POLYMER TESTING
·
2015
·
IF 2.24
Xinchao Bian,Lidong Feng,Gao Li,Zhiming Chen,Xuesi Chen
An analytical method has been developed to quantitatively determine the residual lactide monomer in polylactide (PLA) using an internal standard method of gas chromatography (GC). The experimental results showed that diphenyl ether (DPE) was an appropriate internal standard for quantitative analysis of residual lactide in PLA. PLA and DPE were dissolved in dichloromethane and precipitated in hexane . At the same time, the residual lactide in PLA and DPE as an internal standard were extracted to hexane from the polymer solution . The resulting solution could be directly injected into a GC system. Therefore, the residual lactide was determined quantitatively using an internal standard method of GC. This method is practical for measuring the residual lactide content in PLA. When the lactide content is 5.0%, the relative standard deviation ( RSD ) of the measurements is 1.7%, while RSD is 6.9% at the low level of 0.4%, which indicates that the method is sufficiently precise.
研究领域:
分析化学
·
材料科学
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产品关联
DOI
高影响因子
JOURNAL OF ANALYTICAL CHEMISTRY
·
2022
·Vol. 77
·期 3
·361-368
·
IF 1.237
Xue Liming,Xu Jiale,Feng Chao,Lu Dasheng,Zhou Zhijun
Abstract It is a challenge to perform target screening of metabolites on a large scale in metabolomics study using gas chromatography with mass spectrometry ( GC-MS ). Some metabolites can hardly be detected and identified in biosamples due to their low MS response or poor specificity. Moreover, synthesis and degradation of derivatized metabolites in samples made it difficult to achieve fine method stability. Our method screens 475 metabolites in a single run using GC-MS/MS in MRM mode, and both internal standard and quality control-based normalization strategies were used to correct the peak intensity. A total of 91 and 161 metabolites were detected in plasma and urine, respectively. The method was validated to have fine linearity range and intra-day and inter-day stability. The method was applied to a pilot study, and this study investigated the metabolic perturbation in rats after fluorochloridone ( FLC ) administration. 18 metabolites exhibited statistical significance in rat urine, and they were confirmed to be associated with FLC treatment, where the upregulation of glucose, lactose, and galactose is potentially linked to oxidative stress reaction. This study has proved its value in large-scale detection of metabolites in biosamples using GC-MS/MS with high sensitivity, specificity, and stability. We hope that our study can promote the GC-MS-based metabolomics studies.
研究领域:
分析化学
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代谢组学
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生物医学
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DOI
高影响因子
JOURNAL OF SEPARATION SCIENCE
·
2021
·Vol. 44
·期 9
·1852-1865
·
IF 3.645
Jingjing Wu,Song Zhang,Jiali Li,Xiaoli Zhong,Guiping Feng,Liangqing Hu,Fan He,Hanjing Cen,Yilu Chen,Yanling He,Huasong Zeng,Xiao Chen,Xiaolan Mo
Low-dose methotrexate is the first-line therapy for juvenile idiopathic arthritis. In vivo, methotrexate is converted into a series of methotrexate polyglutamates whose intracellular levels contribute significantly to its efficacy and toxicity. In this study, a novel high-performance liquid chromatography–tandem mass spectrometry method was developed and validated to simultaneously determine erythrocyte methotrexate polyglutamates using stable isotope-labeled internal standards. Erythrocyte samples were precipitated by perchloric acid and then determined on an XBridge BEH C18 column with an XP vanguard precolumn in 12 min. The mobile phase consisted of 10 nM ammonium acetate (pH 10) and methanol under gradient elution. The detection was carried out in multiple reaction monitoring mode via an electrospray ionization source in positive ionization mode. The calibration curve for each metabolite was linear from 2.0 to 500.0 nmol/L ( r 2 > 0.99). The intraday and interday accuracies were between 93.0 and 107.0%, and the corresponding precisions were between 0.8 and 5.2%. The relative recovery ranged from 82.7 to 105.1%, and the relative matrix effect varied from 96.5 to 104.4%. The erythrocyte metabolites were stable for 30 days at −80°C. This simple and accurate method is applicable to routine monitoring of the concentration of erythrocyte methotrexate polyglutamates in patients to achieve individualized treatment.
