ArticlePDF Available

Quantitative analysis of α-pinene and β-myrcene in mastic gum oil using FT-Raman spectroscopy

Authors:

Abstract and Figures

α-Pinene and β-myrcene are compounds that are contained in mastic gum in high concentrations. The β-myrcene percentage determines the marketability of mastic gums. The chemical composition of mastic gum oil of a representative resin quality was evaluated by gas chromatography–mass spectrometry (GC–MS) technique. FT-Raman spectroscopy, based on band intensity measurements, was used for the determination of α-pinene and β-myrcene content in mastic gum. Bands at 1658 and 1633 cm−1 were used for the calibration of α-pinene and β-myrcene, respectively. Calibration curves were linear (correlation coefficient for α-pinene was 0.992 and 0.997 for β-myrcene) in the range 30–80 and 3–45%, respectively. Normalization of calibration curves, against the 802 cm−1 cyclohexane band, minimized the effect of laser beam power fluctuations. The proposed method is rapid and simple. Accordingly, mastic gum oils from Chios island (Greece) contained 38.1–69.5% α-pinene and 4.5–57.9% β-myrcene.
Content may be subject to copyright.
Analytical, Nutritional and Clinical Methods Section
Quantitative analysis of a-pinene and b-myrcene in mastic gum oil
using FT-Raman spectroscopy
D. Daferera, C. Pappas, P.A. Tarantilis, M. Polissiou*
Laboratory of Chemistry, Department of Science, Agricultural University of Athens, 75 Iera Odos, 118 55 Athens, Greece
Received 7 August 2001; received in revised form 22 October 2001; accepted 22 October 2001
Abstract
a-Pinene and b-myrcene are compounds that are contained in mastic gum in high concentrations. The b-myrcene percentage
determines the marketability of mastic gums. The chemical composition of mastic gum oil of a representative resin quality was
evaluated by gas chromatography–mass spectrometry (GC–MS) technique. FT-Raman spectroscopy, based on band intensity
measurements, was used for the determination of a-pinene and b-myrcene content in mastic gum. Bands at 1658 and 1633 cm
1
were used for the calibration of a-pinene and b-myrcene, respectively. Calibration curves were linear (correlation coefficient for a-
pinene was 0.992 and 0.997 for b-myrcene) in the range 30–80 and 3–45%, respectively. Normalization of calibration curves,
against the 802 cm
1
cyclohexane band, minimized the effect of laser beam power fluctuations. The proposed method is rapid and
simple. Accordingly, mastic gum oils from Chios island (Greece) contained 38.1–69.5% a-pinene and 4.5–57.9% b-myrcene. #2002
Elsevier Science Ltd. All rights reserved.
Keywords: a-Pinene, b-Myrcene, Determination, FT-Raman
1. Introduction
Pistacia lentiscus var. Chia, is a tree belonging to the
Anacardiaceae family, which is traditionally cultivated
in south Chios, a Greek island of the east Aegean sea.
Every year, from July to October, on the trunk of the
tree, cuttings are made and a resinous liquid substance
is exuded. This material, remaining under the tree for
many days, is coagulated by the local environmental
conditions. The coagulated product is collected and is
called gum mastic or ‘‘masticha’’ (Perikos, 1993). Mas-
ticha has numerous usages itself, but is also used in
producing gum oil by the steam-distillation method.
Gum mastic oil is used in cosmetics and perfumery, as a
flavouring in food technology and for its antimicrobial
activity, and especially against Helicobacter pylori
(Huwez, Thirwell, Cockayne, & Ala’Alden, 1998;
Magiatis, Melliou, Skaltsounis, Chinou, & Mitaku,
1999; Perikos, 1993).
The gum essential oil chemical composition varies and
depends on the gum quality. The gum quality is influ-
enced by its purity, the collection time and the duration
between exudation from the trunk and the collection.
Studies on the chemical composition of the gum oil
showed the predominant presence of monoterpenes,
a-pinene and b-myrcene, which constitute the majority
of the oil. The a-pinene and b-myrcene contents in
mastic gum oil are typically measured by gas chroma-
tography (GC) (Papageorgiou, Mellidis, & Argyriadou,
1991). Time-consumption and the prior sample hand-
ling are the basic disadvantages of the method. There is
a proportion between the concentrations of a-pinene
and b-myrcene, which characterizes the authenticity of
the gum essential oil. Percentages of about 60–80% for
a-pinene and 7–20% for b-myrcene represent an accep-
table oil quality. Increases of b-myrcene in the oil mix-
ture devalue its quality.
FT-Raman spectroscopy is an analytical technique
based on the interaction of an incident monochromatic
radiation with vibrational energy levels of molecules. It
is widely used for qualitative comparisons between
samples. The concentration of a compound in a mixture
is relatable to the Raman intensities if an appropriate
0308-8146/02/$ - see front matter #2002 Elsevier Science Ltd. All rights reserved.
PII: S0308-8146(01)00382-X
Food Chemistry 77 (2002) 511–515
www.elsevier.com/locate/foodchem
* Corresponding author: Tel.: +30-152-942-41; fax: +30-152-942-65.
