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The classical traditional Chinese formulation LiuweiDihuang, shown to have clinical efficacy for "nourishing kidney-yin" in traditional Chinese medicine, has been used for thousands of years in China. Little attention, however, has been paid to quality control methods for this formulation. Hence, a rapid and sensitive analytical technique is urgently needed for the evaluation of LiuweiDihuang preparations to assess its quality and pharmacological functionality. In this study, an ultra high performance liquid chromatography dual-wavelength method was developed to simultaneously determine 11 constituents in LiuweiDihuang preparations. This robust approach provided a fast and comprehensive quantitative determination of the major bioactive markers within LiuweiDihuang preparations. To distinguish four dosage forms of LiuweiDihuang preparations, a random forest technique was applied on the spectrometric fingerprint data obtained. This combination approach of chromatographic techniques and data analyses might serve as a rapid and efficient tool to ensure the quality of LiuweiDihuang preparations and other Chinese medicinal formulations and can support quality control and scientific research into the pharmacological potential for these formulations.

Retention time shift is one of the most challenging problems during the preprocessing of massive chromatographic datasets. Here, an improved version of the moving window fast Fourier transform cross-correlation algorithm is presented to perform nonlinear and robust alignment of chromatograms by analyzing the shifts matrix generated by moving window procedure. The shifts matrix in retention time can be estimated by fast Fourier transform cross-correlation with a moving window procedure. The refined shift of each scan point can be obtained by calculating the mode of corresponding column of the shifts matrix. This version is simple, but more effective and robust than the previously published moving window fast Fourier transform cross-correlation method. It can handle nonlinear retention time shift robustly if proper window size has been selected. The window size is the only one parameter needed to adjust and optimize. The properties of the proposed method are investigated by comparison with the previous moving window fast Fourier transform cross-correlation and recursive alignment by fast Fourier transform using chromatographic datasets. The pattern recognition results of a gas chromatography mass spectrometry dataset of metabolic syndrome can be improved significantly after preprocessing by this method. Furthermore, the proposed method is available as an open source package at https://github.com/zmzhang/MWFFT2.

Nine compounds were successfully separated from Salvia plebeia R.Br. using two-step high-speed counter-current chromatography with three elution modes. Elution-extrusion counter-current chromatography was applied in the first step, while classical counter-current chromatography and recycling counter-current chromatography were used in the second step. Three solvent systems, n-hexane/ethyl acetate/ethanol/water (4:6.5:3:7, v/v), methyl tert-butyl ether/ethyl acetate/n-butanol/methanol/water (6:4:1:2:8, v/v) and n-hexane/ethyl acetate/methanol/water (5:5.5:5:5, v/v) were screened and optimized for the two-step separation. The separation yielded nine compounds, including caffeic acid (1), 6-hydroxyluteuolin-7-glucoside (2), 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside (3), nepitrin (4), rosmarinic acid (5), homoplantaginin (6), nepetin (7), hispidulin (8), and 5,6,7,4'-tertrahydroxyflavone (9). To the best of our knowledge, 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside and 5,6,7,4'-tertrahydroxyflavone have been separated from Salvia plebeia R.Br. for the first time. The purities and structures of these compounds were identified by high-performance liquid chromatography, electrospray ionization mass spectrometry, (1)H and (13)C NMR spectroscopy. This study demonstrates that high-speed counter-current chromatography is a useful and flexible tool for the separation of components from a complex sample.

Retention indices for frequently reported compounds of plant essential oils on three different stationary phases were investigated. Multivariate linear regression, partial least squares, and support vector machine combined with a new variable selection approach called random-frog recently proposed by our group, were employed to model quantitative structure-retention relationships. Internal and external validations were performed to ensure the stability and predictive ability. All the three methods could obtain an acceptable model, and the optimal results by support vector machine based on a small number of informative descriptors with the square of correlation coefficient for cross validation, values of 0.9726, 0.9759, and 0.9331 on the dimethylsilicone stationary phase, the dimethylsilicone phase with 5% phenyl groups, and the PEG stationary phase, respectively. The performances of two variable selection approaches, random-frog and genetic algorithm, are compared. The importance of the variables was found to be consistent when estimated from correlation coefficients in multivariate linear regression equations and selection probability in model spaces.

