Quality Control Of Essential Oils Research Articles

Terahertz/far infrared spectroscopy as an alternative method for the characterization of major components in Laggera decurrens essential oil

The Fourier Transform Infrared technique was used to determine the major components of Laggera decurrens essential oil. The experiment revealed that there are signatures of thymol, carvacrol and thymoquinone in Laggera decurrens essential oil. This was suggested by the existence of shared absorption bands between these pure compounds and Laggera decurrens essential oil. The PBE0 DFT functional was employed to calculate the theoretical spectra of thymol, carvacrol and thymoquinone. A good correspondence was obtained between the experimental and theoretical spectra of these materials. Peak assignments showed that the Laggera decurrens absorption bands at 5.68 THz, 9.47 THz, 14.20 THz, 15.71 THz and 18.10 THz had corresponding absorption bands in either of the three materials with the same vibration modes. These further confirms the existence of thymol, carvacrol and thymoquinone in Laggera decurrens essential oil. This work presents a novel method for the characterization of major components in essential oils which has otherwise been commonly performed using Gas Chromatography-Mass Spectrometry/ Gas Chromatography-Flame Ionization Detector. This presents the use of terahertz or far infrared spectroscopy for the quality control of essential oils. This study further highlights the effectiveness of the Fourier Transform Infrared method in determining constituents of complex samples.

Make the Quality Control of Essential Oils Greener: Fast Enantioselective GC-MS Analysis of Sweet and Bitter Orange as a Case Study.

Quality control of essential oils is fundamental for verifying their authenticity and conformity with quality standards, ensuring their safety and regulatory compliance, and monitoring their consistency. Companies that produce or market essential oils routinely evaluate the quality and authenticity of their products. However, they also must deal with increasing attention to environmental sustainability as well as practical considerations such as productivity, cost, and simplicity of methods. In this study, enantioselective gas chromatography (GC) was adopted to evaluate the quality of sweet and bitter orange essential oils, used as a case study. The analytical conditions were optimized and translated to fast GC to evaluate the impact of this approach on the environmental footprint of the analyses. The greenness of fast GC, compared with conventional GC, was quantitatively evaluated using a dedicated metric tool (AGREE), and important improvements have been calculated. The developed methods were applied to a set of commercial essential oils, and the data about the enantiomeric composition and relative percentage abundance were elaborated through multivariate statistics (principal component analysis). The results showed that fast chiral gas chromatography enables the classification of citrus essential oil samples and can be considered an environmentally friendly and sustainable approach for evaluating their quality.

СРАВНИТЕЛЬНЫЙ АНАЛИЗ ОБРАЗЦОВ ЭФИРНОГО МАСЛА ПИХТЫ СИБИРСКОЙ И ИХ ПРОТИВОМИКРОБНАЯ АКТИВНОСТЬ

The purpose of this work is to assess the quality of Siberian fir essential oil samples in accordance with the requirements of GOST ISO 10869-2015, as well as to assess antimicrobial activity. The objects of the study were various industrial samples, as well as a sample obtained at Perm pharmaceutical academy from fir paws, a raw material harvested in the Okhansky district of the Perm Territory. According to the research, all samples meet the requirements for consistency and color; a number of samples have the smell of technical fluid; all samples, except for own sample, have a relative density lower than indicated in GOST; the refractive index is underestimated in several samples; some samples in the composition have components that do not dissolve in ethyl alcohol in the ratio proposed by GOST; all samples comply with GOST in terms of acid number and do not contain ethyl alcohol impurities; a number of samples have unacceptable impurities of fatty and mineral oils. According to the study of the chromatographic profile, all the requirements for the ratio of substances and percentage could be met by an oil sample from Evalar. It should also be noted that own sample contains the largest amount of bornyl acetate. The studied samples have high antibacterial activity against the studied strain of Staphylococcus aureus, low antibacterial activity against the studied strain of Escherichia coli, a number of samples have a moderately pronounced antifungal activity against the studied strain of C. albicans. It is necessary to revise the existing regulatory documentation, as well as more stringent quality control of essential oils sold in the pharmaceutical and perfumery markets.

