Isotopomer spectral analysis of triglyceride fatty acid synthesis in 3T3-L1 cells

1992 ◽  
Vol 263 (4) ◽  
pp. E667-E675 ◽  
Author(s):  
A. T. Kharroubi ◽  
T. M. Masterson ◽  
T. A. Aldaghlas ◽  
K. A. Kennedy ◽  
J. K. Kelleher
Keyword(s):  
Spectral Analysis ◽  
Multinomial Distribution ◽  
Acid Synthesis ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Triglyceride Fatty Acid ◽  
Fractional Abundance ◽  
Two Parameters ◽  
Tracer Atom ◽  
Over Time

A new analysis of stable isotope data for biosynthesis reaction, isotopomer spectral analysis (ISA), is demonstrated. ISA is theoretically applicable for polymerization biosynthesis where data are collected using selected ion-monitoring gas chromatography-mass spectrometry. ISA utilizes the discrete spectrum of isotopomer abundances and the multinomial distribution to estimate two key parameters related to the biosynthesis. These parameters are 1) the dilution of the precursor immediately before biosynthesis and 2) the dilution of the newly synthesized product in the sampled compartment. Differentiated 3T3-L1 cells incorporated 2 mM [1,2-13C]acetate into triglyceride palmitate, yielding a spectrum of mass isotopomers of palmitate. The set of equations for the first nine isotopomers were solved for the two parameters using nonlinear regression. We found that precursor dilutions for acetate and glucose were constant over time, whereas the product dilution parameter increased with time, as expected for cells accumulating triglyceride palmitate. Mathematical procedures are presented for calculating 1) the predicted isotopomer fractional abundance values and 2) the correction for atoms other than the tracer atom in the mass ion.

Characterization of drug interferences caused by coelution of substances in gas chromatography/mass spectrometry confirmation of targeted drugs in full-scan and selected-ion monitoring modes

1994 ◽  
Vol 40 (2) ◽  
pp. 216-220 ◽  
Author(s):  
A H Wu ◽  
D Ostheimer ◽  
M Cremese ◽  
E Forte ◽  
D Hill
Keyword(s):  
Mass Spectrometry ◽  
Gas Chromatography Mass Spectrometry ◽  
Spectrometric Analysis ◽  
Targeted Drugs ◽  
Selected Ion Monitoring ◽  
Internal Standards ◽  
Target Drug ◽  
Full Scan ◽  
Chromatographic Mass

Abstract Interference by substances coeluting with targeted drugs is a general problem for gas chromatographic/mass spectrometric analysis of urine. To characterize these interferences, we examined human urine samples containing benzoylecgonine and fluconazole, and other drug combinations including deuterated internal standards that coelute (ISd,c) with target drugs, by selected-ion monitoring (SIM) and full-scan mass spectrometry. We show that, by SIM analysis, detecting the presence of an interferent is dependent on the specific IS used for the assay. When an ISd,c is used, the presence of another coeluting substance (interferent) suggests that the intensity of IS ions is substantially diminished, because the interferent affects both the ISd,c and target drug. When a noncoeluting IS (ISnc) is used, the interferent cannot be discerned unless it coincidently contains one or more of the ions monitored for either the target drug or ISnc. Under full-scan analysis, a coeluting interferent is directly discernable by examining the total ion gas chromatogram.

scholarly journals Application of Bar Adsorptive Microextraction for the Determination of Levels of Tricyclic Antidepressants in Urine Samples

Molecules ◽  
2021 ◽  
Vol 26 (11) ◽  
pp. 3101
Author(s):  
Mariana N. Oliveira ◽  
Oriana C. Gonçalves ◽  
Samir M. Ahmad ◽  
Jaderson K. Schneider ◽  
Laiza C. Krause ◽  
...  
Keyword(s):  
Tricyclic Antidepressants ◽  
Matrix Effects ◽  
Activated Carbons ◽  
Process Efficiency ◽  
Gas Chromatography Mass Spectrometry ◽  
Selected Ion Monitoring ◽  
Experimental Conditions ◽  
Analytical Methodology ◽  
Low Efficiency

This work entailed the development, optimization, validation, and application of a novel analytical approach, using the bar adsorptive microextraction technique (BAμE), for the determination of the six most common tricyclic antidepressants (TCAs; amitriptyline, mianserin, trimipramine, imipramine, mirtazapine and dosulepin) in urine matrices. To achieve this goal, we employed, for the first time, new generation microextraction devices coated with convenient sorbent phases, polymers and novel activated carbons prepared from biomaterial waste, in combination with large-volume-injection gas chromatography-mass spectrometry operating in selected-ion monitoring mode (LVI-GC-MS(SIM)). Preliminary assays on sorbent coatings, showed that the polymeric phases present a much more effective performance, as the tested biosorbents exhibited low efficiency for application in microextraction techniques. By using BAμE coated with C18 polymer, under optimized experimental conditions, the detection limits achieved for the six TCAs ranged from 0.2 to 1.6 μg L−1 and, weighted linear regressions resulted in remarkable linearity (r2 > 0.9960) between 10.0 and 1000.0 μg L−1. The developed analytical methodology (BAμE(C18)/LVI-GC-MS(SIM)) provided suitable matrix effects (90.2–112.9%, RSD ≤ 13.9%), high recovery yields (92.3–111.5%, RSD ≤ 12.3%) and a remarkable overall process efficiency (ranging from 84.9% to 124.3%, RSD ≤ 13.9%). The developed and validated methodology was successfully applied for screening the six TCAs in real urine matrices. The proposed analytical methodology proved to be an eco-user-friendly approach to monitor trace levels of TCAs in complex urine matrices and an outstanding analytical alternative in comparison with other microextraction-based techniques.

