Application of chemometrics in authentication of herbal medicines: a review.

INTRODUCTION Herbal medicines (HM) and their preparations have been widely used for hundreds of years all over the world. However, they have not been officially recognised due to a lack of adequate or accepted research methodology for their evaluation. OBJECTIVE To present a concise overview of the recent applications of chemometrics in solving the ambiguity of herbal medicine authentication during the last two decades. METHODOLOGY Studies involving the applications of chemometric analysis in combination with different analytical methods were classified according to the method of analysis used including chromatographic (HPLC, GC and CE), spectroscopic (NMR, IR, UV and ICP) and genetic analysis (RAPD). The purpose of each of these studies was classified into one of three main categories: taxonomic discrimination, quality assessment or classification between plants of different geographic origins. RESULTS This review comprises over 150 studies, covering the past two decades, emphasising the significance of chemometric methods in the discrimination of many herbs from closely related species and from adulterants, based on the principal bioactive components and phytochemical diversity. Furthermore, the differentiation between varieties and hybrids was achieved in addition to the prediction of the active components by quantitative methods of analysis. Discrimination according to geographical origin and localities, processing methods, DNA profiling and metabolomics were also efficiently investigated. CONCLUSION Chemometric methods have provided an efficient and powerful tool for the quality control and authentication of different herbs.

[1]  A. Shikov,et al.  Metabolic profiling of Rhodiola rosea rhizomes by ¹H NMR spectroscopy. , 2011, Phytochemical analysis : PCA.

[2]  Hartwig Schulz,et al.  Characterisation of essential oil plants from Turkey by IR and Raman spectroscopy , 2005 .

[3]  Paul Brereton,et al.  Application of (1)h NMR and multivariate statistics for screening complex mixtures: quality control and authenticity of instant coffee. , 2002, Journal of agricultural and food chemistry.

[4]  Serge Kokot,et al.  Application of high performance liquid chromatography for the profiling of complex chemical mixtures with the aid of chemometrics. , 2007, Talanta.

[5]  Bang-xing Han,et al.  Rapid detection of Rosa laevigata polysaccharide content by near-infrared spectroscopy. , 2011, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[6]  Andrew Fisher,et al.  The classification of tea according to region of origin using pattern recognition techniques and trace metal data , 2003 .

[7]  L. Salgueiro,et al.  Essential oil composition and variability of Thymus lotocephalus and Thymus×mourae , 2000 .

[8]  Foo-Tim Chau,et al.  Rapid analysis of Radix puerariae by near-infrared spectroscopy. , 2009, Journal of chromatography. A.

[9]  K. Grice,et al.  Application of trace element and stable isotope signatures to determine the provenance of tea (Camellia sinensis) samples , 2010 .

[10]  A. Abbaspour,et al.  Partial least squares-based multivariate spectral calibration method for simultaneous determination of beta-carboline derivatives in Peganum harmala seed extracts. , 2006, Analytica chimica acta.

[11]  Dan-ni Zhu,et al.  Chemical fingerprinting by HPLC-DAD-ELSD and principal component analysis of Polygala japonica from different locations in China. , 2010 .

[12]  Ralph G Smith,et al.  Determination of the country of origin of garlic (Allium sativum) using trace metal profiling. , 2005, Journal of agricultural and food chemistry.

[13]  A. Ferreira,et al.  Metabolic fingerprint of Brazilian maize landraces silk (stigma/styles) using NMR spectroscopy and chemometric methods. , 2010, Journal of agricultural and food chemistry.

[14]  G. R. Edwards,et al.  Chemometrics: Experimental design , 1996 .

[15]  B. Ledda,et al.  Morphological characterization, essential oil composition and DNA genotyping of Ocimum basilicum L. cultivars , 2004 .

[16]  Serge Kokot,et al.  Data Interpretation by some Common Chemometrics Methods , 1998 .

[17]  Run-tao Tian,et al.  Evaluation of traditional Chinese herbal medicine: Chaihu (Bupleuri Radix) by both high-performance liquid chromatographic and high-performance thin-layer chromatographic fingerprint and chemometric analysis. , 2009, Journal of chromatography. A.

[18]  J. Camiña,et al.  Characterisation of two South American food and medicinal plants by chemometric methods based on their multielemental composition. , 2010, Phytochemical analysis : PCA.

[19]  F. Chau,et al.  Rapid simultaneous determination of major isoflavones of Pueraria lobata and discriminative analysis of its geographical origins by principal component analysis. , 2011, Phytochemical analysis : PCA.

