Intelligent geochemical interpretation of mass chromatograms:Based on convolution neural network

Gas chromatography-mass spectrometry(GC-MS)is an extremely important analytical technique that is widely used in organic geochemistry.It is the only approach to capture biomarker features of organic matter and provides the key evidence for oil-source correlation and thermal maturity determination.However,the conventional way of processing and interpreting the mass chromatogram is both timeconsuming and labor-intensive,which increases the research cost and restrains extensive applications of this method.To overcome this limitation,a correlation model is developed based on the convolution neural network(CNN)to link the mass chromatogram and biomarker features of samples from the Triassic Yanchang Formation,Ordos Basin,China.In this way,the mass chromatogram can be automatically interpreted.This research first performs dimensionality reduction for 15 biomarker parameters via the factor analysis and then quantifies the biomarker features using two indexes(i.e.MI and PMI)that represent the organic matter thermal maturity and parent material type,respectively.Subsequently,training,interpretation,and validation are performed multiple times using different CNN models to optimize the model structure and hyper-parameter setting,with the mass chromatogram used as the input and the obtained MI and PMI values for supervision(label).The optimized model presents high accuracy in automatically interpreting the mass chromatogram,with R2values typically above 0.85 and0.80 for the thermal maturity and parent material interpretation results,respectively.The significance of this research is twofold:(i)developing an efficient technique for geochemical research;(ii)more importantly,demonstrating the potential of artificial intelligence in organic geochemistry and providing vital references for future related studies.

Optimization of a Method for the Simultaneous Determination of Phloroglucinol and Trimethylphloroglucinol by High Performance Liquid Chromatography in Routine Use in a Pharmaceutical Industry in Abidjan

In order to provide the population with safe, effective and good quality medicines, the pharmaceutical industries, before releasing batches of their products into the pharmaceutical circuit, put in place internal dosage methods to control the quality of these products. The present study consisted in optimizing a method for the simultaneous determination of Phloroglucinol (PHG) and Trimethylphloroglucinol (TPH) by high performance liquid chromatography (HPLC) routinely used in a pharmaceutical industry located in a township in Abidjan (Ivory Coast). The basic chromatographic conditions were those routinely used for the determination of these two molecules: mobile phase: acetonitrile/water (60/40), stationary phase (C18 BDS Hypersil 250 mm * 4.6 mm - 5 μm), detection wavelength (265 nm), flow rate, injection volume and run time configured at the equipment level were respectively 1 mL/min, 10 μL and 8 min. The method of preparation of the analytes (PHG and TPHG) was also applied by the pharmaceutical industry. The application of these different parameters at the equipment level made it possible to determine a chromatogram which highlights three chromatographic peaks with respective retention times (RT) of 0.773 min (unidentified compound), 2.275 min (PHG) and 7.269 min for an analysis time of 8 min with a better resolution of the peaks and baseline. The progressive optimization of different parameters such as the stationary phase (C18 YMC 150 mm * 4.6 mm - 3 μm), the proportion of the mobile phase: acetonitrile/water (80/20), the flow rate impelled by the pump (0.8 mL/min) and the modification of the analyte preparation mode (same amount of PHG and TPHG in a 50 mL volumetric flask) resulted in a final chromatogram that highlighted two chromatographic peaks at the respective RT of 2.391 min (PHG) and 3.735 min (TPHG) at a run time of 6 min. The chromatographic conditions that led to the final chromatogram can be used routinely by the pharmaceutical industry for the determination of several PHG and TPHG drug matrices after prior validation of the determination method.

烟用香精的GC-MS指纹图谱

在卷烟生产中,烟用香精对卷烟的风格起着决定作用[1],所以稳定的烟用香精质量对卷烟内在品质的控制非常重要.目前,烟用香精的质量控制以物理指标[2]方法为主,对质量的变化反映不显著,给质量控制带来困难.……

