Multiple responses optimization in the development of a headspace gas chromatography method for the determination of residual solvents in pharmaceuticals

An efficient generic static headspace gas chromatography （HSGC） method was developed, optimized and validated for the routine determination of several residual solvents （RS） in drug substance, using a strategy with two sets of calibration. Dimethylsulfoxide （DMSO） was selected as the sample diluent and internal standards were used to minimize signal variations due to the preparative step. A gas chroma- tograph from Agilent Model 6890 equipped with flame ionization detector （FID） and a DB-624 （30 m × 0.53 mm i.d., 3.00 μm film thickness） column was used. The inlet split ratio was 5：1. The influ- encing factors in the chromatographic separation of the analytes were determined through a fractional factorial experimental design. Significant variables： the initial temperature （IT）, the final temperature （FT） of the oven and the carrier gas flow rate （F） were optimized using a central composite design. Response transformation and desirability function were applied to find out the optimal combination of the chromatographic variables to achieve an adequate resolution of the analytes and short analysis time. These conditions were 30 ℃ for IT, 158 ℃ for FT and 1.90 mL/min for F. The method was proven to be accurate, linear in a wide range and very sensitive for the analyzed solvents through a comprehensive validation according to the ICH guidelines.

Analysis of Residual Solvents in Annatto Extracts Using a Static Headspace Gas Chromatography Method

An analytical method for the quantification of residual solvents in annatto extracts, natural food colorants, was established using a static headspace gas chromatography (HSGC) coupled with a flame ionization detector (FID). As a sample diluent in a headspace sampling, dimethylformamide (DMF) was selected owing to its high capacity for dissolving both bixin-based and norbixin-based annatto extracts. The quantification of residual solvents was performed using the external standard method. The linearity of the calibration curves was assured with relative coefficients (R2) that were greater than 0.999. The recoveries of all standard solvents spiked in the annatto extracts were in the range from 95.1% to 107.1% to verify the accuracy and the relative standard deviation (RSD%) values (n = 3) were in the range from 0.57% to 3.31%. The quantification limits (QL) were sufficiently lower than the limits specified by Joint FAO/WHO Expert Committee on Food Additives (JECFA). With the established HSGC method, six residual solvents (methanol, ethanol, 2-propanol, acetone, ethyl acetate, and hexane) in 23 commercial annatto-extract products that consist of seven bixin-based and 16 norbixin-based products were quantified. The levels of residual ethyl acetate and hexane in all products were lower than the specified limits of JECFA. However, three samples of bixin-based products showed higher levels of residual 2-propanol (approximately 313.9 - 427.7 ppm) than the specified limit. Other bixin products also showed higher concentrations of residual methanol (approximately 166.6 - 394.7 ppm) and residual acetone (approximately 75.2 - 179.8 ppm) than the limits of JECFA. In the case of norbixin-based products, nine samples showed higher levels of residual acetone (approximately 42.6 - 139.5 ppm) than the limits of JECFA. This is the first survey of residual solvents in annatto extracts using the validated HSGC method.

Headspace Solid-Phase Micro-Extraction Gas Chromatography/Mass Spectrometry(HS-SPME-GC/MS)-Based Untargeted Metabolomics Analysis for Comparing the Volatile Components from 12 Panax Herbal Medicines