E-mail address: mopol@aua.gr (M. Polissiou).
reference material is used to determine its value (Free-
man & Mayo, 1969; Hancewicz & Petty, 1995; Skoulika,
Georgiou, & Polissiou, 2000; Sun, Ibrahim, Oldham,
Schultz, & Conners, 1997). FT-Raman spectra of a-pinene
have been recorded in order to determined the quanti-
tative relationship between vibrational circular dichro-
ism (VCD) and Raman optical activity (ROA) spectra
(Qu, Lee, Yu, Freedman, & Nafie, 1996).
This paper describes the development of a method for
quantitative analysis of a-pinene and b-myrcene in
mastic gum oil by FT-Raman spectroscopy. The recor-
ded FT-Raman spectra of the gum mastic oils allow us
to correlate their chemical compositions with the per-
centages of a-pinene and b-myrcene. The proposed
method is simple, rapid and nondestructive for the
sample and all samples are measured as neat liquids
without further treatment.
2. Materials and methods
2.1. Materials
A sample of first quality mastic gum and 10 mastic
gum oils from resins collected over different durations
were kindly provided by the Chios gum mastic growers’
association. The 10 samples were randomly character-
ized as ‘‘oil 1’’, ‘‘oil 2’’, ‘‘oil 3’’, ‘‘oil 4’’, ‘‘oil 5’’, ‘‘oil 6’’,
‘‘oil 7’’, ‘‘oil 8’’, ‘‘oil 9’’ and oil 10’’. Standards of
a-pinene and b-myrcene were purchased from the
Sigma-Aldrich Co.
2.2. Isolation of essential oil from the mastic gum
A typical essential oil was isolated according to the
Likens–Nickerson’s method, using a micro steam dis-
tillation extraction apparatus for organic solvents
lighter than water (Daferera, Ziogas, & Polissiou, 2000).
In that way, all the aroma constituents were con-
centrated in the extracting solvent. The procedure was
protected by placing inert gas (N
2
) in the main body of
the apparatus in order to avoid creating oxidized by-
products. The diethylether extract was stored at 4 C
until its analysis by gas chromatography–mass spectro-
metry (GC–MS).
2.3. GC–MS analysis conditions
The analysis of the typical gum essential oil was per-
formed using a Hewlett Packard 5890 II GC, equipped
with a HP-5 capillary column (30 m, 0.25 mm id, 0.25
mm film thickness) and a mass spectrometer 5971 A as
detector. The carrier gas, helium, was stable at 2.5 psi.
Column temperature was initially kept for 3 min at
40 C, then gradually increased to 180 Cat3C/min
and finally increased to 270 Cat30C/min. Injector
and detector (MS transfer line) temperatures were set at
220 and 290 C, respectively. For GC–MS detection, an
electron ionization system was used with ionization
energy of 70 eV. The extract diluted 1:5 (v/v) with di-
ethylether and 1.0 ml of the diluted sample was injected
automatically and split-less.
The samples from the Chios gum mastic growers’
association were also analyzed by the above GC–MS
method in order to determine the a-pinene and b-myr-
cene. The samples diluted with dichloromethane (1:100,
v/v) and 1 ml of the diluted sample was injected auto-
matically and split less.
2.4. FT-Raman spectroscopy
Standard solutions were prepared using the stan-
dards, a-pinene and b-myrcene, in dichloromethane.
FT-Raman spectra of cyclohexane, standard solu-
tions, and ten mastic gum oils from the Chios gum
mastic growers’ association were recorded with a Nico-
let 750 FT-Raman spectrometer, equipped with a
Nd:YAG laser source that emits at 1064 nm. A calcium
fluorine (CaF
2
) beam splitter, an indium-gallium
arsenide (InGaAs) detector and 180backscattering
geometry are used in the spectrometer. An optical bench
alignment was performed before each batch of mea-
surements to ensure that the spectrometer was fine-
tuned and the detector signal maximized. Sample cells
used were cut to 6 cm from Wimad WG-5M NMR
tubes of 4.97 mm outer diameter and 0.38 mm wall
thickness. A motorized positioner focuses the laser
beam to the sample and a manual side-to-side adjuster
allows sample adjustment for maximum optical effi-
ciency. Spectra were accumulated from 100 scans col-
lected during 3 min at a resolution of 4 cm
1
.
The FT-Raman spectra were smoothed and their
baselines were corrected using the ‘‘automatic smooth’’
and the ‘‘automatic baseline correct’’ functions of the
built-in software of the spectrophotometer (OMNIC
3.1). Then the intensities of the 1658 and 1633 cm
1
peaks were measured. The intensity of the 802 cm
1
cyclohexane peak was measured as well.
3. Results and discussion
3.1. GC–MS results
A typical total ion chromatogram (TIC) of the mastic
gum oil, isolated by the Likens-Nickerson method, is
presented in Fig. 1. This mastic gum oil is characterized
by the presence of a-pinene (72.1%), b-pinene (2.9%),
b-myrcene (16.5%), limonene (1.0%), linalool (1.0%)
and caryophyllene (1.1%). All other compounds were
present at relative concentrations less than 1.0% in the
mixture (Table 1).