[20]  S. Nie,et al.  Quality control and original discrimination of Ganoderma lucidum based on high-performance liquid chromatographic fingerprints and combined chemometrics methods. , 2008, Analytica chimica acta.

[21]  Jingwei Xu,et al.  Discrimination of herbal medicines by molecular spectroscopy and chemical pattern recognition. , 2006, Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy.

[22]  John M Baker,et al.  Recent applications of NMR spectroscopy in plant metabolomics , 2007, The FEBS journal.

[23]  R. Vila,et al.  Chemometrics and essential oil analysis: Chemical polymorphism in two Thymus species , 1994 .

[24]  Ana Cristina Agulheiro Santos,et al.  Essential oil composition of south Brazilian populations of Cunila galioides and its relation with the geographic distribution , 2003 .

[25]  Ali Reza Khanchi,et al.  Simultaneous spectrophotometric determination of caffeine and theobromine in iranian tea by artificial neural networks and its comparison with PLS , 2007 .

[26]  Yi-Zeng Liang,et al.  Determination of the volatile chemical constituents of Notoptergium incium by gas chromatography-mass spectrometry and iterative or non-iterative chemometrics resolution methods. , 2003, Journal of chromatography. A.

[27]  Yvan Vander Heyden,et al.  Quality control of Citri reticulatae pericarpium: exploratory analysis and discrimination. , 2011, Analytica chimica acta.

[28]  Jongki Hong,et al.  GC/MS combined with chemometrics methods for quality control of Schizonepeta tenuifolia Briq: Determination of essential oils , 2011 .

[29]  D. Kremer,et al.  Spectrophotometric method for polyphenols analysis: prevalidation and application on Plantago L. species. , 2005, Journal of pharmaceutical and biomedical analysis.

[30]  V. Soler,et al.  Variability of the essential oil of Thymus piperella , 1998 .

[31]  M. A. Strehle,et al.  Chemotaxonomic characterisation of essential oil plants by vibrational spectroscopy measurements , 2004 .

[32]  Sáez Volatile oil variability in Thymus serpylloides ssp. gadorensis growing wild in Southeastern Spain. , 2001, Biochemical systematics and ecology.

[33]  Ying-yong Zhao,et al.  An expeditious HPLC method to distinguish Aconitum kusnezoffii from related species. , 2009, Fitoterapia.

[34]  Richard G. Brereton,et al.  Chemometrics: Data Analysis for the Laboratory and Chemical Plant , 2003 .

[35]  Yizeng Liang,et al.  Mass spectral profiling: An effective tool for quality control of herbal medicines , 2007, Analytica Chimica Acta.

[36]  Yi-Zeng Liang,et al.  Comparison of the volatile constituents of Artemisia capillaris from different locations by gas chromatography-mass spectrometry and projection method. , 2004, Journal of chromatography. A.

[37]  R. F. Vieira,et al.  Chemical profiling of Ocimum americanum using external flavonoids. , 2003, Phytochemistry.

[38]  Randall D. Tobias,et al.  Chemometrics: A Practical Guide , 1998, Technometrics.

[39]  Chu Sing Lim,et al.  Infrared-based protocol for the identification and categorization of ginseng and its products , 2007 .

[40]  F. Tomi,et al.  Composition and chemical polymorphism of the essential oils from Piper lanceaefolium. , 2001, Biochemical systematics and ecology.

[41]  Margriet M. W. B. Hendriks,et al.  Preprocessing and exploratory analysis of chromatographic profiles of plant extracts , 2005 .

[42]  Roberto Kawakami Harrop Galvão,et al.  UV–Vis spectrometric classification of coffees by SPA–LDA , 2010 .

[43]  Young-Ah Woo,et al.  Near-infrared (NIR) spectroscopy for the non-destructive and fast determination of geographical origin of Angelicae gigantis Radix. , 2005, Journal of pharmaceutical and biomedical analysis.

[44]  Kim A Anderson,et al.  Chemical profiling to differentiate geographic growing origins of coffee. , 2002, Journal of agricultural and food chemistry.

[45]  Yan-qing Liu,et al.  Evaluation of trace and toxic element concentrations in Paris polyphylla from China with empirical and chemometric approaches , 2010 .

[46]  F. Pablos,et al.  Differentiation of tea (Camellia sinensis) varieties and their geographical origin according to their metal content. , 2001, Journal of agricultural and food chemistry.

