Use of stable isotopically labeled benzene to evaluate environmental exposures

Abstract

The use of stable, isotopically labeled compounds in controlled exposure experiments at environmentally relevant levels allows for the distinguishing of urinary metabolites associated with known exposure from background levels generally present in the urine. Exposures of volunteers to (13)C-benzene for 2 h at 40+/-10 p.p.b. were conducted after obtaining informed consent, and urinary phenol, catechol, hydroquinone and trans,trans- muconic acid were measured. Each isotopically labeled urinary metabolite was determined in the presence of significantly higher concentrations of the unlabeled metabolite. Following exposure, free and acid hydrolyzed phenol, acid hydrolyzed catechol and hydroquinone, and free trans,trans-muconic acid were determined by GC/MS. The percentage of trans,trans-muconic acid excreted was higher than reported following exposure at occupational levels. The use of isotopically labeled compounds has the potential to investigate the metabolism of common environmental contaminants for validation of toxicokinetic models and improve risk extrapolation from high concentration occupational exposures and animal studies to environmentally relevant pollutant levels.

Evaluation of Isotopic Abundance Ratio in Biofield Energy Treated Nitrophenol Derivatives Using Gas Chromatography-Mass Spectrometry

“…The natural abundance of each isotope can be predicted from the comparison of the height of the isotope peak with respect to the base peak. The values of the natural isotopic abundance of the common elements are obtained from several literatures [43][44][45][46] and presented in Table 1. Where, IAR Treated = isotopic abundance ratio in the treated sample and IAR Control = isotopic abundance ratio in the control sample.…”

“…The gas chromatographymass spectrometry (GC-MS) can perform isotope ratio measurement at low micro molar concentration levels [43][44][45][46]. Recently, it has been reported that Mr. Trivedi's biofield energy treatment (The Trivedi Effect ® ) has the amazing capability to alter the physicochemical and thermal properties of nitrophenol such as crystallite size, particle size and thermal stability that might affect the rate of chemical reaction [24].…”

“…The choice for the isotope ratio analysis is the mass spectrometry (MS) technique [43]. The gas chromatographymass spectrometry (GC-MS) can perform isotope ratio measurement at low micro molar concentration levels [43][44][45][46].…”

Mass Spectrometry Analysis of Isotopic Abundance of <sup>13</sup>C, <sup>2</sup>H, or <sup>15</sup>N in Biofield Energy Treated Aminopyridine Derivatives

“…These deviations from perfect chemical equivalence are termed as isotope effects. The isotopic abundance ratio is commonly reported in terms of atom percent and determined by high resolution mass spectrometry (HRMS spectrometry) [3]. For example, 13 C Atom percent 13 …”

Isotopic Abundance Analysis of Biofield Treated Benzene, Toluene and p-Xylene Using Gas Chromatography-Mass Spectrometry (GC-MS)

“…Absolute abundances of isotopes are commonly reported in terms of atom percent. Various applications of isotope abundance study includes (a) the distribution of contaminant sources of any molecule on a native, regional, and global scale, (b) the identification and quantification of alteration reactions and (c) the characterization of elementary reaction mechanisms that govern product formation [11].…”