The preprocessing of chromatograms is essential to modern chromatography for further qualitative and quantitative analysis, especially when chromatographic instruments are used for herb products analysis involving large number of samples. To accurately compare and analyze the obtained chromatograms, it is necessary to preprocess, especially align retention time shifts. Here moving window fast Fourier transform (FFT) cross-correlation is introduced to perform nonlinear alignment of high-throughput chromatograms. Since elution characteristics of chromatograms will produce local similarity in retention time shifts, moving window procedure seems to be a better substitute of segmentation steps. The retention time shifts can be calculated and accelerated by FFT cross-correlation. The artifacts can be detected and eliminated from the retention time shifts profile since the continuity of moving window procedure. The proposed method is demonstrated in comparison with recursive alignment by FFT on chromatographic datasets from herb products analysis. It is shown that the proposed method can address nonlinear retention time shift problem in chromatograms with the simple moving window procedure, which will not introduce segments size optimization problem. In additional, the parameters are intuitive and easy to adjust, which makes it off-the-shelf toolbox for alignment of chromatograms.

Analysis of volatile components in herbal pair (HP) Semen Persicae-Flos Carthami (SP-FC) was performed by GC-MS coupled with chemometric resolution method (CRM). Furthermore, temperature-programmed retention indices were used together with mass spectra for identification of the volatile components. With the help of CRM, the two-dimensional data obtained from GC-MS instruments were resolved into a pure chromatogram and a mass spectrum of each chemical compound. By use of these methods upon two-dimensional data, 26, 49, and 59 volatile chemical components in essential oils of single herb Semen Persicae, Flos Carthami, and HP SP-FC were determined qualitatively and quantitatively, accounting for 78.42, 81.08, and 82.48% total contents of essential oil of single herb Semen Persicae, Flos Carthami, and HP SP-FC, respectively. It is shown that the accuracy of qualitative and quantitative analysis can be enhanced greatly by means of CRM. It is further demonstrated that the numbers of volatile chemical components of HP SP-FC are almost the addition of those of two single herbs, but the main volatile chemical components of the former are completely different from those of single herb Semen Persicae or Flos Carthami because of chemical reactions and physical changes occurring in the process of decocting two single herbs. This means that chemical components especially pharmacologically active compounds in the recipe might be different from those of single herbs.

Volatile compositions of different parts (stem, branch and root barks) of cortex Magnolia officinalis, cultivated in China, were investigated for the first time by GC-MS with the help of heuristic evolving latent projection (HELP). Identification of components was conducted by similarity matching to NIST mass library but also assisted by comparison of temperature-programmed retention indices (PTRIs) with the data web available. A total of 90, 82 and 76 volatile compounds in the essential oils of the three samples taken from the same batch aforementioned were qualitatively and quantitatively determined, representing 84.03, 83.68 and 83.10% of the total content, respectively. Among the constituents determined, there were 50 components coexisting. Eudesmol and its isomers were shown to be the principal compounds in the studied samples, accounting for 47.66, 36.74 and 36.31%, respectively. The three kinds of isomers (alpha-, beta- and gamma-eudesmol) in houpo volatile oils have been tentatively qualified and quantified simultaneously for the first time. By comparative analysis, significant qualitative and semi-quantitative differences and similarities were observed among the three samples. The results achieved provide a scientific evidence for further exploitation of Magnolia bark and clinical medication.