512 D. Daferera et al. / Food Chemistry 77 (2002) 511–515
Table 2 shows the percentages of a-pinene and
b-myrcene in the samples from the Chios gum mastic
growers’ association, as determined by the GC–MS
analysis. The contents (%) of a-pinene and b-myrcene
in mastic gum oils were 33.7–72.8 and 3.8–63.5,
respectively.
The chemical composition of the oils was determined
by comparing the mass spectra of oil components with
those of mass spectra from the NBS75K data library.
The main components of the oil (a-pinene and b-myr-
cene) were also determined by comparison of their rela-
tive retention times with those of standards.
3.2. FT-Raman results
The FT-Raman spectrum (Fig. 2) of a-pinene showed
characteristic peaks at 1658 cm
1
(C¼C of cyclohex-
ene), 1436 cm
1
(C–H) and 667 cm
1
(C–C ring
breathing), b-myrcene at 1633 cm
1
(R
1
R
2
C¼CH
2
and
R
1
R
2
C¼CHR
3
) (Bour, 1998; Freeman & Mayo, 1969)
and of cyclohexane at 802 cm
1
(C–C, cyclohexane
chair form). The FT-Raman spectrum of mastic gum oil
showed characteristic peaks at 1658 cm
1
, assigned
mainly to a-pinene and at 1633 cm
1
, assigned to b-
myrcene. It was observed that the Raman intensities of
Fig. 1. A representative TIC of gum oil isolated with diethylether by the Likens–Nickerson method.
Table 1
Chemical composition of the essential oil from gum of Pistacia lentiscus var. chia isolated by the Likens–Nickerson method
A/A Retention time (min) Component Composition (%)
1 11.70 4-methylene-1-(1-methylethyl)-bicyclo[3.1.0]hexane(sabinene or 4(10) thujene) 0.6
2 12.82 2,6,6-trimethyl-bicyclo[3.1.1]hept-2-ene(a-pinene) 72.1
3 13.22 2,2-dimethyl-3-methylene-bicyclo[2.2.1]heptane(camphene) 0.7
5 14.62 6,6-dimethyl-2-methylene-bicyclo[3.1.1]heptane(b-pinene) 2.9
6 15.67 7-methyl-3-methylene-1,6-octadiene (b-myrcene) 16.5
7 16.44 1-methoxy-2-methyl-benzene (o-cresol- methyl-ether) 0.7
8 17.16 1-methyl-4-(1-methylethyl)-benzene(p-cymene) 0.2
9 17.36 1-methyl-4-(1-methylethenyl)cyclohexene (limonene) 1.0
10 21.21 3,7-dimethyl-1,6-octadien-3-ol (linalool) 1.0
11 22.48 2,2,3-trimethyl-3-cyclopentene-1-acetaldehyde(a-campholene aldehyde) 0.3
12 23.10 6,6-dimethyl-2-methylene-bicyclo[3.1.1]heptan-3-ol 0.3
13 23.27 4,6,6-trimethyl-bicyclo[3.1.1]hept-3-en-2-ol <0.1
17 25.79 a,a,4-trimethyl-3-cyclohexene-1-methanol (a-terpineol) 0.1
18 26.07 6,6-dimethyl-bicyclo[3.1.1]hept-2-ene-2-methanol 0.2
19 26.74 4,6,6-trimethyl-bicyclo[3.1.1]hept-3-en-2-one(d-verbenone) 0.2
20 30.41 1-methoxy-4-(1-propenyl)-benzene (anethole) 0.1
21 36.63 4,11,11-trimethyl-8-methylenebicyclo[7.2.0]undec-4-ene(caryophyllene) 1.1
22 38.11 2,6,6,9-tetramethyl-1,4,8-cycloundecatriene(a-caryophyllene or a-humulene) 0.1
23 39.96 1,2-dimethoxy-4-(1-propenyl)-benzene(methyl-isoeugenol) <0.1
Others not identified 1.7
Total 100
D. Daferera et al. / Food Chemistry 77 (2002) 511–515 513
the same sample fluctuated after closing–opening of the
Raman source. Normalization minimizes the effect of
laser power fluctuations (Skoulika et al., 2000). So the
percent relative intensities of 1658 and 1633 cm
1
to the
802 cm
1
cyclohexane were measured for every stan-
dard solution and oil sample. Percent normalized inten-
sities of 1658 cm
1
(I
1
) and 1633 cm
1
(I
2
) were
correlated with a-pinene and b-myrcene contents,
respectively. There were two linear relationships: one
between I
1
and a-pinene content, and a second between
I
2
and b-myrcene (Tables 3 and 4; Figs. 3 and 4).