研究领域:
药理学
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分析化学
·
临床医学
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DOI
PubMed
高影响因子
Nanomaterials
·
2022
·Vol. 12
·期 3
·421
·
IF 5.719
Rongyuan Cai,Lijun Yin,Qian Huang,Ruiyun You,Shangyuan Feng,Yudong Lu
In this work, we developed a new type of SERS probe, which was composed of glass-SiO2[email protected]@Ag nanoparticles (NPs) three-dimensional Surface-enhanced Raman spectroscopy (SERS) substrate. When the laser passed through the quartz glass sheet, on the one hand, the SiO2NPs supporting the[email protected]@Ag NPs increase the roughness of the substrate surface, resulting in a large number of hot spots among nanoparticles. On the other hand, based on the focusing effect of silicon dioxide nanospheres, the laser can better focus on the surface of nanoparticles in the inverted SERS probe, thus showing better SERS enhancement. Furthermore, the[email protected]@Ag NPs core-shell structure was used with 4-mercaptobenzoonitrile (MBN) as an internal standard molecule, and the quantitative determination of tyrosine and urea was realized by internal standard correction method. The standard working curves of the two had good linear correlation with R2above 0.9555. The detection limits of tyrosine and urea were in the range of 2.85 × 10−10M~7.54 × 10−6M, which confirms that this design can be used for quantitative and specific detection of biological molecules, demonstrating great practical significance for the research of diseases such as skin lesions and endocrine disorders.Keywords:SERS;endoscope;internal standard;tyrosine;urea;sweat
研究领域:
分析化学
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生物医学工程
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材料科学
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产品关联
DOI
PubMed
高影响因子
ACS Omega
·
2019
·
IF 2.584
Shumei Yang,Lei Mu,Ruxia Feng,Xianglei Kong
Matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS) has shown its great success in the qualitative analysis of a wide range of organic and biological molecules. However, its application in quantitative analysis is still limited by the difficulty in the availability of isotope-labeled internal standards. The present work investigates the relationship between the correlation coefficient of the peak intensities of analyte and candidate internal standard ions and the linearity of possible quantitative analysis. Based on the two analyte examples, ciprofloxacin and substance P, the results show that the performance of the selected nonisotope-labeled internal standard is greatly related to the correlation coefficient. A high positive correlation coefficient (>0.7) between the ions of analyte and candidate standard can result in a good linearity (R2 > 0.98) and vice versa. The results provide a new way to select nonisotope-labeled internal standards for MALDI analysis and thus can be potentially applied in the rapid quantitative mass spectrometry.