固相萃取和气相色谱法测定大米中氟虫腈(锐劲特)残留

建立运用固相萃取技术检测大米中的氟虫腈残留的气相色谱分析方法。样品经过乙腈/丙酮(70/30)抽提,通过硅酸镁(Florisil)固相萃取(SPE)小柱净化,旋转蒸干后用乙腈定容,应用微池电子捕获检测器(μ ECD)检测。样品在10 μ g/kg、15 μ g/kg和30 μ g/kg三个浓度水平添加,回收率为83.18%、 84.49%和88.85%,方法变异系数为1.60%、 1.89%和1.54%。本方法在大米样品中的最低检测定量限为10 μ

GDX203色谱固定相的改性及在羰基合成醋酸中的应用

甲醇羰基化反应制醋酸,是一个重要的化学反应[1],无论在实验室或在工业生产上,其反应过程的监测均是以色谱为分析手段[2,3]。由于该反应产物的组分多(甲醇、水、碘甲烷、乙酸甲酯、醋酸),通常采用色谱程序升温的方法才可达到各组分的分离[4],这种方法由于存在分析周期长和由于反应物在色谱柱中的保留时间长而发生变化影响了定量的准确性的缺点,给对该反应进行的快速、准确的监测带来诸多不便。

柑橘果肉、果皮中酚类物质含量差异性研究

采用高效液相色谱法(high performance liquid chromatographic,HPLC)对8种橙类和杂柑中10种酚类物质含量进行测定,探讨不同柑橘品种果肉和果皮中酚类物质种类和含量的差异,分析其规律。结果表明,10种物质能在55 min内分离,线性范围为0.25~200 mg/L,相关系数达0.999 1~1,精密度(RSD≤1.90%)、重复性(RSD≤3.52%)和稳定性(RSD≤4.22%)较好,平均回收率为90.26%~118.85%(RSD为0.96%~3.01%),表明方法的准确度较高。在橙类和杂柑中,橙类果皮中芥子酸含量显著高于杂柑,杂柑果皮中芦丁含量显著高于橙类;果肉中酚类物质含量低于果皮;果实中酚酸以咖啡酸和绿原酸为主,类黄酮以芦丁和柚皮苷为主;在8个柑橘品种果肉中,金诺的阿魏酸、没食子酸和芦丁含量最高。在8个柑橘品种果皮中,口之津32号的咖啡酸、阿魏酸、对羟基苯甲酸含量最高,沃柑的新橙皮苷、柚皮苷、没食子酸和绿原酸含量最高。

Quick Measurement of CH_4, CO_2 and N_2O Emissions from a Short-Plant Ecosystem

Combining improved injector, gas line and valve-driving models, a gas chromatograph (GC) equipped with Hydrogen Flame Ionization Detector (FID) and Electron Capture Detector (ECD), can measure CH4, CO2, and N2O simultaneously in an air sample in four minutes. Test results show that the system has high sensitivity, resolution, and precision; the linear response range of the system meets the requirement of flux measurements in situ. The system is suitable for monitoring fluxes of the main greenhouse gases in a short-plant field since it is easy to use, efficacious, and constant and reliable in collecting data.

Hydrocarbon migration and accumulation along the fault intersection zone-a case study on the reef-flat systems of the No.1 slope break zone in the Tazhong area, Tarim Basin

Understanding hydrocarbon migration and accumulation mechanisms is one of the key scientif ic problems that should be solved for effective hydrocarbon exploration in the superimposed basins developed in northwest China. The northwest striking No.1 slope break zone, which is a representative of superimposed basins in the Tarim Basin, can be divided into five parts due to the intersection of the northeast strike-slip faults. Controlled by the tectonic framework, the types and properties of reservoirs and the hydrocarbon compositions can also be divided into five parts from east to west. Anomalies of all the parameters were found on the fault intersection zone and weakened up-dip along the structural ridge away from it. Thus, it can be inferred that the intersection zone is the hydrocarbon charging position. This new conclusion differs greatly from the traditional viewpoint, which believes that the hydrocarbon migrates and accumulates along the whole plane of the No.1 slope break zone. The viewpoint is further supported by the evidence from the theory of main pathway systems, obvious improvement of the reservoir quality （2-3 orders of magnitude at the intersection zone） and the formation mechanisms of the fault intersection zone. Differential hydrocarbon migration and entrapment exists in and around the strike- slip faults. This is controlled by the internal structure of faults. It is concluded that the more complicated the fault structure is, the more significant the effects will be. If there is a deformation band, it will hinder the cross fault migration due to the common feature of two to four orders of magnitude reduction in permeability. Otherwise, hydrocarbons tend to accumulate in the up-dip structure under the control of buoyancy. Further research on the internal fault structure should be emphasized.

