Headspace Gas Chromatographic Technique Research Articles

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.

Method Development and Validation for the estimation of Class-2 Residual Solvents in Valacyclovir by HS-GC

A simple headspace gas chromatographic (HS-GC) is a novel approach for the simultaneous detection of residual solvents such as ethanol has been devised and validated. Valacyclovir in ethanol, acetone, isopropyl alcohol, toluene, and acetic acid utilizing nitrogen as the carrier gas at a 4 mL/min flow rate with DB-620 column (80mx0.22mm) 1.8m inner diameter by using a flame ionization detector (FID). The headspace gas chromatographic technique provides an acceptable symmetry and resolution for all these residual solvents. The suggested method was shown to be satisfactory for determining the residual solvents of five distinct types. The method's validation findings showed that it is specific, exact, accurate, rugged, linear, and robust, with recoveries ranging from 80-120%. The %RSD (Relative Standard Deviation) for six injections should be NMT-10%. The correlation coefficient R2 ≥ 0.999.

Calculation and application of partition coefficients of light hydrocarbons in oil-based mud system

To find out the relationship between the oil-based mud, the formation fluid and the extracted gas, we use a thermodynamic approach based on static headspace gas chromatography technique to calculate the partition coefficients of 47 kinds of light hydrocarbons compounds between nC5 and nC8 in two kinds of oil-based mud-air systems, and reconstruct the original formation fluid composition under thermodynamic equilibrium. The oil-based drilling mud has little effect on the formation fluid compositions in the range of nC5–nC8 (less than 1% for low-toxicity oil-based mud and less than 10% for oil-based mud). For most light hydrocarbon compositions, the partition coefficients obtained by vapor phase calibration and the direct quantitative methods have errors of less than 10%, and the partition coefficients obtained by direct quantitative method are more accurate. The reconstructed compositions of the two kinds of crude oil have match degrees of 91% and 89% with their real compositions, proving the feasibility and accuracy of reconstructing the composition of original formation fluid by using partition coefficients of light hydrocarbon compositions between nC5 and nC8.

Identification of the Organic Volatile Impurities in Telmisartan Active Pharmaceutical Ingredient and Its Pharmaceutical dosage forms by using Head Space Gas Chromatography Technique

Identification of the Organic Volatile Impurities in Telmisartan Active Pharmaceutical Ingredient and Its Pharmaceutical dosage forms by using Head Space Gas Chromatography Technique

QUANTITATIVE DETERMINATION OF RESIDUAL SOLVENTS IN PALONOSETRON API BY HS-GC METHOD

Objectives: Palonosetron is an antidote to 5-HT3 in the prevention and treatment of chemotherapy-induced nausea and vomiting (CINV). The presence of residual solvents in pharmaceutical drug substances or products, as well as excipients, can have a detrimental effect on the product’s quality and stability. These substances must be evaluated for safety and efficacy. The primary purpose of this work is to establish a method for validating and quantifying residual solvents in palonosetron API using Head Space Gas Chromatography (HS-GC). Methods: In the proposed HS-GC technique for the quantifying residual solvents - ethanol, acetone, methanol, acetonitrile, and isopropyl alcohol (IPA) in Palonosetron API, the headspace equilibrium was achieved at 100°C and analyzed by DB-624 column (30 m × 0.24 mm, 1.8 μm) with injector and detector temperature set at 200°C and 230°C respectively. The dissolving solvent was dimethyl sulfoxide (DMSO). After the initial holding time of 5mins, the temperature was increased to 120°C from 40°C in 20mins at a rate of 10°C/min using a flow rate of 10 ml/min and a split ratio of 1:25 with nitrogen as carrier gas. The approach created has been validated and quantified as per International Conference on Harmonization’s (ICH) guidelines. Results: All the results obtained were within the ICH specified limits. The validation results for repeatability studies (%RSD values) were found to be &lt;10; recovery studies values were in the range of 90–110% and for the selected linearity range 25–150 μg/ml the correlation coefficients(γ2) for all the solvents were observed to be &gt;0.99. Conclusion: A sensitive, simple, precise, and economic HS-GC method with Flame Ionization Detector (FID) was developed and validated to quantitatively determine the residual solvents in Palonosetron API.

