Analytical Characterization of Fatty Acids Composition of Datura alba Seed Oil by Gas Chromatography Mass Spectrometry

Methyl ester derivatives of fatty acids were analyzed for the determination of the constituents of Datura alba seed oil. Gas chromatography coupled to mass spectrometer was used for these analyses. Results delivered that there were saturated as well as unsaturated fatty acids in Datura alba seed oil. Total of 15 different fatty acid components were identified and quantified. Methyl linoleate was found in highest concentration (16.22%) among the identified analytes of interest. In addition methyl esters of Palmitic acid (6.59%), Oleic acid (5.41%) and Stearic acid (1.35%) were found. Concentrations of rest of the detected fatty acids were less than 1%. From the literature it appears that no such work has been performed for the determination of fatty acids in Datura alba seed oil.     

Application of gas chromatography coupled to chemical ionisation mass spectrometry following headspace solid-phase microextraction for the determination of free volatile fatty acids in aqueous samples

Gas chromatography coupled to positive and negative ion chemical ionisation mass spectrometry was evaluated for the determination of free volatile fatty acids (VFAs) from aqueous samples by headspace solid-phase microextraction. Negative ion chemical ionisation in the selected ion monitoring mode using ammonia as reagent gas provided acceptable sensitivity and the highest selectivity for the determination of C2-C7 fatty acids using a polydimethylsiloxane-Carboxen fibre. Detection limits in the range of 150 microg l(-1) for acetic acid and from 2 to 6 microg l(-1) for the remaining carboxylic acids were achieved. The reproducibility of the method was between 9 and 16%. The developed analytical procedure was applied to the analysis of VFAs in raw sewage. The absence of interfering peaks provided a more accurate determination of acetic, propionic, butyric and isovaleric acids than a similar analytical scheme but using a flame ionisation detector.     

Comparison of soxhlet, ultrasound-assisted and pressurized liquid extraction of terpenes, fatty acids and Vitamin E from Piper gaudichaudianum Kunth

This paper describes a comparative study of extraction methods of terpenes (terpenic alcohols and phytosterols), fatty acids and Vitamin E from leaves of Piper gaudichaudianum Kunth. The analysis of extracts was done by gas chromatography with mass spectrometric detection. The identification and quantification was made by co-injections of the extract with certified standards. The use of pressurized liquid extraction (PLE; Dionex trade name: ASE, for accelerated solvent extraction) decrease significantly the total time of extraction, the amount of solvent and the manipulation of sample and solvents in comparison with soxhlet (SE) and ultrasound-assisted (USE). In addition, PLE was more effective for the extractions of terpenes (terpenic alcohols and phytosterols), fatty acids and Vitamin E.     

Studies of structural alterations of humic acids from conifer bark residue during composting by pyrolysis-gas chromatography/mass spectrometry using tetramethylammonium hydroxide (TMAH-py-GC/MS)

Pyrolysis-gas chromatography/mass spectrometry using tetramethylammonium hydroxide (TMAH-py-GC/MS) was used to characterize the humic acids (HAs) produced during the composting of conifer bark. The syringyl to guaiacyl ratios of HAs during composting were estimated from the peak area ratios for 3,4,5-trimethoxy to 3,4-dimethoxy benzene derivatives (0.11–0.50), which are characteristic of conifer species. The peak areas for nitrogen-containing and fatty acid pyrolysate compounds increased significantly during composting, indicating the degree of humification during composting. HA samples from the bark composts contained higher levels of diterpene resin acids, monoterpenes and sesquiterpenes. To investigate the species of terpenes, the HA was extracted with ethanol, and the components of the extract classified into α-HA and hymatomelanic acid (HMA) fractions, respectively. The peak areas for terpenes in the α-HA fraction were much smaller than those in the original HA, indicating that the majority of terpenes were extracted into the HMA fraction. If terpenes were to bind to HMA via unspecified interactions, no peaks would be apparent for the direct injection of HMA in ethanol into the GC/MS without pyrolysis. A comparison of the total ion chromatograms of HMA for the TMAH-py-GC/MS and GC/MS revealed that terpenes in the HA had been incorporated into polymeric structures of HMA. These results indicate that terpenes are transferred from the raw bark and incorporated into HA fractions during the composting processes.     