Vibrational Spectroscopic Methods for the Identification and Distinction of Essential Oils in Genus Ocimum L.: A Chemometric Approach

Essential oils are mainly analyzed by gas chromatography coupled with mass spectrometry (GC–MS). This is a time consuming technique which requires complex instrumentation assembly. Raman and FTIR spectroscopy are rapid and non-destructive techniques for qualitative characterization, differentiation of principal essential oil components, detection of adulteration in the oil, quality control of essential oil in industry as well as to distinguish different taxa. In the present study, five Ocimum spp. (Ocimum tenuiflorum L., Ocimum gratissimum L., Ocimum × africanum Lour., Ocimum basilicum L. and Ocimum americanum L) have been identified on the basis of essential oil by the Raman and FTIR spectroscopic techniques. It was found that methyl eugenol, eugenol, estragole, and camphor are major essential oils components present in Ocimum L. The results of PCA indicate that all five species of Ocimum L. form different clusters on the basis of principal essential oil components. The components of essential oil predicted by Raman spectroscopy correlate well with that of FTIR data. The present study demonstrates the use of Raman and FTIR spectroscopy techniques to distinguish taxa and characterization of essential oil components.

Adulteration of Essential Oils: A Multitask Issue for Quality Control. Three Case Studies: Lavandula angustifolia Mill., Citrus limon (L.) Osbeck and Melaleuca alternifolia (Maiden & Betche) Cheel.

The quality control of essential oils (EO) principally aims at revealing the presence of adulterations and at quantifying compounds that are limited by law by evaluating EO chemical compositions, usually in terms of the normalised relative abundance of selected markers, for comparison to reference values reported in pharmacopoeias and/or international norms. Common adulterations of EO consist of the addition of cheaper EO or synthetic materials. This adulteration can be detected by calculating the percent normalised areas of selected markers or the enantiomeric composition of chiral components. The dilution of the EO with vegetable oils is another type of adulteration. This adulteration is quite devious, as it modifies neither the qualitative composition of the resulting EO nor the marker’s normalised percentage abundance, which is no longer diagnostic, and an absolute quantitative analysis is required. This study aims at verifying the application of the two above approaches (i.e., normalised relative abundance and absolute quantitation) to detect EO adulterations, with examples involving selected commercial EO (lavender, bergamot and tea tree) adulterated with synthetic components, EO of different origin and lower economical values and heavy vegetable oils. The results show that absolute quantitation is necessary to highlight adulteration with heavy vegetable oils, providing that a reference quantitative profile is available.

The famous Turkish rose essential oil: Characterization and authenticity monitoring by FTIR, Raman and GC–MS techniques combined with chemometrics

There is a necessity for rapid, robust, easy, accurate and cost-effective methodologies for the quality control of essential oils from medicinal and aromatic plants. Rosa damascena essential oil is a high-value natural product with its unique quality properties and economic importance. This research evaluated the capability of Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy and gas chromatography-mass spectrometry (GC–MS) techniques combined with chemometrics for determination of the authenticity of R. damascena essential oil. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) were successfully employed with 100% accuracy for discrimination of authentic R. damascena essential oil samples from fraudulent commercial samples. Consistent results were obtained by FTIR, Raman and GC–MS techniques. Two of twenty commercial samples were determined as authentic R. damascena essential oil samples using the three analytical techniques. Findings showed that FTIR and Raman spectroscopy combined with chemometrics could be used as reliable, robust, rapid, accurate and low-cost analytical techniques for quality evaluation of R. damascena essential oil.

Raman spectroscopy in the detection of adulterated essential oils: The case of nonvolatile adulterants

AbstractEssential oils are liquid mixtures of volatile compounds extracted from plants. Their quality is usually controlled via gas chromatography (GC), although with limitations when adulterants are nonvolatile substances. The essential oils of lavender (Lavandula angustifolia Mill.), peppermint (Mentha piperita L.), patchouli (Pogostemon cablin Benth), and their adulterated versions were measured by GC coupled to flame ionization detector (GC‐FID) and Raman spectroscopy. Canola oil, a nonvolatile substance, was used as the adulterant. The adulterated essential oils contained 1%, 3%, 5%, 10%, 15%, and 20% (v/v) of canola oil. Chromatograms of the adulterated essential oils containing 20% (v/v) of canola oil showed decrements in peak areas of the essential oil components, compared with peaks of the pure essential oils. The highest decrements were observed for the adulterated essential oil of patchouli. In general, detection of adulterated essential oils by simple visual inspection of the Raman features was difficult, due to slight differences observed in the spectra. Principal Components Analysis (PCA) allowed achieving a good spectral discrimination between pure and adulterated essential oils. These results suggest that Raman spectroscopy can overcome limitations of GC‐based methods, thus becoming an interesting alternative and complementary technique for quality control of essential oils.

Optical Investigation of Essential Oils Using Absorbance and Photoluminescence.