[47]  D. Massart,et al.  Elimination of uninformative variables for multivariate calibration. , 1996, Analytical chemistry.

[48]  Y. Heyden,et al.  Dissimilar chromatographic systems to indicate and identify antioxidants from Mallotus species. , 2011, Talanta.

[49]  Y. Vander Heyden,et al.  Chromatographic separation techniques and data handling methods for herbal fingerprints: a review. , 2011, Analytica chimica acta.

[50]  A. Figueiredo,et al.  A combined approach using RAPD, ISSR and volatile analysis for the characterization of Thymus caespititius from Flores, Corvo and Graciosa islands (Azores, Portugal) , 2009 .

[51]  J. Hamman,et al.  A rapid spectroscopic method for quantification of P57 in Hoodia gordonii raw material , 2010 .

[52]  Saifullah,et al.  Metabolic classification of South American Ilex species by NMR-based metabolomics. , 2010, Phytochemistry.

[53]  A. Figueiredo,et al.  Genetic diversity and chemical polymorphism of Thymus caespititius from Pico, São Jorge and Terceira islands (Azores) , 2008 .

[54]  Yi-Zeng Liang,et al.  Development of high-performance liquid chromatographic fingerprints for distinguishing Chinese Angelica from related umbelliferae herbs. , 2005, Journal of chromatography. A.

[55]  M. Defernez,et al.  Metabolite profiling using (1)H NMR spectroscopy for quality assessment of green tea, Camellia sinensis (L.). , 2004, Journal of agricultural and food chemistry.

[56]  Yi-zeng Liang,et al.  Chromatographic fingerprint analysis--a rational approach for quality assessment of traditional Chinese herbal medicine. , 2006, Journal of chromatography. A.

[57]  Hong Xu,et al.  Differentiation of the root of Cultivated Ginseng, Mountain Cultivated Ginseng and Mountain Wild Ginseng using FT-IR and two-dimensional correlation IR spectroscopy , 2008 .

[58]  Gui-hua Ruan,et al.  The study on the chromatographic fingerprint of Fructus xanthii by microwave assisted extraction coupled with GC-MS. , 2007, Journal of chromatography. B, Analytical technologies in the biomedical and life sciences.

[59]  H. Jia,et al.  Qualitative and quantitative characterization of chemical constituents in Xin-Ke-Shu preparations by liquid chromatography coupled with a LTQ Orbitrap mass spectrometer. , 2011, Journal of pharmaceutical and biomedical analysis.

[60]  A. R. Othman,et al.  Chemometric Classification of Herb – Orthosiphon stamineus According to Its Geographical Origin Using Virtual Chemical Sensor Based Upon Fast GC , 2003 .

[61]  Y. Ni,et al.  One- and two-dimensional gas chromatography-mass spectrometry and high performance liquid chromatography-diode-array detector fingerprints of complex substances: a comparison of classification performance of similar, complex Rhizoma Curcumae samples with the aid of chemometrics. , 2012, Analytica chimica acta.

[62]  R. Edrada-Ebel,et al.  A chemometric study of chromatograms of tea extracts by correlation optimization warping in conjunction with PCA, support vector machines and random forest data modeling. , 2009, Analytica chimica acta.

[63]  E. K. Kemsley,et al.  Discrimination between Coffea arabica and Coffea canephora variant robusta beans using infrared spectroscopy , 1995 .

[64]  H. Skaltsa,et al.  A chemotaxonomic investigation of volatile constituents in Stachys subsect. Swainsonianeae (Labiatae). , 2001, Phytochemistry.

[65]  S. Echeverrigaray,et al.  RAPD based genetic relationships between populations of three chemotypes of Cunila galioides Benth. , 2005 .

[66]  Yizeng Liang,et al.  Development of the chromatographic fingerprint of Scutellaria barbata D. Don by GC-MS combined with Chemometrics methods. , 2011, Journal of Pharmaceutical and Biomedical Analysis.

[67]  A. G. González,et al.  Pattern recognition procedures for differentiation of Green, Black and Oolong teas according to their metal content from inductively coupled plasma atomic emission spectrometry. , 2001, Talanta.

[68]  Jiewen Zhao,et al.  Determination of caffeine content and main catechins contents in green tea (Camellia sinensis L.) using taste sensor technique and multivariate calibration. , 2010 .