研究领域:
分析化学
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生物医学
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产品关联
DOI
PubMed
高影响因子
Energies
·
2017
·Vol. 10
·期 7
·967
·
IF 2.262
Fu Wan,Lingling Du,Weigen Chen,Pinyi Wang,Jianxin Wang,Haiyang Shi
Analyzing the concentration of low molecular acids dissolved in oil is vital in the oil-paper insulation aging diagnostic procedure of power transformers. The existing methods cannot distinguish between different acid types and their strengths. In this study, an improved solution Raman detection platform is fabricated. The direct measurement of dissolved acetic acid, a kind of low molecular acids, is observed in transformer oil without extraction. The Raman shift line of oil-dissolved acetic acid at 891 cm−1corresponding to H–C–H symmetrical swing and O–H swing modes is taken as its characteristic value. Taking Raman shift line of pure oil at 932 cm−1as an internal standard, a linear regression curve for quantitative analysis is obtained with a slope of 0.19. The best platform parameter of accumulation number is 300, which is determined by Allan deviation analysis. The current concentration detection limit and accuracy for oil-dissolved acetic acid are obtained at about 0.68 mg/mL and 91.66%, separately. The results show that Raman spectroscopy could be a useful alternative method for evaluation insulation aging state of an operating power transformer in the future.Keywords:power transformer;oil-paper insulation aging state;acetic acid;Raman spectroscopy;internal standard
研究领域:
电气工程
·
分析化学
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产品关联
DOI
高影响因子
JOURNAL OF FOOD COMPOSITION AND ANALYSIS
·
2020
·
IF 3.721
Caiyun Zhang,Jiaxiong Zeng,Wenguang Xiong,Zhenling Zeng
A rapid, simple and reliable method using amoxicillin-D4 as internal standard (IS) for determination of amoxicillin (AMO) in porcine tissues was developed. The analytical methodology used a phosphate buffer (0.01 M, pH = 6.3) with trichloroacetic acid (50 mg/mL) for extraction and Oasis® HLB cartridges for clean-up followed by UPLC-MS/MS analysis. The optimized method was validated according to EU guideline 2002/657/EC and FDA guideline. The LOQ in muscle, fat, liver and kidney were set to 10 μg/kg which was below the maximum residue limits, while the LOD were set to 5 μg/kg. Results showed that using AMO-D4 as IS can effectively eliminate relative matrix interference and improve the recovery and precision. A good linearity was observed at the range of 10−500 μg/kg with a correlation coefficients (R 2 ) larger than 0.99. The mean recoveries were higher than 87.0 %, and the RSDs were lower than 11.2 %. This method could be applied to conveniently analysis the residue of AMO in different porcine tissues.
研究领域:
兽医学
·
分析化学
·
食品安全
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DOI
高影响因子
TALANTA
·
2024
·
IF 5.6
Xiaoming Li,Jiaqi Hu,De Zhang,Xiubin Zhang,Zhetao Wang,Yufeng Wang,Qiang Chen,Pei Liang
Surface-enhanced Raman spectroscopy (SERS) can quickly identify molecular fingerprints and has been widely used in the field of rapid detection. However, the non-uniformity inherent in SERS substrate signals, coupled with the finite nature of the detection object, significantly hampers the advancement of SERS. Nowadays, the existing mature immunochromatographic assay (ICA) method is usually combined with SERS technology to address the defects of SERS detection. Nevertheless, the porous structure of the strip will also affect the signal uniformity during detection. Obviously, a method using SERS-ICA is needed to effectively solve signal fluctuations, improve detection accuracy, and has certain versatility. This paper introduces an internal standard method combining deep learning to predict and process Raman data. Based on the signal fluctuation of single-antigen SERS-ICA test strip, the double-antigen SERS-ICA test strip was constructed. The full spectrum Raman data of double-antigen SERS-ICA test strip was normalized by the sum of two characteristic peaks of internal standard molecules, and then processed by deep learning algorithm. The Relative Standard Deviation (RSD) of Raman data of bisphenol A was compared before and after internal standard normalization of double-antigen SERS-ICA test strip. The RSD processed by this method was increased by 3.8 times. After normalization, the prediction accuracy of Root Mean Square Error (RMSE) is improved by 2.66 times, and the prediction accuracy of R-square (R 2 ) is increased from 0.961 to 0.994. The results showed that RMSE and R 2 were used to comprehensively predict the collected data of double-antigen SERS-ICA test strip, which could effectively improve the prediction accuracy. The internal standard algorithm can effectively solve the challenges of uneven hot spots and poor signal reproducibility on the test strip to a certain extent, so as to improve the semi-quantitative accuracy.