Quality control of ginseng currently is mainly based on ginsenoside analysis,but rarely focuses on the volatile organic components.In the current work,an untargeted metabolomics approach,by headspace solid-phase micro-extraction gas chromatography/mass spectrometry(HS-SPME-GC/MS),was elaborated and further employed to holistically compare the compositional difference of the volatile components simultaneously from 12 Panax herbal medicines,which included P.ginseng(PG),P.quinquefolius(PQ),P.notoginseng(PN),red ginseng(PGR),P.ginseng leaf(PGL),P.quinquefolius leaf(PQL),P.notoginseng leaf(PNL),P.ginseng flower(PGF),P.quinquefolius flower(PQF),P.notoginseng flower(PNF),P.japonicus(PJ),and P.japonicus var.major(PJvm).Chromatographic separation was performed on an HP-5MS elastic quartz capillary column using helium as the carrier gas,enabling good resolution within 1 h.We were able to characterize totally 259 volatile compounds,including 82 terpenes(T),46 alcohols(Alc),29 ketones(K),25 aldehydes(Ald),21 esters(E),and the others.By analyzing 90 batches of ginseng samples based on the untargeted metabolomics workflows,236 differential ions were unveiled,and accordingly 36 differential volatile components were discovered.It is the first report that simultaneously compares the compositional difference of volatile components among 12 Panax herbal medicines,and useful information is provided for the quality control of ginseng aside from the well-known ginsenosides.

Application Progress of Headspace Gas Chromatography in Analytical Chemistry

This paper briefly expounds the basic principle and classification of headspace gas chromatography,summarizes its application in food analysis,environmental analysis and medical analysis,and forecasts the application prospect of headspace gas chromatography in analytical chemistry in the future.

Effect of Replacement of Headspace Gas on N_2O and CO_2Emissions in Anaerobic Incubation of Soil

To study effect of C2H2 and change of headspace gas on N2O emission, denitrification, as well as CO2emission, slumes of an agricultural soil were anaerobically incubated for 7 da3’s at 25 ℃. Both N2O reduction and CO2 emissions were inhibited by the addition of 100 mL L-1 of C2H2. However, the inhibition to CO2 emission was alleviated by the replacement of headspace gas, and the N2O emission was enhanced by the replacement. Acetylene disappeared evidently from the soil slumes during the incubation. Consequently results obtained from the traditional C2H2 blocking technique for determination of denitrification rate, especially in a long-time incubation, should be explained with care because of its side effect existing in the incubation environments without change of headspace gas. To reduce the possible side effect on the processes other than denitrification, it is suggested that headspace gas should be replaced several times during a long-time incubation.

Determination of Aromatic Components of Rosa davurica Pall. by Headspace Solid Phase Microextraction Combined with GC-MS

[Objectives] To determine the aromatic components of Rosa davurica Pall. [Methods] 42 kinds of aromatic components were identified from the flowers of R. davurica by headspace solid phase microextraction( HS-SPME) combined with gas chromatography-mass spectrometry( GC-MS). The main compounds were alcohols( 54. 88%) and aldehydes( 19. 55%). [Results] The top five components with the highest relative content were phenylethyl alcohol( 12. 69%),geraniol( 9. 85%),citronellol( 8. 80%),nerol( 7. 84%) and 2-n-pentylfuran( 7. 45%). [Conclusions] Headspace solid phase microextraction( HS-SPME) combined with gas chromatography-mass spectrometry( GC-MS) can provide basis for further development and utilization of R. davurica.

Integration of GC-MS Based Non-Targeted Metabolic Profiling with Headspace Solid Phase Microextraction Enhances the Understanding of Volatile Differentiation in Tobacco Leaves from North Carolina, India and Brazil

In this report, gas chromatography-mass spectrometry (GC-MS) based non-targeted metabolomics is used to develop appropriate headspace solid phase microextractions (HS-SPME) to enhance the understanding of volatile complexity of flue-cured tobacco leaves. Non-targeted metabolic profiling of GC-MS shows that the extraction condition of HS-SPME at 100?C for 30 min provides a better metabolite profile than other extraction conditions tested. GC-MS and principal component analyses (PCA) show that among five types of fibers tested, 100 μm polydimethylsiloxane (PMDS), 65 μm polydimethylsiloxane/divinylbenzene (PMDS/DVB) and 75 μm carboxen/polydimethylsiloxane (CAR/ PMS) provide a better reproducible metabolite profile. Based on an appropriate PDMS extraction condition optimized, we use GC-MS analysis and PCA to compare metabolite profiles in flue-cured leaves of tobacco plants grown in North Carolina, India and Brazil, respectively. The resulting data of PCA show that the global metabolic profiles in North Carolina samples are separated from those in Brazil and India samples, two groups of which are characterized by a partially overlapped pattern. Several peaks that were differentially accumulated in samples were annotated to known metabolites by deconvolution analysis, such as norsolanadione, solavetivone and rishtin. Norsolanadione is detected only in Brazil samples. Solavetivone is detected in samples of India and Brazil but not in those of North Carolina. Rishtin is detected in samples of North Carolina and India but not in Brazil samples. These data indicate that not only can a non-targeted metabolic profiling approach enhance the understanding of volatile complexity, but also can identify marker volatile metabolites in tobacco leaves produced in different growth regions.