[69]  Yizeng Liang,et al.  Analyzing of the volatile chemical constituents in Artemisia capillaris herba by GC-MS and correlative chemometric resolution methods. , 2004, Journal of pharmaceutical and biomedical analysis.

[70]  Eiichiro Fukusaki,et al.  1H NMR based metabolic profiling in the evaluation of Japanese green tea quality. , 2007, Journal of agricultural and food chemistry.

[71]  Serge Kokot,et al.  Discrimination of Rhizoma Corydalis from two sources by near-infrared spectroscopy supported by the wavelet transform and least-squares support vector machine methods , 2011 .

[72]  H. Vogel,et al.  Quality assessment of ginseng by (1)H NMR metabolite fingerprinting and profiling analysis. , 2009, Journal of agricultural and food chemistry.

[73]  Francis Ez Volatile oil variability in Thymus serpylloides ssp. gadorensis growing wild in Southeastern Spain , 2001 .

[74]  S. Su,et al.  Hypothesis of active components in volatile oil from a Chinese herb formulation, 'Shao-Fu-Zhu-Yu decoction', using GC-MS and chemometrics. , 2008, Journal of separation science.

[75]  V. Tyler Phytomedicines: back to the future. , 1999, Journal of natural products.

[76]  Feng Gan,et al.  New approach on similarity analysis of chromatographic fingerprint of herbal medicine. , 2006, Journal of chromatography. A.

[77]  W. Kong,et al.  Quantitative and chemical fingerprint analysis for quality control of rhizoma Coptidischinensis based on UPLC-PAD combined with chemometrics methods. , 2009, Phytomedicine : international journal of phytotherapy and phytopharmacology.

[78]  Xianqin Wang,et al.  Metabolomics study on quality control and discrimination of three curcuma species based on gas chromatograph-mass spectrometry. , 2011, Phytochemical analysis : PCA.

[79]  S. Piletsky,et al.  Rapid qualitative and quantitative analysis of opiates in extract of poppy head via FTIR and chemometrics: towards in-field sensors. , 2009, Biosensors & bioelectronics.

[80]  Magali Laasonen,et al.  Fast identification of Echinacea purpurea dried roots using near-infrared spectroscopy. , 2002, Analytical chemistry.

[81]  R. F. Vieira,et al.  Characterization of cultivars within species of Ocimum by exudate flavonoid profiles , 2004 .

[82]  M Daszykowski,et al.  Robust partial least squares model for prediction of green tea antioxidant capacity from chromatograms. , 2007, Journal of chromatography. A.

[83]  L. Tommasi,et al.  Essential oil variability in Thymbra capitata (L.) Cav. growing wild in Southern Apulia (Italy) , 2006 .

[84]  K. Ariyama,et al.  Application of inorganic element ratios to chemometrics for determination of the geographic origin of welsh onions. , 2004, Journal of agricultural and food chemistry.

[85]  Lunzhao Yi,et al.  Comparative analysis of essential oil components in Pericarpium Citri Reticulatae Viride and Pericarpium Citri Reticulatae by GC-MS combined with chemometric resolution method. , 2008, Journal of pharmaceutical and biomedical analysis.

[86]  C. Codina,et al.  Bioguided isolation and identification of the nonvolatile antioxidant compounds from fennel (Foeniculum vulgare Mill.) waste. , 2004, Journal of agricultural and food chemistry.

[87]  K. Graikou,et al.  Chemical analysis of edible aromatic plants growing in Tanzania , 2007 .

[88]  Discrimination of Ganoderma lucidum according to geographical origin with near infrared diffuse reflectance spectroscopy and pattern recognition techniques. , 2008, Analytica chimica acta.

[89]  Desire L. Massart,et al.  Feasibility study for the use of near infrared spectroscopy in the qualitative and quantitative analysis of green tea, Camellia sinensis (L.) , 2003 .

[90]  K. Volka,et al.  Application of infrared spectroscopy to the assessment of authenticity of tea. , 1998, Talanta.

[91]  Y. Heyden,et al.  Prediction of total green tea antioxidant capacity from chromatograms by multivariate modeling. , 2005, Journal of chromatography. A.

[92]  Yi-Zeng Liang,et al.  Quality control and discrimination of pericarpium citri reticulatae and pericarpium citri reticulatae viride based on high-performance liquid chromatographic fingerprints and multivariate statistical analysis. , 2007, Analytica chimica acta.

[93]  Saravanan Dharmaraj,et al.  The classification of Phyllanthus niruri Linn. according to location by infrared spectroscopy , 2006 .

