scholarly journals Qualitative and Quantitative Analysis of the Product and By-Products from Transesterification between Phenol and Dimethyl Carbonate

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Tao Liu ◽  
Jing Hu ◽  
Li Yong ◽  
Gang Zhang ◽  
Yi Zhang ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Dimethyl Carbonate ◽  
Correlation Coefficients ◽  
Gas Chromatography Mass Spectrometry ◽  
Qualitative And Quantitative ◽  
Relative Standard ◽  
Hydrogen Flame ◽  
Quantitative Analyses ◽  
Gas Chromatographic Method ◽  
By Products

By-products (phenyl salicylate, phenyl 4-hydroxybenzoate, and xanthone) from transesterification between phenol and dimethyl carbonate (DMC) were qualitatively analyzed by gas chromatography-mass spectrometry, and a gas chromatographic method with directed injection for simultaneous quantitative analysis of the product (DPC) and by-products of the transesterification has been established. Based on the results of qualitative and quantitative analyses, the mechanism of the by-products generation was preliminarily deduced. The sample for quantitative analysis was directly diluted in acetone, and related compounds were separated on an HP-5 capillary column and detected by a hydrogen flame ionization detector (FID). The product and by-products were well separated, the correlation coefficients (r) within the concentration range of 1.0 μg/mL–100 μg/mL were ≥0.9997, the relative standard deviations were between 0.5% and 4.4%, spiked recoveries were between 91.5% and 105.6%, and detection limits were between 0.11 and 0.18 μg/mL. The established method is simple, rapid, accurate, sensitive, and highly specific. It is suitable for simultaneous qualitative and quantitative analyses of the product and by-products of transesterification between phenol and DMC.

scholarly journals Quantitative Analysis by Gas Chromatography / Mass Spectrometry of Heroin Traded in Kuwait during 2016 – 2017, and Its Comparison with Results of Analyzing Heroin Traded during 2012 and Addicts Death Rate Statistics during 2011 – 2018

2020 ◽  
pp. 12-22
Author(s):  
N. A. Al-Abkal ◽  
E. Kh. Metwally ◽  
S. R. Alezzbawy ◽  
Kh. Y. Orabi ◽  
Sh. H. Alshammari
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Quantitative Analysis ◽  
Gas Chromatography Mass Spectrometry ◽  
Qualitative And Quantitative Analysis ◽  
Satisfactory Explanation ◽  
Heroin Addicts ◽  
Qualitative And Quantitative ◽  
Chromatography Mass Spectrometry ◽  
Quantitative Analyses

Aim: To compare the main and additive components of heroin trafficked in the Stateof Kuwait during 2012 with those components of heroin traded recently in the country during 2016 and 2017, and to provide a satisfactory explanation for the increase in deaths among heroin addicts during the period2011 -2018. Study Design: Selected samples of non-pure powder heroin seized in Kuwait during 2016 and 2017, with pure heroin and a set of10 pure different heroin component standards, all have been quantitatively analyzed in the Forensic Laboratories. Place and Duration of Study: All qualitative and quantitative analyses for 2016 and 2017 samples were conducted in the Forensic Laboratories of the General Department of Criminal Evidences – Ministry of Interior – State of Kuwait. Methodology: By using Gas Chromatography/Mass Spectrometry (GC/MS) to qualitative and quantitative analysis have been made on a total of hundred samples of non-pure powder heroin seized in Kuwait during the years 2016 and 2017, in addition to ten pure standards. Results: The concentration of the diacetylmorphine (active substance of heroin) in Kuwait during the year 2017 are much higher than the concentration during the year 2016. The additive substances (adulterants) for the years 2016 and 2017, are shared with the year 2012 by the component's paracetamol, caffeine and diazepam with different concentrations. But new adulterants in recent years are recorded in samples 2016 and 2017, including methamphetamine, dextromethorphan, and methylphenidate which is absent in 2016 samples. Conclusion: The concentration % of illicit heroin traded in Kuwait as diacetylmorphine has increase from 10% to 50% for year 2016, and further from 30% - 70% for year 2017, which marks identified a substantial rising in the purity of heroin. In addition, additive substances in the two years include paracetamol (acetaminophen), caffeine and diazepam, previously recorded in 2012. However, totally different new adulterates are recorded in 2016 and 2017 samples, including methamphetamine, dextromethorphan, and methylphenidate. All new three adulterates are detected in quite a few numbers of samples with methylphenidate recorded in a very low concentration of 0. 01 mg. Both new adulterates and higher purity of heroin constitute the main reasons for rising the rate of deaths between heroin addicts in recent years. Also, recent UN reports (12,18) provide evidence that the GC countries Afghanistan, Iran and Pakistan are still manufacturing and trading the above mentioned new adulterates.

