Headspace Gas Chromatography Research Articles

Deep eutectic solvents as green and sustainable diluents in headspace gas chromatography for the determination of trace level genotoxic impurities in pharmaceuticals

Genotoxic impurities (GTIs) are potential carcinogens that need to be controlled down to ppm or lower concentration levels in pharmaceuticals under strict regulations. The static headspace gas chromatography (HS-GC) coupled with electron capture detection (ECD) is an effective approach to monitor halogenated and nitroaromatic genotoxins. Deep eutectic solvents (DESs) possess tunable physico-chemical properties and low vapor pressure for HS-GC methods. In this study, zwitterionic and non-ionic DESs have been used for the first time to develop and validate a sensitive analytical method for the analysis of 24 genotoxins at sub-ppm concentrations. Compared to non-ionic diluents, zwitterionic DESs produced exceptional analytical performance and the betaine : 7 (1,4- butane diol) DES outperformed the betaine : 5 (1,4-butane diol) DES. Limits of detection (LOD) down to the 5-ppb concentration level were achieved in DESs. Wide linear ranges spanning over 5 orders of magnitude (0.005–100 µg g−1) were obtained for most analytes with exceptional sensitivities and high precision. The method accuracy and precision were validated using 3 commercially available drug substances and excellent recoveries were obtained. This study broadens the applicability of HS-GC in the determination of less volatile GTIs by establishing DESs as viable diluent substitutes for organic solvents in routine pharmaceutical analysis.

Detection and Comparison of Volatile Organic Compounds in Four Varieties of Hawthorn Using HS-GC-IMS

Hawthorn is a type of natural food with significant medicinal and nutritional properties; it has been listed in the “Both Food and Drug” list by the Chinese Ministry of Health Item List since 1997. However, hawthorn varieties have complex origins, and there are significant differences in the content, type, and medicinal efficacy of the chemically active ingredients in different varieties of hawthorn. This leads to the phenomenon of mixed varieties and substandard products being passed off as high-quality. In this work, by using headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS), we identified and analyzed volatile organic compounds (VOCs) in four varieties of hawthorn, establishing their characteristic fingerprints. As a result, a total of 153 peaks were detected, and 139 VOCs were also identified. As shown by the fingerprint profiles, the different hawthorn samples contained different VOCs. Meanwhile, by using principal component analysis (PCA), Euclidean distance, and partial least-squares discriminant analysis (PLS-DA), the relationship between the VOCs found in the different varieties of hawthorn was revealed. This study developed a simple, fast, accurate, and sensitive method for identifying, tracking, and evaluating hawthorn varieties.

High-Throughput CO2 Solubility Measurement in Miscible and Liquid–Liquid Phase Separation Types of Amine Solvent Using Headspace Gas Chromatography

High-Throughput CO₂ Solubility Measurement in Miscible and Liquid–Liquid Phase Separation Types of Amine Solvent Using Headspace Gas Chromatography

Determination of the oil absorption value of inorganic powder by tracer-assisted headspace gas chromatography

This paper reports a method for determining the oil absorption value of inorganic powder based on tracer-assisted headspace gas chromatographic (HS-GC) technique. The method was carried out by adding 25 μL droplet of toluene-Dioctyl Phthalate solution onto the surface of 1.0 g inorganic powder, then sealing the headspace vial and shaking it to make the powder spherical. The amount of toluene that not been adsorbed by inorganic powder was quantified using HS-GC with the optimal equilibrium temperature and time conditions of 100 °C and 7 min, respectively. A new mathematical model shows that the oil absorption value can be determined from the signal of toluene. The results show that the employed method has good precision (the relative standard deviation < 3.6 %) and accuracy (R2 = 0.993). This method is simple and accurate, and can be an reliable tool for testing the oil absorption value of inorganic powder sample.