[94]  Xingyi Huang,et al.  Simultaneous determination of total polyphenols and caffeine contents of green tea by near-infrared reflectance spectroscopy , 2006 .

[95]  Yizeng Liang,et al.  Analysis of volatile components from Cortex cinnamomi with hyphenated chromatography and chemometric resolution. , 2004, Journal of pharmaceutical and biomedical analysis.

[96]  B. Schrader,et al.  Rapid classification of basil chemotypes by various vibrational spectroscopy methods. , 2003, Journal of agricultural and food chemistry.

[97]  D. Kara,et al.  Evaluation of trace metal concentrations in some herbs and herbal teas by principal component analysis , 2009 .

[98]  H. Koh,et al.  Chemical fingerprinting of Isatis indigotica root by RP-HPLC and hierarchical clustering analysis. , 2005, Journal of pharmaceutical and biomedical analysis.

[99]  Elaine Holmes,et al.  Prediction of anti-plasmodial activity of Artemisia annua extracts: application of 1H NMR spectroscopy and chemometrics. , 2004, Journal of pharmaceutical and biomedical analysis.

[100]  Yizeng Liang,et al.  Identification of essential components of Houttuynia cordata by gas chromatography/mass spectrometry and the integrated chemometric approach. , 2005, Talanta.

[101]  S. Jacobsson,et al.  Multivariate analysis of NMR spectra for saponins from Quillaja saponaria Molina , 2001 .

[102]  N. Dupuy,et al.  Comparative chemometric analyses of geographic origins and compositions of lavandin var. Grosso essential oils by mid infrared spectroscopy and gas chromatography. , 2008, Analytica chimica acta.

[103]  G. Xie,et al.  Metabolite profiling of Panax notoginseng using UPLC-ESI-MS. , 2008, Phytochemistry.

[104]  R. Sarin,et al.  Source identification of Indian opium based on chromatographic fingerprinting of amino acids. , 2005, Journal of chromatography. A.

[105]  F. Tomi,et al.  Chemical polymorphism of the essential oil of Thymus carnosus from portugal , 1995 .

[106]  D. Brynn Hibbert,et al.  Chemometric analysis of gas chromatographic data of oils from Eucalyptus species , 1995 .

[107]  Yuzhi Wang,et al.  Identification of Portulaca oleracea L. from different sources using GC-MS and FT-IR spectroscopy. , 2010, Talanta.

[108]  Y. Vander Heyden,et al.  Sequential uniform designs for fingerprints development of Ginkgo biloba extracts by capillary electrophoresis. , 2006, Journal of chromatography. A.

[109]  J. Considine,et al.  Infraspecific variability in the volatile leaf oils of Chamelaucium uncinatum (Myrtaceae) , 1998 .

[110]  Jordi Coello,et al.  Application of near infrared spectral fingerprinting and pattern recognition techniques for fast identification of Eleutherococcus senticosus , 2011 .

[111]  V. Murugesan,et al.  Determination and assessment of the contents of essential and potentially toxic elements in Ayurvedic medicine formulations by inductively coupled plasma-optical emission spectrometry , 2011 .

[112]  Pascal de Tullio,et al.  Metabolomic analysis of Echinacea spp. by 1H nuclear magnetic resonance spectrometry and multivariate data analysis technique. , 2010, Phytochemical analysis : PCA.

[113]  Li Wang,et al.  Near-infrared spectroscopy for classification of licorice (Glycyrrhizia uralensis Fisch) and prediction of the glycyrrhizic acid (GA) content , 2007 .

[114]  S. Mamot,et al.  An experimental design approach for the extraction of volatile compounds from turmeric leaves (Curcuma domestica) using pressurised liquid extraction (PLE) , 2009 .

[115]  A. Schmidt,et al.  Essential oil polymorphism of Thymus praecox subsp. arcticus on the British Isles , 2004 .

[116]  D. Albach,et al.  Acylated flavone glycosides from Veronica. , 2003, Phytochemistry.

[117]  L. Salgueiro,et al.  Composition and variability of the essential oils of Thymus species from section Mastichina from Portugal , 1997 .

[118]  Foo-Tim Chau,et al.  Analysis of berberine and total alkaloid content in cortex phellodendri by near infrared spectroscopy (NIRS) compared with high-performance liquid chromatography coupled with ultra-visible spectrometric detection. , 2007, Analytica chimica acta.

