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1.
High-performance liquid chromatographic conditions are reported for the electrochemical detection (ED) of Gentian Violet, its demethylated metabolites, Leucogentian Violet and Methylene Blue. Gentian Violet, its demethylated metabolites and Leucogentian Violet were separated within 14 min on a cyano column eluted isocratically with methanol-buffer (60:40) as the mobile phase. ED responses for Gentian Violet, Leucogentian Violet and Methylene Blue were linear over the ranges 0.54-6.75, 0.50-25.2, and 5.7-285 ng, respectively. Under these conditions, the compounds were eluted in the following order: Leucogentian Violet, N"-2-tetra-methylparaosaniline chloride, N'-1-tetramethylpararosaniline chloride, pentamethylpararosaniline chloride and Gentian Violet. Methylene Blue and Gentian Violet had essentially the same retention time under these parameters. The detection limit for Gentian Violet, its demethylated metabolites and Leucogentian Violet was determined to be 0.1 pmol. A detection limit of 3 pmol was established for Methylene Blue. Detector response, elution, separation, linearity and sensitivity of detection are discussed. 相似文献
2.
A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method is described for the extraction, cleanup, determination, and confirmation of chloramphenicol (CAP) in cooked crab meat. The method involves pulverization of cooked crab meat with dry ice; extraction of the CAP into ethyl acetate (EtOAc); evaporation (by N2) of the EtOAc; addition of methanol, aqueous NaCl, and heptane; extraction of the lipids into the heptane, followed by extraction of the aqueous phase with EtOAc; evaporation (by N2) of the EtOAc; dissolution into methanol-water; filtration; and separation/detection/confirmation using LC/MS/MS. Crab meat was fortified at 0.25, 0.50, and 1.0 ng/g (ppb) chloramphenicol. Average absolute recoveries were 67, 84, and 86%, respectively, with relative standard deviation values all less than 1%. Four daughter ions (m/z 152, 176, 194, and 257) were monitored off the m/z 321 precursor ion. Determination was based on a standard curve using the peak areas of the m/z 152 daughter ion (the base peak) for standard solutions equivalent to 0.10, 0.20, 0.50, and 1.0 ppb in tissue (made with control crab extract). A set of 6 matrix controls (unfortified crab meat) was also analyzed, in which no chloramphenicol was detected. For identification purposes, the ion ratios (of each daughter ion versus the base daughter ion) of the fortified crab versus those of the chloramphenicol standards agreed within 10% (relative) at fortified chloramphenicol concentrations of 0.25-1.0 ppb. 相似文献
3.
Clark SB Turnipseed SB Nandrea GJ Madson MR Hurlbut JA Sofos JN 《Journal of AOAC International》2002,85(5):1009-1014
A confirmatory method is described for phenylbutazone (PB) residues in bovine kidney tissue. Ground kidney tissue is diluted with water, and the mixture is made basic with 25% ammonium hydroxide in water; the lipids are extracted with ethyl and petroleum ethers. The ether layer is discarded, and the tissue is acidified with 6N HCl. PB residues are extracted with tetrahydrofuranhexane (1 + 4). The extract is passed through a silica solid-phase extraction column, and the eluate is evaporated to dryness. The residue is dissolved in acidified acetonitrile-water-acetic acid (50 + 49.4 + 0.6). A single quadrupole mass spectrometer coupled to a liquid chromatograph with an electrospray interface is used to confirm the identity of the PB residues in the kidney extract. Negative-ion detection with selected-ion monitoring of 4 ions is used. Sets of control and fortified-control kidney tissues (at 50, 100, and 200 ppb PB) and several kidney tissue field samples were analyzed for method validation. The method was tested further during the course of a survey to determine the incidence of PB residues in bovine kidney samples obtained from slaughterhouses across the country. In addition, the method was tested for use with an ion-trap mass spectrometer coupled to a liquid chromatograph, which allowed confirmation of PB at lower levels (5-10 ppb) in kidney tissue. 相似文献
4.
A procedure for the analysis of over 100 pesticides that only contain combinations of carbon, hydrogen, nitrogen, sulfur, and oxygen (i.e., no phosphorous or halogen atoms) has been developed. The procedure employs gas chromatography with a mass selective detector (GC/MSD), electron impact ionization, and selected ion monitoring. This GC/MSD procedure provided lower limits of quantitation and increased confirmational data compared to the traditional element-selective GC procedures that are commonly used for the detection of this "class" of pesticides. These analytical improvements were demonstrated by 26 pesticides that were detected at ng/g levels in a variety of fruit and vegetable matrixes using this procedure; these pesticides were missed by the traditional element-selective GC procedures. Validation of the procedure was performed using acetone extraction with solid-phase extraction cleanup. Twenty representative target pesticides were used to demonstrate repeatability and linearity of the chromatographic response and recovery from fruit and vegetable matrixes. 相似文献
5.
