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Gas Chromatographic Analysis
Published in Adorjan Aszalos, Modern Analysis of Antibiotics, 2020
The electron capture detector (ECD) is somewhat selective in that it responds to halogens, conjugated carbonyls, and some nitrogen and sulfur compounds. In the detector chamber, the effluent gas is flowed between charged electrodes and a source of radioactivity (3H or M63Ni). Nitrogen carrier gas tends to form electrons and positive ions, making a steady flow of current. When a halogen atom, or other forms of negative ions, appears and attracts the positive ions, there is a decrease in current between the electrodes, resulting in detector response.
Gas Chromatography
Published in Joseph Chamberlain, The Analysis of Drugs in Biological Fluids, 2018
The usefulness of the electron-capture detector is its responsiveness to certain types of compounds and its lack of response to even large amounts of other compounds. Thus, the modern electron-capture detector is extremely useful for analyzing drugs in both pharmaceutical preparations and in biological fluids. The most strongly electron capturing compounds are those containing halogens or nitro groups (Table 6.4), or extended conjugated systems, such as for the metabolite of spironolactone, canrenone.471 A popular general method for benzodiazepines is to convert the benzodiazepine to the corresponding benzophenone and determine the highly conjugated. halogenated product by electron-capture gas chromatography (Figure 6.5).526 Typically, the electron-capture detector would be expected to measure drugs at the low ng ml−1 level in biological fluids.
Pesticides and Chronic Diseases
Published in William J. Rea, Kalpana D. Patel, Reversibility of Chronic Disease and Hypersensitivity, Volume 4, 2017
William J. Rea, Kalpana D. Patel
Chlorinated pesticide levels in each patient's body were analyzed from adipose tissue. Sampling was formed at the time of diagnosis or immediately following completion of therapy. Using sterile technique, a left lower quandrant of abdominal incision 5 cm in length was made following injection of local anesthesia. A segment of adipose tissue measuring approximately 4 × 3 × 2 cm was resected and the wound was closed in two layers. The adipose tissue was placed in an amber bottle supplied by the toxicology laboratory, refrigerated, and then sent by overnight courier to Accu-Chem Laboratories in Richardson, Texas. Accu-Chem Laboratories was a CLIA, Cap, and Medicare certified full-service toxicology lab. A panel of 21 chlorinated pesticides (Table 7.1) was analyzed for each specimen of adipose tissue. The method of analysis was high-resolution gas chromatography/electron capture detector. In addition to the cancer patients, two normal controls (37-year-old white male, 40-year-old white female) with no past history of cancer, asthma, rhinitis, hypertension, vascular disease, or autoimmune disease were tested for pesticide residues. Both controls live in Grady County and both had a family history of cancer. Their levels are shown in Tables 7.2 and 7.3, with the averages shown in Table 7.4.
Determination of LCt50 of aerosolized paraquat and its pulmonary toxic implications in non-anesthetized rats
Published in Drug and Chemical Toxicology, 2019
Santa Mandal, Manash Pratim Pathak, Nilutpal Sharma Bora, Pompy Patowary, Pradip Kumar Barman, Sumit Kishor, Danswrang Goyary, Navneet Verma, Pronobesh Chattopadhyay
The animals were exposed to PQ at a target concentration of 40–200 mg/kg and generated the lethality dose-response curves were generated by slight modification of the adaptive dose design described by Feder et al. (1991a,b,c). Twelve rats were allocated randomly to each group per challenge levels per stage and exposed to an aqueous aerosolized mixture of PQ. The presence of PQ in the air of the inhalation chamber was monitored at the 20th minute by gas chromatography and micro electron capture detector (Agilent, Santa Clara, CA). The entire experiment was designed to obtain a graded response of survivability of animals at a given dose for better estimation of the LD50 over time. The dosing stages were continued until the half-width of the 95% confidence intervals (CI; Collins et al.2013) and probit dose-response curve was fitted to the combined data of the mortality (Finney 1971; Feder et al.1991a,b; Collins et al.2013). A 95% CI of LD50 was calculated as described by Miller and Tainter (1944).
Veterinary utility of dried blood spots for analysis of toxic chlorinated hydrocarbons
Published in Toxicology Mechanisms and Methods, 2018
Andreas F. Lehner, Margaret Johnson, John Buchweitz
Analyses are performed on Varian (now part of Agilent Technologies, Santa Clara, CA) 3400 GCs each equipped with an electron capture detector (ECD). Both instruments are operated with helium carrier gas and nitrogen as ECD makeup gas. One instrument is equipped with a DB-1701 column (Agilent, Santa Clara, CA), and is referred to as 1701 GC in this paper; column dimensions are 15 m length × 0.32 mm ID with a 0.25 μm film thickness. The 1701 GC is run with the following temperature settings: (1) injector 250 °C; (2) detector 300 °C; (3) oven program: 150 °C initial, held for 0.5 min, then increasing at 5 °C/min to 280 °C final temperature, which is held for 15 min (total run time, 38 min). The second instrument is equipped with a DB-608 column (Agilent, Santa Clara, CA), and is referred to as 608 GC in this paper; column dimensions are 30 m length × 0.32 mm ID with a 0.5 μm film thickness. The 608 GC is run with the following temperature settings: (1) injector 250 °C; (2) detector 300 °C; (3) oven program: 150 °C initial, held for 0.5 min, then increasing at 12 °C/min to 280 °C final temperature, which is held for 20 min (total run time, 31.3 min). Both instruments are held in splitless mode during injection and from 0.01 to 0.8 min.
Evaluation of organochlorine pesticides in foodstuff of animal origin from middle governorates of Jordan in 2018 and 2019 using GC-ECD
Published in Toxin Reviews, 2021
Tawfiq M. Al-Antary, Mahmoud A. Alawi, Rana Keewan, Nizar A. Haddad
Bruker GC-456 was used in this study. It was equipped with two capillary columns and a 63Ni-Electron Capture Detector (ECD). The column 1 was a non-polar capillary HP-5 (30 m × 0.25 mm; 0.25 µm film thickness). Column 2 was a low/mid polar capillary DB-1701 (30 m × 0.32 mm; 0.2 µm film thickness). The carrier gas was helium with flow rate of 1.1 mL/min. The make-up gas flow rate was 25 mL/min. The injector temperature was 280 °C, and the detector temperature was 300 °C. Column temperature program was 150 °C for 5 min, 150–220 °C (13 °C/min) for 20 min, 220–250 °C (20 °C/min), and 250 °C for 10 min. Injection volume was 1 µL and the split ratio was 1:10 (Alawi et al.2015, AlAntary et al.2018).