研究领域:
分析化学
·
生物医学工程
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产品关联
DOI
PubMed
高影响因子
Frontiers in Chemistry
·
2024
·
IF 3.8
Tian Yongfeng,Zhao Lu,Shen Xiaofeng,Shang Shanzhai,Pan Yonghua,Dong Gaofeng,Huo Wang,Zhu Donglai,Tang Xianghu
Surface enhanced Raman spectroscopy (SERS) is a unique analytical technique with excellent performance in terms of sensitivity, non-destructive detection and resolution. However, due to the randomness and poor repeatability of hot spot distribution, SERS quantitative analysis is still challenging. Meanwhile, snus is a type of tobacco product that can release nicotine and other components in the mouth without burning, and the rapid detection technique based on SERS can reliably evaluate the amount of nicotine released from snus, which is of great significance for understanding its characteristics and regulating its components. Herein, the strategy was proposed to solve the feasibility of SERS quantitative detection based on self-assembled core-shell nanoparticles with embedded internal standards (EIS) due to EIS signal can effectively correct SERS signal fluctuations caused by different aggregation states and measurement conditions, thus allowing reliable quantitative SERS analysis of targets with different surface affinity. By means of process control, after the Au nanoparticles (Au NPs) were modified with 4-Mercaptobenzonitrile (4-MBN) as internal standard molecules, Ag shell with a certain thickness was grown on the surface of the AuNP@4-MBN, and then the Au@4-MBN@Ag NPs were used to regulate and control the assembly of liquid-liquid interface. The high-density nano-arrays assembled at the liquid-liquid interface ensure high reproducibility as SERS substrates, and which could be used for SERS detection of nicotine released from snus products. In addition, time-mapping research shows that this method can also be used to dynamically monitor the release of nicotine. Moreover, such destruction-free evaluation of the release of nicotine from snus products opens up new perspectives for further research about the impact of nicotinoids-related health programs.
研究领域:
分析化学
·
烟草研究
·
健康科学
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产品关联
DOI
PubMed
高影响因子
ANALYST
·
2021
·Vol. 146
·期 23
·7168-7177
·
IF 4.616
Bingyong Lin,Yuanyuan Yao,Yueliang Wang,Palanisamy Kannan,Lifen Chen,Longhua Guo
The uneven distribution of metal nanoparticles is a vital influencing factor in the poor uniformity of surface-enhanced Raman scattering (SERS) substrates, which is a challenge in SERS quantitative analysis. Recent reports showed that the reproducibility of a nonuniform SERS substrate can be effectively improved by the use of an internal standard (IS). However, most of these approaches require the investment of time for precise regulation, and those approaches based on the addition of an IS are specific to a certain substrate. In this work, we proposed a simple, rapid and universal method to incorporate an IS into a SERS substrate for improving the reproducibility of Raman signals based on the systematic evaluation of the influencing factors of the competitive adsorption between the IS and the target analytes. Following the proposed pressure drop-coating (PDC) method, an IS-modified gold nanobipyramids (Au NBPs)/anodic aluminum oxide (AAO) SERS substrate was fabricated within 1 min, showing high reproducibility of Raman signals. In addition, the IS-modified Au NBPs/AAO SERS substrate was successfully applied to analyze thiram in freshly squeezed apple juice and the result showed a stable Raman signal with a relative standard deviation of less than 6.00%. What is more, three different commercial SERS chips were modified with an IS molecule using the PDC method. Compared to the traditional SERS chips, the Raman signal reproducibility of the functionalized SERS chips was improved significantly. Since the addition of an IS is not based on a certain substrate, the proposed approach could be useful for all the researchers working in the field of SERS.