Volatile components of Rhizoma Alpiniae Officinarum using three different extraction methods combined with gas chromatography-mass spectrometry

Volatile components from Rhizoma Alpiniae Officinarum were respectively extracted by three methods including hydrodistillation, headspace solid-phase microextraction （HS-SPME） and diethyl ether extraction. A total of 40 （hydrodistillation）, 32 （HS-SPME） and 37 （diethyl ether extraction） compounds were respectively identified by gas chromatography-mass spectrometry （GC/MS） and 22 compounds were overlapped, including β-farnesene, 7-muurolene, 2,6-dimethyl-6- （4-methyl-3-pentenyl）bicyclo[3.1.1]hept-2-ene, eucalyptol and cadina-1（10）, 4-diene and so forth, varying in relative contents. HS-SPME is fast, sample saving and solvent-free and it also can achieve similar profiles as those from hydrodistillation and solvent extraction. Therefore, it can be the priority for extracting volatile components from medicinal plants.

Characterization and discrimination of fermented sweet melon juice by different microbial strains via GC-IMS-based volatile profiling and chemometrics

The main purpose of this study was to investigate the effect of different lactic acid bacteria and yeast strains on the volatile composition of fermented sweet melon juice.Headspace gas chromatography-ion mobility spectrometry(HS-GC-IMS)coupled with chemometrics was performed to identify the potential volatiles for the discrimination of different fermented sweet melon juice.In total,70 volatile compounds were found in the fermented sweet melon juices.Of them,45 compounds were annotated according to the GC-IMS database and classified into esters,alcohols,aldehydes,ketones and furans.Results from the multivariate analysis reveal that sweet melon juice fermented by different combinations of microbial strains could be distinctly separated from each other.A total of 15 volatiles with both variable importance in projection value>1 and P<0.05 were determined as potential markers for the discrimination of fermented sweet melon juice.This study confirms the effect of microorganisms on the flavor of the fermented sweet melon juice and shows the potential of HS-GC-IMS combined with chemometrics as a powerful strategy to obtain volatile fingerprints of different fermented sweet melon juice.

Measurement and prediction of isothermal vapor–liquid equilibrium of a-pinene+camphene/longifolene+abietic acid+palustric acid+neoabietic acid systems

The vapor–liquid equilibrium(VLE)data of a-pinene+camphene+[abietic acid+palustric acid+neoabietic acid]and a-pinene+longifolene+[abietic acid+palustric acid+neoabietic acid]systems at 313.15 K,333.15 K and 358.15 K were measured by headspace gas chromatography(HSGC).These data was compared with the predictions value by conductor-like screening model for realistic solvation(COSMO-RS).Moreover,the calculated data of COSMO-RS and Non-Random Two-Liquids(NRTL)models showed good agreement with the experimental data.It was found that the three resin acids inhibited the volatility of a-pinene,camphene and longifolene and resulted in the decrease of total pressure.Moreover,HE(HB)contributes the most to the excess enthalpy and the hydrogen bonding interaction is the dominant intermolecular force of a-pinene,camphene and longifolene with the three resin acids.In addition,the geometric structures optimization and binding energy were obtained by the DFT to further illustrate the hydrogen bonding interaction and the effects of the addition of the three resin acids on the isothermal VLE.