Purification and use of crude green glycerol from the transesterification of triglycerides in the formulation of an alcohol gel hand sanitizer

The aim of this study was to produce an alcohol gel hand sanitizer containing green glycerol. Crude glycerol was purified using chemical and physical treatments. The sanitizer was prepared using 71.100 g of 99.3° GL ethanol, 28.0 g H2O, 0.5 g of Carboxypolymethylene [Carbopol 940® or Carbomer], 5 drops of triethanolamine (pH 5–7), and glycerol (1.5% w/w). The thermal behavior of the ethanol, carbopol, triethanolamine, glycerol, and alcohol gels were evaluated using Thermogravimetry and Differential Thermal Analysis. The apparent viscosity was obtained using a rotary viscometer. The determination of in vitro spreadability was achieved by an adaptation of the Knorst method. The ethanol content was measured by headspace gas chromatography using a flame ionization detector. The thermal behavior of the gels was influenced by the presence of glycerol, which confirms the possible network interactions formed. The relative densities of the samples were between 0.887 and 0.890 g/cm3. No alteration of the pH of the formulation resulted from the incorporation of glycerol. The apparent viscosities of the alcohol gels were greater than 20,000 cP. No alteration in the in vitro spreadability of the gel alcohol (530.6 mm2) resulted from the addition of glycerol. Hand sanitizer was produced using glycerol from a transesterification reaction. It represents an alternative use for the glycerol being produced in biodiesel processes. The product satisfied the requirements of WHO that preconize a formulation containing 1.45% glycerol as an humectant to protect skin against dryness and dermatitis.

Comprehensive volatile composition of vegetative parts of Bunium persicum B. Fedtsch.: Spice of alpine Himalaya

In the present study, headspace gas chromatography coupled with mass spectrometry (HS–GC/MS) was applied to profile volatile components of Bunium persicum samples (rhizomes, roots, stems, leaves, flowers and unripe & ripe seeds), which were collected from two locations of Indian alpine Himalaya. Thirty-six different volatile metabolites were characterized in all samples, representing (77.9-96.9%) of the total oils. Extracted volatile oils (VOs) were dominated by monoterpenes (37.9-94.8%), oxygenated monoterpenes (0.1-28.8%) and sesquiterpenes (0.2-24.3%) hydrocarbons. γ-Terpinene (6.0-64.1%), α-terpinolene (1.1-43.7%), p-cymene (0.4-8.9%), o-cymene (1.4-14.8%), sabinene (0.1-12.3%), β-pinene (0.7-14.2%), β-myrcene (1.2-11.0%), limonene (1.3-9.3%), sylvestrene (3.1-7.7%), and cymen-7-al (6.9-10.9%) were key volatile components identified in different parts of B. persicum using HS–GC/MS. These findings revealed a very high quantitative variation of VOs composition among the samples. The multivariate statistical analysis also classified these variations within the plants and their parts at two locations. HS-GC/MS technique can be utilized for the quality assessment and discrimination analysis of B. persicum, especially its essential oil (BEO). Further, essential oils of both the seed samples showed significant antioxidant activity in DPPH and ABTS assay. The current methodology will help to monitor the varietal development and smart agriculture practices as quality perspectives.

A comparison between the enzymatic oxidation method and headspace gas chromatography with a flame ionization detector in the determination of postmortem blood ethanol.

Ethanol is the most commonly encountered substance in forensic toxicology. Determining blood alcohol concentration (BAC) in autopsies accounts for the majority of work in forensic diagnosis. The most common method to assess BAC is the enzymatic oxidation method because of its low cost, easy operation, and high throughput. Still, the elevated lactate and lactate dehydrogenase (LDH) levels in postmortem blood may affect accuracy. This study uses headspace gas chromatography with a flame ionization detector (HS-GC/FID) to assess the interference of lactate and LDH levels on BAC in 110 autopsied blood samples determined by the enzymatic oxidation method. The results showed that lactate and LDH levels in postmortem blood were higher than in normal blood. There was a weak correlation between the lactate levels and BAC difference (r = 0.23, p < 0.05) and a strong correlation between LDH levels and BAC difference (r = 0.67, p < 0.001). The differentiation of BAC between the enzymatic oxidation method and HS-GC/FID was significant (p < 0.001), confirming the interference significantly. All postmortem blood samples with lactate and LDH levels higher than regular lead to a positive error in determining BAC by enzymatic oxidation method. The study results suggest that the HS-GC/FID method should be used to determine BAC in postmortem blood samples instead of the enzymatic oxidation method to avoid mistakes in forensic diagnosis.

