共查询到20条相似文献,搜索用时 546 毫秒
1.
F. R. van de Voort A. A. Ismail J. Sedman J. Dubois T. Nicodemo 《Journal of the American Oil Chemists' Society》1994,71(9):921-926
A rapid method for the quantitative determination of peroxide value (PV) of vegetable oils by Fourier transform infrared (FTIR)
transmission spectroscopy is described. Calibration standards were prepared by the addition oft-butyl hydroperoxide to a series of vegetable oils, along with random amounts of oleic acid and water. Additional standards
were derived through the addition of mono- and diglyceride spectral contributions, as well as zero PV spectra obtained from
deuterated oils. A partial least squares (PLS) calibration model for the prediction of PV was developed based on the spectral
range 3750–3150 cm−1. Validation of the method was carried out by comparing the PV of a series of vegetable oils predicted by the PLS model to
the values obtained by the American Oil Chemists Society iodometric method. The reproducibility of the FTIR method [coefficient
of variation (CV)=5%)] was found to be better than that of the chemical method (CV =9%), although its accuracy was limited
by the reproducibility of the chemical method. The method, as structured, makes use of a 1-mm CaF2 flow cell to allow rapid sample handling by aspiration. The spectrometer was preprogrammed in Visual Basic to guide the operator
in performing the analysis so that no knowledge of FTIR spectroscopy is required to implement the method. The method would
be suitable for PV determinations in the edible oil industry and takes an average of three minutes per sample. 相似文献
2.
Simone C. Godoy Marco Flôres Ferrão Annelise E. Gerbase 《Journal of the American Oil Chemists' Society》2007,84(6):503-508
A rapid method for the quantitative determination of the hydroxyl value (OHV) of hydroxylated soybean oils by HATR/FTIR spectroscopy
is described. Calibration standards were prepared by the formic acid/hydrogen peroxide method and OH values were determined
by the official method of AOCS Tx 1a-66, covering an analytical range of 3.5–125 mg of KOH/g of sample. A partial least squares
(PLS) calibration model for the prediction of the hydroxyl value (OHV) was developed based on eight different spectral subregions
between 3,150 and 990 cm−1 and combinations of them. On average, 36 samples were used for the modeling and 17 were used for external validation. The
resulting calibration was linear over the analytical range and had a standard deviation of 2.334. Validation of the method
was carried out by comparing the OHV of a series of hydroxylated soybean oils predicted by the PLS model to the values obtained
by the AOCS standard method. A correlation coefficient of R
2 = 0.9843 and RMSEC and RMSEP values of, respectively, 3.393 and 3.643 were obtained. After the calibration of the spectrometer,
the OHV could be obtained in 2–3 min per sample, a major improvement over conventional wet chemical methods. The advantages
of these methodologies are that they do not destroy the sample, have a lower cost, expedite the analysis and do not produce
residues. Therefore, they may yield excellent results when used to quantify OHV of soybean polyols obtained by hydroxylation
reaction. 相似文献
3.
Jacqueline Sedman F. R. van de Voort Ashraf A. Ismail 《Journal of the American Oil Chemists' Society》2000,77(4):399-403
A method for the simultaneous determination of iodine value (IV) and trans content from the Fourier transform infrared (FTIR) spectra of neat fats and oils recorded with the use of a heated single-bounce
horizontal attenuated total reflectance (SB-HATR) sampling accessory was developed. Partial least squares (PLS) regression
was employed for the development of the calibration models, and a set of nine pure triacylglycerols served as the calibration
standards. Regression of the FTIR/PLS-predicted IV and trans contents for ten partially hydrogenated oil samples against reference values obtained by gas chromatography yielded slopes
close to unity and SD of <1. Good agreement (SD<0.35) also was obtained between the trans predictions from the PLS calibration model and trans determinations performed by the recently adopted AOCS FTIR/SBHART method for the determination of isolated trans isomers in fats and oils. 相似文献
4.