Comprehensive Analysis of Volatile Compounds in Mouthpiece Cigarette Adhesive by Coupling Headspace with Gas Chromatography-Mass Spectrometry

2020 ◽  
Author(s):  
Min Wei ◽  
Feng Zheng ◽  
Xuyan Song ◽  
Ran Li ◽  
Xi Pan ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Quantitative Analysis ◽  
Volatile Compounds ◽  
Analytical Method ◽  
Gas Chromatography Mass Spectrometry ◽  
Qualitative And Quantitative Analysis ◽  
Qualitative And Quantitative ◽  
Chromatography Mass Spectrometry ◽  
Relative Standard

Abstract Background Some volatile compounds in mouthpiece cigarette adhesive emit irritating odors and affect the taste of smoking cigarettes. Therefore, it is necessary to monitor the volatile compounds in mouthpiece cigarette adhesive. Objectives A rapid and simple analytical method of volatile compounds in mouthpiece cigarette adhesive was established. Methods In this study, headspace (HS) injection coupled with gas chromatography-mass spectrometry (GC-MS) was utilized for qualitative and quantitative analysis. Initially, the volatile compounds in mouthpiece cigarette adhesives were detected by HS-GC-MS, followed by spectrum library retrieval. The detected compounds with the similarity to spectrum library of more than 85% were further identified by comparing the retention time and mass spectra of the detected volatile compounds and those of the corresponding standard samples. The quantitative analysis of 9 identified volatile compounds was performed. Results Eleven volatile compounds in the mouthpiece cigarette adhesive were accurately identified. The quantitative analytical method of 9 volatile compounds in mouthpiece cigarette adhesive was validated to have good linearities (R2 > 0.9932) within the range of 20–5000 ng/g. The detection limits of 9 compounds were within the range of 3.1–147.7 ng/g. The intra- and inter-day relative standard deviations (RSDs) were less than 19.8%. The recoveries of these 9 compounds spiked into mouthpiece cigarette adhesive were from 68.1% to 108.3%. Conclusions The proposed method is rapid, simple, and accurate for qualitative and quantitative analysis of volatile compounds in the mouthpiece cigarette adhesive. Highlights The developed analytical method is expected to be used to monitor volatile compounds in various adhesives.

scholarly journals Quantitative analysis of hydrogen and chalcogen bonds in two pyrimidine-5-carbonitrile derivatives, potential DHFR inhibitors: an integrated crystallographic and theoretical study

RSC Advances ◽  
2020 ◽  
Vol 10 (60) ◽  
pp. 36806-36817
Author(s):  
Lamya H. Al-Wahaibi ◽  
Kushumita Chakraborty ◽  
Nora H. Al-Shaalan ◽  
Mohamed Yehya Annavi Syed Majeed ◽  
Olivier Blacque ◽  
...  
Keyword(s):  
Quantitative Analysis ◽  
Theoretical Study ◽  
Qualitative And Quantitative ◽  
Quantitative Analyses ◽  
Dhfr Inhibitors

Qualitative and quantitative analyses of hydrogen and chalcogen bonds in two pyrimidine-5-carbonitrile derivatives are described.

scholarly journals Quantitative Characteristics of Toxic Compounds According to the Solvent Type

2019 ◽  
Vol 2019 ◽  
pp. 1-9
Author(s):  
Young-Ji An ◽  
Seong-Jin Choi ◽  
Yong-Hyun Kim ◽  
Kyuhong Lee
Keyword(s):  
Quantitative Analysis ◽  
Analytical Data ◽  
Gas Chromatography Mass Spectrometry ◽  
Toxic Compounds ◽  
Solvent Type ◽  
Target Analytes ◽  
Relative Standard ◽  
Rf Values ◽  
Benzene Toluene ◽  
Working Standards