Empirical equations of calibration curves are,
Table 2
The percentages of a-pinene and b-myrcene in samples from the Chios
gum mastic growers’ association, as determined by GC–MS analysis
Mastic gum oil a-pinene (%) b-myrcene (%)
Oil 1 70.4 22.9
Oil 2 72.8 6.0
Oil 3 65.6 26.9
Oil 4 59.1 33.5
Oil 5 63.2 28.6
Oil 6 54.0 3.8
Oil 7 68.4 25.4
Oil 8 64.9 28.3
Oil 9 71.5 19.4
Oil 10 33.7 63.5
Fig. 2. FT-Raman spectra (1800–600 cm
1
) of mastic gum oil, a-pinene, b-myrcene and cyclohexane.
Fig. 4. The calibration curve of b-myrcene.Fig. 3. The calibration curve of a-pinene.
Table 3
Contents (%) of a-pinene standards correlated with normalized inten-
sity at 1658 cm
1
Content (%)
of a-pinene
(%) Normalized intensity
at 1658 cm
1
S.D. (n=3)
30.0 10.90.4
40.0 13.00.8
50.0 14.50.2
60.0 16.70.6
70.0 19.10.4
80.0 21.80.9
514 D. Daferera et al. / Food Chemistry 77 (2002) 511–515
for a-pinene:
I1¼ð4:20:6Þþð0:21 0:01Þa-pinene ð%Þ
ðr¼0:882;n¼3Þ
for b-myrcene:
I2¼ð3:30:8Þþð1:11 0:03Þb-myrcene ð%Þ
ðr¼0:997;n¼3Þ
The % RSD fluctuated from 1.4 to 6.2% for the cali-
bration curve of a-pinene and 1.3 to 2.9% for the cali-
bration curve of b-myrcene.
Contents (%) of a-pinene and b-myrcene of mastic
gum oils of Chios were measured by using the earlier
empirical equations (Table 5). According to the pro-
posed method, the mastic gum oils contained 38.1–
69.5% a-pinene and 4.5–57.9% b-myrcene. The % RSD
fluctuated from 1.5 to 5.3% for a-pinene and 1.2 to
3.1% for b-myrcene.
The large range of a-pinene and b-myrcene percen-
tages was due to the collection time of resin and the
duration between its exudation from the trunk and the
collection. The concentration of b-myrcene was
increased and exceeded a-pinene in resins collected
immediately (oil 10), decreased to less than 20%, in
resins left to mature physiologically over a maximum
time of 2 months (‘‘oil 1’’, ‘‘oil 2’’, ‘‘oil 6’’, ‘‘oil 9’’) and
was intermediate in other cases: ‘‘oil 3’’, ‘‘oil 4’’, ‘‘oil 5’’,
‘‘oil 7’’, ‘‘oil 8’’.
In conclusion, comparison of the GC–MS and FT-
Raman methods shows that the results are similar. The
quantitative analysis of a-pinene and b-myrcene in gum
oil can be determined by FT-Raman spectroscopy. The
main advantage of this method over the existing GC–
MS method is its simplicity, immediacy, speed and
being non-destructive to the sample.
Acknowledgements
We thank ‘‘The Chios Gum Mastic Growers Asso-
ciation’’ for providing of samples and the Hellenic
Ministry of Development, General Secretarial of
Research and Technology for financial support.
References
Bour, P. (1998). Calculation of the Raman optical activity via the sum-
over-states expansion. Chemical Physics Letters,228, 363–370.
Daferera, D. J., Ziogas, B. N., & Polissiou, M. G. (2000). GC–MS
analysis of essential oils from some Greek aromatic plants and their
fungitoxicity on Penicillium digitatum. Journal of Agricultural and
Food Chemistry,48, 2576–2581.
Freeman, S., & Mayo, D. (1969). Application of laser-excited Raman
spectroscopy to organic chemistry I. Raman spectra of some acyclic
monoterpenes. Applied Spectroscopy,23(6), 610–615.
Hancewicz, T., & Petty, C. (1995). Quantitative analysis of vitamin A
using Fourier transform Raman spectroscopy. Spectrochimica Acta
Part A,51, 2193–2198.
Huwez, F. U., Thirwell, D., Cockayne, A., & Ala’Alden, D. A. A.
(1988). Mastic gum kills Helicobacter pylori. New England Journal
of Medicine,339, 1946.
Magiatis, P., Melliou, E., Skaltsounis, A., Chinou, I., & Mitaku, S.
(1999). Chemical coposition and antimicrobial activity of essential
oils ofPistaca lentiscus var. chia. Planta Medica,65, 749–752.
Papageorgiou, V., Mellidis, A., & Argyriadou, N. (1991). The chemi-
cal composition of the essential oil of mastic gum. Journal of
Essential Oil Research,3, 362–365.
Perikos, J. (1993). The Chios gum mastic. Athens, Greece: Print All
Ltd. Graphic Arts.
Qu, X., Lee, E., Yu, G., Freedman, T., & Nafie, L. (1996). Quantita-
tive comparison of experiential infrared and Raman optical activity
spectra. Applied Spectroscopy,50(5), 649–657.
Skoulika, S. G., Georgiou, C. A., & Polissiou, M. G. (2000). FT-
Raman spectroscopy—analytical tool for routine analysis of diazi-
non pesticide formulations. Talanta,51, 599–604.