F. R. van de Voort A. A. Ismail J. Sedman 《Journal of the American Oil Chemists' Society》1995,72(8):873-880
A rapid Fourier transform infrared (FTIR) method was developed to simultaneously determine percentcis andtrans content of edible fats and oils. A generalized, industrial sample-handling platform/accessory was designed for handling both
fats and oils and was incorporated into an FTIR spectrometer. The system was calibrated to predict thecis andtrans content of edible oils by using pure triglycerides as standards and partial least squares as the chemometric approach. The
efficacy of the calibration was assessed by triglyceride standard addition, by mixing of oils with varyingcis/trans contents, and by analyzing fats and oils of known iodine value. Each of the approaches verified that the FTIR method measured
thecis andtrans content in a reproducible (±0.7%) manner, with the measured accuracies being 1.5% for standard addition and 2.5% for the
chemically analyzed samples. Comparisons also were made to the conventional American Oil Chemists’ Society (AOCS) method for
the determination oftrans isomers by IR spectroscopy. The FTIR-partial least squares approach worked well over a wide range oftrans contents, including those between 0 and 15%. The sample-handling accessory designed for this application is robust, flexible,
and easy to use, being particularly suited for quality-control applications. In addition, the analysis was automated by programming
the spectrometer in Visual Basic (Windows), to provide a simple, prompt-based user interface and to allow an operator to carry
outcis/trans analyses without any knowledge of FTIR spectroscopy. A typical analysis requires less than two minutes per sample. The derived
calibration is transferable between instruments, eliminating the need for recalibration. The integrated analytical system
provides a sound basis for the implementation of FTIR methods in place of a variety of AOCS wet chemical methods when analytical
speed, cost, and environmental concerns are issues. 相似文献
5.
A new method was developed to determine the gossypol content in cottonseed oil using FTIR spectroscopy with a NaCl transmission
cell. The wavelengths used were selected by spiking clean cottonseed oil to gossypol concentrations of 0–5% and noting the
regions of maximal absorbance. Transmittance values from the wavelength regions 3600–2520 and 1900–800 cm−1 and a partial least squares (PLS) method were used to derive FTIR spectroscopic calibration models for crude cottonseed,
semirefined cottonseed, and gossypol-spiked cottonseed oils. The coefficients of determination (R
2) for the models were computed by comparing the results from the FTIR spectroscopy against those obtained by AOCS method Ba
8-78. The R
2 were 0.9511, 0.9116, and 0.9363 for crude cottonseed, semirefined cottonseed, and gossypol-spiked cottonseed oils, respectively.
The SE of calibration were 0.042, 0.009, and 0.060, respectively. The calibration models were cross-validated within the same
set of oil samples. The SD of the difference for repeatability and accuracy of the FTIR method were better than those for
the chemical method. With its speed (ca. 2 min) and ease of data manipulation, FTIR spectroscopy is a useful alternative to standard wet chemical methods for rapid
and routine determination of gossypol in process and/or quality control for cottonseed oil. 相似文献
6.
F. R. van de Voort K. P. Memon J. Sedman A. A. Ismail 《Journal of the American Oil Chemists' Society》1996,73(4):411-416
A unique and rapid Fourier transform infrared (FTIR) spectroscopic method for the determination of solid fat index (SFI) of
fats and oils was developed, which is capable of predicting the SFI profile of a sample in approximately two minutes, without
the need for tempering. Hydrogenated soybean oil samples (n=72), pre-analyzed for SFI by dilatometry, were melted and their FTIR spectra acquired using a 25 μm NaCl transmission flow
cell maintained at 80°C. Approximately half the samples were used for calibration, with the balance used as validation samples.
Partial least squares (PLS) calibrations were developed from selected spectral regions that are associated with thecis, trans, ester linkage and fingerprint regions of the spectrum and related to the dilatometric SFI values obtained at 50, 70, 80,
and 92°F. The calibrations were initially optimized and cross-validated by using the “leave one out” approach, with the accuracy
and reproducibility of the calibration models assessed by predicting the validation samples. The overall cross validation
accuracy of the PLS calibration models was in the order of ±0.71 SFI units over the four temperatures. Week-to-week validation
accuracy and reproducibility was determined to be ±0.60 and ±0.38 SFI units, respectively, the reproducibility being within
the specifications associated with the dilatometric reference method. To facilitate routine “on-line” FTIR analyses, a Visual
Basic program was written to drive the spectrometer, prompt the user to load the sample, calculate, and print the SFI values
determined from the PLS calibrations. As structured, the FTIR method has the potential to serve as a viable substitute for
the traditional dilatometric SFI method, with the elimination of the tempering step reducing analysis time from hours to minutes.
