Validation of an analytical method for simultaneous high-precision measurements of greenhouse gas emissions from wastewater treatment plants using a gas chromatography-barrier discharge detector system

Development of a Multiplexing Injector for Gas Chromatography for the Time-Resolved Analysis of Volatile Emissions from Lithium-Ion Batteries

Multiplex sampling, so far mainly used as a tool for S/N ratio improvement in spectroscopic applications and separation techniques, has been investigated here for its potential suitability for time-resolved monitoring where chromatograms of transient signals are recorded at intervals much shorter than the chromatographic runtime. Different designs of multiplex sample introduction were developed and utilized to analyze lithium-ion battery degradation products under normal or abuse conditions to achieve fast and efficient sample introduction. After comprehensive optimization, measurements were performed on two different GC systems, with either barrier discharge ionization detection (BID) or mass spectrometric detection (MS). Three different injector designs were examined, and modifications in the pertinent hardware components and operational conditions used. The shortest achievable sample introduction time was 50 ms with an interval of 6 s. Relative standard deviations were lower than 4% and 10% for the intra- and inter-day repeatability, respectively. The sample introduction system and column head pressure had to be carefully controlled, as this parameter most critically affects the amount of sample introduced and, thus, detector response. The newly developed sample introduction system was successfully used to monitor volatile degradation products of lithium-ion batteries and demonstrated concentration changes over the course of time of the degradation products (e.g., fluoroethane, acetaldehyde and ethane), as well as for solvents from the battery electrolyte like ethyl carbonate.

Monitoring of atmospheric CH<sub>4</sub>, CO, CO<sub>2</sub>, N<sub>2</sub>O and SF<sub>6</sub> using three-channel gas chromatography

我国正处于“碳达峰、碳中和”的关键时期,准确认识我国温室气体浓度时空格局以及变化对于评估“碳达峰”和“碳中和”行动成效非常重要。当前我国近地面温室气体高精度监测主要依赖进口的光学监测主机,单台仪器成本高且监测要素有限。为此,该研究基于传统的气相色谱法,自主设计了一套三通道气相色谱分析系统,在单台仪器上实现了5种主要长寿命温室气体(CH₄、CO、CO₂、N₂O和SF₆)的高精度监测。对该系统的精密度、线性响应情况和准确度进行的针对性测试实验表明系统检测性能满足世界气象组织/全球大气观测(WMO/GAW)质控标准。针对环境浓度的CH₄、CO、CO₂、N₂O和SF₆的连续分析精密度分别达0.08%、1.90%、0.05%、0.08%、0.66%。准确度测试中,5种气体(CH₄、CO、CO₂、N₂O和SF₆)使用回归方程计算所得值与标称摩尔分数间的偏差分别达0.15×10^-9、0.20×10^-9、0.37×10^-6、0.35×10^-9、0.02×10^-12(摩尔分数),CH₄、CO、CO₂、N₂O和SF₆仪器响应值与标称摩尔分数的线性拟合相关系数(R²)均为0.9999,线性拟合残差和准确度基本达到WMO/GAW拓展质控目标。该系统对杭州城区大气温室气体在线连续监测结果显示,2021年5~7月期间大气CH₄、CO、CO₂和N₂O呈明显的日变化特征,主要受人为活动影响。综合测试和试运行结果表明,该研发系统具备良好的精密度、准确度、线性和稳定性,与目前国内广泛进口的仪器相比,具有技术自主可控、运行成本更低、自动化水平更高等优势,能满足多种温室气体在线监测研究的需求。

Natural Polymeric Materials: A Solution to Plastic Pollution from the Agro-Food Sector

Conventional petroleum-derived plastics represent a serious problem for global pollution because, when discarded in the environment, are believed to remain for hundreds of years. In order to reduce dependence on fossil resources, bioplastic materials are being proposed as safer alternatives. Bioplastics are bio-based and/or biodegradable materials, typically derived from renewable sources. Food waste as feedstock represents one of the recent applications in the research field of bioplastics production. To date, several food wastes have been used as raw materials for the production of bioplastics, including mostly fruit and vegetable wastes. The conversion of fruit and vegetable wastes into biomaterials could occur through simple or more complex processes. In some cases, biopolymers extracted from raw biomass are directly manufactured; on the other hand, the extracted biopolymers could be reinforced or used as reinforcing agents and/or natural fillers in order to obtain biocomposites. The present review covers available results on the application of methods used in the last 10 years for the design of biomaterials obtained from formulations made up with both fruits and vegetables by-products. Particular attention will be addressed to the waste pre-treatment, to the bioplastic formulation and to its processing, as well as to the mechanical and physical properties of the obtained materials.