A preparative high-speed counter-current chromatography method for separation and purification of liensinine, isoliensinine and neferine from seed embryo of Nelumbo nucifera GAERTN was successfully established by using n-hexane-ethyl acetate-methanol-water (5:8:4:5, v/v, containing 0.5% NH(4)OH) as the two-phase solvent system. From 200 mg of crude extract, 18.4 mg of liensinine, 19.6 mg of isoliensinine and 58.4 mg of neferine were obtained with the purity of 96.8, 95.9, and 98.6%, respectively. The identification of the three alkaloids was performed with (1)H NMR and (13)C NMR.

Comparative analysis of volatile constituents between recipe jingfangsan and its single herbs was performed by GC-MS combined with alternative moving window factor analysis (AMWFA), a new chemometric resolution method. Identification of the compounds was also assisted by comparison of temperature-programmed retention indices (PTRIs) on the OV-1 column with authentic samples. In total, 36, 29, and 42 volatile components in essential oil of Herba schizonepetae (HS), Radix saposhnikoviae (RS), and the recipe were respectively determined qualitatively and quantitatively, accounting for 81.80, 82.62 and 85.98% total contents of volatile oil of HS, RS, and the recipe respectively. Analysis by the method of AMWFA indicates that there are 22 common volatile constituents between the recipe and single herbal medicine HS, and 14 common volatile constituents between the recipe and single herb medicine RS. The experimental results also show that the volatile components of the recipe in number are almost addition of that of two single herbal medicines HS and RS, and are mainly from the single herbal medicine HS.

Emodin and physcion are abundant anthraquinone compounds found in the traditional Chinese medicinal herb Polygonum cuspidatum Sied. et Zucc. In this paper, emodin and physcion were successfully extracted with supercritical CO2 plus ethanol modifier after the extraction conditions were optimized with uniform design-sequential optimization. Results showed that the ethanol modifier concentration was the main factor for the effective extraction of the emodin. The optimal extraction condition was obtained: 20 MPa, 30 degrees C, and 95% ethanol, at which the yields of emodin and physcion were 0.616 and 0.178 g/100 g, respectively. The yield obtained by supercritical fluid extraction (SFE) was a little lower than that obtained by sonication extraction (SE). The crude extract obtained by SFE was further isolated and purified by semipreparative chromatography with the mobile phase composed of methanol-water (90:1, v/v). Emodin and physcion were obtained with purity 98.6 and 99.1%, respectively, when determined by HPLC, and identification was performed by retention time and UV spectra of the standards. The result suggested that SFE is an alternative and promising method for extraction of the two compounds from P. cuspidatum owing to its environment-friendly properties and fewer coextracts.

Damage of blood-brain barrier is a common result of traumatic brain injury. This damage can open the blood-brain barrier and allow drug passage. An ultraperformance liquid chromatography with tandem mass spectrometry method was established to determine the concentration of rhein in the biofluids (plasma and cerebrospinal fluid) of patients with a compromised blood-brain barrier following traumatic brain injury after rhubarb administration. Furthermore, the pharmacokinetic profiles were analyzed. A triple-quadruple tandem mass spectrometer with electrospray ionization was used for rhein detection. The mass transition followed was m/z 283.06→239.0. The calibration curve was linear in the concentration range of 10-8000 ng/mL for the biofluids. The intra- and interday precisions were less than 10%. The relative standard deviation of recovery was less than 15% in biological matrices. The pharmacokinetic data showed that rhein was rapidly transported into biofluids, and exhibited a peak concentration 1 h after rhubarb administration. The elimination rate of rhein was slow. The AUCcerebrospinal fluid /AUCplasma (AUC is area under curve) of rhein was approximately 17%, indicating that portions of rhein could pass the impaired blood-brain barrier. The method was successfully applied to quantify rhein in the biofluids of all patients. The data presented can help to guide clinical applications of rhubarb for treating traumatic brain injury.

