Liquid chromatography/ultraviolet detection

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

Heat and reflux a 5-g portion of soil sample with 50 mL of methanol-phosphate buffer (pH 7)-water (15 7 28, v/v/v) solvent mixture in a round-bottom flask for 1 h. After cooling, transfer a 10-mL portion of the supernatant to a test-tube and mix with 11 mL of 0.02M H3PO4 solution. Load this solution on to a silica-based SPE cartridge (Analytichem International Clin-Elut 1020) at a flow rate of 1-2 drops per second. Discard this fraction. Elute the analytes with 30 mL of dichloromethane. Concentrate the eluate to dryness with air in a water-bath at a temperature of 40 °C (do not use vacuum). Dissolve the residues in 5mL of HPLC injection solution [900 mL of water - - 50 mL of phosphate buffer (pH 7) 4-50 mL of ACN 4-4 g of TBABr]. Pinal analysis is performed using liquid chromatography/ultraviolet detection (LC/UV) with a three-column switching system. 

These authors noted the potential for the assay to underestimate the concentration of TSR due to decreased binding of metabolites relative to parent spinosad. However, the major residue found was parent spinosad, so underestimation of residues is not likely to be problematic. Overall, this method was validated in 34 matrices and showed excellent agreement with results obtained with a high-performance liquid chromatography/ultraviolet detection (HPLC/UV) method. ... 

Liquid chromatography/ultraviolet detection Monoamine oxidase Mechanism-based inhibition Metabolic intermediate complex Molybdenum-containing oxidase Multi parameter optimization... 

For reliable identification of a residue, detailed information about the molecular structure of the analyte is essential. The total information about the molecular structure of the analyte is the sum of the information derived from each individual analytical step of tire method. Frequently used selective analytical steps based on chromatography or immunoaffinity, provide more or less general indirect information. For example, solid-phase extraction (SPE) cleanup followed by liquid chromatography/ultraviolet detection (LC/UV) has been suggested for screening and quantification of ivermectin residues in liver, but presumptive positive samples can be confirmed by derivatizing an aliquot of the SPE eluate and reanalyzing the fluorescent derivative of ivermectin in an LC-fluorescence system (17). 

Gong, A.J., C.M. Ye, Z.F. Lei, and J.A. Liu. (1999). Pre-column derivatization reaction coupled with ultrasonic wave extraction for the trace analysis of atrazine and simazine in soil and crops by liquid chromatography, ultraviolet detection. J. Liq. Chrom. Rel. Technol., 22 2535-2545. 

Specialized Stationary Phases for Liquid Chromatography Chiral Stationary Phases for Liquid Chromatography Detectors for Liquid Chromatography Ultraviolet Detection of Chromophoric Groups Derivatizing Reagents for HPLC... 

Awidi A et al (2010) Determination of imatinib plasma levels in patients with chronic myeloid leukemia by high performance liquid chromatography-ultraviolet detection and liquid chromatography-tandem mass spectrometry methods comparison. Leuk Res 34 714-717... 

HPLC-UV = high-pressure liquid chromatography-ultraviolet detection... 

CLP = contract laboratory program EC = electron capture detection FSCC-MS/DS = fused silica capillary, mass spectrometry/data system GC = gas chromatography HPLC-UV = high-resolution liquid chromatography - ultraviolet detection 2-NP = 2-nitrophenol 4-NP = 4-nitrophenol... 

Bossi, R., Vejrup, K., and Jacobsen, C. S., Determination of sulfonylurea degradation products in soil by liquid chromatography-ultraviolet detection followed by confirmatory liquid chromatography-tandem mass spectrometry, J. Chromatogr. A, 855, 575-582, 1999. 

Wu, J., Ee, K.H., and Lee, H.K., Automated d)mamic liquid-liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet detection for the determination of phenoxy acid herbicides in environmental waters, J. Chromatogr. A, 1082,121, 2005. 

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