[119]  N. Papp,et al.  Chemical and genetic relationships among sage ( Salvia officinalis L.) cultivars and Judean sage ( Salvia judaica Boiss.). , 2009, Journal of agricultural and food chemistry.

[120]  S. Echeverrigaray,et al.  Essential oil variability within and among populations of Cunila incisa Benth. , 2006 .

[121]  Yi-Zeng Liang,et al.  Pretreatments of chromatographic fingerprints for quality control of herbal medicines. , 2006, Journal of chromatography. A.

[122]  S. D. Jong,et al.  Handbook of Chemometrics and Qualimetrics , 1998 .

[123]  Multivariate chromatographic fingerprint preparation and authentication of plant material from the genus Bauhinia. , 2008, Phytochemical analysis : PCA.

[124]  Ling-bo Wang,et al.  Automatic authentication and distinction of Epimedium koreanum and Epimedium wushanense with HPLC fingerprint analysis assisted by pattern recognition techniques , 2012 .

[125]  Peter Filzmoser,et al.  Partial robust M-regression , 2005 .

[126]  M. J. Adams,et al.  Chemometrics in Analytical Spectroscopy , 1995 .

[127]  Peter H. Raven,et al.  Biology of plants , 1976 .

[128]  Hyung-Kyoon Choi,et al.  Fingerprinting analysis of fresh ginseng roots of different ages using1H-NMR spectroscopy and principal components analysis , 2007, Archives of pharmacal research.

[129]  Yi-Zeng Liang,et al.  Comparative analysis of volatile components from Clematis species growing in China. , 2007, Analytica chimica acta.

[130]  Wolfgang Lindner,et al.  Ganoderma species discrimination by dual-mode chromatographic fingerprinting: a study on stationary phase effects in hydrophilic interaction chromatography and reduction of sample misclassification rate by additional use of reversed-phase chromatography. , 2010, Journal of chromatography. A.

[131]  Haibin Qu,et al.  Classification and quantification analysis of Radix scutellariae from different origins with near infrared diffuse reflection spectroscopy , 2011 .

[132]  S. Deans,et al.  Chemical polymorphism of populations of Thymus caespititius grown on the islands Corvo, Flores, São Miguel and Terceira (Azores) and on Madeira, assessed by analysis of their essential oils , 2005 .

[133]  V. Cavrini,et al.  GC/MS evaluation of thyme (Thymus vulgaris L.) oil composition and variations during the vegetative cycle. , 2002, Journal of pharmaceutical and biomedical analysis.

[134]  R. Karousou,et al.  Essential oil composition is related to the natural habitats: Coridothymus capitatus and Satureja thymbra in NATURA 2000 sites of Crete. , 2005, Phytochemistry.

[135]  S. Wold,et al.  Orthogonal projections to latent structures (O‐PLS) , 2002 .

[136]  C. Shilin,et al.  Authentication of medicinal plants by DNA-based markers and genomics. , 2010 .

[137]  J. Ward,et al.  Assessment of 1H NMR spectroscopy and multivariate analysis as a technique for metabolite fingerprinting of Arabidopsis thaliana. , 2003, Phytochemistry.

[138]  Yizeng Liang,et al.  Evaluation of separation quality in two-dimensional hyphenated chromatography , 2001 .

[139]  K. Bae,et al.  Discrimination of cinnamon bark and cinnamon twig samples sourced from various countries using HPLC-based fingerprint analysis. , 2011, Food chemistry.

[140]  Hartwig Schulz,et al.  Characterization of peppercorn, pepper oil, and pepper oleoresin by vibrational spectroscopy methods. , 2005, Journal of agricultural and food chemistry.

[141]  F. Chau,et al.  Determination of volatile components in peptic powder by gas chromatography-mass spectrometry and chemometric resolution. , 2001, Journal of chromatography. A.

[142]  F. Saez Essential oil variability of Thymus baeticus growing wild in southeastern Spain , 1995 .

[143]  Fingerprinting alterations of secondary metabolites of tangerine peels during growth by HPLC-DAD and chemometric methods. , 2009, Analytica chimica acta.

[144]  Y. Choi,et al.  Metabolomic investigation of the ethnopharmacological use of Artemisia afra with NMR spectroscopy and multivariate data analysis. , 2010, Journal of ethnopharmacology.

[145]  Y. Heyden,et al.  Development of HPLC fingerprints for Mallotus species extracts and evaluation of the peaks responsible for their antioxidant activity. , 2009, Journal of pharmaceutical and biomedical analysis.

