Journal of chromatography open最新文献

Old vine Chenin blanc (OVC) wines are produced from grapes harvested from vines older than 35 years, verified as Certified Heritage Vineyards in South Africa. This emerging premium wine style is of interest due to the purported unique sensory properties of these wines, including their complex aroma. There is however limited information available on the volatile constituents of these wines, which are primarily responsible for perceived aroma. The wine volatilome is exceedingly complex, and requires advanced analytical approaches to investigate. The present contribution reports the evaluation of comprehensive two-dimensional gas chromatography (GC × GC) as a powerful separation technique to gain qualitative insight into the volatile composition of OVC wines. Extraction of volatile compounds was performed using headspace solid-phase microextraction (HS-SPME), while the GC × GC separation was hyphenated to high speed high resolution time-of-flight MS (HR-TOF-MS) for compound identification. A representative set of eight Chenin blanc wines produced from young vines (YVC) was also analysed to investigate the potential use of GC × GCHR-MS data to differentiate these two wine styles based on differences in their volatile composition. The results confirm the utility of GC × GCHR-MS for the detailed qualitative analysis of wine volatiles, with a total of 277 compounds identified in the studied wines. 53 compounds were uniquely identified in the OVC samples, and 52 in YVC wines. Successful differentiation of the young- and old-vine wines was achieved based on tile-based Fisher (F) ratios and principal component analysis (PCA), although this differentiation could not be clearly linked to winemaking practices (wood maturation) or viticultural origin.

This study evaluates the relationship between the power supply output (voltage (V), current (I), power (W)), used for heating a second dimension (²D) column, and the maximum heating rate and temperature offset achievable by custom built ²D temperature programming system (²DTPS). The influence of the gas chromatograph (GC) oven temperature, ²D column flow rate, and ²D column dimensions when heating the ²D column were also explored. This data provided the minimum power needed for heating a ²D column (normalized to its length), based on the heating rate or temperature offset relative to the first dimension (¹D) column. During the study, optimization of the temperature control algorithm was also carried out to expand the dynamic range of the heating rate for a single power supply output (V, I), while maintaining a temperature deviation of < 0.75 °C between the measured temperature and temperature setpoint. This simplified the power supply specification recommendation to voltages which provide 1.5 A for heating rates and maximum temperature offsets below 28 °C/s and 70 °C, respectively, and 1.9 A when higher heating rates or temperature offsets were needed.

Volatile organic compounds(VOCs) are very toxic and harmful to living organisms and easily found as major pollutans in contaminated areas such as military bases and industrial sites. Qualitative and quantitative analysis of VOCs is required as part of the site assessment. VOC analysis is usually followed several complex steps such as solvent extraction, reverse extraction, and purification. Needle Trap Devices (NTDs) as an miniaturized adsorbent sampler can improve and simplify this analysis process. NTD is a one-step sampling, sample preparation and injection device optimized for gas chromatography, which is eco-friendly because no extraction solvent is required to extract VOCs from the sample matrix. This report uses the advantages of NTD to report the results of sampling and analysis from the monitoring well. That is, seven VOCs were identified and their concentration gradients according to the sampling depth were successfully figured out. VOCs decreased exponentially by diffusion as they moved away from contaminated groundwater, of which Tetrachloroethylene was the most detected component at 80.74 ng/mL at a depth of 1.5 m.

Reverse fill/flush (RFF) differential flow modulators are a lower cost, consumable free, robust option to achieve comprehensive two-dimensional gas chromatography (GC × GC) with FID and MS dual detection. For the required highly detailed separation of all hydrocarbon classes for a petroleum industry setting thermal-based modulators are considered the “gold standard” for their high performance, but there are substantial costs involved. In an industrial setting, there is a necessary balance between the separation performance, cost of instrumentation and costs of operation. It is uncertain if an RFF modulator chromatographic performance is sufficient to achieve the demands of an industrial research laboratory as a cost-effective alternative to thermal modulation. This paper reports an evaluation of the capabilities of a new prototype RFF flow modulator with flow splitter system and its chromatographic performance relative to thermal modulation for detailed hydrocarbon analysis. The prototype RFF modulator splitter system was easy to use with straightforward method optimization due to the lack of restrictors and implementation of back pressure regulation for variable restriction. It also provided good peak shapes, accurate quantification, and maintained constant split to both detectors throughout the analysis. The data processing workflow was greatly improved with the alignment of the MS and FID traces in the software. However, the chromatographic performance of the RFF was found to be less and insufficient for detailed hydrocarbon analysis when compared to thermal modulation. The greatest discrepancy was found in the differentiation of the saturate class, specifically the alkanes, iso-alkanes, and cycloalkanes from each other and other monoaromatics. A comparable separation was found in the lower carbon range of C₇-C₁₄ while the region of C₁₆-C₂₂ was challenging for the RFF modulator. Overall, the detailed analysis of a middle distillate was found to be too complex for the RFF flow modulator in comparison to thermal modulator.