HS-SPME-GC-MS技术分析不同加工阶段的甲鱼腥味成分变化

为研究不同加工方式对甲鱼腥味成分的影响,采用HS-SPME-GC-MS技术对甲鱼预煮、卤制、烘烤不同加工阶段的腥味物质进行分析。结果表明,经NIST/Willey质谱数据库检索和文献对照,新鲜甲鱼共检出48种挥发成分,确定36种成分,包括烃类21种、醛类12种、醇类化合物5种、芳香类5种、羧酸类3种、酮类1种、酯类1种。其中以己醛的百分含量最多,为29.1%,有青草味;庚醛占10.69%,具有强烈的油脂氧化味;壬醛占12.58%,提供鱼腥味;占2.02%的对二甲苯有刺激味;占2.36%的1-辛烯-3-醇具有土腥味。认为己醛、壬醛、庚醛、1-辛烯-3-醇等共同形成了甲鱼的腥味。通过预煮、卤制、烘烤等加工工艺后,腥味成分已减少至只能检测出己醛和壬醛,且含量都不超过1%。表明经预煮、卤制、烘烤等加工可以有效控制甲鱼的腥味。

应用顶空-固相微萃取结合气相色谱-质谱联用技术分析传统锦州虾酱中挥发性物质

传统锦州虾酱是以白虾和乌虾为原料,在高盐条件下经长时间发酵形成海产风味食品。采用HPSPME/GC-MS结合保留指数方法分析虾酱中的挥发性物质,并对萃取条件进行优化。从DVB/PDMS、CAR/PDMS和DVB/CAR/PDMS筛选出最佳萃取头,同时采用正交试验优化SPME参数条件,确定适宜萃取条件为75μm CAR/PDMS萃取头,样品质量为5.0 g,萃取温度为70℃,萃取时间为50 min。对虾酱的风味物质分析得到44种挥发性物质,分别为醛类、酮类、酯类、酸类、酚类、烷烃类、吡嗪类和其他化合物。其中白虾虾酱主要呈香物质是醛类、吡嗪类和酚类等低阈值化合物,3-甲硫基丙醛、四甲基吡嗪和吲哚可能是白虾虾酱有别于乌虾虾酱的特有风味物质。乌虾虾酱主要呈香物质是醛类、酯类、酸类和酚类等低阈值化合物,酸类化合物是乌虾虾酱有别于白虾虾酱特有的风味物质,酯类化合物也可能是乌虾虾酱中风味物质的增味剂。

一种快速测定厌氧污泥活性的顶空气相色谱技术

将含有厌氧污泥的样品放入一顶空样品瓶内,在恒定的温度下平衡,并通过多次顶空抽提的方式对样品瓶中所产生的甲烷量随时间的变化进行气相色谱检测,从而实现厌氧污泥比产甲烷活性的检测。实验表明,多次顶空抽提-气相色谱测定厌氧污泥产甲烷活性的技术用约3h就可以得出厌氧污泥产甲烷的线性规律,其结果与对比试验的数据相近。因而该方法适用于厌氧污泥活性的快速预测,可大大提高相关厌氧污泥活性测定及废水处理领域研究的效率。