In this paper, the combination of gas chromatography-mass spectrometry with chemometric local resolution techniques such as subwindow factor analysis (SFA) and orthogonal projection resolution (OPR) is investigated as a method of determining volatile components present in a traditional Chinese medicinal formulation known as si-wu decoction and its two individual herbs Rhizoma chuanxiong and Radix angelicae sinensis. In order to validate the reliability of the results obtained, the volatile components of interest were further separated on open glass columns and then analyzed in the same way as above. With the help of SFA and OPR approaches, the purity of chromatographic peaks can first be identified. Then, the pure chromatogram and mass spectrum of each component involved in a target peak cluster can be easily resolved and subsequently subjected to similarity searches in the NIST MS database to qualitatively and quantitatively determine the volatile components. Our results showed that about 127, 80, and 97 chemical components could be separated and 81, 49, and 55 of them identified, representing 83.95%, 91.86%, and 85.11% of the total relative content of volatile components from Rhizoma chuanxiong, Radix angelicae sinensis, and si-wu decoction, respectively. The results obtained in this work strongly indicate that the combination of GC-MS with chemometric local resolution methods could greatly improve the chromatographic separation ability by means of mathematical approaches. Moreover, they indicated the reliability and practicability of this combined technique.

Nine compounds were successfully separated from Salvia plebeia R.Br. using two-step high-speed counter-current chromatography with three elution modes. Elution-extrusion counter-current chromatography was applied in the first step, while classical counter-current chromatography and recycling counter-current chromatography were used in the second step. Three solvent systems, n-hexane/ethyl acetate/ethanol/water (4:6.5:3:7, v/v), methyl tert-butyl ether/ethyl acetate/n-butanol/methanol/water (6:4:1:2:8, v/v) and n-hexane/ethyl acetate/methanol/water (5:5.5:5:5, v/v) were screened and optimized for the two-step separation. The separation yielded nine compounds, including caffeic acid (1), 6-hydroxyluteuolin-7-glucoside (2), 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside (3), nepitrin (4), rosmarinic acid (5), homoplantaginin (6), nepetin (7), hispidulin (8), and 5,6,7,4'-tertrahydroxyflavone (9). To the best of our knowledge, 5,7,3',4'-tetrahydroxy-6-methoxyflavanone-7-glucoside and 5,6,7,4'-tertrahydroxyflavone have been separated from Salvia plebeia R.Br. for the first time. The purities and structures of these compounds were identified by high-performance liquid chromatography, electrospray ionization mass spectrometry, (1)H and (13)C NMR spectroscopy. This study demonstrates that high-speed counter-current chromatography is a useful and flexible tool for the separation of components from a complex sample.

The preprocessing of chromatograms is essential to modern chromatography for further qualitative and quantitative analysis, especially when chromatographic instruments are used for herb products analysis involving large number of samples. To accurately compare and analyze the obtained chromatograms, it is necessary to preprocess, especially align retention time shifts. Here moving window fast Fourier transform (FFT) cross-correlation is introduced to perform nonlinear alignment of high-throughput chromatograms. Since elution characteristics of chromatograms will produce local similarity in retention time shifts, moving window procedure seems to be a better substitute of segmentation steps. The retention time shifts can be calculated and accelerated by FFT cross-correlation. The artifacts can be detected and eliminated from the retention time shifts profile since the continuity of moving window procedure. The proposed method is demonstrated in comparison with recursive alignment by FFT on chromatographic datasets from herb products analysis. It is shown that the proposed method can address nonlinear retention time shift problem in chromatograms with the simple moving window procedure, which will not introduce segments size optimization problem. In additional, the parameters are intuitive and easy to adjust, which makes it off-the-shelf toolbox for alignment of chromatograms.