Sun, Z., Ibrahim, A., Oldham, P., Schultz, T., & Conners, T. (1997).
Rapid lignin measurement in hardwood pulp samples by near-
infrared transform Raman spectroscopy. Journal of Agricultural and
Food Chemistry,45, 3088–3091.
Table 4
Contents (%) of b-myrcene standards correlated with normalized
intensity at 1633 cm
1
Content (%) of
b-myrcene
(%) Normalized intensity
at 1633 cm
1
S.D. (n=3)
3.0 6.20.1
10.0 14.10.4
18.0 23.80.7
25.0 32.60.5
35.0 41.00.7
45.0 53.30.7
65.0 81.20.3
Table 5
Contents (%) of a-pinene and b-myrcene of mastic gum oils measured
by the FT-Raman spectroscopic method
Mastic
gum oil
Normalized
intensity
at 1658 cm
1
Normalized
intensity
at 1633 cm
1
a-Pinene
content (%)
b-Myrcene
content (%)
Oil 1 17.5 23.8 63.31.4 18.5 0.2
Oil 2 18.8 11.3 69.51.9 7.2 0.8
Oil 3 17.8 34.3 64.81.1 27.9 0.7
Oil 4 17.7 39.0 64.33.4 32.2 1.0
Oil 5 16.4 32.5 58.11.2 26.3 0.5
Oil 6 14.5 8.3 49.0 0.8 4.5 0.1
Oil 7 18.1 31.7 66.21.0 25.6 0.6
Oil 8 17.8 33.5 64.81.6 27.2 0.5
Oil 9 16.4 22.4 58.11.7 17.2 0.2
Oil 10 12.2 67.6 38.11.2 57.9 1.7
D. Daferera et al. / Food Chemistry 77 (2002) 511–515 515
... chia essential oils obtained from gums based on data from Scopus, Google Scholar, Pubmed, Web of Science and Chemical Abstracts from 1990 to 2020 using the keywords "mastic gum essential oil" and "Pistatica lentiscus var. chia essential oil" [5,[33][34][35][36][37][38][39][40][41][42]. Mastic essential oils obtained from aerial parts such as leaves, branches, and fruits were excluded from the literature search process. ...
... In this case, soil type and climate zones such as humidity, temperature, and light, might be affecting the chemical profile of MGEOs. Other than environmental conditions, the composition of mastic gum is influenced by extraction methods (Table 2) and the storage duration of mastic gums [36,40,44]. Table 2. Essential oils from the gum of P. lentiscus var. ...
... Table 2. Essential oils from the gum of P. lentiscus var. chia collected from different geographic locations, main components, and extraction methods based on the literature survey from 1990 to 2020 [5,[33][34][35][36][37][38][39][40][41][42]. ...
Article
Full-text available
The essential oils (EOs) were isolated by hydrodistillation from wild and cultivated Pistacia lentiscus L. var. chia—mastic gum tree (Anacardiaceae) from two natural habitats, namely from Cesme–Uzunkoy (1) and Mordogan (2), and one cultivated source, Cesme–Germiyan (3), in Izmir, Turkey. This comparative study evaluated the chemical composition and biological activity of mastic gum essential oils (MGEOs). For this purpose, MGEOs 1–3 were analyzed by gas chromatography–flame ionization detection (GC-FID), gas chromatography–mass spectrometry (GC-MS), and chiral GC for α-pinene. Laboratory assays were conducted to assess for potential in vitro cytotoxicity (multiple in vitro cancer cell lines), antimicrobial properties (five bacterial species and yeast), anti-inflammatory activity (inhibition of inducible nitric oxide synthase, iNOS), and the attraction of Ceratitis capitata (Mediterranean fruit fly, medfly), respectively. Chemical analysis indicated that MGEOs 1 and 2 were rich in α-pinene (56.2% and 51.9%), myrcene (20.1% and 18.6%), and β-pinene (2.7% and 3.1%), respectively; whereas MGEO-3 was characterized by a high level of α-pinene (70.8%), followed by β-pinene (5.7%) and myrcene (2.5%). Chiral GC analyses showed that concentration ratios between (−)/(+)-α-pinene and (−)-α-pinene/myrcene allowed for differentiation between wild and cultivated MGEO sources. In biological assays, MGEOs 1–3 did not exhibit significant antimicrobial effects against the pathogens evaluated and were not strong attractants of male medflies; however, all three MGEOs displayed a dose-dependent inhibition of iNOS, and MGEOs 1 and 2 exhibited selective in vitro cytotoxicity against human cancer cells. These results suggest that wild-type mastic gum oils from Cesme and Mordogan (MGEOs 1 and 2) are potential sources of beneficial products and warrant further investigation.
... Multiple linear regression (MLR) was applied for the quantification of the constituents from their Raman spectra, using the measured spectra of pure compounds as reference. This approach is an alternative to the construction of a calibration curve that is frequently used in the literature [19,26,27], which requires the preparation of standard solutions of known concentrations for each compound to be determined, and thus, requires a larger amount of reference compounds. It is also an alternative to the use of partial least squares (PLS) regression analysis, where the reference set is usually provided by available sample spectra that have been already quantified by another, usually chromatographic, technique [13,18]. ...