The FTIR approach should also be applicable to the determination of solid fat content if calibrated against solids data obtained
by nuclear magnetic resonance. 相似文献
7.
F. R. van de Voort J. Sedman G. Emo A. A. Ismail 《Journal of the American Oil Chemists' Society》1992,69(11):1118-1123
A simple, rapid and reproducible method of determining the iodine value (IV) and saponification number (SN) for fats and oils
was developed with an attenuated total reflectance/Fourier transform infrared spectrometer and commercially available triglycerides
as calibration standards. Partial least squares was used to determine the spectral regions correlating with the known chemical
IV and SN values, and the calibration set was augmented with additional standards generated by spectral co-adding techniques.
The calibration model obtained was used to analyze commercially available fats and oils with a wide range of IV and SN values,
and the results were compared to the values obtained by American Oil Chemists’ Society methods. With the spectrometer calibrated
and programmed, IV and SN results could be obtained within 2–3 min per sample, a major improvement over conventional wet chemical
methods. 相似文献
8.
The Use of FTIR Spectroscopy and Chemometrics for Rapid Authentication of Extra Virgin Olive Oil 总被引:1,自引:0,他引:1
Abdul Rohman Y. B. Che Man Farahwahida Mohd. Yusof 《Journal of the American Oil Chemists' Society》2014,91(2):207-213
The authenticity of high value edible fats and oils including extra virgin olive oil (EVOO) is an emerging issue, currently. The potential employment of Fourier transform infrared (FTIR) spectroscopy in combination with chemometrics of multivariate calibration and discriminant analysis has been exploited for rapid authentication of EVOO from canola oil (Ca‐O). The optimization of two calibration models of partial least square (PLS) and principle component regression was performed in order to quantify the level of Ca‐O in EVOO. The chemometrics of discriminant analysis (DA) was used for making the classification between pure EVOO and EVOO adulterated with Ca‐O. The individual oils and their blends were scanned on good contact with ZnSe crystals in horizontal attenuated total reflectance, as a sampling technique. The wavenumbers of 3,028–2,985 and 1,200–987 cm?1 were used for quantification and classification of EVOO adulterated with Ca‐O. The results showed that PLS with normal FTIR spectra was well suited for quantitative analysis of Ca‐O with a value of the coefficient of determination (R2) > 0.99. The error, expressed as root mean square error of calibration obtained was relatively low, i.e. 0.108 % (v/v). DA can make the classification between pure EVOO and that adulterated with Ca‐O with one misclassified reported. 相似文献
9.
Stoichiometric determination of hydroperoxides in fats and oils by fourier transform infrared spectroscopy 总被引:1,自引:0,他引:1
K. Ma F. R. van de Voort J. Sedman A. A. Ismail 《Journal of the American Oil Chemists' Society》1997,74(8):897-906
A primary Fourier transform infrared (FTIR) spectroscopic method for the determination of peroxide value (PV) in edible oils
was developed based on the stoichiometric reaction of triphenylphosphine (TPP) with hydroperoxides to produce triphenylphosphine
oxide (TPPO). Accurate quantitation of the TPPO formed in this reaction by measurement of its intense absorption band at 542
cm−1 provides a simple means of determining PV. A calibration was developed with TPPO as the standard; its concentration, expressed
in terms of PV, covered a range of 0–15 PV. The resulting calibration was linear over the analytical range and had a standard
deviation of ±0.05 PV. A standardized analytical protocol was developed, consisting of adding ∼0.2 g of a 33% (w/w) stock
solution of TPP in hexanol to ∼30 g of melted fat or oil, shaking the sample, and scanning it in a 100-μm KCI IR transmission
cell maintained at 80°C. The FTIR spectrometer was programmed in Visual Basic to automate scanning and quantitation, with
the reaction/FTIR analysis taking about 2 min per sample. The method was validated by comparing the analytical results of
the AOCS PV method to those of the automated FTIR procedure by using both oxidized oils and oils spiked with tert-butyl hydroperoxide. The two methods correlated well. The reproducibility of the FTIR method was superior (±0.18) to that
of the standard chemical method (±0.89 PV). The FTIR method is a significant improvement over the standard AOCS method in
terms of analytical time and effort and avoids solvent and reagent disposal problems. Based on its simple stoichiometry, rapid
and complete reaction, and the singular band that characterizes the end product, the TPP/TPPO reaction coupled with a programmable
FTIR spectrometer provides a rapid and efficient means of determining PV that is especially suited for routine quality control
applications in the fats and oils industry. 相似文献
10.