林芝松口蘑与红菇蜡伞子实体香气成分比较

研究采用顶空固相微萃取技术联合气质联用技术分别对松口蘑和红菇蜡伞子实体香气成分进行分析测定和比较分析,以期建立准确、快速、高效的鉴别方法。结果显示,松口蘑检测到74种香气成分,红菇蜡伞检测到72种香气成分,松口蘑相较红菇蜡伞检测到特有的香气成分14种,包括乙醛、庚醛等6种醛类,2(5H)-呋喃酮1种酮类,3-苯丙醇1种醇类,正己酸乙酯、丙位戊内酯2种酯类,萜品烯和异松油烯等4个烯烃类;红菇蜡伞相较松口蘑,检测到特有的香气成分16种,包括2-丁基-2-辛烯醛1种醛类,3-羟基-2-丁酮、甲基庚烯酮等4种酮类,丁醇等5种醇类,(1-羟基-2,4,4-三甲基戊-3-基) 2-甲基丙酸酯1种酯类,异丁酸、丁酸等3种羧酸类,邻甲酚1种酚类,乙二醇单丁醚1种醚类,N-甲基吡咯烷酮1种含氮化合物。经过主成分分析,得到红菇蜡伞中的主要特征性香气成分为:己醛、3-羟基-2-丁酮、3-辛烯酮、2-甲烯基丁内酯、异戊酸;松口蘑中为:异戊醛、庚醛、壬醛、2,5,2-三甲基吡嗪、2,6,2-三甲基吡嗪。同时对松口蘑与红菇蜡伞干品挥发性香气成分相对含量对比发现,松口蘑主要香气成分含量关系为醛类>烯烃类>醇类>酯类,红菇蜡伞主要香气成分含量关系为醛类>醇类>烯烃类>酯类。通过松口蘑与红菇蜡伞子实体干品香气成分的比较分析可为市售的2种产品的快速检验鉴别奠定理论基础。

Differential volatile organic compounds in royal jelly associated with different nectar plants

The aim of this work was to distinguish volatile organic compound（VOC） profiles of royal jelly（RJ） from different nectar plants. Headspace solid-phase microextraction（HS-SPME） was used to extract VOCs from raw RJ harvested from 10 nectar plants in flowering seasons. Qualitative and semi-quantitative analysis of VOCs extracts were performed by gas chromatography-mass spectrometry（GC-MS）. Results showed that VOC profiles of RJ from the samples were rich in acid, ester and aldehyde compound classes, however, contents of them were differential, exemplified by the data from acetic acid, benzoic acid methyl ester, hexanoic acid and octanoic acid. As a conclusion, these four VOCs can be used for distinguishing RJ harvested in the seasons of different nectar plants.

Comparison of volatile constituents in two types of mugwort leaves(produced in Qichun and Nanyang) using the headspace GC-MS

Objective： To compare the volatile constituents in mugwort leaves produced in Qichun, Hubei Province and Nanyang, Henan Province. Methods： The volatile constituents were extracted using headspace heating and analyzed using gas chromatography-mass spectrometry （GC-MS）. Then a qualitative analysis was made according to the standard database provided by the National Institute of Standards and Technology （NIST） and the relative contents of each constituent were calculated using the peak area normalization method. Results： A total of 59 compounds were identified from the mugwort leaves from Qichun and 51 compounds were identified from the mugwort leaves from Nanyang. These mainly include monoterpenoids, sesquiterpenoids, C^HvOz and other compounds involving the aldehyde, ketone, alkane and benzene. The mugwort leaves from Qichun and Nanyang share 32 common volatile constituents. The chromatographic peak area of identified compounds accounting for 96.38% of GC-MS total chromatographic peak areain Qichun mugwort leaves, versus 95.54% of that in Nanyang mugwort leaves. Conclusion： The headspace heating extraction combined with GC-MS technology can evidently display similarities and differences of volatile constituents in mugwort leaves produced in different areas and thus provide scientific basis for the quality and screening of mugwort leaves.

Research on Preparation Method of Static Head Space for Volatile Organic Compounds in Drinking Water

[Objective] This research aimed to study the pre-treatment conditions of head space so as to establish a HS-GC determination method, which is suitable for China's conditions, for trace volatile organic compounds in drinking water. [Method]The preparation method of head space was adopted for the volatile organic compounds in drinking water. [Result] The 20 kinds of volatile organic compounds in drinking water all could be detected simultaneously by using HS-GC-FID method,and they all could be separated well. The HS-GC-FID method could analyze the detected substances qualitatively and quantitatively. In addition, this detection method was characterized by larger linear range of concentration, higher precision, higher detection limit and higher recovery rate. [Conclusion] Under certain conditions, HSGC can reduce the loss of volatile organic compound in drinking water and improve the sensitivity of detection. Moreover, the detection results meet the requirements by quality control.