Comparative study of the whisky aroma profile based on headspace solid phase microextraction using different fibre coatings

A dynamic headspace solid-phase microextraction (HS-SPME) and gas chromatography coupled to ion trap mass spectrometry (GC-(IT)MS) method was developed and applied for the qualitative determination of the volatile compounds present in commercial whisky samples which alcoholic content was previously adjusted to 13% (v/v). Headspace SPME experimental conditions, such as fibre coating, extraction temperature and extraction time, were optimized in order to improve the extraction process. Five different SPME fibres were used in this study, namely, poly(dimethylsiloxane) (PDMS), poly(acrylate) (PA), Carboxen-poly(dimethylsiloxane) (CAR/PDMS), Carbowax-divinylbenzene (CW/DVB) and Carboxen-poly(dimethylsiloxane)-divinylbenzene (CAR/PDMS/DVB). The best results were obtained using a 75 microm CAR/PDMS fibre during headspace extraction at 40 degrees C with stirring at 750 rpm for 60 min, after saturating the samples with salt. The optimised methodology was then applied to investigate the volatile composition profile of three Scotch whisky samples--Black Label, Ballantines and Highland Clan. Approximately seventy volatile compounds were identified in the these samples, pertaining at several chemical groups, mainly fatty acids ethyl esters, higher alcohols, fatty acids, carbonyl compounds, monoterpenols, C13 norisoprenoids and some volatile phenols. The ethyl esters form an essential group of aroma components in whisky, to which they confer a pleasant aroma, with "fruity" odours. Qualitatively, the isoamyl acetate, with "banana" aroma, was the most interesting. Quantitatively, significant components are ethyl esters of caprilic, capric and lauric acids. The highest concentration of fatty acids, were observed for caprilic and capric acids. From the higher alcohols the fusel oils (3-methylbutan-1-ol and 2.phenyletanol) are the most important ones.     

脂肪酸的色谱保留时间规律与质谱特征研究及其在食品分析中的应用

用石油醚提取食品中的脂肪,经甲酯化反应后,采用HP-88(100m×0.25mm,0.33μm)弹性石英毛细管柱分离脂肪酸甲酯的同系物及异构体,GC/MS法测定。研究了不同链长脂肪酸的同系物及异构体的气相色谱出峰顺序,得到其保留时间规律;研究了不同脂肪酸的质谱断裂规律,选择3个特征离子来鉴定脂肪酸成分。建立了3个特征离子确定脂肪酸碳数及双键数目,色谱保留时间规律确定脂肪酸顺反异构体及双键位置异构体的方法。本法无需标准品即可快速测定脂肪酸同系物及异构体的含量,适用于脂肪酸组成的研究;及油脂、食品中脂肪酸,特别是反式脂肪酸的测定。     

Gas chromatography - optical fiber detector for assessment of fatty acids in urban soils

Fatty acids have been used as biomarkers of the microbial community composition of soils and they are usually separated and quantified by gas-chromatography coupled to a flame ionization detector (GC-FID). The aim of this study was to develop, validate and apply a methodology based on gas chromatography coupled to optical fiber detection (GC-OF) for screening five fatty acids used as indicators of fungal and bacterial communities in urban soils. The performance of the GC-OF methodology (optical fiber detector at 1550 nm) was evaluated by comparison with the GC-FID methodology and it was found that they were comparable in terms of linear range, detection limit and analytical errors. Besides these similar analytical characteristics, the GC-OF is much cheaper than the GC-FID methodology. Different concentrations were determined for each fatty acid indicator which in turn varied significantly between the soil samples analyzed from Lisbon ornamental gardens. Additionally, the GC-OF showed a great potential as alternative for determination of eleven or more fatty acids in urban soils.     

Optimization of Fatty Acid Determination in Selected Fish and Microalgal Oils

The use of ten fatty acid methyl ester reference standards coupled with a detailed quantification method was shown to significantly optimize the fatty acid determination of selected fish and microalgal oils when compared to methods that use only one reference standard (C19:0 or C23:0) as a relative response factor. When using the mixture of ten reference standards after transesterifying oils with NaOH/BF₃, determination of total fatty acids, eicosapentaenoic acid and docosahexaenoic acid improved by an average of 7.3, 11.5 and 8.4%, respectively. Furthermore, improvements of 13.9, 18.9 and 6.8% of total fatty acids, EPA and DHA, respectively, were obtained when using the mixture of reference standards for fatty acid determination after directly extracting and transesterifying oil contained in microalgal cells with a mixture of methanol, HCl and chloroform. Fatty acid methyl ester standards dissolved in isooctane showed <5% variability throughout 130 days of stability testing when stored at ?20 °C. The optimized method can be used for improving the quantification of fatty acids in both oils (fish and microalgal oils) and dry microalgal cells.     