For the work on the synthesis of 2-acyl-5-methoxynaphthoquinones as tricyclic analogues of daunomycinone1, we wanted to develop an efficient regioselective synthesis of 5-methoxy-2-acyl-1-naphthols without using Lewis acids. This requirement precluded the use of the thermal Fries but not the photo-Fries rearrangement. Although the mechanistic aspects of the photo reaction have received much study2, the reaction has been little used preparatively3 because it usually gives poor yields of hydroxy ketones even when only one product is possible. 相似文献
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Bruins EE Bauer TS den Bok HW Duif CP van Hoek WC de Lange DJ Misiejuk A Papandreou Z Sichtermann EP Tjon JA Willering HW Yeomans DM Reike H Durek D Frommberger F Gothe R Jakob D Kranefeld G Kunz C Leiendecker N Pfeiffer G Putsch H Reichelt T Schoch B Wacker D Wehrmeister D Wilhelm M Jans E Konijn J de Vries R Furget C Voutier E Arenhövel H 《Physical review letters》1995,75(1):21-24
8.
We report the wavelength dependencies of the two- and three-photon absorption coefficients of undoped GaAs in the spectral range 1.3-3.5 microm, as well as nonlinear refractive index n2 in the range 1.7-3.25 microm. The data were obtained by using the single-beam Z-scan method with 100-fs-long optical pulses. Anisotropy of the three-photon absorption coefficient was observed and found to be consistent with the crystal symmetry of GaAs. 相似文献
9.
Turnipseed SB Roybal JE Rupp HS Gonzales SA Pfenning AP Hurlbut JA 《Rapid communications in mass spectrometry : RCM》1999,13(6):493-499
A multi-residue LC/MS method has been developed to confirm avermectin drug residues in several food matrices. Ivermectin (IVR), doramectin (DOR), eprinomectin (EPR) and moxidectin (MOX) are confirmed using atmospheric pressure chemical ionization (APCI) with negative ion detection and selected ion monitoring of three to four ions for each compound. The drug residues are extracted from tissue or milk using previously published procedures. IVR and DOR are confirmed at 20 ppb levels in fortified salmon muscle; IVR is also confirmed in tissue from salmon dosed with the drug. Residues of DOR, IVR, and EPR are confirmed in fortified milk at the 20 ppb level and in fortified beef liver at 40 ppb. Residues of MOX can also be confirmed in these matrices, but at slightly higher levels (40-80 ppb). 相似文献
10.
Hurlbut DB Primus TM Goodall MJ Volz SA Johnston JJ 《Journal of AOAC International》1999,82(6):1321-1328
Propionylpromazine hydrochloride (PPZHCl) has been investigated for use with leghold traps to reduce the amount of self-inflicted trauma experienced by animals restrained by these traps. Three types of PPZHCl formulations made with Karo dark syrup, K-Y Jelly, and Vaseline were used in 2 types of tranquilizer trap devices (TTDs). A reversed-phase ion-pair liquid chromatography (LC) method using a small bore C18 column was used to: (1) determine the purity of the PPZHCl material used in these formulations, and (2) to determine the resulting PPZHCl content of each formulation. Analyte quantitation was done using UV absorption at 280 nm. Regression analysis of calibration standard solutions indicated a linear and directly proportional relationship between analyte response and PPZHCl concentration over the range evaluated. Recovery data from: (1) Vaseline formulations containing 38.8, 16.2, and 8.78% PPZHCl were 104, 92.9, and 90.2%, respectively, (2) Karo dark syrup formulations containing 26.5, 18.1, and 10.3% PPZHCl were 97.7, 99.3, and 106%, respectively, and (3) K-Y Jelly formulations containing 33.0, 23.5, and 13.4% PPZHCl were 100, 99.4, and 88.7%, respectively. The relative standard deviation (RSD) values from triplicate analysis of these formulations ranged from 0.7 to 6.7%. The PPZHCl content from 9 manufactured TTDs, 3 for each formulation type, were analyzed in triplicate and produced RSD values ranging from 0.7-6.8%. These results indicate that the formulation extraction presented could be used to evaluate the PPZHCl content in TTDs prior to field use. The use of a small bore LC column reduced the amount of solvents consumed and hazardous waste generated, compared to sample analysis that uses a more conventional analytical LC column. 相似文献