Method for rapid on-site identification of VOCs

Rapid on-site identification of volatile organic compounds （VOCs） in ambient air is an important first step in remediation efforts. This study describes modification of a commercially available, portable GC/MS system and development of an analysis protocol for rapid （〈 3 min） sampling and identification of VOCs typically found at contaminated sites at the low ppbv level.

Development of chromatographic technologies for the quality control of Traditional Chinese Medicine in the Chinese Pharmacopoeia

As an important branch of medicine, Traditional Chinese Medicine(TCM) has been applied for the treatment of diseases for thousands of years in China and other countries in East Asia. The Chinese Pharmacopoeia(ChP) is a drug code formulated by the Chinese government, and it includes a special volume for the monographs of TCM, which plays an important role in ensuring the quality of drugs. The use of quality control technology has always been a complex and important factor in TCM. Owing to the chemical diversity of TCM, chromatography technology has been proven to be a comprehensive strategy for the assessment of the overall quality of TCM and has become the main analytical method in the ChP.This article provides an overview of the classical and modern chromatographic technologies applied in the ChP, and summarizes the advantages and disadvantages of each technique in the TCM monographs.In 2020, the new edition of the Ch P(the 2020 edition) has been implemented at the end of 2020. This paper also contains a brief introduction about the application of chromatographic technologies in the new edition of the ChP.

Determination of Organochlorine and Nitrogen Containing Pesticide Residues in Water,Sediments and Fish Samples by Reverse Phase High Performance Liquid Chromatograph

With high performance liquid chromatography, the concentrations of α-endosulfan, DDE, parathion methyl, isoproturon, atrazine, carbaryl and carbofuran were determined in farmed raised fish Labeo rohita of two weight groups. All these pesticide residues were detected in fish meat samples. All these pesticide residues except isoproturon were identified in soil sediments, whereas all these pesticide residues except isoproturon, carbaryl and DDE were also present in water samples. DDT, heptachlor, β-endosulfan, chlorpyrifos, dimethoate, captan, cypermethrin, chlorobromuron and chlorotoluron were absent in all samples of water, sediments and fish flesh. The pesticide residues levels were in order of parathion methyl 〉 DDE 〉 carbofuran 〉 atrazine 〉 α-endosulfan 〉 isoproturan 〉 carbaryl. The concentrations of pesticides were higher in fish weighing 800 -1 300 g than in those weighing 250 -750 g. The DDE was remained highest in sediments, while that was not detected in water samples. The pesticides （endosulfan, parathion methyl, atrazine and carbofuran） had crossed their MRL values （0.001 μg/g） in water samples.

Analysis of vacuum chamber suppressing gas explosion

In order to suppress the harm of gas explosion,the current study researched on the body of vacuum chamber.The previous studies verifed that it could obviously lower the explosion overpressure by reasonably arranging vacuum chamber on pipe.That is to say,the vacuum chamber has the effect of absorbing wave and energy.To further deeply analyze the vacuum chamber suppressing gas explosion,this research designed the L-type pipe of gas explosion,and compared the experimental results of gas explosion with vacuum chamber and without vacuum chamber.Besides,using the gas chromatograph,this study also investigated the gas compositions in the pipe before and after explosion.The results show that:(1)without vacuum chamber,the maximum value of explosion overpressure is 0.22 MPa,with60 ms duration,and after explosion,the concentration of oxygen drops to 12.07%,but the concentration of carbon monoxide increases to 4392.3 10à6,and the concentration of carbon dioxide goes up to7.848%,which can make the persons in danger suffocate and die;(2)with vacuum chamber,explosion overpressure drops to 0.18 MPa,with 20 ms duration or less,and after explosion,the concentration of oxygen still remains 12.07%,but the concentration of methane is 7.83%,however the concentration of carbon monoxide is only 727.24 10à6,and the concentration of carbon dioxide is only 1.219%,at the this moment the concentration ratio of toxic gas drops by more than 83%in comparison to be that without vacuum chamber.Consequently,the vacuum chamber can guarantee that most methane does not take part in chemical reaction,and timely quenches the deflagration reaction of gas and oxygen.Because of the two points mentioned above,it reduces the explosion energy,and lowers that the overpressure of blast wave impacts and damages on the persons and facilities,and also decreases the consumption of oxygen and the production of the toxic gas.Therefore,it is safe to conclude that the vacuum chamber not only absorbs wave and energy,but also prevents and suppresses explosion.