To gain a deep insight and to obtain a superior understanding about guanosine-based pathway, this paper reports an innovative approach to study this critical subject. Firstly, after an exhaustive analysis of literature with a focus in legal medicine and extracellular vesicles, it was understood that a new method is inevitable to follow, determine, and quantify these analytes (Guanosine monophosphate - GMP, guanosine diphosphate - GDP, guanosine triphosphate - GTP, Guanosine, Neopterin, and tetrahydrobiopterin - BH4).

Starting from a previously method, we implemented and validated a new HPLC-DAD method in gradient elution mode with these six target analytes fully resolved in 18 min. The HPLC-DAD method uses a stationary phase XTIMATE C18 (4.6 mm × 250 mm, 5 µm, Welch, Shanghai, China) and mobile phase's phosphate buffer (40 mM, pH 7) (A) and Acetonitrile (B). Good correlation goes from 0.05 to 10 µg/mL with a limit of detection equal to 0.02 µg/mL and a limit of quantification equal to 0.05 µg/mL (R² ≥ 0.9824).

Method was tested on human extracellular vesicles, isolated from different human parts, like urine, saliva and muscle, giving interesting results as different quantification of analytes depending on the sample matrix used. Interesting to underline is that saliva was the poorest source of these analytes, if compared with growth medium and urine.

Phomopsin A (PHO-A), a potent mycotoxin produced by the pathogenic fungus Diaporthe toxica, is a growing international concern due to the high toxicity and prevalence in lupin plants, a vital source of food and feed. This hexapeptide mycotoxin has raised health concerns for both animals and humans, prompting regulatory bodies to set maximum allowable levels in lupin products.

Different analytical methods have been developed for PHO-A detection, including Enzyme-Linked Immuno-Sorbent Assay (ELISA) and high-performance liquid chromatography (HPLC) coupled with different detectors; they often lack sensitivity and selectivity required to meet maximum regulatory limits (MRL). In this work, we present a robust and sensitive method for PHO-A quantification and determination, developed using ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS).

This method incorporates a selective clean-up step using Micro Solid Phase Extraction (µ-SPE) to efficiently purify samples, ensuring a rapid, efficient, and selective recovery of PHO-A from the complex lupin matrix. The clean-up step not only helps in achieving lower detection limits but also minimizes matrix effects and contamination. The proposed method was validated following international guidelines, demonstrating reliable recovery, matrix effects, linearity, accuracy, and precision.

Additionally, this method was successfully applied to artificially contaminated Lupinus albus L. samples, confirming the suitability for assessing PHO-A contamination. This analytical approach fills a critical gap in the literature by providing a specific, sensitive, and selective method for PHO-A analysis, contributing to the safety of lupin products and field monitoring.

Quantification of virus like particles (VLPs) is challenging due to the large size and structural heterogeneity of the molecule. Structural heterogeneity arises due to random assemblage of L1 protein with other host cell proteins. With multiple VLPs under development as potential biotherapeutic products, defining their identity, purity and potency is of great interest. Most analytical methods used at present for VLP quantification are laborious and at best semi-quantitative. Thus, there is a need for an analytical technique that is capable of quantitatively estimating both purity and titre at all stages of the process. In this study, we propose use of Reversed phase chromatography for separation and identification of VLP L1 proteins in inhouse crude and purified samplesand quantification of L1 protein at different process points. The proposed method takes about 20 min and has been demonstrated to be highly sensitive, robust, and selective as confirmed through mass spectrometry.