The analysis of volatile flavor components of Jin Xiang garlic and Tai’an garlic

The volatile flavor compounds of Jin Xiang garlic and Tai’an garlic in chemical composition were detected and analyzed and the contents of them were compared and determinated. The volatile constituents of Jin Xiang garlic and Tai’an garlic were compared and analyzed by automatic static headspace and gas chromatography-mass spectrometry. Qualitative analysis of samples was made through the analysis of gas chromatography-mass spectrometry and NIST mass spectral library computer retrieval, and quantitative analysis was made by using area normalization method. The analysis results show that the slight difference of the volatile flavor compounds was detected in different places of origin garlic and Jin Xiang garlic was detected more total sulfur-containing compounds than Tai’an garlic. Meanwhile, the contents of sulfur compounds of the fresh garlic were more than the stored garlic and there were significant differences between them. The tests results indicated that flavor substances’ types were slightly different between Jin Xiang garlic and Tai’an garlic, and regional differences cannot affect the garlic flavor substances type. Jin Xiang garlic has more obvious flavor substances than Tai’an garlic which play a decisive role in the garlic flavor, such as 1,3-dithiane, and allyl trisulfide and allyl disulfide and diallyl tetrasulphide. The result of this research indicates that Automatic static headspace and gas chromatography-mass spectrometry is a fast, easy, efficient and accurate method to analyze and identify the volatile flavor components of garlic.

Study on the Difference between Volatile Constituents of the Different Parts from <i>Elsholtzia ciliata</i>by SHS-GC-MS

In this study, the comparison of Elsholtzia ciliata volatile compounds from the stem (with leaf) and flower was acquired. The volatile compounds of these two parts from Elsholtzia ciliata aerial parts were respectively analyzed by a rapid and convenient static headspace injection technique coupled with gas chromatography-mass spectrometry and the relative contents of each constituent between the two different parts were determined by peak area normalization. 61 compounds were identified in the stem (with leaf) and flower, among which 39 components simultaneously exist. 47 and 53 compounds were separated and identified in the volatile compounds from the different parts of Elsholtzia ciliata, respectively. There were differences among some volatile constituents of the two parts, but the main constituents were all Elsholtzia ketone, caryophyllene, 3-octanol and Dehydroelsholtzia ketone. The most abundant components in the stem (with leaf) included Elsholtzia ketone (84.20%), caryophyllene (4.3%) and 3-octanol (3.11%), while Elsholtzia ketone (88.03%), caryophyllene (3.33%) and 3-octanol (1.53%) were the main components in the flower. 8 single constituents were identified in the stem (with leaf) volatiles including 3-heptanone and linalool, while 14 constituents only including 2-methylbutanoic acid and Perillene have been found in the flower volatiles. Elsholtzia ketone was the main compound, and its concentration was significantly higher than other substances (>80% of the total oils in Elsholtzia ciliata). The study provided an important scientific base for the further utilization of Elsholtzia ciliata resources and may be helpful for systematically understanding the constituents of volatile compounds of Elsholtzia ciliata.

Effects of Grafting on Volatile Compounds in Bitter Gourd Fruit

[Objectives]This study was conducted to explore the effects of grafting on volatile compounds in bitter gourd fruit.[Methods]The volatile compounds and relative contents of grafted and non-grafted fruit were analyzed by headspace solid phase micro-extraction with gas chromatography-mass spectrometry.[Results]There were 59 volatile compounds in Haiyan No.2S,including six unique compounds.There were 58 volatile compounds in Haiyan No.2J,including five unique compounds.[Conclusions]This study provides a scientific basis for further analysis of bitter gourd flavor regulation mediated by grafting.