The quantitative analysis of target substances is an important part of assessing the toxicity of diverse materials. Usually, the quantitation of target compounds is conducted by instrumental analysis such as chromatography and capillary electrophoresis. If solvents are used in the pretreatment step of the target analyte quantification, it would be crucial to examine the solvent effect on the quantitative analysis. Therefore, in this study, we assessed the solvent effects using four different solvents (methanol, hexane, phosphate buffered saline (PBS), and dimethyl sulfoxide (DMSO)) and three toxic compounds (benzene, toluene, and methylisothiazolinone (MIT)). Liquid working standards containing the toxic compounds were prepared by dilution with each solvent and analyzed by gas chromatography-mass spectrometry (GC-MS). As a result, we found that the response factor (RF) values of the target analytes were different, depending on the solvent types. In particular, benzene and toluene exhibited their highest RF values (33,674 ng−1 and 78,604 ng−1, respectively) in hexane, while the RF value of MIT was the highest (9,067 ng−1) in PBS. Considering the correlation (R2) and relative standard deviation (RSD) values, all target analytes showed fairly good values (R2 > 0.99 and RSD < 10%) in methanol and DMSO. In contrast, low R2 (0.0562) and high RSD (10.6%) values of MIT were detected in hexane, while benzene and toluene exhibited relatively low R2 and high RSD values in PBS (mean R2 = 0.9892 ± 0.0146 and mean RSD = 13.3 ± 4.1%). Based on these findings, we concluded that the results and reliability of the quantitative analysis change depending on the analyte and solvent types. Therefore, in order to accurately assess the toxicity of target compounds, reliable analytical data should be obtained, preferentially by considering the solvent types.

scholarly journals Determination of Pyrethroids in Tea Brew by GC-MS Combined with SPME with Multiwalled Carbon Nanotube Coated Fiber

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
Dongxia Ren ◽  
Chengjun Sun ◽  
Guanqun Ma ◽  
Danni Yang ◽  
Chen Zhou ◽  
...  
Keyword(s):  
Solid Phase ◽  
Steel Wire ◽  
Correlation Coefficients ◽  
Organic Reagent ◽  
Gas Chromatography Mass Spectrometry ◽  
Multiwalled Carbon ◽  
Coated Fiber ◽  
Relative Standard ◽  
Reagent Consumption ◽  
Optimized Conditions

A new method has been developed to simultaneously determine 7 pyrethroid residues in tea brew using gas chromatography-mass spectrometry (GC-MS) combined with solid phase microextraction (SPME) with multiwalled carbon nanotubes (MWCNTs) coated fiber. The MWCNTs coated fiber of SPME was homemade by using stainless steel wire as coating carrier and polyacrylonitrile (PAN) solution as adhesive glue. Under the optimized conditions, a good linearity was shown for bifenthrin, fenpropathrin, permethrin, and cyfluthrin in 1–50 ng mL−1 and for cypermethrin, fenvalerate, and deltamethrin in 5–50 ng mL−1. The correlation coefficients were in the range of 0.9948–0.9999. The average recoveries of 7 pyrethroids were 94.2%–107.3% and the relative standard deviations (RSDs) were less than 15%. The detection limit of the method ranged from 0.12 to 1.65 ng mL−1. The tea brew samples made from some commercial tea samples were analyzed. Among them, bifenthrin, fenpropathrin, and permethrin were found. The results show that the method is rapid and sensitive and requires low organic reagent consumption, which can be well used for the detection of the pyrethroids in tea brew.