Development of a headspace solid-phase microextraction procedure for the determination of free volatile fatty acids in waste waters

An analytical procedure based on headspace solid-phase microextraction (SPME) coupled to GC-flame ionization detection/Negative Chemical Ionization Mass Spectrometry has been developed for the determination of free volatile fatty acids (C2-C7) in waste water samples. Five different coatings have been evaluated and polydimethylsiloxane-Carboxen was the only fiber that allows a successful extraction of the shortest chain fatty acids (acetic and propionic). Several parameters such as extraction time and temperature, desorption conditions, agitation speed and sample volume have been optimized using the polydimethylsiloxane-Carboxen fiber. The linear dynamic range was over two-four orders of magnitude, depending on the acid. Procedural detection limits were in the low to medium microg/l levels and the RSDs were between 5.6% and 13.3%. To evaluate the applicability of the developed SPME procedure on real samples, fermented urban wastewaters were analysed.     

Determination of PAHs, PCBs, minerals, trace elements, and fatty acids in Rapana thomasiana as an indication of pollution

The aim of this investigation was to introduce several analytical methods for determination of polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), minerals, trace elements, and fatty acids in Rapana thomasiana as a marine pollution indicator organism. The chemical differences of the gastropod Ra. thomasiana from polluted and nonpolluted sites of the Black Sea on the Bulgarian coast were investigated. Chromatography and high-resolution inductively coupled plasma/MS analyses were used for evaluation of PAHs, PCBs, fatty acids, minerals, and trace elements. These methods can be applied to other marine products.     

Investigation of Fatty Acid Composition of Ammi majus Seed Oil by Gas Chromatography Mass Spectrometry

The Ammi majus seeds oil constituents of methyl ester derivatives of fatty acids were analyzed using Gas Chromatography coupled to mass spectrometer. The results obtained containing the saturated as well as unsaturated fatty acids of majus seeds oils. A total of 18 different components were identified and quantified. Methyl ester of linoleic acid was found in high concentration 9.00%, among the identified analytes of interest. In addition methyl ester of Oleic acid 5.60%, Palmitic acid 3.98% Linolenic acids 1.42% were found. Concentration of the rest of identified fatty acids analytes were less than 1%. Thus from the results it is apparent that due to the presence of high percentage of valuable analytes concentrations detected in the fatty acid of A. majus, has increased its importance for the consumption in the pharmaceuticals as well as its applications in the new formulations for various skin diseases to prevent and cure from different infections.     

Rapid identification of triterpenoid sulfates and hydroxy fatty acids including two new constituents from Tydemania expeditionis by liquid chromatography-mass spectrometry

Tydemania expeditionis Weber-van Bosse (Udoteaceae) is a weakly calcified green alga. In the present paper, liquid chromatography coupled with photodiode array detection and electrospray mass spectrometry was developed to identify the fingerprint components. A total of four triterpenoid sulfates and three hydroxy fatty acids in the ethyl acetate fraction of the crude extract were structurally characterized on the basis of retention time, online UV spectrum, and mass fragmentation pattern. Furthermore, a detailed liquid chromatography-mass spectrometry analysis revealed two new hydroxy fatty acids, which were then prepared and characterized by extensive nuclear magnetic resonance (NMR) analyses. The proposed method provides a scientific and technical platform for the rapid identification of triterpenoid sulfates and hydroxy fatty acids in similar marine algae and terrestrial plants.     

Ultra-fast screening of free fatty acids in human plasma using ion mobility mass spectrometry

Free fatty acids are involved in many metabolic regulations in the human body. In this work, an ultra-fast screening method was developed for the analysis of free fatty acids using trapped ion mobility spectrometry coupled with mass spectrometry. Thirty-three free fatty acids possessing different unsaturation degrees and different carbon chain lengths were baseline separated and characterized within milliseconds. Saturated, monounsaturated, and polyunsaturated free fatty acids showed different linearities between collision cross-section values and m/z. The establishment of correlations between structures and collision cross-section values provided additional qualitative information and made it possible to determine free fatty acids which were out of the standards pool but possessed the confirmed linearity. The gas-phase separation made the quantitative analysis reliable and repeatable at a much lower time cost than chromatographic methods. The sensitivity was comparable to and even better than the reported results. The method was validated and applied to profiling free fatty acids in human plasma. Saturated free fatty acids abundance in the fasting state was found to be lower than that in the postprandial state, while unsaturated species abundance was found higher. The method was fast and robust with minimum sample pretreatment, so it was promising in the high-throughput screening of free fatty acids.     