Multiresidue analysis and evaluation of the matrix effect on 20 pesticides in Brazilian maize (Zea mays L.) flour

Maize consists of a cereal widely used in the preparation of different food products. Brazil is one of the world's largest maize producers. Several types of pesticides have been applied in maize crop, which can lead to the contamination of the derived products. The present work aims at the validation of multiresidue method to analyze the matrix effect and level of pesticides in maize flour. Twenty residues were investigated in samples commercialized in the state of Ceará, Brazil. The method was satisfactorily validated, according to parameters recommended by European Union. About 55% of the pesticides had an intense negative matrix effect. Multiresidue analyzes showed the presence of traces of fenitrotion in 20% of maize flour samples. Detected levels were below maximum residue limits recommended for maize. The results indicate that maize products need continuous monitoring to ensure food security.

Purge-and-trap Determination of Ammonia in Water Samples Using Needle-type Extraction Coupled with Gas Chromatography-Barrier Discharge Ionization Detection

This manuscript describes the determination of ammonia (NH₃) in aqueous samples by purge-and-trap extraction using a needle-type extraction device with gas chromatography-barrier discharge ionization detector (GC-BID). NH₃ was purged from the aqueous samples in basic conditions and then salted out with sodium chloride. Purged ammonia was trapped onto non-volatile carboxylic acid-coated macroporous terephthalic acid particles, which were contained within the needle-type extraction device. The analyte (NH₃) was thermally desorbed by heating the extraction needle in the GC injection port, and detected by BID. After the optimization of both purge and extraction conditions, the linearity and sensitivity of the proposed method were evaluated. The limit of detection was found to be 2.0 mg L^-1 at a headspace sampling volume of 100 mL. The method applicability was confirmed by the determination of spiked NH₃ in tap water and river water samples.

CO2 and N2O from water resource recovery facilities: Evaluation of emissions from biological treatment, settling, disinfection, and receiving water body

Water resource recovery facilities (WRRFs) contribute to climate change and air pollution, as they are anthropogenic potential sources of direct and indirect emission of greenhouse gases (GHGs). Studies concerning the monitoring and accounting for GHG emissions from WRRFs are of increasing interest. In this study, the floating hood technique for gas collection was coupled with the off-gas method to monitor and apportion nitrous oxide (N₂O) and carbon dioxide (CO₂) emissions from both aerated and non-aerated tanks in a municipal water resource recovery facility, in order to investigate its carbon footprint (CFP). To our knowledge, this is the first time that the chamber technique was applied to evaluate gas fluxes from the settler, where an emission factor (EF) of 4.71 ∗ 10^-5 kg_CO2,eq kg_bCOD^-1 was found. Interesting results were found in the disinfection unit, which was the major contributor to direct N₂O emissions (with a specific emission factor of 0.008 kg_CO2,eq kg_bCOD^-1), due to the chemical interaction between hydroxylamine and the disinfectant agent (hypochlorite). The specific emission factor of the biological aerated tank was 0.00112 kg_CO2,eq kg_bCOD^-1. The average direct CO₂ emission was equal to 0.068 kg_CO2 kg_bCOD^-1 from the activated sludge tank and to 0.00017 kg_CO2 kg_bCOD^-1 from the secondary clarifier. Therefore, taking into account the contribution of both direct N₂O and CO₂ emissions, values of 0.069 kg_CO2,eq kg_bCOD^-1, 0.008 kg_CO2,eq kg_bCOD^-1 and 0.00022 kg_CO2,eq kg_bCOD^-1_, were found for the net CFP of the aerated compartment, the disinfection unit and the clarifier, respectively. The plant energy Footprint (eFP) was also evaluated, confirming that the aeration system is the major contributor to energy consumption, as well as to indirect CO₂ emission, with a specific eFP of 1.49 kWh kg_bCOD^-1.

Environmental factors influencing landfill gas biofiltration: Lab scale study on methanotrophic bacteria growth

The post-management of landfills represents an important challenge for landfill gas treatment. Traditional systems (energy recovery, flares, etc.) present technical problems in treating flow with low methane (CH₄) concentrations. The objective of this study was to isolate methanotrophic bacteria from a field-scale biofilter in order to study the bacteria in laboratories and evaluate the environmental factors that mostly influence Microbial Aerobic Methane Oxidation (MAMO). The soil considered was sampled from the biofilter located in the landfill of Venosa (Basilicata Region, Italy) and it was mainly composed of wood chips and compost. The results showed that methanotrophic microorganisms are mainly characterized by a slow growth and a significant sensitivity to CH₄ levels. Temperature and nitrogen (N) also have a very important role on their development. On the basis of the results, biofilters for biological CH₄ oxidation can be considered a viable alternative to mitigate CH₄ emissions from landfills.