Method Evaluation Computer Program for Quantitative Analysis of PBBs and PBDEs in Plastics

2010 ◽  
Vol 36 ◽  
pp. 337-343
Author(s):  
Punnee Sittidech ◽  
Manop Sittidech
Keyword(s):  
Quantitative Analysis ◽  
Computer Program ◽  
Analytical Method ◽  
Limit Of Detection ◽  
Diphenyl Ether ◽  
Research Work ◽  
Test Method ◽  
Gas Chromatography Mass Spectrometry ◽  
Polybrominated Biphenyls ◽  
Relative Standard

Polybrominated biphenyls (PBBs) and polybrominated biphenyl ethers (PBDEs) are substances used in electrical and electronic products. They are restricted substances due to their potential risk to human health and the environment. In this research work, a test method was evaluated for the quantitative analysis of polybrominated diphenyl ethers (PBDEs) and polybrominated biphenyls (PBBs) in acrylonitrile-butadiene–styrene (ABS) plastic and polyethylene materials, based on solvent extraction of a plastic sample with soxhlet extraction techniques and detection by gas chromatography/mass spectrometry. We have also developed a computer program for checking the suitability of the analytical method by evaluating validation characteristics, including accuracy, precision, specificity/selectivity, limit of detection (LOD), limit of quantification (LOQ), linearity, range and sensitivity. The computer program was successfully applied for evaluation of the analytical method for prohibited PBBs and PBDEs in plastics. Graphical charts for the evaluation of the analytical method are presented along with their values, and researchers can get insight into evaluating several parameters together. It was found that the analytical method was able to quantify monobrominated - decabrominated biphenyl and monobrominated diphenyl ether–nonabrominated diphenyl ether between 100-1750 mg/kg and decabrominated diphenyl ether between 100–8,000 mg/kg. In addition, ERM-EC590 Polyethylene certified reference material from the Institute for Reference Materials and Measurements (IRMM) was used to validate the analytical method for PBBs and PBDEs in plastics. The obtained accuracy and precision indicate that the method successfully meets the required accuracy expressed as % recovery (70-130%) and the required precision expressed as percentage relative standard deviation (less than 20% RSD) of the IEC 62321:2008 international standard method.

scholarly journals Ultrahigh Performance Liquid Chromatography–Electrospray Ionization Tandem Mass Spectrometry Method for Qualitative and Quantitative Analyses of Constituents of Corydalis bungeana Turcz Extract

Molecules ◽  
2019 ◽  
Vol 24 (19) ◽  
pp. 3463
Author(s):  
Miao Tian ◽  
Chunjuan Yang ◽  
Jing Yang ◽  
Hongrui Dong ◽  
Lu Liu ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Acetic Acid ◽  
Quantitative Analysis ◽  
Electrospray Ionization ◽  
Mobile Phase ◽  
Gradient Elution ◽  
Tandem Ms ◽  
Qualitative And Quantitative ◽  
Esi Ms ◽  
Quantitative Analyses

In this study, the constituents of a Corydalis bungeana Turcz extract were qualitatively analyzed using gradient elution with a mobile phase of 0.2% acetic acid and acetonitrile. We obtained comprehensive insight into the constituents of C. bungeana Turcz extracts through the quantitative analysis of 14 compounds by comparison with authentic reference standards, and tentatively identified an additional 44 compounds through electrospray ionization mass spectrometry (ESI–MS) and tandem MS detection. The separation was successfully achieved using an Agilent SB-C18 column (1.8 µm, 150 × 2.1 mm; Agilent, Santa, CA, USA). A tandem quadrupole spectrometer was operated in either full-scan mode or multiple reaction monitoring (MRM) for the qualitative and quantitative analyses of the constituents, respectively. Validation data (inter-day and intra-day combined) for accuracy and precision ranged from −4.80% to 4.73%, and 0.30% to 4.97%, respectively. An ultrahigh performance liquid chromatographic–ESI–tandem MS (UHPLC–ESI–MS/MS) method for qualitative of C. bungeana Turcz (C. bungeana) extract and the quantification of 14 alkaloids, namely, A–N, was developed and validated. Quantitative analysis involved gradient elution with a mobile phase of 0.1% acetic acid and methanol for 45 min. The separation was successfully achieved using a Waters SB-C18 column (1.8 µm, 100 mm × 2.1 mm, Waters, Milford, Massachusetts, USA). The repeatability and stability of the method also met USFDA criteria with CV values lower than 5%. The limit of detection of the 14 alkaloids ranged from 9.74 to 13.00 ng/mL, whereas the linearities of the standard curves were between 0.9991 and 0.9995. In total, 15 commercial samples from 11 different sources were analyzed.

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