JOURNAL OF CHROMATOGRAPHY B-ANALYTICAL TECHNOLOGIES IN THE BIOMEDICAL AND LIFE SCIENCES
·
2016
·
IF 2.687
Zhongyi Zhang,Jing Tian,Hongwei Xiao,Nengjian Zheng,Xiaofei Gao,Renguo Zhu,Huayun Xiao
The signatures of natural stable nitrogen isotopic composition (δ 15 N) of individual amino acid (AA) have been confirmed to be a potentially effective tool for elucidating nitrogen cycling and trophic position of various organisms in food webs. In the present study, a two-stage derivatisation approach of esterification followed by acylation was evaluated. The biological samples underwent acid hydrolysis and the released individual AA was derivatived into corresponding N -pivaloyl-isopropyl (NPIP) esters for nitrogen isotopic analysis in gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Usually, 13 individual AA derivatives were separated with fine baseline resolution based on a nonpolar gas chromatography column (DB-5 ms). The minimum sample amount required under the presented conditions is larger than 20 ngN on column in order to accurately determine the δ 15 N values. The δ 15 N values determined by GC-C-IRMS with a precision of better than 1‰, were within 1‰ after empirical correction compared to the corresponding measured by element analysis (EA)-IRMS. Bland-Altman plot showed highly consistency of the δ 15 N values determined by the two measurement techniques. Cation-exchange chromatography was applied to remove interfering fraction from the extracts of plant and animal samples and without nitrogen isotope fractionation during the treatment procedure. Moreover, this approach was carried out to estimate the trophic level of various natural organisms in a natural lake environment. Results highly proved that the trophic level estimated via the presented AA method well reflected the actual food web structure in natural environments.
研究领域:
生态学
·
分析化学
✓ 已验证
DOI
PubMed
高影响因子
ENVIRONMENTAL RESEARCH
·
2024
·
IF 7.7
Dawei Wang,Gaoen Wu,Jing Tian,Chan Li,Jiemin Liu,Longchao Liang,Guangle Qiu
Compound-specific isotope analysis of nitrogen in amino acids (CSIA-AA, δ 15 N AA ) has gained increasing popularity for elucidating energy flow within food chains and determining the trophic positions of various organisms. However, there is a lack of research on the impact of hydrolysis conditions, such as HCl concentration and hydrolysis time, on δ 15 N AA analysis in biota samples. In this study, we investigated two HCl concentrations (6 M and 12 M) and four hydrolysis times (2 h, 6 h, 12 h, and 24 h) for hydrolyzing and derivatizing AAs in reference materials (Tuna) and biological samples of little egret (n = 4), night heron (n = 4), sharpbelly (n = 4) and Algae (n = 1) using the n-pivaloyl-iso-propyl (NPIP) ester approach. A Dowex cation exchange resin was used to purify amino acids before derivatization. We then determined δ 15 N AA values using gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). The results revealed no significant differences (p > 0.05) in δ 15 N AA values among samples treated with different HCl concentrations or hydrolysis times, particularly for δ 15 N Glx (range: 21.0–23.5‰) and δ 15 N Phe (range: 4.3–5.4‰) in Tuna (12 M). Trophic positions (TPs) calculated based on δ 15 N AA at 2 h (little egret: 2.9 ± 0.1, night heron: 2.8 ± 0.1, sharpbelly: 2.0 ± 0.1 and Algae: 1.3 ± 0.2) were consistent with those at 24 h (3.1 ± 0.1, 2.8 ± 0.1, 2.2 ± 0.1 and 1.1 ± 0.1, respectively), suggesting that a 2-h hydrolysis time and a 6 M HCl concentration are efficient pretreatment conditions for determining δ 15 N AA and estimating TP. Compared to the currently used hydrolysis conditions (24 h, 6 M), the proposed conditions (2 h, 6 M) accelerated the δ 15 N AA assay, making it faster, more convenient, and more efficient. Further research is needed to simplify the operational processes and reduce the time costs, enabling more efficient applications of CSIA-AA.
