China
Africa
Explore chapters and articles related to this topic
Analysis Update—Full Spectrum Cannabis
Published in Betty Wedman-St Louis, Cannabis as Medicine, 2019
Robert Clifford, Scott Kuzdzal, Paul Winkler, Will Bankert
After the column separates the compounds, they pass through a detector, which does exactly what it states as it detects each compound. GC and LC utilize different types of detectors. For example, a GC can use a flame ionization detector (FID), thermal conductivity detector (TCD), electron capture detector (ECD), flame photometric detector (FPD), and a flame thermionic detector (FTD). If one were using a FID detector the technique would be referred to as GC/FID. A GC/FID system could be utilized for terpene analysis with the addition of a headspace autosampler. The headspace autosampler has two functions. The autosampler is an automated robot bringing the next sample in line to be analyzed. The headspace heats up the cannabis sample between 70°C and 275°C, so the volatile terpenes can be separated from most of the cannabis matrix, which contains over 500 compounds, allowing for easier separation in the column.
Drug Monitoring by Capillary Electrophoresis
Published in Steven H. Y. Wong, Iraving Sunshine, Handbook of Analytical Therapeutic Drug Monitoring and Toxicology, 2017
For electrokinetic separations, small amounts of samples (typically nL volumes or pmol to subfmol solute quantities) are introduced by electrokinetic or hydrodynamic techniques. Upon application of power (about 5 to 30 kV, 1 to 150 μA) samples are transported through the capillary by the combined action of electrophoresis and electroosmosis. Detection principles applied include, on-column direct and indirect absorbance, direct and indirect fluorescence, and occasionally, radiometry, as well as end-column or off-column monitoring employing conductivity, mass spectrometry (MS), or amperometry. Until recently, most of the employed instruments have been assembled in the researchers laboratories. Whereas the first commercial instrument emerged in 1988, there are currently about a dozen companies manufacturing electrokinetic capillary instrumentation.7 Many of these apparatuses are fully automated comprising an autosampler, as well as data gathering, and evaluation with a computerized data station.
Gas Phase Sequence Analysis of Proteins/Peptides
Published in Ajit S. Bhown, Protein/Peptide Sequence Analysis: Current Methodologies, 1988
With conventional HPLC analysis, the PTH samples are left in the sequencer either in solution or as a dried residue in fraction collector vials. Samples must be removed from the collector and manually prepared for analysis. Virtually any type of HPLC system can then be used, although a good HPLC autosampler is essential for reproducible results. One of the primary drawbacks of this technique is the significant delay between the Edman chemistry and obtaining the analytical results. This delay reduces the efficiency of the sequencer by as much as half. Moreover, the manual sample preparation often causes contamination, sample loss, and PTH degradation — problems that are particularly damaging to microsequencing results.
Validation of an automated UPLC-MS/MS method for methylmalonic acid in serum/plasma and its application on clinical samples
Published in Scandinavian Journal of Clinical and Laboratory Investigation, 2022
The calibration curve was from 0.044 to 1.63 µmol/L with R2 = 0.999 and this was also the linearity range applied in the method for quantifying clinical samples. There was no carry over detected following a sample with the MMA concentration of 2 µmol/L. The LLOQ concentration was set at 0.044 µmol/L which was also the lowest calibration level. At this concentration the CV was close to 20%, Table 2. The reported CV values in Table 2 were calculated from six repeated runs of the calibration curves. Stability in the autosampler was at least four days. MMA stability has been reported to be at least 6 months to 1-year at 5 °C and 20 °C [20]. This stability was confirmed by analyzing external control and clinical samples which had been stored for 4 months and a few samples which had been stored for 1 year in a freezer at −20 °C.
Propionate catabolism by CD-associated adherent-invasive E. coli counteracts its anti-inflammatory effect
Published in Gut Microbes, 2021
Allison Agus, Damien Richard, Tiphanie Faïs, Emilie Vazeille, Mélissa Chervy, Virginie Bonnin, Guillaume Dalmasso, Jérémy Denizot, Elisabeth Billard, Richard Bonnet, Anthony Buisson, Nicolas Barnich, Julien Delmas
Analyses were performed on an HP5973 MS with an HP6890 series GC (Agilent Technologies, Atlanta, GA, USA). Automatic injections were performed using an HP6890 autosampler. The temperatures of the injector and the transfer line detector were 180°C and 280°C, respectively. The GC was operated in splitless injection mode with a constant flow of 1 ml/min of helium through the HP-5 MS column (30 m × 0.25 mm i.d. with 0.25 µm film thickness (J&W, Folsom, CA)). The GC oven temperature was programmed to start at 70°C, increasing first to 150°C at 20°C/min and then to 290°C at 30°C/min. The retention times were 3.39 min, 3.93 min and 5.35 min for acetate, propionate and MVA, respectively. Ions were detected by selective ion monitoring (SIM) for quantification (Q) and confirmation (q): m/z 240 (Q), 197 and 181 (q) for acetate; m/z 254 (Q), 197 and 181 (q) for propionate; and m/z 97 (Q), 57 and 115 (q) for MVA. Identification of the target compound was carried out by comparing the retention time and m/z ratio with those of the standards. HP Chemstation software was used to control the equipment and carry out the data processing. The concentrations of acetate and propionate in the biological samples were determined based on their area ratios to that of the IS using a weighted quadratic fit. The lower limit of quantification (LLOQ) for each compound was 5 mg/L, and the upper limit of quantification (ULOQ) was 1000 mg/L in biological samples without dilution.
Metabonomics analysis of liver in rats administered with chronic low-dose acrylamide
Published in Xenobiotica, 2020
Yanli Liu, Ruijuan Wang, Kai Zheng, Youwei Xin, Siqi Jia, Xiujuan Zhao
Chromatographic separation of liver samples (the extracts obtained after tissue processing) was performed on a UPLC BEH C18 column (100 × 2.1 mm, i.d.=1.7 [mu]m, Waters Corp., Milford, MA, USA) using an ACQUITY UPLC System (Waters Corp., Wexford, Ireland). The temperatures of the column and autosampler were maintained at 35 and 4 °C, respectively. At a flow rate of 0.35 mL/min, and a 2 µL aliquot of each sample was injected onto the column. The mobile phase consisted of 0.1% aqueous formic acid (solution A) and acetonitrile (solution B). The metabolites were eluted using a linear gradient of 2%–20% B for 0–1.5 min, 20%–70% B for 1.5–6 min, 70%–98% B for 6–10 min, 98% B for 10–12 min, 98%–70% B for 12–14 min and 70%–2% B for 14–16 min. After each injection, a wash cycle was used on the autosampler to eliminate the carryover between analyses. In addition, the eluent was directed to the MS system in split mode.