A QSRR Study on the Chromatographic Retention Indices of Hydroxylated Polychlorinated Biphenyls

Hydroxylated Polychlorinated Biphenyls （HO-PCBs） are the metabolite of polychlorinated biphenyls and have drawn much attention because they have hazard on human health and ecosystems. Molecular connectivity index calculation has been performed for 19 HO-PCB compounds. A number of statistically based parameters have been extracted. Linear relationship between chromatographic retention index （RI） and the molecular connectivity index of 15 compounds in the training set has been established by multiple linear regression method. The other 4 HO-PCBs are used as the external test set. The result shows that the parameters can be well used to express the quantitative structure-retention relationship （QSRR） of HO-PCBs. Good stability and predictive ability have been demonstrated by leave-one-out cross-validation and the external test set.

Improvement of Similarity Measure： Pearson Product-Moment Correlation Coefficient

Aim To study the reason of the insensitiveness of Pearson product-momentcorrelation coefficient as a similarity measure and the method to improve its sensitivity. MethodsExperimental and simulated data sets were used. Results The distribution range of the data setsinfluences the sensitivity of Pearson product-moment correlation coefficient. Weighted Pearsonproduct-moment correlation coefficient is more sensitive when the range of the data set is large.Conclusion Weighted Pearson product-moment correlation coefficient is necessary when the range ofthe data set is large.

Quantitative Correlation of Chromatographic Retention and Acute Toxicity for Alkyl(1-phenylsulfonyl) Cycloalkane Carboxylates and Their Structural Parameters by DFT

Twenty eight alkyl(1-phenylsulfonyl) cycloalkane carboxylates were computed at the B3LYP/6-31G* level. Based on linear solvation energy theory, two quantitative correlation equations of the molecular structures of alkyl(1-phenylsulfonyl) cycloalkane carboxylate com- pounds to their chromatographic retention (capacity factor lgKW) and the toxicity for photo- bacterium phosphoreum (–lgEC50) were developed by using the molecular structural parameters as theoretical descriptors (r2 = 0.9501, 0.9488). The two quantitative correlation equations were consequently cross validated by leave-one-out (LOO) validation method with q2 of 0.9113 and 0.9281, respectively. The result showed that the two equations achieved in this work by B3LYP/6-31G* are both more advantageous than those from AM1, and can be used to predict the lgKW and –lgEC50 of congeneric organics.

Analysis of Sucrose Esters with Long Acyl Chain by Coupling of HPLC-ELSD with ESI-MS System

The analysis of sucrose esters with long acyl chain by improved high performance liquid chromatographic method with evaporative light scattering detection （HPLC-ELSD） and electrospray ionization mass spectrum （ESI-MS） is investigated. The improved HPLC-ELSD method for the separation and quantitation of commercial and synthesized sucrose esters is described. Samples are analyzed by means of a reversed-phase （RP） HPLC using a Hypersil C8 column （250 mm× 4.6 mm, 5 μm particle size） with methanol-tetrahydrofuran （vo）ume ratio of 90 ： 10） and water under gradientcondition as the mobile phase, in which the flow rate is 1.0 ml·min^-1 and the column temperature is set at 40℃. This procedure provides a complete separation and determination ot monoester, diester, triester and higher esters with different acyl chain lengths in each fraction by a single run, in combination with the ESI-MS technology. With this method, it is possible to determine the approximate compositions of monoto polyesters in one analysis and quantitate pure positional isomers precisely using an external standard method. It is found that the method of ESI-MS coupling with HPLC system for the analysis of sucrose esters is straight forward, rapid and inexpensive, and can be readily applied in synthesis, purification and structure studies.