[146]  Robert Verpoorte,et al.  Metabolomic differentiation of Cannabis sativa cultivars using 1H NMR spectroscopy and principal component analysis. , 2004, Journal of natural products.

[147]  Zhihong Cheng,et al.  Combinative method using HPLC fingerprint and quantitative analyses for quality consistency evaluation of an herbal medicinal preparation produced by different manufacturers. , 2010, Journal of pharmaceutical and biomedical analysis.

[148]  Yu Jin,et al.  Fingerprint analysis of Ligusticum chuanxiong using hydrophilic interaction chromatography and reversed-phase liquid chromatography. , 2009, Journal of chromatography. A.

[149]  Hari Niwas Mishra,et al.  FT-NIR spectroscopy for caffeine estimation in instant green tea powder and granules , 2009 .

[150]  S. Sung,et al.  Differentiation of cultivation sources of Ganoderma lucidum by NMR-based metabolomics approach. , 2010, Phytochemical analysis : PCA.

[151]  Samuel H. Tersigni,et al.  Pharmaceutical fingerprinting: evaluation of neural networks and chemometric techniques for distinguishing among same-product manufacturers. , 1996, Analytical chemistry.

[152]  Chew-Tin Lee,et al.  Flavonoids and phenolic acids from Labisia pumila (Kacip Fatimah). , 2011, Food chemistry.

[153]  José Eduardo de Oliveira,et al.  Classification of Aristolochia species based on GC-MS and chemometric analyses of essential oils. , 2008, Phytochemistry.

[154]  D. Massart Chemometrics: A Textbook , 1988 .

[155]  Keduo Qian,et al.  A novel strategy to rapidly explore potential chemical markers for the discrimination between raw and processed Radix Rehmanniae by UHPLC-TOFMS with multivariate statistical analysis. , 2010, Journal of pharmaceutical and biomedical analysis.

[156]  Dan-ni Zhu,et al.  Chemical Fingerprinting by HPLC-DAD-ELSD and Princi-pal Component Analysis of Polygala japonica from Different Locations in China: Chemical Fingerprinting by HPLC-DAD-ELSD and Princi-pal Component Analysis of Polygala japonica from Different Locations in China , 2011 .

[157]  Hyung-Kyoon Choi,et al.  NMR-based metabolic profiling and differentiation of ginseng roots according to cultivation ages. , 2012, Journal of pharmaceutical and biomedical analysis.

[158]  Rudolf Bauer,et al.  Quality Criteria and Standardization of Phytopharmaceuticals: Can Acceptable Drug Standards Be Achieved? , 1998 .

[159]  F. Saez Essential oil variability of Thymus zygis growing wild in southeastern spain , 1995 .

[160]  Y. Heyden,et al.  Potential antioxidant compounds in Mallotus species fingerprints. Part I: Indication, using linear multivariate calibration techniques. , 2009, Analytica chimica acta.

[161]  Simon,et al.  Genetic diversity of Ocimum gratissimum L. based on volatile oil constituents, flavonoids and RAPD markers. , 2001, Biochemical systematics and ecology.

[162]  N. Vlachos,et al.  Applications of Fourier transform-infrared spectroscopy to edible oils. , 2006, Analytica chimica acta.

[163]  Vila,et al.  Chemotaxonomic study on Thymus villosus from Portugal. , 2000, Biochemical systematics and ecology.

[164]  P. Gemperline Practical Guide To Chemometrics , 2006 .

[165]  E. Chan,et al.  Ultra-high performance liquid chromatography/time-of-flight mass spectrometry (UHPLC/TOFMS) for time-dependent profiling of raw and steamed Panax notoginseng. , 2010, Journal of pharmaceutical and biomedical analysis.

[166]  R. Chizzola,et al.  Antioxidative properties of Thymus vulgaris leaves: comparison of different extracts and essential oil chemotypes. , 2008, Journal of agricultural and food chemistry.

[167]  L. Angenot,et al.  Metabolomic analysis of Strychnos nux-vomica, Strychnos icaja and Strychnos ignatii extracts by 1H nuclear magnetic resonance spectrometry and multivariate analysis techniques. , 2004, Phytochemistry.

[168]  S. Kreft,et al.  Differences among Epilobium and Hypericum species revealed by four IR spectroscopy modes: transmission, KBr tablet, diffuse reflectance and ATR. , 2011, Phytochemical analysis : PCA.

