment methods. METHODS: The contents of baicalin, baicalein and scutellarin in Huang-qin from five different origins were analyzed by FT-IR and NIR spectra combined with multivariate data technology. The quality of Huang-qin from different origins was evaluated by TOPSIS and consistency analysis based on the content of three active ingredients. The correlation between ecological factors and the accumulation of active ingredients was explored. RESULTS: Satisfactory prediction results of PLS models were obtained. Relatively, the model based on FT-IR combined with the PLS regression method has higher R2 and smaller RMSE than the NIR combined with the PLS method. TOPSIS and consistency analysis results showed that the quality of Huang-qin from different geographical origins was significantly different. The results showed that the quality of Huang-qin produced in Shanxi Province was the best among the five origins studied. The results also found that the quality of Huang-qin in different growing areas of the same origin was not completely consistent. The correlation study showed that altitude, sunshine duration and rainfall were the main factors that caused the quality difference of medicinal materials in different geographical origins. CONCLUSION: This study provides a reference for the rapid quantitative analysis of the active components of herbal medicine and the quality evaluation of them.

Rapid identification of Radix Astragali origin by using fluorescence probe combined with chemometrics.

Fluorescent probes for metal ion recognition can be divided into selective probes, weakly selective probes, and non-selective probes roughly. Weakly selective probes are not often used for quantitative analysis of metal ions due to their overlapping spectra resulting from simultaneous interactions with multiple metal ions. Conversely, the different metal ions contained in herbal medicine extracts from different geographical origins will produce corresponding fluorescence fingerprint profiles after interaction with weakly selective fluorescence probes. The performance can be used in the study of origin tracing of food or Chinese herbal medicine. Weakly selective fluorescent probes of benzimidazole derivatives have been synthesized and attempted to be used in the origin tracing of Radix Astragali in this work. Radix Astragali from different origins will produce different fluorescence fingerprint spectra due to the difference of metal ions and content in combination with the probe. Excitation-emission matrix (EEM) fluorescence spectroscopy in conjunction with N-way partial least squares discriminant analysis (N-PLS-DA), and unfolded partial least squares discriminant analysis (U-PLS-DA) were used to identify the origin of 150 Radix Astragali samples from five geographical origins. The prediction results showed that the correct recognition rates of the U-PLS-DA model and N-PLS-DA model are 95.92% and 93.88%, respectively. In comparison, the results of U-PLS-DA are slightly better than those of N-PLS-DA. These findings indicate that EEM fluorescence spectroscopy based on weakly selective fluorescent probes combined with multi-way chemometrics provides a good idea for the origin tracing of traditional Chinese medicine.

Rapid detection and quality evaluation of Shuang-Huang-Lian injection by ATR-IR and NIR spectroscopy combined with chemometrics.

Quality evaluation and consistency evaluation of drugs are the keys to ensure the therapeutic effect and safety of drugs. In this study, attenuated total refraction infrared (ATR-IR) spectroscopy and near-infrared (NIR) spectroscopy combined with chemometrics were used for rapid detection and quality evaluation of active components of Shuang-Huang-Lian injection (SHLI), a traditional Chinese medicine preparation commonly used in China. Taking the chromatographic detection results as a reference, the partial least squares (PLS) model based on ATR-IR and NIR data was constructed by removing the bands with serious noise interference and low signal frequency band. The results showed that the PLS model achieved satisfactory results for the prediction of the three active components (chlorogenic acid, baicalin and phillyrin) in SHLI, indicating that the two spectral techniques combined with the PLS regression method could be successfully used for rapid quantitative analysis of the three active ingredients in SHLI. Relatively, the PLS model based on the ATR-IR spectrum has higher R2 and smaller RMSE than it based on the NIR spectrum. Furthermore, based on the rapid quantitative analysis of the three active ingredients in SHLI, the quality of 140 SHLI samples from seven manufacturers was evaluated by TOPSIS (technique for order preference by similarity to the ideal solution) analysis, and the consistency of different batches of SHLI products from the same manufacturer was evaluated. The results showed that there were differences in the quality of SHLI produced by different manufacturers, and the quality of different batches of SHLI produced by the same manufacturer was not completely consistent. In conclusion, ATR-IR and NIR spectroscopy combined with chemometrics can be used for accurate and rapid quantitative analysis and quality evaluation of SHLI. This study provides a good idea for the rapid quantitative analysis and quality evaluation of drugs or food based on spectroscopic technology and chemometrics.