Method development and optimization for the determination of benzene, toluene, ethylbenzene and xylenes in water at trace levels by static headspace extraction coupled to gas chromatography-barrier ionization discharge detection

Benzene, toluene, ethylbenzene, and xylenes, more commonly named BTEX, represent one of the most ubiquitous and hazardous groups of atmospheric pollutants. The goal of our research was the trace quantification of BTEX in water by using a new simple, low-cost, and accurate method, based on headspace (HS) extraction and gas chromatography (GC) coupled to barrier ionization discharge detector (BID). This water application dealt with simple matrices without protein, fat, or humic material that adsorb target analytes, thus the external standard calibration was suitable to quantify each compound. The validation steps included the study of linearity, detection and quantification limits, and accuracy. LODs and LOQs varied from 0.159 to 1.845 μg/L and from 0.202 to 2.452 μg/L, respectively. The recovery was between 0.74 ± 0.13 and 1.15 ± 0.09; relative standard deviations (% RDSs) were less than 12.81% (n = 5) and 14.84% (n = 10). Also, GC performance was evaluated in term of efficiency, peak tailing and resolution. Preliminary results from practical applications to analyses of real samples are presented. The results indicate that static HS coupled to GC-BID is a successful method for BTEX analysis in water samples at the μg/L levels, provided that hydrocarbons interference occur at similar concentration levels. GC-BID may become a routine reference method alongside the official analytical techniques for quality control purposes of contaminated waters. Moreover, the new method is amenable to automation by using commercial HS units.

Determination of soyasaponins in Fagioli di Sarconi beans (Phaseolus vulgaris L.) by LC-ESI-FTICR-MS and evaluation of their hypoglycemic activity

Soyasaponins are oleanene-type triterpenoid saponins, naturally occurring in many edible plants that have attracted a great deal of attention for their role in preventing chronic diseases. The aim of this study was to establish the distribution and the content of soyasaponins in 21 ecotypes of Fagioli di Sarconi beans (Phaseolus vulgaris, Leguminosae). High-performance reversed-phase liquid chromatography (RPLC) with positive electrospray ionization (ESI(+)) and Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) in conjunction with infrared multiphoton dissociation (IRMPD) was applied for the unambiguous identification of soyasaponins Ba (m/z 959.5213, [C₄₈H₇₉O₁₉]⁺), Bb (m/z 943.5273, [C₄₈H₇₉O₁₈]⁺), Bd (m/z 957.5122, [C₄₈H₇₇O₁₉]⁺), and Be (m/z 941.5166, [C₄₈H₇₇O₁₈]⁺), which are the only commercially available reference standards. In addition, the several diagnostic product ions generated by IRMPD in the ICR-MS cell allowed us the putative identification of soyasaponins Bb' (m/z 797.4680, [C₄₂H₆₉O₁₄]⁺), αg (m/z 1085.5544, [C₅₄H₈₅O₂₂]⁺), βg (m/z 1069.5600, [C₅₄H₈₅O₂₁]⁺), and γg (m/z 923.5009, [C₄₈H₇₅O₁₇]⁺), establishing thus their membership in the soyasaponin group. Quantitative and semiquantitative analysis of identified soyasaponins were also performed by RPLC-ESI(+) FTICR-MS; the total concentration levels were found ranging from 83.6 ± 9.3 to 767 ± 37 mg/kg. In vitro hypoglycemic outcomes of four soyasaponin standards were evaluated; significant inhibitory activities were obtained with IC₅₀ values ranging from 1.5 ± 0.1 to 2.3 ± 0.2 μg/mL and 12.0 ± 1.1 to 29.4 ± 1.4 μg/mL for α-glucosidase and α-amylase, respectively. This study represents the first detailed investigation on the antidiabetic activity of bioactive constituents found in Fagioli di Sarconi beans. Graphical abstract The first detailed RPLC-ESI(+) FTICR-MS investigation of the qualitative and semiquantitative profile of soyasaponins, occurring in 21 ecotypes of Fagioli di Sarconi beans (P. vulgaris L.).

The applicability of a large-volume injection (LVI) system for quantitative analysis of permanent gases O2 and N2 using a gas chromatograph/barrier discharge ionization detector

To develop accurate quantitation methods for two major permanent gases, N₂ and O₂, a series of calibration experiments were carried out using a gas chromatograph (GC)/barrier discharge ionization detector (BID) equipped with a large-volume injection (LVI) system. To this end, gaseous working standards (WSs) diluted with helium gas were prepared at ten different concentration levels representing three different concentration ranges (in ppm) in 1-L polyester aluminum (PEA) bags ((1) low, 209~2090 (O₂) and 791~7910 (N₂); (2) moderate, 2090 ~ 20,900 (O₂) and 7910~79,100 (N₂); and (3) high, 20,900~209,000 (O₂) and 79,100~791,000 (N₂)). Cross-calibration experiments for each individual WS were carried out using the loop injection system with four different capacities (0.01, 0.5, 1, and 10 mL). The calibration results were then evaluated with respect to key variables including loop capacity, concentration, and mass quantity. Accordingly, we observed the optimal performance of the BID in terms of sensitivity and linearity (R ² > 0.98) when the WS of the moderate concentration range was analyzed with the small loop (0.01 and 0.5 mL). The method detection limit (MDL) values of the four loop sizes (between 0.01 and 10 mL) were 7~500 ng for O₂ (38.4~557 ppm) and 24~2230 ng for N₂ (195~2105 ppm).