Genotoxic Effects of PAH Containing Sludge Extracts in Chinese Hamster Ovary Cell Cultures

Objective Many studies have been conducted in order to evaluate the genotoxicity of chemicals and waste materials, which utilized in vivo test protocols. The use of animals for routine toxicity testing is now questioned by a growing segment of society. Methods Keeping the above fact in mind, we have conducted in the present study the genotoxicity evaluation of oily sludge samples generated from a petroleum refinery and petrochemical industry and ETP sludge from petroleum refinery using DNA damage, chromosomal aberration, p53 protein induction and apoptosis in short term in vitro mammalian Chinese Hamster Ovary cell cultures. Results It is evident from the results that the oily sludge compounds derived from petroleum refinery and petrochemical industry could cause DNA damage, chromosomal aberration, p53 protein accumulation and apoptotic cell death on exposure to oily sludge extracts in the presence of metabolic activation system (S-9 mix), however, ETP sludge extract could not cause significant genotoxicity in comparison to oily sludge extract and negative control. Conclusion The effect may be attributed to polycyclic aromatic hydrocarbons present in the samples as evidenced from GC-MS.

Effects of mineral-organic fertilizer on the biomass of green Chinese cabbage and potential carbon sequestration ability in karst areas of Southwest China

The karst mountain areas of Southwest China contain barren farmland soils and suffer from nutritional and water deficiencies that affect crop productivity. Hence,it is imperative to apply suitable fertilizers to restore soil fertility and maintain crop yield. The aim of this study is to investigate the effects of mineral-organic fertilizer(MOF)made of potassic rock and organic waste on the growth of crops. For this purpose, green Chinese cabbage grown using three different fertilization methods including MOF,inorganic fertilizer(IF), and a control was evaluated. We determined soil water content, agronomic characteristics,and biomass of green Chinese cabbage in different treatments. Furthermore, surface runoff from the pot experiments and soil leachate from pot experiments were collected to determine water temperature, pH, and cation and anion concentrations. The results demonstrate thatMOF can improve the soil water-holding capacity of soil,and the basic agronomic characteristics of the cabbage treated with MOF were superior to those with IF. Using MOF can promote the increase in cabbage biomass.Additionally, the concentration of inorganic carbon(largely in the form of HCO_3^-) in surface runoff water treated by MOF was higher than the other treatments, establishing carbon sequestration potential. This work provides a novel and environmentally friendly fertilization pattern in karst areas, which will improve crop yield and also increase the carbon sequestration potential of crops.

Optimization by orthogonal array design of ion-pair HPLC separation of the enzymatic hydrolysis products of yeast RNA

The separation of enzymatic hydrolysis products of yeast RNA by ion-pair HPLC was studied.A modified chromatographic response function（MCRF） was proposed to appraise the effectiveness of chromatographic separation.This function takes the number of peaks,resolution and the retention time of the last peak into consideration.It shows advantages for optimization of HPLC separation of complex mixtures.An orthogonal array design was used to separate the hydrolysate of yeast RNA and the optimal chromatographic conditions were obtained.

Experimental investigation on combustion and unregulated emission characteristics of butanol-isomer/gasoline blends

Effects of butanol isomers on characteristics of combustion and emission were studied on PFI SI engine. Experiments were operated under the condition of 3 and 5 bar brake mean effective pressure (BMEP) engine loads and different equivalence ratios (φ=0.83-1.25) with engine speed of 1200 r/min using blends made of 70 vol.% gasoline and 30 vol.% butanol isomers (N30, S30, I30 and T30). The results indicated that compared with gasoline, all butanol isomer blends have higher cylinder pressure. N30 has the highest and most advanced peak pressure, and T30 shows a higher brake specific fuel consumption (BSFC) and lower brake thermal efficiency (BTE). N30 presents a lower UHC emissions and I30 has slightly higher CO emissions than other blends. For unregulated emissions, compared with gasoline, butanol isomer blends have higher acetaldehyde, and N30 produces a higher emission of 1,3-butadiene than other blends. A reduction in benzene, toluene, ethylbenzene and xylene (BTEX) has been found with butanol isomer blends.