研究领域:
生态学
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生物地球化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
JOURNAL OF CHROMATOGRAPHY A
·
2024
·
IF 3.8
Yirang Wang,Jingyi Fan,Xian Fang,Yue Zhuo,Siyan Xu,Lei Liao,Xiaojun Deng,Bing Liu
AICAR (5-amino-4-imidazolecarboxyamide ribonucleoside), as a metabolic modulator, is classified in the S4 category by the World Anti-Doping Agency (WADA). Carbon Isotope Ratio Mass Spectrometry (CIR) is the mainstream method for distinguishing the endogenous and exogenous sources of AICAR in urine due to the significant individual difference in the concentration. The purpose of this study is to establish a gas chromatography combustion Isotope Ratio Mass Spectrometry (GC/C/IRMS) method for AICAR based on efficient two-dimensional liquid chromatography (2D-HPLC) separation. Method In this study, an automated 2D-HPLC separation technique was used to separate and purify AICAR and endogenous reference substances in urine samples. Then, AICAR was derivatized with 3-TMS as the main derivative product, while the endogenous reference compounds remained in their original form. Subsequently, the developed GC/C/IRMS method was utilized for the detection of the target and reference substances. Followed, we evaluated the applicability of this method using urine samples from two Asian males administered a low dose of AICAR (3 grams). Results The advantages of this study include: 1) reduced sample pretreatment time: the established 2D-HPLC separation method can separate the target and endogenous reference substances in one step; 2) low interference: the isotope chromatograms have low background interference, and the separation of endogenous reference substances is purer; 3) more accurate result calculations: this method only requires derivatization and result correction for AICAR, with the endogenous reference substances measured in their original form, reducing biases from corrections of multiple substances. The detection method performed well, with a concentriton limit of 2500 ng/mL, meeting the needs of routine detection concentrations. The CIR results from volunteer samples indicated that samples collected within 16 hours post-administration exceeded the threshold set in the literature. Conclusion This study successfully established a 2D-HPLC-GC/IRMS method that integrates CIR as the most stable indicator for distinguishing the internal and external sources of AICAR. After administering a low dose of AICAR to the Asian population, exogenous drug characteristics were manifested within 16 hours. This observation, when compared to the 40-hour detection window cited in the literature, suggests that the length of the detection window is positively correlated with the dosage of the test drug.
研究领域:
分析化学
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药理学
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反兴奋剂研究
✓ 已验证
产品关联
DOI
PubMed
高影响因子
CHROMATOGRAPHIA
·
2016
·Vol. 79
·期 17
·1197-1205
·
IF 1.332
Zhang Zhongyi,Xiao Huayun,Zheng Nengjian,Gao Xiaofei,Zhu RenGuo
Individual free amino acid δ 15 N values in plant tissue reflect the metabolic pathways involved in their biosynthesis and catabolism and could thus aid understanding of environmental stress and anthropogenic effects on plant metabolism. In this study, compound-specific nitrogen isotope analysis of amino acid by gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS) was carried out to determine individual free amino acid δ 15 N values. High correlations were observed between the δ 15 N values obtained by GC-C-IRMS and elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) determinations, and the mean precision measured was better than 1 ‰. Cation-exchange chromatography was employed to purify the sample, and the difference between prior to and following passage through the resin was within 1 ‰. The amino acid δ 15 N values of plant leave samples following incubation in 15 N-nitrate at different time points were determined. A typical foliar free amino acid 15 N-enrichment pattern was found, and glutamine was the most rapidly labeled amino acid; other amino acids derived from the GS-GOGAT cycle were also enriched. The pyruvate family amino acids were labeled less quickly followed by the aromatic amino acids. This study highlighted that amino acid metabolism pathways had a major effect on the δ 15 N values. With the known amino acid metabolism pathways and δ 15 N values determined by the presented method, the influence of various external factors on the metabolic cycling of amino acid can be understood well.
研究领域:
植物生理学
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同位素地球化学
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环境科学
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分析化学
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）