研究领域:
分析化学
·
材料科学
·
纳米技术
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产品关联
DOI
PubMed
高影响因子
BMC Chemistry
·
2025
·Vol. 19
·期 1
·1-10
·
IF 4.6
Niu Jiajia,He Aimin,Gao Feng,Yu Zhenhua,Li Jiehui,Liu Yang,Hao Hongling,Chen Jingzheng,Zhang Fengmei,Chen Chen,Yue Liqing
It is important to accurately test the content of the main components (i.e., oxyacetyl, vinyl, and vinyl alcohol) of VAE-type adhesives/emulsions. In this study, we first investigated the solubility of dried VAE samples. Dimethyl sulfoxide (DMSO) was the best solvent tested, and at a sample concentration of 10,000 µg/mL, complete dissolution was achieved after 3 h of ultrasonication. Second, different chemical shifts of protons in the 1H NMR spectrum of VAE samples were assigned as follows: 2.01 ppm for CH3 of oxyacetyl groups, 1.5–1.8 ppm for the backbone CH2 connected to vinyl alcohol or oxyacetyl groups, and 1.2 ppm for the backbone CH2. Based on these assignments, an 1H NMR normalization-based quantification method was established. Meanwhile, correction factors of each VAE functional group relative to the internal standard benzyl benzoate were calculated to establish an 1H NMR internal standard-based quantification method. For the vinyl acetate monomer that was tested as a proxy for the oxyacetyl group, the 1H NMR internal standard-based quantification method yielded a closer result (37.44%) to the classical method (37.30%) than the normalization-based method. The method exhibited good repeatability and reproducibility (repeatability RSD < 5%, reproducibility RSD: vinyl and oxyacetyl < 5%, vinyl alcohol < 11.24%). In contrast, a 13C NMR internal standard-based quantification method was deemed unsuitable for the quantitative analysis of VAE main components due to its high sample concentration requirements, lengthy test durations, and tendency to underestimate the actual contents. Finally, a 1H NMR internal standard-based quantification method was established for the determination of the main components of VAE-type adhesives/emulsions.
研究领域:
分析化学
·
高分子科学
·
材料工程
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产品关联
DOI
PubMed
高影响因子
ANALYTICAL CHEMISTRY
·
2025
·
IF 6.7
Huan Yao,Ting Huang,Zhifang Li,Huaxin Wu,Xueyao Li,Hua Tang,Fuhai Su,Xinliang Jin,Wei Zhang
Purity assessment is critical for the quality control of active pharmaceutical ingredients (APIs). However, there is a lack of rapid and accurate purity assessment methods that operate independently of target-specific certified reference materials (CRMs). Herein, we proposed a traceable quantification method, named SFC-ISC-qNMR, for purity assessment and quantitative determination of low-purity APIs, which was accomplished by tracing the test solution to the reference solution via supercritical fluid chromatography (SFC) collection with internal standard-correction (ISC), followed by an SI-traceable quantitative nuclear magnetic resonance (qNMR) analysis of the reference solution (SI = International System of Units). Digitoxin, a widely used cardiac glycoside in the treatment of heart failure and arrhythmias, was used as a model compound. By employing a mobile phase of supercritical CO2 modified with 24%–26% methanol, digitoxin with a purity exceeding 99.87% was isolated and collected. A national CRM of ethyl para-hydroxybenzoate was used as the IS for digitoxin. The SFC-ISC reference solution can be prepared in 15 min without the need for precise weighing, simply by reconstitution of the SFC collected high-purity analyte in deuterated methanol containing IS. The feasibility and reliability of the SFC-ISC-qNMR method were exhibited through the quantitative determination of digitoxin in chemical mixtures. The purity of a commercially available digitoxin reagent was determined to be 94.17% ± 0.15%, which was consistent with high-resolution qNMR analysis. The contents of spiked digitoxin in a digoxin analytical standard were measured at 1.06%, 1.37%, 2.39%, and 4.43%, respectively, showing high consistency with the gravimetric value with a bias less than 0.13%. In contrast, direct qNMR with deconvolution and HPLC analysis failed to provide accurate measurements. These results highlight the applicability of the SFC-ISC-qNMR method for drug evaluation and research, demonstrating its significant potential for the purity assessment of APIs.
研究领域:
分析化学
·
药物分析
·
色谱分析
·
核磁共振（NMR）
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产品关联
DOI
PubMed
高影响因子
危险品化学品经营许可证（带存储）