Solid sorbents based on silica and polyethyleneimine (PEI) are intensively investigated in the field of carbon capture and storage (CCS). Pyrolysis was proposed as a thermal process to recover the pure silica from exhausted sorbents and convert PEI into potentially useful products, such as alkylated pyrazines. A GC–MS method based on internal standardisation with 2-methoxypyrazine was developed and evaluated to determine the concentration of six pyrazines in the pyrolysis oils of exhausted silica-PEI sorbent pyrolysed at 400, 500, 600 and 650 °C. The most abundant pyrazines were 2-ethyl and 2,3-dimethyl, occurring at concentrations of 5–28 mg g^–1, followed by pyrazine, 2-methyl, 2-ethyl-3-methyl and 2-propylpyrazine. The GC–MS results were compared to those from a HPLC-DAD method using the Welch's test. The 37 % discrepancy of concentrations was attributed to spectral interference in LC-DAD. GC was slightly less precise than HPLC, calibration errors were lower and enabled the identification of highly alkylated pyrazines. Both methods provided comparable values of total pyrazine yields (around 4–7 % by weight).

In this study, consumer and lab grade plastic food storage bags were subjected to a variety of analytical techniques to investigate the presence and levels of per- and polyfluoroalkyl substances (PFAS). Samples were extracted and analyzed by both targeted and non-targeted analyses using liquid chromatography tandem mass spectrometry and Orbitrap high resolution mass spectrometry. Of the 18 bags tested, 57 % had detectable levels of PFAS ranging from 0.5 – 26.6 ng/g. Perflurorobutane sulfonic acid (PFBS) was detected at the highest concentration while 6:2 fluorotelomer phosphate diester (6:2 diPAP) was the most frequently detected. No other PFAS were found in the targeted method. Non-targeted analysis resulted in six potential new PFAS candidates not found within the targeted method, however the lack of available analytical standards did not allow for confirmation. Eight samples with detectable PFAS were chosen for both migration and total oxidizable precursor (TOP) assay experiments to understand the potential impact to dietary exposure. No 6:2 diPAP was found to migrate however migration of PFBS was found to be rapid (2 h) and with relatively high migration efficiencies (22 – 75 %). To estimate potential exposure to PFBS migrating from food storage bags, tolerable weekly intake (TWI) values were calculated at 2.12 ng/kg body weight/week, and were below the regulatory TWI value of 4.4 ng/kg established by the European Food Safety Authority (EFSA).

Revised descriptors for 74 varied compounds recommended for the characterization of reversed-phase silica columns using the solvation parameter model are assigned by the Solver method from experimental retention factors for calibrated gas-liquid and reversed-phase liquid chromatographic (RPLC) and biphasic liquid-liquid partition systems. These descriptors are taken as the best estimate of the true descriptor values and used to evaluate several RPLC systems as a single-technique approach for descriptor assignments. Various combinations of isocratic single column and multiple mobile phase compositions, multiple columns with a single mobile phase composition, and multiple columns and multiple mobile phase compositions are evaluated. A multiple column (Discovery HS C18 and HS F5, Fluophase-RP, and XBridge Shield RP₁₈, Phenyl, and C₁₈) with acetonitrile- and methanol-water mobile phases provided the best results with an absolute average deviation (AAD) of 0.043 for the electron lone pair interaction descriptor E, 0.047 for the dipole-type interaction descriptor S, 0.020 for the hydrogen-bond acid descriptor A, and 0.010 for the hydrogen-bond base descriptor B° for 46 varied compounds. These values compare favorably with the larger all columns and mobile phase composition RPLC dataset with the best estimate of the true descriptors, or all data set, with AAD = 0.026 for E, 0.044 for S, 0.027 for A, and 0.011 for B° for 74 varied compounds. The preferred RPLC systems for descriptor assignments contain columns identified as belonging to different selectivity groups that maximize the relative magnitude of the dipole-type contribution, s system constant, hydrogen-bond basicity, a system constant, and electron lone pair interactions, e system constant. RPLC systems are well suited to assigning the B° descriptor and, with proper system selection, the A and S descriptors. The E descriptor for compounds unavailable by calculation is more problematic and a few extreme values with an AAD > ± 0.1 were observed and can affect the reliability of the S descriptor assignments for these compounds. The likelihood of poor descriptor assignments using the Solver method can be identified by evaluating descriptor wells.