Optimization of an ultrasound-assisted derivatization for GC/MS analysis of oxygenated organic species in atmospheric aerosol

Reproducible Polybutylene Succinate (PBS)-Degrading Artificial Consortia by Introducing the Least Type of PBS-Degrading Strains

Polybutylene succinate (PBS) stands out as a promising biodegradable polymer, drawing attention for its potential as an eco-friendly alternative to traditional plastics due to its biodegradability and reduced environmental impact. In this study, we aimed to enhance PBS degradation by examining artificial consortia composed of bacterial strains. Specifically, Terribacillus sp. JY49, Bacillus sp. JY35, and Bacillus sp. NR4 were assessed for their capabilities and synergistic effects in PBS degradation. When only two types of strains, Bacillus sp. JY35 and Bacillus sp. NR4, were co-cultured as a consortium, a notable increase in degradation activity toward PBS was observed compared to their activities alone. The consortium of Bacillus sp. JY35 and Bacillus sp. NR4 demonstrated a remarkable degradation yield of 76.5% in PBS after 10 days. The degradation of PBS by the consortium was validated and our findings underscore the potential for enhancing PBS degradation and the possibility of fast degradation by forming artificial consortia, leveraging the synergy between strains with limited PBS degradation activity. Furthermore, this study demonstrated that utilizing only two types of strains in the consortium facilitates easy control and provides reproducible results. This approach mitigates the risk of losing activity and reproducibility issues often associated with natural consortia.

Analytical derivatizations in environmental analysis

Analytical derivatization is a technique that alters the structure of an analyte and produces a product more suitable for analysis. While this process can be time-consuming and add reagents to the procedure, it can also facilitate the isolation of the analyte(s), enhance analytes' stability, improve separation and sensitivity, and reduce matrix interferences. Since derivatization is a functional group analysis, it improves selectivity by separating reactive from neutral compounds during sample preparation. This technique introduces detector-orientated tags into analytes that lack suitable physicochemical properties for detection at low concentrations. Notably, many regulatory bodies, especially those in the environmental field, require these characteristics in analytical methods. This review focuses on note-worthy analytical derivatization methods employed in environmental analyses with functional groups, phenol, carboxylic acid, aldehyde, ketone, and thiol in aqueous, soil, and atmospheric sample matrices. Both advantages and disadvantages of analytical derivatization techniques are discussed. In addition, we discuss the future directions of analytical derivatization methods in environmental analysis and the potential challenges.

Standard-Free Quantification of Dicarboxylic Acids: Case Studies with Salt-Rich Effluents and Serum

The present study evaluates the ionization efficiency (IE) of linear and branched C₂-C₁₄ dicarboxylic acids (DCAs) by electrospray ionization (ESI) under different conditions. The influence of the concentration of organic modifier (MeOH); mobile phase additive; and its concentration, pH, and DCA structure on IE values is studied using flow injection analysis. The IE values of DCAs increase with the increase of MeOH concentration but also decrease with an increase of pH. The former is due to the increase in solvent evaporation rates; the latter is caused by an ion-pairing between the diacid and the cation (ammonium), which is confirmed by the study with different amines. The investigation of DCA ionization in the presence of different acidic mobile phase additives showed that a significant improvement in the (-)ESI responses of analytes was achieved in the presence of weak hydrophobic carboxylic acids, such as butyric or propanoic acid. Conversely, the use of strong carboxylic acids, such as trichloroacetic acid, was found to cause signal suppression. The results of the IE studies were used to develop the liquid chromatography-high-resolution mass spectrometry (LC-HRMS) method that provided instrumental limits of detection in the range from 6 to 180 pg. Furthermore, upon applying the nonparametric Gaussian process, a model for the prediction of IE values was developed, which contains the number of carbons in the molecule and MeOH concentration as model parameters. As a case study, dicarboxylic acids are quantified in salt-rich effluent and blood serum samples using the developed LC-HRMS method.

Gas chromatography/mass spectrometry analysis of organic acid profiles in human serum: A protocol of direct ultrasound-assisted derivatization

RATIONALE

Low-molecular-weight organic acids that generally contain one to three carboxyl groups are involved in many important biological processes; therefore, it is important to develop a quantitative method for analyzing organic acids in serum in order to allow an evaluation of metabolic changes. In this study, we evaluated a protocol for detecting 26 organic acids in serum based on ultrasound-assisted derivatization by gas chromatography/mass spectrometry (GC/MS).