Headspace Gas Chromatographic Method for Carbonate Content Determination in Layered Double Hydroxides

AbstractThe determination of carbonate content is the basic procedure for studies related to layer double hydroxides (LDHs). This paper reports a rapid and accurate headspace gas chromatographic (HS‐GC) technique for the determination of carbonate content in LDHs. The content of carbonate was expressed by the amount of CO2 generated by the reaction of sulfuric acid and carbonate, which can be measured by HS‐GC technique using a thermal conductivity detector. It was found that a complete conversion of carbonate to CO2 can be achieved at 45 °C for about 4 min and a sulfuric acid dosage of 200 μL in the headspace vial. Under optimized conditions, the limit of detection and relative standard deviation of HS‐GC method is 0.79 μmol and 1 %, respectively.

Noncovalent Association and Partitioning of Some Perfume Components at Infinite Dilution with Myelin Basic Protein Pseudophase in Normal Saline

Myelin basic protein (MBP), one of the major protein constituents of the myelin sheath, possesses unique ligand-binding features. We present a novel equilibrium headspace gas chromatographic technique to examine the thermodynamics of noncovalent interactions between common perfume components: Lilial, Hedione, Hexylcinnamic aldehyde, and Versalide with MBP monomers and its hexameric MBP-pseudophase. A general theoretical model is used to calculate the critical aggregation concentration (cac) of MBP, perfume component binding constants with monomeric MBP, K11, and MBP as pseudophase, Kn1, and free energies for perfume component binding with monomeric MBP, ΔGb,11, and MBP as pseudophase, ΔGb,n1. In addition, the pseudophase-water partition coefficients, Kx, the free energies of transfer of perfume from bulk water to the MBP-pseudophase, ΔGt, and the intra-aggregate activity coefficients, γm∞, at infinite dilution were also determined. The cac value measured by the method of fractional distribution is a unique and precise approach in understanding the aggregation phenomenon. Within the experimental error, the 1:1 binding free energies did not differ by more than 1 kJ/mol among the perfume components but favored the MBP pseudophase binding by 6 kJ/mol. Therefore, that protein aggregation can enhance the binding of small molecules is probably a general conclusion. While the magnitudes of K11, Kn1, ΔGb, Kx, and ΔGt show weak trends, the γm∞ values show a strong and distinct trend in interaction, spanning 4 orders of magnitude among the perfume components.

Development and Characterization of Inhaled Ethanol as a Novel Pharmacological Strategy Currently Evaluated in a Phase II Clinical Trial for Early-Stage SARS-CoV-2 Infection.

Inhaled administration of ethanol in the early stages of COVID-19 would favor its location on the initial replication sites, being able to reduce the progression of the disease and improving its prognosis. Before evaluating the efficacy and safety of this novel therapeutic strategy in humans, its characterization is required. The developed 65° ethanol formulation is stable at room temperature and protected from light for 15 days, maintaining its physicochemical and microbiological properties. Two oxygen flows have been tested for its administration (2 and 3 L/min) using an automated headspace gas chromatographic analysis technique (HS-GC-MS), with that of 2 L/min being the most appropriate one, ensuring the inhalation of an ethanol daily dose of 33.6 ± 3.6 mg/min and achieving more stable concentrations during the entire treatment (45 min). Under these conditions of administration, the formulation has proven to be safe, based on histological studies of the respiratory tracts and lungs of rats. On the other hand, these results are accompanied by the first preclinical molecular imaging study with radiolabeled ethanol administered by this route. The current ethanol formulation has received approval from the Spanish Agency of Medicines and Medical Devices for a phase II clinical trial for early-stage COVID-19 patients, which is currently in the recruitment phase (ALCOVID-19; EudraCT number: 2020-001760-29).

Quantitative determination of the oleophobicity of food packaging paper using headspace gas chromatographic technique

This study demonstrates a method to quantitatively measure the oleophobicities of food packaging paper via using a tracer‐assisted headspace gas chromatography by adding a 40‐μL droplet of toluene‐doped oil onto a sample surface, wherein toluene behaves as volatile tracer. After 20 s, the sample was turned vertically to remove the oil and placed in a headspace vial. The amount of toluene in the residual oil adhered to the sample surface was quantified using headspace gas chromatography under full‐evaporation conditions. The results exhibit satisfactory precision (RSDs &lt; 2.5%) and provide quantitative information on oleophobicity. The proposed method is simple, efficient and suitable for batch sample testing.