Industrial validation of fourier transform infrared trans and lodine value analyses of fats and oils
J. Sedman F. R. van de Voort A. A. Ismail P. Maes 《Journal of the American Oil Chemists' Society》1998,75(1):33-39
A Fourier transform infrared (FTIR) edible oil analysis package designed to simultaneously analyze for trans content, cis content, iodine value (IV), and saponification number (SN) of neat fats and oils by using calibrations based on pure triglycerides
and derived by application of partial-least-squares (PLS) regression was assessed and validated. More than 100 hydrogenated
rapeseed and soybean samples were analyzed by using the edible oil analysis package as well as the newly proposed modification
of the AOCS IR trans method with trielaidin in a trans-free oil as a basis for calibration. In addition, ∼1/3 of the samples were subsequently reanalyzed by gas chromatography
(GC) for IV and trans content. The PLS approach predicted somewhat higher trans values than the modified AOCS IR method, which was traced to a combination of the inclusion of trilinolelaidin in the calibration
set and the effects of baseline fluctuations. Eliminating trilinolelaidin from the triglyceride standards and the use of second-derivative
spectra to remove baseline fluctuations produced excellent concurrence between the PLS and modified AOCS IR methods (mean
difference of 0.61% trans). Excellent internal consistency was obtained between the IV and cis and trans data provided by the edible oil analysis package, and the relationship was close to that theoretically expected [IV=0.86
(cis + trans)]. The IV data calculated for the GC-analyzed samples matched the PLS IV predictions within 1 IV unit. The trans results obtained by both IR methods were linearly related to the GC data; however, as is commonly observed, the GC values
were significantly lower than the IR values, the GC and IR data being related by a slope factor of ∼0.88, with an SD of ∼0.80.
The concurrence between the trans data obtained by the two FTIR methods, and between the FTIR and GC-IV data, as well as the internal consistency of the IV,
cis and trans FTIR predictions, provides strong experimental evidence that the edible oil analytical package measures all three variables
accurately.
Co-Director, McGill IR Group. 相似文献
11.
Fourier transform infrared (FTIR) spectroscopy with transmission cell is described to predict anisidine value of palm olein.
The calibration set was prepared by mixing the thermally oxidized palm olein and the unoxidized palm olein with certain ratios
(w/w) covering a wide range of anisidine values. A partial least square (PLS) regression technique was employed to construct
a calibration model. This model was further accomplished by a validation step. The standard error of prediction found was
0.51. The precision of this method was shown to be comparable to the accuracy of the American Oil Chemists’ Society method
used for measurement of anisidine value, with coefficient of determination (R
2) of 0.99. The study showed that mid-band FTIR spectroscopy combined with a PLS calibration technique is a versatile, efficient,
and accurate technique for the estimation of anisidine value of palm olein within about 2 min with less than 2 mL of sample. 相似文献
12.
The FTIR spectroscopy method was developed for the determination of hexane residues in palm and groundnut (peanut) oils. The
method was based on horizontal attenuated total reflectance with a ZnSe crystal at 45° at room temperature, and partial least
squares (PLS) statistics were used to derive calibration models. The accuracy of the method was comparable to that of the
AOCS Method Ca 3b-87, with coefficients of determination (R
2) of 0.9866 and 0.9810 for palm and groundnut oils, respectively, and SE of calibration of 3.83 and 4.91, respectively. The
calibration models were validated, and the R
2 of validation and the SE of prediction computed. The SD of the difference for repeatability for the method was comparable
to that for the standard AOCS method when used for palm and groundnut oils. With its speed and ease of data manipulation by
computer software, FTIR spectroscopy has an advantage over present chemical methods, which require preparation of the oil
using toxic solvents before GC. 相似文献
13.