METHODS

Serum samples were prepared using ultrasound-assisted silane derivatization before GC/MS analysis to quantify concentrations of organic acids. Additionally, we investigated the variables affecting derivatization yields, including the extraction solvent, derivatization reagents, and derivatization conditions (reaction temperature, duration, and sonication parameters). The protocol was ultimately applied to detect organic acid profiles related to obesity.

RESULTS

We used acetone as the extraction solvent and determined suitable derivatization conditions, as follows: BSTFA + 1% TMCS, 50°C, 10 min, and 100% ultrasound power. The protocol showed satisfactory linearity (r = 0.9958-0.9996), a low limit of detection (0.04-0.42 μmol/L), good reproducibility (coefficient of variation (CV) %: 0.32-13.76%), acceptable accuracy (recovery: 82.97-114.96%), and good stability within 5 days (CV%: 1.35-12.01% at room temperature, 1.24-14.09% at 4°C, and 1.01-11.67% at -20°C). Moreover, the protocol was successfully applied to obtain the organic acid profiles from obese and healthy control subjects.

CONCLUSIONS

We identified and validated a protocol for ultrasound-assisted derivatization prior to GC/MS analysis for detecting 26 kinds of organic acids in serum. The results suggest the efficacy of this protocol for clinical applications to determine metabolic changes related to fluctuations in organic acid profiles.

Determination of Nitrofuran Metabolites in Fish by Ultraperformance Liquid Chromatography-Photodiode Array Detection with Thermostatic Ultrasound-Assisted Derivatization

Nitrofuran (NF) is a class of broad-spectrum antibiotics that are used illegally in animal feeding. NF and its metabolites have proven to pose potential risk to human health. To address the current analytical needs to quantify low levels of NF metabolites in animal foods, a sensitive method was developed for simultaneous detection of four NF metabolites in fish products by an ultraperformance liquid chromatography-diode array detector (UPLC-DAD). With 2-nitrobenzaldehyde (2-NBA) as the derivatizing reagent, the metabolites were hydrolyzed and derivatized under the assistance of thermostatic ultrasound. Compared with the current detection methods, the time of the derivatization reaction has been shortened from 16 to 2 h. The relative coefficient of four NF metabolite derivatives reached more than 0.998, with excellent linear relationship. The limits of detection (LODs) and limits of quantification (LOQs) of six repeated determinations reached 0.25-0.33 and 0.80-1.10 μg/kg, respectively. For all four NF metabolites, the limit of detection of the method was below the minimum required performance limit (MRPL) of 1.0 μg/kg, which makes it compatible with the EU requirements. The recoveries ranging from 89.8 to 101.9% with relative standard deviation below 6.5% were obtained for all of the NF metabolites. What's more, this method was successfully applied for the determination of four NF metabolites in the fish products. As a promising approach, this method could also be extended for the quantitation of NF metabolites in aquaculture and poultry products.

Use of spent coffee ground biochar as ambient PAHs sorbent and novel extraction method for GC-MS analysis

In recent years, biochar has received a significant amount of attention for its potential beneficial applications in various fields due to its bio-physico-chemical properties. The spent coffee ground biochar was prepared by slow pyrolysis for adsorption of 16-polycyclic aromatic hydrocarbons (PAHs) in ambient air. New materials and extraction methods were developed for PAHs analysis, particularly for low molecular weight (2-4 rings) PAHs, which are likely to evaporate at room temperature. Production and characterization of biochar and its extraction parameters after PAHs adsorption were investigated and optimized. The biochar production at 500 °C provided adequate quality for PAHs adsorption with a 35% yield. An effective clean-up method for biochar was proposed. A new method of PAHs extraction from biochar was developed using 25 mL of a mixture of dichloromethane and 2-propanol (4:1) for 30 min at low temperatures (5-10 °C). A test on the efficiency of the extraction method was carried out and recoveries of 85-104% of PAHs were obtained. The lab-made biochar was also tested for its potential in ambient PAHs sampling and compared with a commercial sorbent (XAD-2). The results revealed that almost the same concentrations of ambient PAHs (ng/m³) were absorbed by both sorbent types, particularly with regard to the 4 ring-PAHs.