China
Africa
Explore chapters and articles related to this topic
Measurement of Exposure and Dose
Published in Samuel C. Morris, Cancer Risk Assessment, 2020
Each participant carried a personal air sampler throughout a normal 24-hour day, collecting two 12-h samples (a daytime sample and an overnight sample). Identical samplers were run in fixed locations in the backyard of one participant’s home in each of over 100 “clusters” to measure ambient air concentrations. At the end of the 24-h period, a sample of exhaled breath was collected from each participant. The study was conducted during three seasons (summer, fall, and winter), although samples were not taken in all cities during all three seasons. The air sampler was a glass cartridge containing a granular sorbent called Tenax-GC. The sampler was attached to a vest to hold it near the person’s breathing zone and air was pulled through the cartridge at 30 ml per minute by a small pump. Roughly 20 liters of air was pulled through the cartridge for each 12 h sample. The samples were analyzed by capillary gas chromatography mass spectrometry (GC-MS) techniques followed by a combination of manual and automated spectra analyses.
Cobalamin C, D, F, G diseases; methylmalonic aciduria and variable homocystinuria
Published in William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop, Atlas of Inherited Metabolic Diseases, 2020
William L. Nyhan, Georg F. Hoffmann, Aida I. Al-Aqeel, Bruce A. Barshop
The biochemical picture of methylmalonic acidemia and homocystinuria and the acute hematologic and clinical neurologic picture of Cbl C disease have been encountered in the exclusively breastfed infants of strict vegan mothers [30, 38], as well as in the breastfed infants of mothers with subclinical pernicious anemia and in TCII deficiency [39]. It is also seen in the Immerslund-Grasbeck defect in ileal absorption of the B12-intrinsic factor complex (Figures 4.5 and 4.6) [40]. Problems in the differential diagnosis of patients with methylmalonic acidemia were highlighted by a patient who died of mutase deficiency, ultimately diagnosed when a sibling was found to have the disease, but not before the mother was incarcerated for homicide because a commercial clinical laboratory misidentified the propionic acid in the blood as ethylene glycol [41]. This experience points up the importance of quantification and identification by gas chromatography-mass spectrometry (GCMS) as opposed to identification based on elution times in gas chromatography.
Detection and Identification of Amphetamine and Related Stimulants
Published in John Caldwell, S. Joseph Mulé, Amphetamines and Related Stimulants: Chemical, Biological, Clinical, and Sociological Aspects, 2019
The majority of systems described in the literature employ flame ionization detectors (FID), but additional sensitivity has been obtained for the amphetamines by the application of electron capture detectors (ECD) to appropriate derivatives,2, 13 and the application of nitrogen/phosphorus detectors (NPD).2, 8 Derivatization techniques have also been used to supply additional retention data and functional group information to improve the specificity of GLC.2,3,11,12 Combined gas chromatography-mass spectrometry provides the ultimate in GLC systems. This technique is able to provide definitive, quantitative data with very high sensitivities. An example of its use for amphetamine-related drugs is the identification and quantification in serum of methylphenidate and its major metabolite, ritalinic acid.14
Fumigant toxicity of three Satureja species on tomato leafminers, Tuta absoluta (Meyrick) (Lepidoptera: Gelechiidae)
Published in Toxin Reviews, 2021
Gas chromatography–mass spectrometry (GC–MS) analysis was performed on an Agilent 6890 N gas chromatograph using a 5973 mass-selective detector (Agilent Technologies, Palo Alto, CA) run in Faculty of Chemistry, University of Tabriz, Iran. A GC column HP-5 MS (30 m × 0.25 mm i.d., and film thickness 0.25 mm) was used for separating the ingredients with helium at flow rate of 1.0 ml/min applied as the carrier gas. The temperature program of oven was scheduled as follows: initial temperature 70 °C (held 3 min), 70–120 °C at a rate of 10 °C/min (held at 150 °C for 2 min), 120–150 °C at a rate of 10 °C/min (held at 150 °C for 2 min) and 150–240 °C at a rate of 7 °C/min (held at 240 °C for 5 min). The injector was set in a split mode with a split ratio of 1:30. The mass spectra were recorded at 70 eV of ionization voltage with a scan time of 1 s and a mass range of 50–550 m/z. The ionization mode was electron impact and the temperature of the ionization source was kept at 250 °C. For recognizing each compound, its mass spectra were compared to those stored in the Wiley 7.0 and Adams mass spectral-retention index libraries (Adams 2007).
In vitro abrasivity and chemical properties of charcoal-containing dentifrices
Published in Biomaterial Investigations in Dentistry, 2020
Foteini Machla, Aida Mulic, Ellen Bruzell, Håkon Valen, Ida Sofia Refsholt Stenhagen
Suspensions of COCO in a mixture of methanol and toluene (6:1) and NAO in toluene (0.25 g/mL) were sonicated for 4 h at 45 °C. The choice of solvents was determined by initial qualitative screening studies. The suspension was centrifuged twice, first at 5000 RCF for 8 min (Heraeus Multifuge X3 FR, Thermo Fischer, Oslo, Norway) and secondly at 12,300 RCF for 5 min (VWR MicroStar 12, Leuven, Belgium) to remove the charcoal particles. Both qualitative and quantitative studies were carried out using gas chromatography mass spectrometry (GC-MS) analysis (Agilent, Santa Clara, CA). In the qualitative studies, an aliquot of the reaction solution (100 µL) was removed and added to acetone (400 µL). For quantification of PAHs, an aliquot (100 µL) was removed and added to a mixture of internal standard (phenyl methacrylate, 100 µL) and acetone (300 µL) prior to analysis. A standard mixture of the 16 PAHs (Sigma-Aldrich, Oslo, Norway) on the US Environmental Protection Agency’s (EPA) list and the instrument’s reference library of compounds (National Institute of Standards and Technology, Gaithersburg, MD) were used to identify hazardous PAHs for subsequent quantification. A calibration curve of known concentrations of the substance of interest was used for quantification. Three extraction experiments were carried out for each charcoal dentifrice.
Effects of intranasal administration of violet oil in dry eye disease
Published in Clinical and Experimental Optometry, 2019
Aniseh Saffar shahroodi, Mahmood Nejabat, Majid Nimrouzi, Hossein Aghaei, Alireza Salehi, Ali Rezaei mokarram
The treatment (VAO) was prepared and formulated by Noshad Pharmaceutical Company (Isfahan, Iran) based on the enfleurage method.2013 Briefly, soft and fragrant dried aerial parts of the herb (flowers and leaves) were soaked and gently stirred in sweet AO (as the non‐irritant vehicle) at room temperature for a week while replacing the consumed parts with fresh ones until the colour of the oil changed to brownish yellow. The oil was clarified by centrifugation at 1000-g and passed through a 0.45‐μm membrane filter. The test drug was standardised based on total flavonoid 0.09-mg in 5-ml. The total flavonoid content was determined by using the aluminium chloride colorimetric assay and expressed as mg of quercetin equivalent in 5-ml. A gas chromatography–mass spectrometry method was performed to determine the extracted matter.