... Unlike the case of using PLS for quantification [13,18], which is usually based on data obtained by GC-MS, the current approach relies on data generated by the same technique (Raman spectroscopy), yielding independent results that can be compared with those from other techniques. Furthermore, calibration curves of the reference compounds [19,26,27] are not required, saving materials and time. ...
Article
Full-text available
A novel, inexpensive and simple experimental setup for collecting μ-Raman spectra of volatile liquids in very small quantities was developed. It takes advantage of capillary forces to detain minute volatile liquid volumes. Spectra of volatile and even scattering or absorbing media can be measured more effectively. The method is used to facilitate the collection of intensity-consistent Raman spectra from a series of reference compounds present in Origanum essential oils, in order to quantify their constituents by multiple linear regression. Wild grown Origanum plants, collected from five different regions in Greece and taxonomically identified as O. onites, O. vulgare subsp. hirtum and O. vulgare subsp. vulgare, were appropriately distilled to acquire their essential oils. Comparison of the Raman results with those from headspace gas chromatography–mass spectrometry (HS GC-MS) confirmed the successful relative quantification of the most abundant essential oil constituents, highlighting the similarities and differences of the three Origanum taxa examined. Finally, it is demonstrated that directly measuring the leaf peltate glandular hairs yields exploitable results to identify the main components of the essential oil they contain, underlining the potential of in situ (field or industry) measurements utilizing microscope-equipped portable Raman spectrometers.
... Analysis, Extraction, and Quantification of β-Myrcene β-Myrcene is considered an important intermediate compound which can be derivatized to produce numerous end products, such as, citronellol, citronellal, geraniol, nerol and linalool (2). Several methods of determining β-myrcene content have been published and developed to achieve more simple, rapid and efficient quantitative analytical methods ( Table 2) (55,58). Naturally, β-myrcene exists as complex mixtures with other monoterpenes. ...
... Controlling these factors can produce a highly efficient and reproducible method for extraction and analysis of β-myrcene. Fourier transform Raman Spectroscopy has also been used to determine the percentage of β-myrcene in mastic gum oil based on band intensity measurements (55). The method is extremely rapid, simple and non-destructive for the sample. ...
Article
Full-text available
Myrcene (β-myrcene) is an abundant monoterpene which occurs as a major constituent in many plant species, including hops and cannabis. It is a popular flavouring and aroma agent (food additive) used in the manufacture of food and beverages. This review aims to report on the occurrence, biological and toxicological profile of β-myrcene. The main reported biological properties of β-myrcene—anxiolytic, antioxidant, anti-ageing, anti-inflammatory, analgesic properties—are discussed, with the mechanisms of activity. Here we also discuss recent data regarding the safety of β-myrcene. Overall, β-myrcene has shown promising health benefits in many animal studies. However, studies conducted in humans is lacking. In the future, there is potential for the formulation and production of non-alcoholic beers, functional foods and drinks, and cannabis extracts (low in THC) rich in β-myrcene.
... CMO constitutes approximately 3% of the resin weight when harvested by the traditional way and about 13% when harvested in a fluid form [38]. The chemical composition of the essential oil has been studied mainly by the GC-MS and GC-FID techniques [38][39][40]. ...
Article
Full-text available
Chios Mastic Gum (CMG) and Chios Mastic Oil (CMO) are two unique products of the tree Pistacia lentiscus var. Chia, cultivated exclusively on the Greek island of Chios. In the present study, the method proposed by the European Pharmacopoeia for mastic identification was employed using HPTLC together with an in-house method. A GC-MS methodology was also developed for the chemical characterization of CMOs. α-Pinene and β-myrcene were found in abundance in the fresh oils; however, in the oil of the aged collection, oxygenated monoterpenes and benzenoids such as verbenone, pinocarveol, and α-campholenal were found at the highest rates. Additionally, the antimicrobial activity of Chios Mastic Gums (CMGs) with their respective Chios Mastic Oils (CMOs) was evaluated, with growth tests against the fungi Aspergillus nidulans, Aspergillus fumigatus, Candida albicans, Mucor circinelloides, and Rhizopus oryzae, and the bacteria Escherichia coli, Pseudomonas aeruginosa and Bacillus subtilis, with the samples exhibiting a moderate activity. To our knowledge, this is the first time that an HPTLC method is proposed for the analysis of mastic and its essential oil and that a standardized methodology is followed for the distillation of CMO with a parallel assessment of the ageing effect on the oil’s composition.