Characteristic flavor compounds in Guizhou green tea and the environmental factors influencing their formation: Investigation using stable isotopes, electronic nose, and headspace-gas chromatography ion migration spectrometry

The Guizhou province is a significant contributor to the production of green tea within China. The present study aims to examine the characteristic flavor compounds found in Guizhou green tea and explore the environmental factors that contribute to the development of these unique flavor compounds. Accordingly, headspace-gas chromatography-ion mobility spectrometry (HS-GC-IMS) and electronic nose were employed in conjunction with odor activity value (OAV) analysis to develop an orthogonal projections to latent structures discriminant analysis (OPLS-DA) model that was capable of discerning between the three distinct habitats (QE, QM, QW) of Guizhou green tea based on their flavor constituents. The findings show that the primary constituents contributing to the flavor profile of Guizhou green tea consisted of 3-methyl-2-butenal, butanal, pentanal, linalool, 6-methyl-5-hepten-2-one, dimethyl disulfide, and dimethyl sulfide. Subsequently, the stable isotope technique was employed to examine the growth environmental factors of Guizhou green tea, based on the identification of the flavoring compounds that differentiate green tea from various habitats within the Guizhou province. Accordingly, temperature and sunshine were found to have the greatest impact on the flavor compounds present in Guizhou green tea.

Diversity of fungi and dynamics of ethanol concentration during fermentation of porang (Amorphophallus oncophyllus)

Abstract. Helmi H, Kusmiadi R, Mahardika RG, Karsiningsih E. 2024. Diversity of fungi and dynamics of ethanol concentration during fermentation of porang (Amorphophallus oncophyllus). Biodiversitas 25: 542-552. Fermentation can be an alternative to process porang (Amorphophallus oncophyllus). As one of the fermentation products, ethanol can degrade starch and consequently increase the purity of glucomannan in porang flour. However, ethanol can also inhibit the growth of microorganisms that play a role in fermentation. This study aimed to determine the ethanol concentration and investigate the fungal diversity during the fermentation of porang tubers. Ethanol analysis was analyzed by Headspace Gas Chromatography coupled with flame ionization detection, and Starch content was analyzed by colorimetric method. Fungal metagenome was amplified at the Internal transcribed spacer (ITS) region of nuclear DNA (rDNA) and followed by sequencing using Oxford Nanopore Technology (ONT). The result showed that the ethanol concentration increased during 48 hours of fermentation, followed by decreased starch content. The highest fungal diversity index occurred at 48 hours of fermentation. Ethanol and fungal enzymatic activity can degrade the starch. During fermentation, the Candida parapsilosis population increased until 24 hours after fermentation. Cyberlindnera subsufficiens population increased at 48 hours fermentation until 72 hours fermentation. Fungal diversity and ethanol concentration had decreased at 72 hours of fermentation, so porang fermentation should be stopped at 48 hours. Candida parapsilosis could be the candidate of starter for fermentation porang due to the capability of this species to produce ethanol to degrade starch.

Detection of Adulterated Oregano Samples Using Untargeted Headspace-Gas Chromatography-Ion Mobility Spectrometry Analysis.

Oregano is often adulterated for economic reasons. This fraud mainly consists of adding other species with lower commercial value, such as olive leaves. To ensure the authenticity of oregano, an analytical method based on the analysis of the volatile organic compound (VOC) profile obtained by headspace gas chromatography coupled to ion mobility spectrometry (HS-GC-IMS) was developed and validated. Samples of ecological Mediterranean oregano adulterated with different percentages of two types of olive leaves (cornicabra and manzanilla) were studied using a non-targeted analysis. Moreover, a total of 30 VOCs were identified in the analyzed samples, and 24 compounds could be quantified using calibration curves based on Boltzmann's equation. A chemometric model based on orthogonal partial least squares discriminant analysis (OPLS-DA) was used to detect the adulterated oregano samples, obtaining a 100% validation success rate, and partial least squares (PLS) analysis was used to quantify the percentage of adulterant. Finally, the proposed methodology was applied to 15 commercial oregano samples, resulting in two of them being classified as adulterated with 31 and 43% of olive leaves, respectively.