A numerical model is developed to describe the separation process of countercurrent chromatography (CCC) in this work. The theory of countercurrent extraction table (TCCET) is first proposed to calculate concentration distributions of chemical components in the CCC, which is essential for a numerical model to describe the dynamic equilibrium of mass transfer. According to the theory of countercurrent extraction, the concentration in chromatography obeys binomial distribution, while the outflow from the n-th stage is a negative binomial distribution. As a result of the central limit theorem, they will obey normal distribution for sufficiently large n. Row-stage ratio (R(RS)) is then defined to determine the K value or retention time because it has a linear relationship to K value and retention time. The stage for a certain K value can be subsequently obtained with a very simple form, n(k)=1/(2piq(k)X(2)(k, max)), which can be calculated from the peak height obtained from experiments. Finally, the actual stage for a separation chromatogram can be acquired with using this simple expression. The agreement between theoretic and experimental results is quite satisfactory in the normal-phase and reversed-phase elution mode.

The similarities and differences of essential oil components in Album Citri reticulatae (ACR), Cylindricae Citri reticulatae (CCR), folium Citri reticulatae (FCR), exocarpium Citri Grandis (ECG), pericarpium Citri reticulatae Viride (PCRV) and pericarpium Citri reticulatae (PCR) were investigated by GC-MS combined with a chemometric method named alternative moving window factor analysis (AMWFA). And temperature-programmed retention indices (PTRIs) were used together with mass spectra for identification of the essential oil components. In essential oils of ACR, CCR, FCR, ECG, PCRV and PCR, 28, 26, 61, 62, 52 and 48 components were determined representing 93.13, 94.44, 93.53, 87.67, 99.03 and 98.03% of the total relative content, respectively. Also, the essential oils significantly differed both qualitatively and quantitatively. There were 14 common components among ACR, CCR, FCR, ECG, PCRV and PCR, their abundance varied in the ranges from 32.39% in FCR to 94.66% in PCRV. The results obtained may be helpful to the further study of pharmacological activity for their potential utilization as therapeutical agents.

Systematic comparative research was conducted on essential oils from eight traditional Chinese medicines (TCM) of pungent flavor and cool nature because the essential oils are the main active ingredients of herbs of this kind. The work was based on their component analysis by gas chromatography-mass spectrometry (GC-MS), on their retention indices, as well as on chemometric resolution methods. A total of 144 compounds were tentatively identified, accounting for 69.0% to 91.8% of the total essential oils. It is worth noting that there are 67 compounds in at least three of these eight essential oils. Moreover, many biologically active compounds, such as hexanal, alpha-pinene, camphene, beta-pinene, p-cymene, limonene, eucalyptol, (Z)-ocimene, gamma-terpinene, camphor, p-menthone, 4-terpineol, alpha-terpineol, carvone, eugenol, caryophyllene, beta-farnesene, alpha-curcumene, beta-selinene, delta-cadinene, caryophyllene oxide, cedrol, n-hexadecanoic acid, benzaldehyde, benzeneacetaldehyde, phthalic acid diisobutyl ester, linoleic acid, tetradecanoic acid, (Z,Z,Z)-9,12,15-octadecatrienoic acid, eucalyptol, pentadecanoic acid, hexadecanoic acid methyl ester, linoleic acid methyl ester, exist in at least four of the eight essential oils. These results might help us to understand why the eight herbs are all of pungent flavor and cool nature according to the theory of TCM, and may provide a useful chemical basis for future research on herbs of this kind.

A signal-processing method known as spectral correlative chromatography (SCC) for two-dimensional data obtained from hyphenated chromatography is developed and applied to chemical chromatographic fingerprint data sets of herbal medicine under specific experimental conditions. The method can judge the presence or absence of a spectral correlative peak among the spectrochromatograms. A local least squares regression model (LLS) is constructed in a piecewise manner to correct the shifts of retention time of some peaks of interest in the chromatograms of various test samples. The results compare favorably with those obtained by a two-point calibrated algorithm. It is shown that performing SCC and LLS on the piecewise clusters of various chromatographic fingerprints is more helpful in practice in revealing their common nature and for characterizing the chemical constituents. This approach holds great potential for facilitating quality control of herbal medicines.