Article
In this study, the Restoration color of three manufacturers (Companies A, B, and C) used for retouching are selected, and the differences in paint properties based on the resin type used by each manufacturer as the medium are compared. The results indicate that the paint produced by each manufacturer differs in terms of the ingredients, color development characteristics, durability, and reversibility. The paint by Company A (binder: mastic resin) shows the best reversibility; however, it exhibits significant discoloration and numerous cracks after deterioration, as well as chalking in some colors. The paint by Company B (binder: acrylic resin) is superior to those of other manufacturers in terms of discoloration and cracking, although its reversibility is unsatisfactory. The paint by Company C (binder: aldehyde resin) shows significant discoloration, and small holes are observed on the sample surface after deterioration. The results are consistent with the deterioration characteristics of the resin used as the medium; additionally, the restoration color differs in terms of durability and reversibility depending on the resin used as the medium. It is expected that the above results can be used not only as essential reference data when selecting materials for retouching, but also to predict problems that may appear in the restoration part of the work using Restoration color and to come up with management measures.
Chapter
This chapter introduces plant-derived solvents production and purification methods. The plant-derived solvents are classified as sustainable, bio-based, green solvents. Therefore, at first, the importance and classification of green solvents are presented. Then some of the sustainable solvents that are renewable and environmentally friendly, which called bio-based solvents are introduced. Next, the details of the most important bio-based solvents derived from plants, such as their sources, chemical structure, and the uses are reviewed. Finally, the purification methods for the plant-derived solvents are extensively discussed.
Chapter
The use of petrochemical solvents in the extraction of phytochemicals from plants and natural sources has recently become worrisome despite its huge popularity. Their severe health implications and environmental impact have led to the search for better, safer, and more environmentally friendly alternative solvents—green solvents. Limonene obtained from citrus peel serves as a better alternative compared to the organic nonpolar solvents employed in the extraction of bioactive phytochemicals. This chapter elucidates a concise theoretical background on its biological sources, physicochemical properties, structural chemistry, medicinal, and nutraceutical benefits as well as its pharmaceutical and industrial applications.
Article
Background: Mastisol Liquid Adhesive is widely used on the skin, especially after surgical procedures. It contains gum mastic, gum storax, methyl salicylate, and ethanol. Objective: The aims of the study were to review our experience patch testing patients allergic to Mastisol and to assess coreacting substances. Methods: We identified 18 patients who were allergic to Mastisol. Most of these had a history of postoperative or cardiac electrode dermatitis and underwent patch testing with multiple surgically related substances, including ingredients of Mastisol, compound tincture of benzoin, and fragrance-related ingredients and botanicals. Results and conclusions: Among Mastisol-allergic patients, 13 (72%) of 18 were allergic to gum mastic, whereas 7 (44%) of 16 were allergic to gum storax. There was frequent coreactivity with various fragrance-related materials, including Majantol, Styrax benzoin, Myroxylon balsamum, Myroxylon pereirae, propolis, and others. Two gum mastic-allergic patients had positive patch tests with hydroperoxides of linalool and several other linalool-containing essential oils. As gum mastic contains linalool, it may explain some gum mastic reactions. Among patients without a history of postoperative contact dermatitis, 1 (0.4%) of 250 was patch test positive for gum mastic. This patient had allergic contact dermatitis from fragrances, so the gum mastic reaction was likely a true-positive relevant reaction.
Chapter
Full-text available
Azadirachta indica is native to the Indian subcontinent. Neem oil is a golden to dark-brown liquid with a strongly unpleasant and offensive odor and is obtained from fruits, seeds, and flowers of the neem tree. It contains fatty acids, limonoids, vitamin E, triglycerides, antioxidants, and calcium. This plant is very important in many sectors including agriculture and medicine. Pusa neem golden urea is an agrochemical which is a mixture of neem oil and urea, and is used for inhibiting nitrification. Neem oil can be used as a green solvent because it is eco-friendly and its residues degrade quickly in the environment. The neem seed contains up to 40% oil and has high potential for production of biodiesel. There are many methods for extracting neem oil but the most commonly used method is solvent extraction because it extracts clear oil with high yield as compared to other methods. Considering its importance, the United Nations declared the neem tree as the tree of the 21st century. Extensive research is being carried out around the world to reveal the benefits of this divine tree.
Article
The chemical composition, vibrational spectroscopy and DFT studies of the essential oils from Lippia sidoides constituents were performed in this study. The harvesting time periods greatly affect the yields of the essential oil extracted from the leaves of the Lippia sidoides plant material. The chemical composition of the essential oil by gas chromatography coupled to mass spectrometry (GC-MS) showed thymol as the main constituent of the essential oil. Through Fourier transform Raman (FT-Raman) and attenuated total reflection infrared (ATR-IR) spectroscopy measurements exhibited a good agreement of the thymol component from the essential oil and the polycrystalline thymol. The Density Functional Theory (DFT) calculations were performed over the molecular structure of the thymol and predicted its Raman and infrared spectra. A good correlation between the experimental spectra of the essential oil and the thymol was observed. Complete assignments of the normal modes were presented for both Raman and infrared spectra of the thymol.
Article
A new ab initio calculational method for simulations of the Raman optical activity spectra is proposed. The method is based on the sum-over-states formalism (SOS). Unlike the finite difference coupled-perturbed calculations (CP) used previously, the new scheme provides analytical derivatives of the polarization tensors and is less demanding with respect to the computer power. Although the new method is not suitable for accurate benchmark calculations, similar accuracy of the SOS and CP results was observed for the spectra of α-pinene and trans-pinane.