Measurement uncertainty of blood alcohol concentration (BAC) by headspace gas chromatography: comparison of different strategies

Measurement uncertainty of blood alcohol concentration (BAC) by headspace gas chromatography: comparison of different strategies

A primary study of ethanol production in postmortem liver and muscle tissue of rats

ObjectiveTo study the characteristics of postmortem ethanol production and its relation with alcohol congeners in postmortem rat liver and muscle tissues. MethodPostmortem liver and muscle tissues in Sprague–Dawley rats, from postmortem time interval (PMI) day 0–20, were analyzed via headspace gas chromatograph flame ionization detection to observe production of postmortem ethanol and 5 selected alcohol congeners. Result1. Putrid ethanol production increased gradually to a peak and then decreased with the prolongation of PMI; 2. Acetaldehyde, 1-propanol, and 3-methyl-butyraldehyde were produced along with postmortem ethanol; 1-butanol was only detected from day 11–20; 3. The concentrations of acetaldehyde, 1-propanol and 3-methyl-butyraldehyde was related with ethanol production. Fifteen mathematical models were constructed for putrid ethanol production based on acetaldehyde, 1-propanol, and 3-methyl-butyraldehyde. ConclusionA peak in postmortem ethanol production was identified. The production trends of acetaldehyde, 1-propanol, and 3-methyl-butyraldehyde in the liver, and of 1-propanol in muscle, were consistent with those of ethanol, and could potentially to be used as biomarkers of postmortem ethanol production. Further human samples and data analysis are needed to verify this.

Antioxidant Activity and Volatile Oil Analysis of Ethanol Extract of Phoebe zhennan S. Lee et F. N. Wei Leaves

The medicinal value of P. zhennan has been documented in traditional Chinese medicine books. The aim of this paper was to study the antioxidant activity of alcoholic extracts of P. zhennan leavesusing 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2-phenyl-4,4,5,5-tetramethylimidazolineoxyl-1-oxyl-3-oxide (PTIO) radical scavenging and ferric ion reducing antioxidant power (FRAP) assays. The active components of the leaves were identified via headspace solid-phase microextraction and gas chromatography–mass spectrometry (HS-SPME-GC-MS). The results showed that the scavenging rate of DPPH was 94.67%with an EC50 value of 0.674 mg/mL at a concentration of 2 mg/mL. The maximum scavenging rate was 47.40% at a Trolox equivalent of 0.33 mg TE/mL for PTIO radicals. The FRAP reached 84.80% at 0.20 mg/mL concentration. The results confirmed the strong antioxidant activity of the extracts. Furthermore, 44 compounds, mostly terpenoids, obtained from the alcoholic extracts of P. zhennan leaves were analyzed using HS-SPME-GC-MS and 15 of these compounds had a relative content exceeding 1%. The strong antioxidant activity of the alcoholic extracts of P. zhennan leaves could be attributed to the presence of copaene (33.97%), β-caryophyllene (4.42%), δ-cadinene (11.04%), γ-muurolene (4.78%), cis-calamenene (2.02%), linalool (1.04%), α-pinene (1.46%), borneol acetate (1.5%), and γ-terpinene (0.66%). This study demonstrates the potential medicinal value of alcoholic extracts of P. zhennan leaves.

Discrimination and characterization of volatile organic compounds in Lonicerae Japonicae flos and Lonicerae flos using multivariate statistics combined with headspace gas chromatography-ion mobility spectrometry and headspace solid-phase microextraction gas chromatography-mass spectrometry techniques.

The volatile organic compounds (VOCs) of Lonicerae Japonicae flos (LJF) and Lonicera flos (LF) play a pivotal role in determining their sensory characteristics, medicinal properties, and subsequent impact on market pricing and consumer preferences. However, the differences and specificity of these VOCs remain obscure. Hence, it is crucial to conduct a comprehensive characterization of the VOCs in LJF and LF and pinpoint their potential differential VOCs. In this study, headspace gas chromatography-ion mobility spectrometry (HS-GC/IMS) and headspace solid-phase microextraction gas chromatography-mass spectrometry (HS-SPME-GC/MS) were employed to comprehensively investigate the compositional characteristics and distinctions in VOCs between LJF and LF. Multivariate statistical analysis was used to identify candidate differential VOCs of LJF and LF samples. A total of 54 and 88 VOCs were identified using HS-GC/IMS and HS-SPME-GC/MS analysis, respectively. Primary VOCs detected in LJF include leaf alcohol, (E)-2-hexen-1-ol dimer, 2-octyn-1-ol, and (E)-3-hexen-1-ol. Key VOCs prevalent in LF encompass farnesol, heptanoic acid, octanoic acid, and valeric acid. Multivariate statistical analysis indicates that compounds such as phenethyl alcohol and leaf alcohol were selected as potential VOCs for distinguishing between LJF and LF. This research conducted a comprehensive analysis of the fundamental volatile components in both LJF and LF. It subsequently elucidated the distinctions and specificities within their respective VOC profiles. And this study enables differentiation between LJF and LF through the analysis of VOCs, offering valuable insights for enhancing the quality control of both LJF and LF.