Y. B. Che Man M. H. Moh F. R. van de Voort 《Journal of the American Oil Chemists' Society》1999,76(4):485-490
A rapid direct Fourier transform infrared (FTIR) spectroscopic method using a 100 μ BaF2 transmission cell was developed for the determination of free fatty acid (FFA) in crude palm oil (CPO) and refined-bleached-deodorized
(RBD) palm olein, covering an analytical range of 3.0–6.5% and 0.07–0.6% FFA, respectively. The samples were prepared by hydrolyzing
oil with enzyme in an incubator. The optimal calibration models were constructed based on partial least squares (PLS) analysis
using the FTIR carboxyl region (C=O) from 1722 to 1690 cm−1. The resulting PLS calibrations were linear over the range tested. The standard errors of calibration (SEC) obtained were
0.08% FFA for CPO with correlation coefficient (R
2) of 0.992 and 0.01% FFA for RBD palm olein with R
2 of 0.994. The standard errors of performance (SEP) were 0.04% FFA for CPO with R
2 of 0.998 and 0.006% FFA for RBD palm olein with R
2 of 0.998, respectively. In terms of reproducibility (r) and accuracy (a), both FTIR and chemical methods showed comparable results. Because of its simpler and more rapid analysis, which is less
than 2 min per sample, as well as the minimum use of solvents and labor, FTIR has an advantage over the wet chemical method. 相似文献
14.
Kangming Ma F. R. van de Voort A. A. Ismail Hualong Zhuo Binjing Cheng 《Journal of the American Oil Chemists' Society》2000,77(6):681-685
A Fourier transform infrared (FTIR) spectrometer equipped with an attenuated total reflectance (ATR) sample handling accessory
was used to rapidly monitor the peroxide value (PV) of oils undergoing catalytic oxidation to produce sulfonated fatliquors
used in the leather industry. PV quantitation was based on the stoichiometric reaction of triphenylphosphosphine (TPP) with
hydroperoxides to produce triphenylphosphine oxide (TPPO). By using a germanium ATR accessory that has a very short effective
pathlength, the spectral contributions of the base oil could be subtracted out, eliminating any oil-dependent intereferences
as well as providing a facile means of observing the spectral changes associated with the TPP/TPPO reaction. A calibration
was devised by adding a constant amount of TPP-saturated chloroform to oils containing varying amounts of tert-butyl hydroperoxide (TBHP) to produce TPPO that had a measurable band at 1118 cm−1. this band was linearly related to TBHP concentration and the calibration devised had an SD of ∼3.4 PV over the range of
0–250 PV. The ATR-PV method was standardized and the spectrometer programmed using Visual Basic to automate the analysis.
the automated FTIR-ATR method was found to be a convenient means of tracking PV of oils undergoing oxidation, and the results
correlated well with the PV values obtained using the AOAC iodometric method (r=0.94). The FTIR-ATR PV methodology provides a simple means of monitoring the PV of oils undergoing rapid oxidation and could serve
as a quality-control tool in the production of sulfonated oils for the leather industry. 相似文献
15.
Application of FTIR Spectroscopy for the Determination of Virgin Coconut Oil in Binary Mixtures with Olive Oil and Palm Oil 总被引:1,自引:0,他引:1
Abdul Rohman Yaakob B. Che Man Amin Ismail Puziah Hashim 《Journal of the American Oil Chemists' Society》2010,87(6):601-606
Rapid Fourier transform infrared (FTIR) spectroscopy combined with attenuated total reflectance (ATR) was applied for quantitative
analysis of virgin coconut oil (VCO) in binary mixtures with olive oil (OO) and palm oil (PO). The spectral bands correlated
with VCO, OO, PO; blends of VCO and OO; VCO and PO were scanned, interpreted, and identified. Two multivariate calibration
methods, partial least square (PLS) and principal component regression (PCR), were used to construct the calibration models
that correlate between actual and FTIR-predicted values of VCO contents in the mixtures at the FTIR spectral frequencies of
1,120–1,105 and 965–960 cm−1. The calibration models obtained were cross validated using the “leave one out” method. PLS at these frequencies showed the
best calibration model, in terms of the highest coefficient of determination (R
2) and the lowest of root mean standard error of calibration (RMSEC) with R
2 = 0.9992 and RMSEC = 0.756, respectively, for VCO in mixture with OO. Meanwhile, the R
2 and RMSEC values obtained for VCO in mixture with PO were 0.9996 and 0.494, respectively. In general, FTIR spectroscopy serves
as a suitable technique for determination of VCO in mixture with the other oils. 相似文献
16.