Article
Infrared vibrational circular dichroism (VCD) and vibrational Raman optical activity (ROA) have been measured and compared quantitatively over the frequency range from 835 to 1345 cm-1 for trans-pinane, cis-pinane, α-pinene, and β-pinene. For these molecules in this region of spectral overlap between VCD and ROA, the average ratio of VCD or ROA to its parent vibrational intensity favors ROA by a factor of two to three. Several vibrational modes in each molecule yield both large VCD and large ROA, while several other modes show little propensity toward significant VCD or ROA intensity. Beyond this general property of a few strongly chiral and strongly achiral vibrational modes, little additional correlation between VCD and ROA intensity is found. This quantitative compilation of VCD, infrared, ROA, and Raman intensities provides an experimental basis for computational intensity studies of VCD, ROA, and their theoretical comparison.
Article
Laser-Raman spectra of 12 acyclic terpenoids has been recorded. Assignments were made for stretching mode vibrations of carbon-carbon double bonds by comparison with infrared spectra. The results of intensity and depolarization studies are discussed.
Article
The essential oil, which was obtained by steam distillation from two qualities of mastic gum, was subjected to analysis by GC and GC/MS. It was found that the oil contained 62 constituents, 61 of which were identified. The main components were α-pinene (58.86–77.10%), camphene (0.75–1.04%), β-pinene (1.26–2.46%), myrcene (0.23–12.27%), linalool (0.45–3.71%), and β-caryophyllene (0.70–1.47%). These six components total more than 90% of the oil. Some qualitative and quantitative differences were found between the two oils.
Article
FT-Raman spectroscopy is used for rapid quantification of hardwood pulp lignin. The ratio of the integrated area of the lignin band near 1600 cm-1 to that of cellulose in the region of 1200−1010 cm-1 behaves linearly with measured κ number for two separate sets of kraft hardwood pulp samples. Spectra and quantitative results of the hardwood samples, both with and without base line correction, are compared. Sources of error and measurement reproducibility are discussed. The method described shows potential for at-line process analysis of wood pulp. Keywords: FT-Raman spectroscopy; wood pulp; lignin; κ number
Article
A computationally convenient and reasonably accurate scheme of computation of the Raman Optical Activity (ROA) is presented and tested on model examples. Electromagnetic tensors were obtained using the sum-over-states (SOS) methodology, while their nuclear derivatives were estimated through numerical differentiation. An origin dependence of the results was overcome by a distributed origin gauge transformation. Becke-3LYP functional and corresponding Kohn–Sham orbitals are used for the excited states. The method was compared to a benchmark coupled-perturbed (CP) calculation on formamide and a standard ROA spectral simulation and experiment for α-pinene. Spectra of four standard peptide conformations (α-helix, 310-helix, coil, and β-sheet) were simulated with smaller fragments and compared to previous experimental observations. © 2001 John Wiley & Sons, Inc. J Comput Chem 22: 426–435, 2001
Article
FT-Raman spectroscopy based on band intensity and band area measurements, was used for the quantitative determination of diazinon in pesticide formulations. Bands at 554, 604, 631, 1562 and 2971 cm−1 were used for calibration. Spectra were acquired by averaging 100 scans at a resolution of 4 cm−1. Calibration curves were linear (correlation coefficients, 0.992–0.9992 and 0.99–0.999 for band intensity and band area measurements, respectively) in the range of 0.2–3.5 M for 554 and 2971 cm−1, 0.3–3.5 M for 604 cm−1, 0.6–3.5 M for 1562 cm−1 and 1.0–3.5 M for 631 cm−1 bands. Normalization of calibration curves against the 802 cm−1 cyclohexane band improved their long term stability and minimized the effect of laser beam power fluctuations. No interference was found by commonly used surfactants and the proposed method was applied to the analysis of diazinon formulations. Results obtained compare well as indicated by the t-test, with those obtained by the HPLC reference method. Precision ranged between 0.2–7.8 and 0.1–7.2% RSD, (n=4) for band intensity and band area measurements, respectively. The proposed method is rapid, simple and safe, as toxic samples are analyzed ‘as received’ without sample pre-treatment, permiting the routine analysis of pesticides formulations.
Near infrared Fourier transform Raman spectroscopy has been successfully used to quantitatively analyze vitamin A additives in a sorbitan mono-oleate base vehicle. Although measurements can be made on the raw materials, their high viscosity causes them to be difficult to handle in an industrial testing lab. Accurate quantitation is possible using a simple dilution of the sample. This reduces the overall measurement time by speeding up preparation and clean-up. Results are quantified over a range of 0.05 ml−1 up to 1 mg ml−1 using a partial least-squares analysis model. A discussion is made of factors affecting quantitative analysis using FT Raman instrumentation in an industrial environment. Application of the multiplicative scatter correction (MSC) as a pretreatment step for Raman data is discussed with reference to the partial least squares (PLS) calibration. A discussion is presented to the information imbedded in the latent PLS factors and how analysis of these factors can often add to an understanding of the chemical information being modeled.