Authenticity assessment of ground black pepper by combining headspace gas-chromatography ion mobility spectrometry and machine learning

Currently, the authentication of ground black pepper is a major concern, creating a need for a rapid, highly sensitive and specific detection tool to prevent the introduction of adulterated batches into the food chain. To this aim, head space gas-chromatography ion mobility spectrometry (HS-GC-IMS), combined with machine learning, is tested in this initial, proof-of-concept study. A broad variety of authentic samples originating from eight countries and three continents were collected and spiked with a range of adulterants, both endogenous sub-products and an assortment of exogenous materials. The method is characterized by no sample preparation and requires 20 min for chromatographic separation and ion mobility data acquisition. After an explorative analysis of the data, those were submitted to two different machine learning algorithms (partial least squared discriminant analysis-PLS-DA and support vector machine-SVM). While the PLS-DA model did not provide fully satisfactory performances, the combination of HS-GC-IMS and SVM successfully classified the samples as authentic, exogenously-adulterated or endogenously-adulterated with an overall accuracy of 90 % and 96 % on withheld test set 1 and withheld test set 2, respectively (at a 95 % confidence level). Some limitations, expected to be mitigated by further research, were encountered in the correct classification of endogenously adulterated ground black pepper. Correct categorization of the ground black pepper samples was not adversely affected by the operator or the time span of data collection (the method development and model challenge were carried out by two operators over 6 months of the study, using ground black pepper harvested between 2015 and 2019). Therefore, HS-GC-IMS, coupled to an intelligent tool, is proposed to: (i) aid in industrial decision-making before utilization of a new batch of ground black pepper in the production chain; (ii) reduce the use of time-consuming conventional analyses and; (iii) increase the number of ground black pepper samples analyzed within an industrial quality control frame.

Analytical methods for detecting butane, propane, and their metabolites in biological samples: Implications for inhalant abuse detection

Worldwide, various inhalants are widely abused for recreational purposes, with butane and propane emerging as among the most commonly misused volatile substances, posing a significant risk of sudden death. The rapid elimination and oxidation of these highly volatile compounds upon inhalation necessitate the identification of butane and propane along with their metabolites in biological samples. Hence, the primary objective of this study is twofold: firstly, to establish a method for analyzing butane, propane, and metabolites, and secondly, to demonstrate the detection window and exposure indicators associated with the inhalation of butane and propane. In pursuit of this objective, we developed analytical methods for the determination of isobutane, n-butane, propane, and their nine metabolites in both blood and urine. Headspace-gas chromatography–mass spectrometry (GC–MS) and solid-phase microextraction-GC–MS were employed for the analyses, demonstrating acceptable precision and accuracy. An animal study revealed that isobutane and n-butane were only detectable below the limit of quantification (LOQ) in rat blood 5 min after exposure. Meanwhile, the three major metabolites—2-methyl-2-propanol, 2-butanol, and 2-butanone—were observed 5 min after exposure but persisted in rat urine even 5 h post-exposure. Additionally, human urine samples identified other metabolites, including acetone, acetoin, and 2,3-butanediol isomers. The presence of specific metabolites corresponding to each inhalant confirmed the abuse of butane and propane. This comprehensive approach provides valuable insights into the detection and assessment of inhalation to these volatile substances.

