scholarly journals New Spectrofluorimetric Method for Determining Serotonin: Application to Human Urine

2015 ◽  
Vol 7 (2) ◽  
pp. 85
Author(s):  
Abdourahmane Khonté ◽  
Diène Thiaré ◽  
Cheikh Diop ◽  
Lamine Cissé ◽  
François Delattre ◽  
...  
Keyword(s):  
Solid Phase ◽  
Standard Addition ◽  
Liquid Extraction ◽  
Good Reproducibility ◽  
Factors Affecting ◽  
Liquid Liquid Extraction ◽  
Spectrofluorimetric Method ◽  
Physicochemical Factors ◽  
Chemical Pretreatments

In this present paper, we investigate the development of simple, rapid, accurate, reproducible and sensitive methods for the determination of serotonin (5-HT) in urine. For this purpose stationary fluorescence was used as method. With regard to the analysis of serotonin, the liquid-liquid extraction (LLE) solid phase extraction (SPE) and standard addition procedures were used. Several physicochemical factors affecting the sensitivity of the fluorescence intensity of serotonin were optimized, including the system of solvent (organic, micellar), the pH and the salts. The study of the analytical performances of the method led to very low limits of detection (LOD) varying between 0.1 and 3 ng/mL and to limits of quantification (LOQ) ranging between 0.4 and 10 ng/mL. This confirms the sensitivity of the method. Thus the low values of standard deviations (DRS) (between 0.3 and 6.6%) testify the good reproducibility of the measurements with satisfactory covering rate (89 to 111%). Accordingly, our results show that the spectrofluorimetric method is simple, fast and sensitive and can be applied to the routine analysis and does not require expensive equipment nor tiresome chemical pretreatments.

scholarly journals Determination of Eight Coccidiostats in Eggs by Liquid–Liquid Extraction–Solid-Phase Extraction and Liquid Chromatography–Tandem Mass Spectrometry

Molecules ◽  
2020 ◽  
Vol 25 (4) ◽  
pp. 987 ◽  
Author(s):  
Bo Wang ◽  
Jianyu Liu ◽  
Xia Zhao ◽  
Kaizhou Xie ◽  
Zhixiang Diao ◽  
...  
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Tandem Mass Spectrometry ◽  
Solid Phase ◽  
Liquid Extraction ◽  
Tandem Mass ◽  
Liquid Liquid Extraction ◽  
Chromatography Tandem Mass Spectrometry ◽  
Liquid Chromatography Tandem Mass

A method for the simultaneous determination of robenidine, halofuginone, lasalocid, monensin, nigericin, salinomycin, narasin, and maduramicin residues in eggs by liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed. The sample preparation method used a combination of liquid–liquid extraction (LLE) and solid-phase extraction (SPE) technology to extract and purify these target compounds from eggs. The target compounds were separated by gradient elution using high-performance liquid chromatography (HPLC) and ultra-performance liquid chromatography (UPLC). Tandem mass spectrometry was used to quantitatively and qualitatively analyze the target compounds via electrospray ionization (ESI+) and multiple reaction monitoring mode. The HPLC–MS/MS and UPLC–MS/MS methods were validated according to the requirements defined by the European Union and the Food and Drug Administration. The limits of detection and limits of quantification of the eight coccidiostats in eggs were 0.23–0.52 µg/kg and 0.82–1.73 µg/kg for HPLC–MS/MS, and 0.16-0.42 µg/kg and 0.81-1.25 µg/kg for UPLC–MS/MS, respectively. The eggs were spiked with four concentrations of the eight coccidiostats, and the HPLC–MS/MS and UPLC–MS/MS average recoveries were all higher than 71.69% and 72.26%, respectively. Compared with the HPLC–MS/MS method, utilizing UPLC–MS/MS had the advantages of low reagent consumption, a short detection time, and high recovery and precision. Finally, the HPLC–MS/MS and UPLC–MS/MS methods were successfully applied to detect eight coccidiostats in 40 eggs.

scholarly journals Determination of Nitroimidazoles and Their Metabolites in Swine Tissues by Liquid Chromatography

2003 ◽  
Vol 86 (3) ◽  
pp. 505-509 ◽  
Author(s):  
Jianzhong Shen ◽  
Yue Yhang ◽  
Suxia Zhang ◽  
Shuangyang Ding ◽  
Xinhua Xiang
Keyword(s):  
Chromatographic Method ◽  
Solid Phase ◽  
Liquid Extraction ◽  
Phase Extraction ◽  
Liquid Liquid Extraction ◽  
Liquid Chromatographic Method ◽  
Swine Tissue ◽  
Liquid Chromatographic ◽  
Sensitive Method

Abstract A liquid chromatographic method was developed for determination of metronidazole (MNZ), ronidazole (RNZ), dimetridazole (DMZ), and 2-hydroxymethyl-1-methyl-5-nitroimidazole (DMZOH) in swine tissue. After extraction with ethyl acetate and evaporation, the nitroimidazoles were redissolved in hydrochloric acid. Hexane was used in the liquid–liquid extraction to remove fat. An Oasis® HLB solid-phase extraction was performed after neutralization of the acidic extract. The limits of detection were 1.0–2.0 μg/kg for DMZOH, MNZ, RNZ, and DMZ in muscle and liver. Average recoveries ranged from 80.1 to 83.9% in muscle fortified at 10, 20, and 50 μg/kg; average re-coveries in liver ranged from 78.9 to 82.3%. The procedure provides a simple and sensitive method for monitoring DMZOH, MNZ, RNZ, and DMZ residues in swine tissues.

Modification of the analytical procedures for the determination of herbage and faecal n-alkanes used in the estimation of herbage intake

1995 ◽  
Vol 124 (1) ◽  
pp. 71-77 ◽  
Author(s):  
S. A. Vulich ◽  
J. P. Hanrahan ◽  
B. A. Crowley
Keyword(s):  
Chemical Analysis ◽  
Analytical Procedure ◽  
Solid Phase ◽  
Liquid Extraction ◽  
Hazardous Chemical ◽  
Liquid Liquid Extraction ◽  
Herbage Intake ◽  
Sample Extract ◽  
Faecal Samples

SUMMARYThe evaluation of n-alkane concentrations in herbage and faeces is the basis of a methodology that yields precise estimates of herbage intake. Established chemical analysis procedures for the determination of n-alkane concentrations in herbage and faecal samples involve an elaborate sequence of steps utilizing n-hexane as solvent for both the liquid-liquid extraction of n-alkanes from the sample and the solid-phase separation of n-alkanes in the extract. Composites of herbage and faecal samples from studies with sheep provided the experimental material used to evaluate a series of modifications which would simplify and reduce the workload involved in the chemical analysis. The results show that a less hazardous chemical, n-heptane, can replace n-hexane at all stages of the analytical procedure. They also show that evaporation of the sample extract and redissolving it prior to the separation of the n-alkanes, using a silica gel column, is unnecessary and that the volume of solvent used can be reduced. Procedures for saponification of samples prior to extraction can also be simplified as the process can be run overnight involving a slow build-up of temperature to 90 °C. The gain in precision from processing samples in duplicate was negligible and it would be more appropriate to invest extra efforts on an increased number of experimental animals. The results snowed that the workload and cost of using the n-alkane technique to estimate herbage intake can be reduced substantially.

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