[169]  R. Reid,et al.  Differentiation of opium and poppy straw using capillary electrophoresis and pattern recognition techniques. , 2007, Analytica chimica acta.

[170]  S. Casal,et al.  Discrimination between arabica and robusta coffee species on the basis of their amino acid enantiomers. , 2003, Journal of agricultural and food chemistry.

[171]  A. Kimbaris,et al.  Classification of Greek Mentha pulegium L. (Pennyroyal) samples, according to geographical location by Fourier transform infrared spectroscopy. , 2012, Phytochemical analysis : PCA.

[172]  J. Desjobert,et al.  Chemical and genetic differentiation of Corsican subspecies of Teucrium flavum L. , 2011, Phytochemistry.

[173]  Simon,et al.  Variation in volatile compounds from tansy (Tanacetum vulgare L.) related to genetic and morphological differences of genotypes. , 2001, Biochemical systematics and ecology.

[174]  Xiaohui Fan,et al.  Multiple chromatographic fingerprinting and its application to the quality control of herbal medicines , 2006 .

[175]  Yi-Zeng Liang,et al.  Quality control of herbal medicines. , 2004, Journal of chromatography. B, Analytical technologies in the biomedical and life sciences.

[176]  S. Deans,et al.  Chemical polymorphism of the essential oils from populations of Thymus caespititius grown on the island S. Jorge (Azores). , 2000, Phytochemistry.

[177]  Discrimination of geographical origin and adulteration of radix astragali using fourier transform infrared spectroscopy and chemometric methods. , 2010, Phytochemical analysis : PCA.

[178]  J. Namieśnik,et al.  Classification and fingerprinting of kiwi and pomelo fruits by multivariate analysis of chromatographic and spectroscopic data , 2012 .

[179]  Frank A. Gomez,et al.  Chemometric Methods in Capillary Electrophoresis , 2009 .

[180]  F. Tomi,et al.  Composition and infraspecific variability of essential oil from Thymus camphoratus , 1997 .

[181]  Serge Kokot,et al.  Fingerprinting of complex mixtures with the use of high performance liquid chromatography, inductively coupled plasma atomic emission spectroscopy and chemometrics. , 2008, Analytica Chimica Acta.

[182]  P. Andrade,et al.  Analysis of vervain flavonoids by HPLC/Diode array detector method. Its application to quality control. , 1999, Journal of agricultural and food chemistry.

[183]  Cennet Karadaş,et al.  Chemometric approach to evaluate trace metal concentrations in some spices and herbs , 2012 .

[184]  M. Simmonds,et al.  Chemical characterisation of wild populations of Thymus from different climatic regions in southeast Spain , 2008 .

[185]  Lin Peng,et al.  Fingerprint profile of active components for Artemisia selengensis Turcz by HPLC–PAD combined with chemometrics , 2011 .

[186]  Y. Choi,et al.  Metabolic characterization of Brassica rapa leaves by NMR spectroscopy. , 2007, Journal of agricultural and food chemistry.

[187]  Quansheng Chen,et al.  Feasibility study on qualitative and quantitative analysis in tea by near infrared spectroscopy with multivariate calibration. , 2006, Analytica chimica acta.

[188]  Yizeng Liang,et al.  Comparative analysis of chemical components of essential oils from different samples of Rhododendron with the help of chemometrics methods , 2006 .

[189]  Zheng-Tao Wang,et al.  HPLC fingerprints combined with principal component analysis, hierarchical cluster analysis and linear discriminant analysis for the classification and differentiation of Peganum sp. indigenous to China. , 2010, Phytochemical analysis : PCA.

[190]  Antonio González,et al.  Characterization of green coffee varieties according to their metal content , 1998 .

[191]  F. Gong,et al.  Gas chromatography-mass spectrometry and chemometric resolution applied to the determination of essential oils in Cortex cinnamomi. , 2001, Journal of chromatography. A.

[192]  Y. Vander Heyden,et al.  Exploration of linear multivariate calibration techniques to predict the total antioxidant capacity of green tea from chromatographic fingerprints. , 2008, Journal of chromatography. A.

[193]  M. Millikan,et al.  Evaluation of mineral content of Chinese medicinal herbs used to improve kidney function with chemometrics , 2011 .

[194]  Y. Choi,et al.  Classification of Ilex species based on metabolomic fingerprinting using nuclear magnetic resonance and multivariate data analysis. , 2005, Journal of agricultural and food chemistry.