Sarfaraz A. Mahesar Alessandra Bendini Lorenzo Cerretani Matteo Bonoli‐Carbognin Syed Tufail Hussain Sherazi 《European Journal of Lipid Science and Technology》2010,112(12):1356-1362
A rapid Fourier transformed infrared (FTIR) attenuated total reflectance (ATR) spectroscopic method coupled with partial least squares (PLS), was developed to estimate the oxidation degree of extra virgin olive oil (EVOO). The reference values of EVOO oxidation for the FTIR calibration were obtained by the specific absorptions at 232 and 270 nm, due to the presence of conjugated diene (CD) and conjugated triene (CT) groups, as monitored by the UV spectrophotometric determination. Specific washing procedures were applied to the EVOO to obtain EVOOP and EVOOTP samples, without phenolic compounds and without tocopherols and phenols, respectively. To obtain different oxidation degrees covering wide CD and CT ranges, EVOO, EVOOP, and EVOOTP samples were subjected to a forced oxidation at 60°C for 20 days and aliquots of the oils were daily analyzed. Regression of the FTIR/PLS‐predicted CD and CT of individual oxidized oils EVOO, EVOOP, EVOOTP, and all combined oils (EVOOALL) against UV–Visible reference values demonstrated the good quality of the models in terms of R2 and RMSECV values. The results of the study indicated that a strong correlation existed between FTIR and UV–Visible peak intensities. Practical applications: The FTIR‐ATR method coupled with PLS elaboration was developed and applied to predict the oxidation degree of EVOO samples with considerable advantages in terms of simplicity, analysis time, and solvent consumption as compared to the standard method. Moreover, suitable adjustments of the equipment could permit a rapid control at‐line in oil sector. 相似文献
17.
J. Sedman F. R. van de Voort A. A. Ismail 《Journal of the American Oil Chemists' Society》1997,74(8):907-913
An automated protocol for the direct, rapid determination of isolated trans content of neat fats and oils by Fourier transform infrared (FTIR) spectroscopy was devised, based on a simple modification
of the standard AOCS trans method, eliminating the use of CS2 and methylation of low trans samples. Through the use of a commercially available, heated transmission flow cell, designed specifically for the analysis
of neat fats and oils, a calibration (0–50%) was devised with trielaidin spiked into a certified, trans-free soybean oil. The single-beam spectra of the calibration standards were ratioed against the single-beam spectrum of the
base oil, eliminating the spectral interference caused by underlying triglyceride absorptions, facilitating direct peak height
measurements as per the AOCS IR trans method. The spectrometer was preprogrammed in Visual Basic to carry out all spectral manipulations, measurements, and calculations
to produce trans results directly as well as to provide the operator with a simple interface to work from. The derived calibration was incorporated
into the software package, obviating the need for further calibration because the program includes an automatic recalibration/standardization
routine that automatically compensates for differences in optical characteristics between instruments, instrument drift over
time, and cell wear. The modified AOCS FTIR analytical package was evaluated with Smalley check samples for repeatability,
reproducibility, and accuracy, producing SD of ± 0.07, 0.13, and 0.70 trans, respectively, the FTIR predictions being linearly related to the Smalley means (r=0.999; SD=± 0.46), and well within one SD of the Smalley sample means. Calibration transfer was assessed by implementing
the calibration on a second instrument and reanalyzing the Smalley check samples in cells of two different pathlengths (25-
and 50-μm). There were no statistically significant differences between the FTIR trans predictions obtained for the Smalley samples from the two instruments and two cells, indicating that the software was able
to adjust the calibrations to compensate for differences in instrument response and cell pathlength. The FTIR isolated trans analysis protocol developed by the McGill IR Group has the benefit of being based on the principles of an AOCS-approved method,
matches its accuracy, and allows the analysis to be performed on both neat fats and oils, producing trans predictions in less than 2 min per sample. It is suggested that this integrated approach to trans analysis, which requires a minimum level of sample manipulation and operator skill, be considered as a modification of the
proposed Recommended Practice CD14b-95. 相似文献
18.