Essential oils are complex mixtures of organic substances with large commercial importance in the pharmaceutical, food, fragrance, and cosmetic industries due to their organoleptic and biological properties. Also, these materials are also luminescent what has taken several studies about its potential uses for the detection and quality control of essential oils, imaging, and for the investigation of the synergies of their constituents. Concerning this, the present work is dedicated to studying the optical properties of selected essential oils: citronella (Cymbopogon winterianus), Japanese mint (Mentha arvensis), clove bud (Syzygium aromaticum), and bergamot (Citrus bergamia). We carried out a comparative study of the photoluminescence and the ultraviolet-visible optical absorption (abs-UV-Vis) of these essential oils with their typical constituents. To inspect the effects of the intermolecular interactions on the optical response of these systems, mixtures between the essential oils constituents following the expected average percent mass fraction were also studied. From these experiments, the main results were bathochromic effects in the abs-UV-Vis spectra; excimer formation in citral, isopulegol, isomenthone, eugenol, and eugenyl acetate; excimer emission enhancing and specific solvent effect in the essential oils photoluminescence spectra. These results contribute to the knowledge of essential oils' applications, especially in the evaluation of components' interactions through a simple abs-UV-Vis assay.

Smart sensor based distillation for fractionating citronella oil: current research challenges

Citronella oil is one of the essential oils derived from the leaves and stem of lemongrass (Cymbopogon nardus). At present, most of the lemongrass oil industry in Indonesia is still in the form of upstream industries which only provide crude purified oils with low purity for export with a fairly low sales value. Technology in improving the purity of citronella oil needs innovation in following the development of the industrial revolution 4.0. This article presents an overview of the research opportunities in the development of distillation for fractionating citronella oil referring to automation of optimization processes in the vacuum fractional distillation accompanied by inspection of the quality of essential oil isolation run in the line process based on smart sensors integrated in a computer program. The combination technique of quality control of essential oils in line process system combined with the optimization technique of the vacuum fractional distillation process has not been studied by advanced researchers. Therefore, this study has a state of the art process engineering and smart sensor-based quality control systems that can be developed for strengthening the Indonesian citronella oil industry.

Development of an electrochemical method to determine phenolic monoterpenes in essential oils

A simple, rapid and non-expensive method is proposed to determine phenolic monoterpenes such as thymol and carvacrol in essential oils of thyme and oregano. The linear sweep voltammetry based on glassy carbon electrodes was the electrochemical technique used. Thymol and carvacrol have one main oxidation peak in non-aqueous media centered at about 1.3 V vs. Ag/AgCl. The electron transfer process is mainly diffusion controlled.The calibration plots generated using the commercial standards of thymol and carvacrol were used to estimate the total content in real samples. The calibration plots were linear in the concentration range from 8.5 × 10−5 to 1.3 × 10−3 mol L−1 and 7.9 × 10−5 to 1.2 × 10−3 mol L−1 for thymol and carvacrol, respectively.Results obtained with the electrochemical method are in good agreement with those of the official method (gas chromatography). In addition, the analytical procedure does not require previous preparation of the sample or modification of the electrode surface. The electrochemical technique used is very simple to apply. Under these conditions, the methodology proposed is a good, simple and fast option to perform a quality control of essential oils.

Is Low-field NMR a Complementary Tool to GC-MS in Quality Control of Essential Oils? A Case Study: Patchouli Essential Oil.

High-field NMR is an expensive and important quality control technique. In recent years, cheaper and simpler low-field NMR has become available as a new quality control technique. In this study, 60 MHz 1H-NMR was compared with GC-MS and refractometry for the detection of adulteration of essential oils, taking patchouli essential oil as a test case. Patchouli essential oil is frequently adulterated, even today. In total, 75 genuine patchouli essential oils, 10 commercial patchouli essential oils, 10 other essential oils, 17 adulterants, and 1 patchouli essential oil, spiked at 20% with those adulterants, were measured. Visual inspection of the NMR spectra allowed for easy detection of 14 adulterants, while gurjun and copaiba balsams proved difficult and one adulterant could not be detected. NMR spectra of 10 random essential oils differed not only strongly from patchouli essential oil but also from one another, suggesting that fingerprinting by low-field NMR is not limited to patchouli essential oil. Automated chemometric evaluation of NMR spectra was possible by similarity analysis (Mahalanobis distance) based on the integration from 0.1 - 8.1 ppm in 0.01 ppm increments. Good quality patchouli essential oils were recognised as well as 15 of 17 deliberate adulterations. Visual qualitative inspection by GC-MS allowed for the detection of all volatile adulterants. Nonvolatile adulterants, and all but one volatile adulterant, could be detected by semiquantitation. Different chemometric approaches showed satisfactory results. Similarity analyses were difficult with nonvolatile adulterants. Refractive index measurements could detect only 8 of 17 adulterants. Due to advantages such as simplicity, rapidity, reproducibility, and ability to detect nonvolatile adulterants, 60 MHz 1H-NMR is complimentary to GC-MS for quality control of essential oils.