漂浮液滴固化分散液液微萃取与高效液相色谱联用检测环境水样中的3种烷基苯酚

建立了漂浮液滴固化分散液液微萃取(DLLME-SFO)方法,以脂肪酸作为萃取剂,以甲醇作为分散剂,与高效液相色谱联用检测了环境水样中3种烷基苯酚。对影响前处理方法的因素进行了详细考察,在最佳萃取条件(60μL萃取剂辛酸、600μL分散剂甲醇、pH值为2.0~8.0、10 mL水样中加入0.5 g NaCl)下,3种烷基苯酚在20~1 500μg/L范围内具有良好的线性关系,相关系数不小于0.998 5,3种目标化合物的检出限为0.45~0.61μg/L,富集倍数为145~169,实际样品中3个水平的加标回收率为80.1%~109.9%。该方法将脂肪酸作为萃取剂,与HPLC联用实现了烷基苯酚的富集与检测,为环境水样中烷基苯酚的检测提供了对环境友好的前处理新方法。     

Determination of selected fatty acids in dried sweat spot using gas chromatography with flame ionization detection

A method is described for the determination of fatty acids in dried sweat spot and plasma samples using gas chromatography with flame ionization detection. Plasma and dried sweat spot samples were obtained from a group of blood donors. The sweat was collected from each volunteer during exercise. Sweat was spotted onto collection paper containing butylated hydroxytoluene. Fatty acids were derivatized with acetyl chloride in methanol to form methyl esters of fatty acids. The fatty acids in dried sweat spot samples treated with butylated hydroxytoluene and stored at –20°C were stable for 3 months. Our results indicate that sweat contains, among fatty acids with short chain, also fatty acids with long chain and unsaturated fatty acids. Linear relationships between percentage content of selected fatty acids in dried sweat spot and plasma were observed.     

Coordination-Ionspray-MS (CIS-MS), a Universal Detection and Characterization Method for Direct Coupling with Separation Techniques

By on-line addition of a central atom (for example, Ag^I, B^III, Pd^II, Li^I) positively or negatively charged complexes of analytes can be formed for CIS-MS. This technique is applicable to both polar and nonpolar compounds—for example, for alcohols, ethers, and a large number of olefins, polyolefins, and arenes as well as steroids, vitamins of the D and E families, carotinoids, polystyrols, terpenes, and unsaturated fatty acids—and can be readily coupled with separation techniques.     

苦丁茶冬青挥发油成分的GC-MS分析

采用乙醚超声萃取-水蒸气蒸馏方法提取苦丁茶冬青的挥发油，用气相色谱-质谱联用分析，鉴定了挥发油中的57个成分，其中主要成分是醇、醛、酮、醚、脂肪酸、脂肪酸酯及含氧萜类等化合物。     

Fast,sensitive and highly discriminant gas chromatography–mass spectrometry method for profiling analysis of fatty acids in serum

A method for the determination of fatty acids in serum based on GC–MS (micro-SIS detection mode) has been developed and the separation and cis/trans isomers have been identified. A prior two-step extraction/derivatization procedure accelerated by ultrasound allows individual determination of esterified (EFAs) and non-esterified fatty acids (NEFAs), and shortening of the derivatization steps to 5 min for EFAs and 15 min for NEFAs. The total analysis time for 39 fatty acids was 61 min. The minimum LOD and LOQ values were 0.002 and 0.006 μg/ml, respectively. The proposed method was validated for EFAs and NEFAs using two different methods and the results show no statistical differences between the proposed method and those used as reference. The proposed derivatization–extraction methodology is suitable for fatty-acid analysis of human serum, and can be applied to nutritional and epidemiological studies.     

Rapid analysis of non-esterified fatty acids as methyl esters from different biological specimens by gas chromatography after one-step esterification

A rapid gas chromatographic method for the determination of medium-chain and long-chain free fatty acids (C14:0 to C24:0 fatty acids) from different biological specimens is presented. After a rapid one-step transesterification method in methanol-acetyl chloride (50:1, v/v), fatty acid methyl esters were extracted into n-hexane and analysed on a 15-m Durabond-Wax column within a 12-min chromatographic run. The detection limit is 500 pg per injection.     

Development and application of an analytical method for the determination of storage lipids, fatty acids and fatty alcohols in Calanus finmarchicus

A method was developed for the determination of the major storage lipids, wax ester and triglycerides, in the copepod Calanus finmarchicus. A variation of the Folch method was used to extract the lipid. The method was scaled down to enable the extraction of either pooled (-1 mg) or individual (approximately 200 microg) copepods. The major lipid classes were identified using TLC and quantified using HPLC coupled with evaporative light scattering detection. Analysis of laboratory reference materials indicated that this method underestimated the minor triglyceride component, but gave a good estimate of the major wax ester component. The fatty acid and fatty alcohol composition of the C. finmarchicus were determined following trans-esterification of the lipid extract in methanol. Fatty acids and fatty alcohols were initially identified by comparison with authentic standard and by mass spectroscopy. Using GC with flame ionisation detection the normalised area percentage of the fatty alcohols and fatty acid methyl esters was determined simultaneously in one run for either pooled or individual copepod samples. These methods were applied to C. finmarchicus collected from the Irminger Sea, North Atlantic in 2001 and 2002.