Measuring gluconeogenesis using a low dose of2H2O: advantage of isotope fractionation during gas chromatography

2003 ◽  
Vol 284 (5) ◽  
pp. E1043-E1048 ◽  
Author(s):  
Jill Katanik ◽  
Brendan J. McCabe ◽  
Daniel Z. Brunengraber ◽  
Visvanathan Chandramouli ◽  
Fumie J. Nishiyama ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Blood Glucose ◽  
Isotope Fractionation ◽  
Low Dose ◽  
Glucose Production ◽  
Body Water ◽  
Gas Chromatography Mass Spectrometry ◽  
Chromatographic Retention ◽  
The Difference

The contribution of gluconeogenesis to glucose production can be measured by enriching body water with2H2O to ∼0.5% 2H and determining the ratio of 2H that is bound to carbon-5 vs. carbon-2 of blood glucose. This labeling ratio can be measured using gas chromatography-mass spectrometry after the corresponding glucose carbons are converted to formaldehyde and then to hexamethylenetetramine (HMT). We present a technique for integrating ion chromatograms that allows one to use only 0.05% 2H in body water (i.e., 10 times less than the current dose). This technique takes advantage of the difference in gas chromatographic retention times of naturally labeled HMT and [2H]HMT. We discuss the advantage(s) of using a low dose of 2H2O to quantify the contribution of gluconeogenesis.

scholarly journals Isotope Fractionation during Gas Chromatography Can Enhance Mass Spectrometry-Based Measures of 2H-Labeling of Small Molecules

Metabolites ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 474
Author(s):  
Daniel P. Downes ◽  
Takhar Kasumov ◽  
Natalie A. Daurio ◽  
Neil B. Wood ◽  
Michael J. Previs ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Isotope Fractionation ◽  
Isotope Labeling ◽  
Gas Chromatography Mass Spectrometry ◽  
Isotope Tracers ◽  
Powerful Approach ◽  
Low Levels ◽  
Data Acquisition And Processing ◽  
Enhance Mass

Stable isotope tracers can be used to quantify the activity of metabolic pathways. Specifically, 2H-water is quite versatile, and its incorporation into various products can enable measurements of carbohydrate, lipid, protein and nucleic acid kinetics. However, since there are limits on how much 2H-water can be administered and since some metabolic processes may be slow, it is possible that one may be challenged with measuring small changes in isotopic enrichment. We demonstrate an advantage of the isotope fractionation that occurs during gas chromatography, namely, setting tightly bounded integration regions yields a powerful approach for determining isotope ratios. We determined how the degree of isotope fractionation, chromatographic peak width and mass spectrometer dwell time can increase the apparent isotope labeling. Relatively simple changes in the logic surrounding data acquisition and processing can enhance gas chromatography-mass spectrometry measures of low levels of 2H-labeling, this is especially useful when asymmetrical peaks are recorded at low signal:background. Although we have largely focused attention on alanine (which is of interest in studies of protein synthesis), it should be possible to extend the concepts to other analytes and/or hardware configurations.

Identification of Trialkyl and Triaryl Phosphates in Distilled and Super-Q Water

1981 ◽  
Vol 64 (3) ◽  
pp. 635-640
Author(s):  
David T Williams ◽  
Guy L Lebel ◽  
Frank M Benoit
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Flame Retardant ◽  
Mass Spectra ◽  
Gas Chromatography Mass Spectrometry ◽  
Chromatographic Retention ◽  
Unknown Compound ◽  
Chromatographic Columns ◽  
Diphenyl Phosphate ◽  
Q System

Abstract An unknown compound detected in an extract from water purified through a Millipore Super-Q system has been identified as tributoxyethyl phosphate by gas chromatographic retention times and by gas chromatography/mass spectrometry. Purified water from distillation systems also contained trialkyl/aryl phosphate plasticizers/flame retardant additives: Tris(l,3-dichloropropyl) phosphate and triphenyl phosphate were formally identified and isopropylphenyl diphenyl phosphate was tentatively identified from mass spectra interpretation and from GC retention times on 2 chromatographic columns.

scholarly journals Effects of malathion exposure on glucose tolerance test in diabetic rats; emphasis on oxidative stress and blood concentration of malathion by gas chromatography mass spectrometry

2021 ◽  
Vol 4 (02) ◽  
pp. 60-71
Author(s):  
Seyedeh-Azam Hosseini ◽  
Ali Faghihi zarandi ◽  
Somayyeh Karami-Mohajeri
Keyword(s):  
Oxidative Stress ◽  
Mass Spectrometry ◽  
Gas Chromatography ◽  
Blood Glucose ◽  
Glucose Tolerance ◽  
Glucose Tolerance Test ◽  
Tolerance Test ◽  
Diabetic Rats ◽  
Gas Chromatography Mass Spectrometry ◽  
Blood Samples

Malathion is one of the widely used broad-spectrum organophosphate insecticides (OPI) in Iran. Malathion affects carbohydrate metabolism, causes hyperglycemia and increases the risk of diabetes. The present study was undertaken to investigate the potential of malathion to exacerbate diabetes-induced oxidative stress and impairment in blood glucose level and glucose tolerance in a sub-acute study. Malathion concentration in blood analyzed with gas chromatography mass spectrometry (GC-MS) after sample preparation of blood samples based on magnetic Fe3O4-supported graphene oxide (Fe3O4@ GO) nanoparticles. Type 1 diabetes was experimentally induced by intraperitoneal administration of streptozocin (65 mg kg-1). Diabetic and non-diabetic rats were treated with malathion at the dose of 150 mg kg-1day-1 or 0.5-4.0 mg L-1 in blood for 4 weeks. Fasting blood glucose was measured every week. At the end of the study, blood samples were investigated for markers of oxidative stress. Exposure to multiple doses of malathion decreased the total antioxidant capacity of plasma and the activity of catalase and superoxide dismutase enzymes in diabetic rats. Blood glucose and glucose tolerance test (GTT) and oxidative damages did not change significantly in diabetic rats exposed to malathion. However, malathion concentration in blood caused to increase GTT in malathion-treated non-diabetic rats. 

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