Performance Comparison of Fuzzy ARTMAP and LDA in Qualitative Classification of Iranian Rosa damascena Essential Oils by an Electronic Nose.

Quality control of essential oils is an important topic in industrial processing of medicinal and aromatic plants. In this paper, the performance of Fuzzy Adaptive Resonant Theory Map (ARTMAP) and linear discriminant analysis (LDA) algorithms are compared in the specific task of quality classification of Rosa damascene essential oil samples (one of the most famous and valuable essential oils in the world) using an electronic nose (EN) system based on seven metal oxide semiconductor (MOS) sensors. First, with the aid of a GC-MS analysis, samples of Rosa damascene essential oils were classified into three different categories (low, middle, and high quality, classes C1, C2, and C3, respectively) based on the total percent of the most crucial qualitative compounds. An ad-hoc electronic nose (EN) system was implemented to sense the samples and acquire signals. Forty-nine features were extracted from the EN sensor matrix (seven parameters to describe each sensor curve response). The extracted features were ordered in relevance by the intra/inter variance criterion (Vr), also known as the Fisher discriminant. A leave-one-out cross validation technique was implemented for estimating the classification accuracy reached by both algorithms. Success rates were calculated using 10, 20, 30, and the entire selected features from the response of the sensor array. The results revealed a maximum classification accuracy of 99% when applying the Fuzzy ARTMAP algorithm and 82% for LDA, using the first 10 features in both cases. Further classification results explained that sub-optimal performance is likely to occur when all the response features are applied. It was found that an electronic nose system employing a Fuzzy ARTMAP classifier could become an accurate, easy, and inexpensive alternative tool for qualitative control in the production of Rosa damascene essential oil.

Characterisation of the Metabolism of Pogostone In Vitro and In Vivo Using Liquid Chromatography with Mass Spectrometry

Pogostone possesses potent anti-bacterial and anti-fungal activities and has been used for the quality control of essential oil of Pogostemon cablin. Pogostone is easily absorbed after oral administration but its metabolism in mammals remains elusive. To investigate the metabolic profile of pogostone in vitro and in vivo. High-performance liquid chromatography coupled with mass spectrometry (LC–MS) techniques were employed. Orbitrap MS and ion trap tandem mass spectrometry (MS/MS) were utilised to analyse the metabolism of pogostone by virtue of the high sensitivity and high selectivity in the measurement. In vitro experiment was carried out using rat liver microsomes while the in vivo study was conducted on rats, which were orally administered with pogostone (80 mg/kg). In total, three mono-hydroxylated, one di-hydroxylated, one mono-oxygenated, one di-oxygenated metabolite, one hydrolysis and one hydroxy conjugated metabolites were found. In addition hydroxylation was demonstrated to be a major metabolic pathway of pogostone. LC–MS was demonstrated to be a powerful tool for the metabolite identification of pogostone. The tentative identification of metabolites provides an insight for the metabolic clues of pogostone.

Application of the chromatographic fingerprint for quality control of essential oil from GuangXi Curcuma kwangsiensis

To evaluate the validation tests of precision and repeatability in quality control of essential oil from Curcuma kwangsiensis, ten different batches of Curcuma kwangsiensis samples from three producing areas in Guangxi province were studied by gas chromatography mass spectrometry (GC-MS). The characteristic differences in the producing areas and the chemical variances in the toasting process were obtained and studied by principal components analysis (PCA) and similarity analysis. The results suggest that the chromatographic fingerprint developed by hydrodistillation coupled with GC-MS provides useful information to reveal the quality of Curcuma kwangsiensis and evaluate the quality changes in the producing process.

The peroxide value—a new tool for the quality control of essential oils

The peroxide value—a new tool for the quality control of essential oils

Chiral compounds of essential oils. VIII: Stereodifferentiation of linalool using multidimensional gas chromatography

AbstractThis paper reports on the chiral evaluation of linalool as an additional criterion of authenticity of lavender oils, using enantioselective multidimensional gas chromatography with a column combination of Superox and heptakis(2,3,6‐tri‐O‐ethyl)‐β‐cyclodextrin in OV‐1701‐vi. This method is extended to some other valuable spice oils‐investigations on the enantiomeric distribution of their linalool content are discussed in terms of quality control of essential oil.