[Recent advances in surface-enhanced Raman scattering technique for pollutant detection in Chinese medicinal material].

Chinese medicinal material is the foundation of traditional Chinese medicine(TCM) industry. Its quality is not only closely related to the health of residents but also the key to the development of the TCM industry. Pesticide residues, heavy metals and mycotoxins are the major pollutants of Chinese medicinal materials. In recent years, quite a number of rapid detection methods for pollutants have been constructed. Among them, surface-enhanced Raman scattering(SERS), which has been widely used in food chemistry, environmental analysis, and other fields because of its speediness and non-destructiveness, shows its great potential in the pollutant detection in Chinese medicinal material. This paper firstly reviews the application of SERS for the detection of common pollutants in Chinese medicinal material. We then discussed the characteristics and advantages of SERS technique for pesticide detection, including the principle, SERS substrate design, specific recognition, etc. Finally, simultaneous detection of multiple pesticide residues in Chinese medicinal material was explored.

Trace determination of carbamate pesticides in medicinal plants by a fluorescent technique.

The safety issue of using carbamate pesticides in medicinal plants (MPs) has been a global concern and hence attracted attention of many researchers to develop analytical tools for trace pesticides detection. Derived from the fluorescence-based techniques, a rapid, convenient and efficient method for the detection of three carbamate pesticides, including carbofuran, aldicarb and methomyl has been developed by using core-shell QDs. By optimizing experimental parameters, the system demonstrated high detection sensitivities for the investigated carbamates, with the lowest detectable concentrations less than 0.05 µM. The molecular docking study indicated that the selected carbamate pesticides bound to the catalytic active site of acetylcholinesterase via π-π or H-π interactions, which also revealed the potential mechanism of the differences in inhibition strength among the three pesticides on AChE. Moreover, in order to investigate the applicability and reliability of the proposed method for the pesticide analysis in real sample with complex matrix, the matrix effects of eight common MPs have been systematically explored. These findings suggested that this technique was a simple, sensitive and reliable method for rapid determination of carbamate pesticides in real samples, especially those with complex matrices like MPs, vegetables, fruits, and other agricultural crops.

Sensitive Detection of Organophosphorus Pesticides in Medicinal Plants Using Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Combined with Sweeping Micellar Electrokinetic Chromatography.

A simple, rapid, and sensitive method using ultrasound-assisted dispersive liquid-liquid microextraction (UA-DLLME) combined with sweeping micellar electrokinetic chromatography (sweeping-MEKC) has been developed for the determination of nine organophosphorus pesticides (chlorfenvinphos, parathion, quinalphos, fenitrothion, azinphos-ethyl, parathion-methyl, fensulfothion, methidathion, and paraoxon). The important parameters that affect the UA-DLLME and sweeping efficiency were investigated. Under the optimized conditions, the proposed method provided 779.0-6203.5-fold enrichment of the nine pesticides compared to the normal MEKC method. The limits of detection ranged from 0.002 to 0.008 mg kg(-1). The relative standard deviations of the peak area ranged from 1.2 to 6.5%, indicating the good repeatability of the method. Finally, the developed UA-DLLME-sweeping-MEKC method has been successfully applied to the analysis of the investigated pesticides in several medicinal plants, including Lycium chinense, Dioscorea opposite, Codonopsis pilosula, and Panax ginseng, indicating that this method is suitable for the determination of trace pesticide residues in real samples with complex matrices.

Qualitative and quantitative characterization of phenolic and diterpenoid constituents in Danshen (Salvia miltiorrhiza) by comprehensive two-dimensional liquid chromatography coupled with hybrid linear ion trap Orbitrap mass.

Danshen is one of the most frequently used traditional Chinese herbs owing to its remarkable and reliable therapeutic effects. Phenolic acids and diterpenoids have proved to be the bioactive substance groups. In order to fully profile its chemical compositions and explore new potential bioactive compounds, a comprehensive two-dimensional liquid chromatography system coupled to DAD detector and hybrid linear ion trap (LTQ) Orbitrap mass spectrometry (LC × LC-DAD-ESI/HRMS/MS(n)) was set up in this study based on the column combination of Hypersil gold CN (150 mm × 1 mm, 3 µm) and Accucore C18 (50 mm × 4.6 mm, 2.6 µm). Using the optimal segment gradient program, phenolic acids and diterpenoids were separated into two independent groups and a total of 328 peaks were successfully detected on the contour plot of Danshen. By means of the accurate mass and reliable MS(n) data, 102 compounds were identified or tentatively identified and 7 of them were discovered from Danshen for the first time. Moreover, the LC × LC-DAD system was validated for the quantitative analysis of 14 bioactive analytes using the contour plot, exhibiting satisfactory linearity (r ≥ 0.9976) and high precision for both peak locating (≤ 1.07%) and peak volume calculating (0.34%-4.11%). The established method could afford powerful separation capability, reliable identification data and accurate quantitative results, which is very suitable for analysis of complex herbal samples.

Application of two-dimensional chromatography in the analysis of Chinese herbal medicines.

For the purpose of better understanding the complex Chinese herbal medicines (CHMs) and controlling their quality, powerful analytical techniques are essential. Although conventional one-dimensional (1D) chromatographic approaches have been widely used for the analysis of multiple components in CHMs, the complexity of CHM samples often exceeds the maximal capacity of any single separation mode. Therefore, in past decades, many researchers have attempted to explore the coupling of independent separation techniques to improve the resolving power for complex CHM samples. Two-dimensional (2D) separation systems, based on two independent columns with different separation mechanisms, have proven to be more powerful than 1D techniques and have been used successfully to separate and analyze CHM samples with excellent performance. This article aims to review the most recent advances in the strategies for analyzing CHMs using 2D chromatography. For this purpose, some remarkable applications of the commonly used couplings, mainly including 2D-GC and 2D-LC for analysis of CHMs, are described. Moreover, their major advantages and shortcomings are discussed, which might be helpful to the researchers who focus on quality control of CHMs.