Dynamic Headspace GC–MS Method to Detect Volatile Extractables from Medical Device Materials

Dynamic Headspace GC–MS Method to Detect Volatile Extractables from Medical Device Materials

Using HS-GC-MS and flash GC e-nose in combination with chemometric analysis and machine learning algorithms to identify the varieties, geographical origins and production modes of Atractylodes lancea

Atractylodes lancea (AL) is argued to be the best botanical source of the atractylodes rhizome (AR), which is used within traditional Chinese medicine. However, in recent years there have been a number of issues around the production and use of AR, including authenticity, confusion, and mislabeling between AL and Atractylodes chinensis (AC) isolates, geographical origins, and production modes. These discrepancies can impact both the quality and commercial value of the crop. In this study, volatile organic compounds from 173 batches of AR isolated from both AL and AC plants were compared using a flash gas chromatography electronic nose (flash GC e-nose) and headspace gas chromatography–mass spectrometry (HS-GC-MS). The flash GC e-nose revealed that the main aromas of AR were spicy, sweety, and fruity, and the flavor differences of Atractylodes lancea from different geographical origins are mainly reflected in sweetness and spicy taste. Furthermore, HS-GC-MS showed that terpenoids are key indicators for determining the quality and further clarifying the origin of AL. Eight terpenoids including 2-pinen-10-ol and β-elemene were higher in abundance in AL than AC; seven terpenoids including α-curcumene and α-pinene were higher in abundance in wild AL than cultivated AL; and there were significantly different quantities of ten terpenoids including agarospirol and β-bisabolene present in samples of AL taken from Jiangsu, Henan and Hubei provinces. Finally, the performance of eight machine-learning algorithms to distinguish between AL and AC, and recognize different regions and production patterns of AL, were compared. Among them, XGBoost had the highest differentiation accuracy of 86.17 ± 7.48%. This study provides a rapid and accurate strategy for addressing quality control and market regulation issues for AL and other industrial crops.

DEVELOPMENT AND VALIDATION OF THE HS-GC-FID METHOD FOR THE QUANTIFICATION OF RESIDUAL SOLVENTS IN DESLORATADINE

Testing for residual solvents is a crucial component of both reference material certification and pharmaceutical quality control. Developing and validating a head space-gas chromatography method for measuring residual solvents in desloratadine in pharmaceutical dosage forms was the aim of the current investigation. To create desloratadine, an active ingredient in pharmaceuticals, the pharmaceutical industry commonly uses organic solvents such as methanol, diethyl ether, dichloromethane, and tetrahydrofuran. A novel technique for measuring residual solvents in desloratadine was created using a flame ionization detector and headspace gas chromatography. HP1 Column (30m×0.53mm, 1.8µm), intake port maintained at 250°C, detector temperature 260°C, oven temperature 190°C, and injection volume 1µl with 1:50 split ratio utilizing nitrogen as a carrier gas at a flow rate of 1ml/min were the optimum chromatographic conditions. Using criteria from the International Conference on Harmonization, the method's linearity, range, detection limit, quantitation limit, accuracy, precision, specificity, system appropriateness, and robustness were all validated. It was determined that the idea was appropriate for determining four distinct residual solvents. The approach is particular, linear, exact, accurate, and sensitive, according to validation data, where recoveries varied from 90 to 110 percent. This thoroughly tested technique has been used to identify any remaining solvents in actual desloratadine bulk samples.

A Static Headspace Gas Chromatography Method for Quantitation of Residual Solvents in Nanoformulations.

Various organic solvents are widely used in the manufacturing, processing, and purification of drug substances, drug products, formulations, excipients, etc. These solvents must be removed to the lowest amount permitted, as they do not possess any therapeutic advantages and may cause undesirable toxicities. Therefore, a rapid and sensitive analytical method for the quantitation of residual solvents is needed. The following chapter presents a static headspace gas chromatographic (HSGC) method for determining the concentration of common residual solvents in various nanoformulations. An efficient and sensitive HSGC method has been developed using PerkinElmer's headspace autosampler/gas chromatographic system with a flame ionization detector (FID) and validated according to the International Conference for Harmonization (ICH) guideline Q3C. The method validation indicates that the method is specific, linear, accurate, precise, and sensitive for the analyzed solvents. The method is suitable for the analysis of 13 residual solvents (methanol, ethanol, acetone, diethyl ether, 2-propanol, acetonitrile, 1-propanol, ethyl acetate, tetrahydrofuran, dichloromethane, chloroform, 1-butanol, and pyridine) and utilizes an Elite 624 Crossbond 6% cyanopropylphenyl, 94% dimethylpolysiloxanes column with helium as a carrier gas.