Monitoring colorless electroactive chemicals in complex background based on electrochemical difference absorption spectroscopy with twin flow cells.

Conventional UV/Vis absorption spectroscopy is an economical and user-friendly technique for online monitoring, however, by which some electroactive chemicals are hardly determined in the presence of fluctuating background due to the formation of colored chemicals. Here, we propose an electrochemical difference absorption spectroscopy (EDAS) to accurately quantify colorless chemicals based on visible color change via electrolysis with strong variation in the background. EDAS is realized by twin spectroelectrochemical flow cells system, replacing the two cuvette cells of a dual beam spectrophotometer. Each cell consists of a three-electrode system, quartz windows and a thin flow channel. Flowing of analyte from one cell (reference cell) to the other (sample cell) can eliminate the influence of colored interferents even while their concentrations are changing. When different potentials are applied on the sample and reference cells respectively, electrolysis occurs and colored products flowing through quartz windows can absorb the incident light, resulting in difference absorption spectra induced from potential difference. We find that steady-state difference absorbance (ΔA) at characteristic wavelength is linearly changed with sample concentrations. EDAS is firstly verified by Fe(CN)64- at different potentials and flow rates, in good agreements with a simplified theory that describes linear relationship between ΔA and analyte concentration. Then EDAS is used to determine Cu(I) in Cu(I)-Cu(II) mixed solutions and tetramethylbenzidine in its partially oxidized solutions to illustrate the powerful ability to detect colorless chemicals with varied background, implying its promising potential applications in the chemical industry.

Self-Reference Analysis Based on Temperature Difference Absorption Spectra.

The direct qualitative identification of pure liquids in laboratories and in security checks is generally performed by the detection of the refractive index or the permittivity. However, refractive indices are strongly influenced by temperature, while the permittivities of some organics are difficult to differentiate. On the other hand, the quantitative monitoring of samples with high concentration in plating baths and in chemical production lines are generally performed via a "Sampling-Dilution-Analysis" approach because of significant deviations from the linear range at high concentration, which makes the real-time monitoring of concentrated samples difficult. Here, we propose a self-reference analysis (SRA) method to directly analyze pure liquids and concentrated samples based on temperature difference absorption spectra (TDAS) without the need for dilution. This method was performed by simultaneously scanning the spectra of the reference and the sample, which are both obtained from the same analyte for detection but are at different temperatures. Compared to conventional absorption spectra with a blank reference, the red-shifted peak wavelengths of TDAS enable the detection of many far UV absorptive compounds in the near-ultraviolet region (λ > 190 nm). More importantly, organic compounds with similar structures can be easily distinguished. In addition, TDAS can also be used for the quantitative detection of concentrated analytes. The proposed SRA-TDAS method is a rapid and effective method; this approach does not require dilution and utilizes a self-reference, implying the wide potential applicability in security checks, and the real-time monitoring of concentrated compounds in chemical production lines.

Molar Range Detection Based on Sideband Differential Absorption Spectroscopy with a Concentrated Reference.

Conventional absorption spectroscopy (CAS) with a blank reference has only a slight capacity to detect high concentrations at characteristic wavelengths owing to the corresponding large molar absorption coefficient (ε) on the scale of 103 or 104 cm-1 M-1. To monitor concentrated analytes as high as the molar range in a plating bath and on a chemical production line, we propose a new approach using sideband differential absorption spectroscopy (SDAS). SDAS is obtained by subtracting the absorption spectra of the samples, A(λ,Cx), from that of a reference containing a concentrated standard analyte, A(λ,Cref>Cx), resulting in concave spectra with peaks at the sideband of conventional spectra with generally low ε values on the scale of 100 cm-1 M-1 or less. The negative absorbance changes linearly with the sample concentration at a certain peak wavelength, obeying Lambert-Beer's law. In this work, SDAS was obtained and verified using inorganic and organic substances, such as chromate potassium, rhodamine B, and paracetamol.