Determination of activity of denitrifying enzyme in soil samples by a headspace gas chromatographic technique

This paper reported a headspace gas chromatography (HS-GC) for the determination of denitrifying enzyme activity in soil samples. It was based on measuring the NO2 signal in a set of closed/air-free vials containing soil samples that incubated at the designated conditions. The results showed that the method has a good measurement precision (RSD < 5.0%) and reasonable accuracy for determining the denitrifying enzyme activity in soil samples. It is simple and efficient, and very suitable to be used in batch sample analysis.

Identification of the Organic Volatile Impurities in Telmisartan Active Pharmaceutical Ingredient and Its Pharmaceutical Dosage forms by using Head Space Gas Chromatography Technique

Identification of the Organic Volatile Impurities in Telmisartan Active Pharmaceutical Ingredient and Its Pharmaceutical Dosage forms by using Head Space Gas Chromatography Technique

Viable but nonculturable state of Escherichia coli, Pseudomonas putida and Lactococcus lactis during exposure to toxic chemicals, as revealed by headspace gas chromatography and indirect conductivity techniques

Viable but nonculturable state of Escherichia coli, Pseudomonas putida and Lactococcus lactis during exposure to toxic chemicals, as revealed by headspace gas chromatography and indirect conductivity techniques

Enhanced separation of benzene and cyclohexane by homogeneous extractive distillation using ionic liquids as entrainers

The worldwide production of cyclohexane is mainly carried out through the hydrogenation of benzene. Unreacted benzene is separated from produced cyclohexane, being one of the most challenging processes in the petrochemical industry due to their extremely close boiling points and the presence of an azeotrope. In this work, an experimental screening of seven ionic liquids has been done in order to check the suitability of the extractive distillation with ionic liquids. The vapor-liquid or vapor-liquid-liquid equilibria (VLE/VLLE) of {cyclohexane/benzene + ionic liquid} binary systems and {cyclohexane + benzene + ionic liquid} ternary systems have been determined by Headspace-Gas Chromatography technique. The Non-Random Two Liquids (NRTL) thermodynamic model has been used to fit the experimental VLE/VLLE accurately. Although all the selected ionic liquids enhanced the cyclohexane/benzene relative volatility (α1,2) in comparison with conventional solvents, the [4bmpy][TCM] was chosen and implemented in Aspen Plus to simulate the extractive distillation process of benzene from cyclohexane with ionic liquids. The associated operating costs and the energy savings in comparison with conventional process, using N-methyl-2-pyrrolidone (NMP) as solvent, show that the extractive distillation with the [4bmpy][TCM] ionic liquid improves the conventional process, standing as an enhancer technology in the field.

A simple and rapid method for the determination of lead dioxide in minium by headspace gas chromatographic technique

This paper demonstrated a simple and rapid approach for the determination of lead dioxide in minium using a headspace gas chromatographic (GC) technique. This new approach was based on the measurement of carbon dioxide from the redox reaction between lead dioxide and oxalic acid in a sealed headspace vial. The obtained results indicated that the new approach had good measurement accuracy (relative errors ≤8.71%) and precision (RSD ≤2.86%). Moreover, the limit of quantification (LOQ) and limit of detection (LOD) for this new approach were respectively 0.34% and 0.10%, and the recoveries ranged from 97.9 to 101.7%. The new approach is low-cost and reliable, which has potential for use in the analysis of lead dioxide in minium and related products.

Simultaneous Determination of the Degree of Deacetylation and Substitution on Carboxymethyl Chitosan by Headspace Gas Chromatography

This study reported a new headspace gas chromatography (HS-GC) for simultaneously determining the degree of deacetylation (DD) and the degree of substitution (DS) in carboxymethyl chitosan (CMCS), which were based on HS-GC measuring the amounts of CO2 released from both the bicarbonate decomposition suppressed by -NH2 and the reaction between the bicarbonate and the acidified carboxymethyl and amino groups in CMCS. The results showed that the present method has a good measurement precision (RSD < 2.55%) and accuracy (relative differences <5.90%). Compared with the current titration-based method, the present HS-GC techniques provide a more reliable testing in the quantification of amino and carboxymethyl contents in CMCS. Moreover, since the HS-GC can perform an automated sample reaction equilibration and measurement, it could be much more efficient than the existing methods in the batch sample analysis.

