Sample HPLC

Currently, HPLC/fiuorescence is still the most common technique for the determination of residues of oxime carbamates. With the introduction of ESI and APCI MS interfaces, HPLC/MS analysis for oxime carbamates in various sample matrices has become widespread. However, for a rapid, sensitive, and specific analysis of biological and environmental samples, HPLC/MS/MS is preferred to HPLC/MS and HPLC/fiuorescence. With time, improved and affordable triple-quadrupole mass spectrometers will be available in more analytical laboratories. With stricter regulatory requirements, e.g., highly specific and conclusive methods with lower LOQ, HPLC/MS/MS will be a method of choice for oxime carbamates and their metabolites. 

From the available analytical techniques, the most commonly employed is HPLC coupled with an ultraviolet (UV) detector, which provides a rapid, relatively cheap and easy routine analysis of conjugated BAs from serum samples. HPLC with UV detection determination does not require sample derivatisation, but the sensitivity of... 

Chip HPLC—Nano-flow, micro-sample HPLC system in which the packed column resides within the body of the injector. Originally touted as the HPLC of the future for nano-level LC/MS, but its potential has been slow to materialize. 

In 59 patients treated with HL at fixed daily doses (3-10 mg/d) over at least 4 months prior to sampling, HPLC determinations of both HL and reduced metabolite (RHL) content in hair showed significant correlations with the daily dose of HL (r = 0.682, p < 10 3, n = 59 for HL, and r = 0.813, p < 10, n = 59 for RHL). A cross-sectional analysis, carried out in five patients whose HL dose regimen had been decreased or discontinued a few months before sampling, showed in all cases an abrupt drop of both HL and RHL hair levels at the time at which dosage changed. 

It is important to determine early on whether the reaction conditions previously developed for the assay of a given activity can be adapted for use with HPLC assay. For example, is the reaction mixture of sufficient volume to permit the withdrawal of multiple samples For assays carried out in volumes of a few microliters, it is virtually impossible to withdraw samples of sufficient volume for analysis on the HPLC system. Thus, unless dilutions can be made after sampling, HPLC analysis must be ruled out in such cases. 

Although tocopherols and tocotrienols can be detected by UV absorbance at 280 nm, fluorescence detection (excitation 294 nm and emission 326 nm), as shown in Figure 11.3, has proven to be a much more sensitive method. Electrochemical detection such as pulsed amperometric and coulometric (Uspitasari-Nienaber, 2002) has also proven to be sensitive and potentially valuable for the quantitative analysis of tocopherols and Tocotrienols (Abidi, 2000), especially for tocol analysis in blood and serum samples. HPLC mass detectors such as flame-ionization detectors, evaporative light-scattering detectors, and charged aerosol detectors have proven to be valuable for the quantitative analysis of many types of lipids, but because tocols have... 

Figure 16-4. Leachable peaks from nitrile gloves found in the sample. HPLC conditions Column temperature 35°C, column YMC ODS-AQ, S-3,120A, 3.0 mm x 150 mm, wavelength, 267 nm. Gradient Mobile phase A Water/acetonitrile/TFA (950/50/1, v/v/v). Mobile phase B Water/acetonitrile/TFA (50/950/1, v/v/v). Injection volume, 15 mL flow rate, 0.8mL/min.

Luminous compounds were successfully extracted by ethyl acetate from lyophilized sample. HPLC separated three luminescent peaks, Fr.l, 2 and 3 as shown in Fig. 2. Interestingly, no peak was observed at fluorescence detector. 

Metabolism and pharmacokinetics Metabolic profiling and bioanalytical assays of animal models of clinical samples HPLC, GC MS/MS, UV, ECD... 

The activation of DNT has been shown to be a multistep process involving metabolism in the liver, excretion into the bile, deconjugation of metabolites and further metabolism by the intestinal flora, re-uptake (enterohepatic transport) of metabolites into liver, and finally activation and binding to cellular macromolecules in the liver [56], More recent studies [57] involving rats pretreated with coal tar creosote, which potentiates the genotoxicity of 2,6-DNT, elucidated a complex interaction that balances metabolic activation, uptake, and detoxification. The study monitored intestinal flora enzyme activities, bacterial analysis, mutagenicity of urine samples, HPLC analysis, and hepatic DNA adducts over a five-week exposure period. The location of nitroreductase activity was an... 

Methimazole Various biol. samples HPLC LPME3 (ion pair) [218]... 

Although the principal area of application of HPLC-ED has been in the analysis of naturally-occurring analytes, such as catecholamines, and pharmaceuticals in biological samples, HPLC-ED has also been applied to the analysis of pesticides and other analytes of interest to the toxicologist. This section details some of these additional applications,... 

Samples recovered from the nitrocellulose target have successfully been submitted to HPLC, reduction and alkylation, enzymatic digestion, cleavage with cyanogen bromide, and methyl esterification. Multiple analyses on the sample originally placed on the target, combining recovery, reactions on the recovered sample, HPLC and reapplication of the sample to nitrocellulose for further mass spectrometric analysis, followed by transfer to the sequencer, are possible (Jespersen et ah, 1993). 

Real Samples HPLC-MS/MS Target Analysis (QuEChERS dSPE Extracts, Matrix-Matched Calibration) Compared to pL-FIA-TOFMS Analysis (HTpSPE Extracts) Using the Database-Dependent Target Screening... 

Analyte Analyzed sample HPLC mode Electrochemical detection References... 

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