Observation of gliding tremors from the Gulf of Guinea might help solve over 50 year old mystery

2021 ◽  
Author(s):  
Charlotte Bruland ◽  
Sarah Mader ◽  
Céline Hadziioannou
Keyword(s):  
Spectral Analysis ◽  
Volcanic Activity ◽  
Rayleigh Waves ◽  
Spectral Characteristics ◽  
Gulf Of Guinea ◽  
Seismic Amplitude ◽  
Long Period ◽  
Amplitude Spectra ◽  
Using Data ◽  
Over Time

<p>In the 1960's a peak in the seismic amplitude spectra around 26 s was discovered and detected on stations worldwide. The source was located in the Gulf of Guinea, with approximate coordinates (0,0), and was believed to be generated continuously. A source with similar spectral characteristics was discovered near the Vanuatu Islands, at nearly the antipodal location of the Gulf of Guinea source. Since it was located close to the volcanoes in Vanuatu, this source is commonly attributed to magmatic processes. The physical cause of the 26 s microseism, however, remains unclear.</p><p>We investigate the source location and evolution of the 26 s microseim using data from permanent broadband stations in Germany, France and Algeria and temporary arrays in Morocco, Cameroon and Botswana for spectral analysis and 3-C beamforming to get closer to resolving the source mechanism responsible for this enigmatic signal. We find that the signal modulates over time and is not always detectable, but occasionally it becomes so energetic it can be observed on stations worldwide. Such a burst can last for hours or days. The signal is visible on stations globally approximately 30 percent of the time. Our beamforming analysis confirms that the source is located in the Gulf of Guinea, as shown in previous studies, and that the location is temporally stable. Whenever the signal is detectable, both Love and Rayleigh waves are generated. We discover a spectral glide effect associated with the bursts, that so far has not been reported in the literature. </p><p>The spectral glides last for about two days and are observed on stations globally. Although at higher frequencies, very long period tremors and gliding tremors are also observed on volcanoes as Redoubt in Alaska and Arenal in Costa Rica, suggesting that the origin of the 26 s tremor is also volcanic. However, there is no reported volcanic activity in the area where the source appears to be located.</p><p> </p>

A Comparison of Soxhlet Extraction and Ultrasonic-Assisted Extraction for Analysis of Photoinitiators in Printed Cartonboard Food-Packaging Materials

2012 ◽  
Vol 262 ◽  
pp. 561-566
Author(s):  
Chao Ding ◽  
Fang Wang ◽  
Mei Xia Pang ◽  
Xin Xin Yi ◽  
Feng Tan ◽  
...  
Keyword(s):  
Food Packaging ◽  
Soxhlet Extraction ◽  
Gas Chromatography Mass Spectrometry ◽  
Packaging Materials ◽  
Selected Ion Monitoring ◽  
Food Packaging Materials ◽  
Assisted Extraction ◽  
Relative Standard ◽  
Ultrasonic Assisted ◽  
Phenyl Ketone

A new method was established for detecting a series of photoinitiators (PIs) in printed cartonboard food-packaging materials, which were benzophenone (BP), 4-methylbenzophenone (MBP), 1-hydroxycyclohexyl phenyl ketone (Irgacure184), ethyl-4-dimethylaminobenzoate (EDAB), 2-ethylhexyl-4-dimethylaminobenzoate (EHDAB) and 2-isopropylthioxanthone (ITX) by gas chromatography–mass spectrometry (GC/MS). Extraction was carried out with ethyl acetate by ultrasonic solvent extraction. Samples were analyzed by GC/MS in selected ion monitoring (SIM) mode. The results indicated that six kinds of PIs had good linear relations (R2>0.9989) in the range of 10~200 μg/L. Limit of Detections (LODs) and Limit of Quantifications ( LOQs ) of all kinds of PIs were 0.3~2.6 μg /kg and 1~8 μg/kg, respectively. The recoveries of six kinds of PIs at three kinds of concentrations researched (0.30 μg/kg, 0.60 μg/ kg, 1.0 μg/kg) were ranging from 66.7%~89.4%, with the Relative Standard Deviation (RSD) of 4.2%~10.6% (n=6). The results also suggested that PIs were detected in food packaging materials.

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