Cyclohexane/cyclohexene separation by extractive distillation with cyano-based ionic liquids

Cyclohexane/cyclohexene separation is one of the most complex and relevant hydrocarbon separations due to the close boiling points of these two cyclic hydrocarbons and the relevance of both compounds in the petrochemical industry. The production of cyclohexane, cyclohexene, and benzene usually means the existence of cyclohexane/cyclohexene mixtures and the necessity of their separation. A current approach in search of new processes for this challenging separation is the development of liquid-liquid extraction technology using ionic liquids. Nevertheless, systematic limitations observed for the extensive collection of ionic liquids proved so far have boosted to further investigate the extractive distillation with ionic liquids as a better separation technology. Five selected cyano-based ionic liquids were tested in the cyclohexane/cyclohexene separation. Vapor-liquid equilibria (VLE) data were determined by a combined headspace–gas chromatography technique (HS-GC) and fitted to the non-random two liquids (NRTL) model. From the obtained results, the cyclohexane/cyclohexene relative volatility with the studied ionic liquids is enhanced in comparison with that provided by conventional solvents. Then, extractive distillation with cyano-based ionic liquids stands as a suitable way to perform the cyclohexane/cyclohexene separation.

A fast and simple headspace gas chromatographic technique for quantitatively analyzing urea in human urine

A fast and convenient headspace gas chromatographic (HS-GC) approach was described for the estimation of urea in human urine. The HS-GC could detect the generated carbon dioxide derived from the urease-catalyzed hydrolysis of urea. It was found that the hydrolysis of urea catalyzed by urease was completed within 40 min at 35 °C. The results proved the great accuracy (relative errors ≤ 8.48%) and precision (RSD ≤ 2.66%) of the HS-GC approach. Moreover, the recoveries ranged from 97.9% to 101.5%. The new approach is rapid and automated, which provides a new way to routinely analyze urea in urine for the control of metabolic disease.

High-throughput determination of the organic matter content in soil and municipal sludge by headspace gas chromatography

This paper reports on a new headspace gas chromatographic technique for rapid determination of organic matter (OM) in soil and municipal sludge samples, based on a redox reaction, i.e., converting OM into CO2 by dichromate at an acidic medium.

Determination of iodate in iodized edible salt based on a headspace gas chromatographic technique

This paper introduces a convenient approach for determining iodate in iodized salt by headspace gas chromatography (HS-GC). The analytical technique can measure the generated carbon dioxide from the redox reaction between iodate and sodium oxalate in the presence of strong acid. The formed carbon dioxide from this reaction in a closed vial is measured by GC. It was observed that the redox reaction in the vial was completed in 40 min at 95 °C. The results indicated that this analytical technique is precise (RSD ≤ 2.69%) and accurate (relative errors ≤ 7.21%). The present approach is fast and simple, providing a robust avenue to the routine estimation of iodate in iodized salt in a wide variety of applications from processing to quality monitoring.

Accurate determination of melting Point of industrial grade alkyl ketene dimer wax by a simple and automated headspace gas chromatographic technique

This study demonstrated a novel method for determining the melting point (MP) of industrial grade alkyl ketene dimer (AKD) wax by an automated headspace gas chromatographic (HS-GC) technique, in which methanol was used as the tracer. It was based on measuring the GC signal of methanol released from an aqueous solution during the temperature increasing. When the temperature of AKD MP reached, the AKD granules floated on the surface aqueous solution was liquidized and completely isolated the methanol transfer from the solution to the headspace. Thus, a transition point, corresponding to the MP of AKD wax, was observed when plotting the GC signal of methanol vs. the temperature. The results showed that the method has a good measurement precision (RSD < 0.68%) and accuracy (the relative differences were < 7.16%, compared to a reference method). The present method is simple, accurate and particularly suitable to be used in the batch sample testing. This new measurement concept can be also adopted to many related applications.