T. Verleyen R. Verhe A. Cano A. Huyghebaert W. De Greyt 《Journal of the American Oil Chemists' Society》2001,78(10):981-984
A rapid and direct Fourier transform infrared (FTIR) spectroscopic method using a 25-μm NaCl transmission cell was developed
for the determination of free fatty acids (FFA) in six important vegetable oils (corn, soybean, sunflower, palm, palm kernel,
and coconut oils) that differ in fatty acid profile. The calibrations were established by adding either standard FFA (oleic,
lauric acids) or a representative mixture of FFA obtained after saponification of the refined oils. For all oils, up to a
FFA level of 6.5% for coconut oil, the best correlation coefficient was obtained by linear regression of the free carboxyl
absorption at 1711 cm−1. All correlation coefficients were greater than 0.993, and no significant difference between the calibration methods could
be detected. Upon validation of the calibration, no significant difference (α=0.05) between the “actual” and the “FTIR predicted”
FFA values could be observed. The calibration models developed for the six oils differed significantly and indicate the need
to develop a calibration that is specific for each oil. In terms of repeatability and accuracy, the FTIR method developed
was excellent. Because of its simplicity, quick analysis time of less than 2 min, and minimal use of solvents and labor, the
introduction of FTIR spectroscopy into laboratory routine for FFA determination should be considered. 相似文献
19.
Rapid Method for the Determination of Moisture Content in Biodiesel Using FTIR Spectroscopy 总被引:1,自引:0,他引:1
Mohamed E. S. Mirghani Nasreldin A. Kabbashi Md. Zahangir Alam Isam Y. Qudsieh Ma’an F. R. Alkatib 《Journal of the American Oil Chemists' Society》2011,88(12):1897-1904
A new, rapid, and direct method was developed for the determination of moisture content in biodiesel produced from various
types of oils using Fourier transform infrared (FTIR) spectroscopy with an attenuated total reflectance (ATR) element. Samples
of biodiesels used in this study were produced using sludge palm oil (SPO). The calibration set was prepared by spiking double-distilled
water into dried biodiesel samples in ratios (w/w) between 0 and 10% moisture. Absorbance values from the wavelength regions
3,700–3,075 and 1,700–1,500 cm−1, and the partial least square (PLS) regression method were used to derive a FTIR spectroscopic calibration model for moisture
content in biodiesel samples. The coefficient of determinations (R
2) for the models was computed by comparing the results obtained from FTIR spectroscopy against the values of the moisture
concentrations (%) determined using the American Oil Chemists’ Society (AOCS) oven method Ca 2d-25. Same comparison was done
using International Union of Pure and Applied Chemistry (IUPAC) distillation method 2.602. R
2 was 0.9793 and 0.9700 using AOCS and IUPAC methods, respectively. The standard error (SE) of calibration was 1.84. The calibration
model was cross validated within the same set of samples, and the standard deviation (SD) of the difference for repeatability
(SDDr) and accuracy (SDDa) of the FTIR method was determined. With its speed and ease of data manipulation, FTIR spectroscopy
is a useful alternative method to other methods for rapid and routine determination of moisture content in biodiesel for quality
control. 相似文献
20.
M. E. S. Mirghani Y. B. Che Man S. Jinap B. S. Baharin J. Bakar 《Journal of the American Oil Chemists' Society》2002,79(2):111-116
A new analytical method was developed for the determination of soap in palm and groundnut oils by FTIR spectroscopy. Soap
from 0 to 80 mg/kg oil was produced in situ in the oils by adding sodium hydroxide. The FTIR spectroscopy was with a sodium chloride transmission cell, and the partial
least-squares statistical method was used to calibrate a model for each oil. The accuracy of the method was comparable to
that of AOCS Method Cc17-95, with coefficients of determination (R
2) of 0.98 and 0.98 for both palm and groundnut oils. The standard errors of calibration were 1.84 and 1.36 for the two oils,
respectively. The calibration models were cross-validated, and the R
2 of cross-validation and standard errors of cross validation were computed. The standard deviation of the difference for repeatability
of the FTIR method was better than that for the chemical method used for determining soap in palm and groundnut oils. With
its speed and ease of data manipulation by computer software, FTIR spectroscopy is a possible alternative to the standard
wet chemical methods for rapid (2 min) and accurate routine determination of soap in chemically refined vegetable oils. 相似文献