RESUMEN
ABSTRACT: Objective To establish a method for determination of escitalopram in biological samples by ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with gas chromatography-tandem mass spectrometry ï¼GC-MS/MSï¼ and provide evidences for forensic determination of cases related to escitalopram. Methods The 1-hexyl-3-methylimidazolium hexafluorophosphate ï¼[C6MIM][PF6]ï¼ was selected as an extract solvent to process biological samples. Ultrasound-assisted extraction was used on the samples. Then the samples were detected by GC-MS/MS. Results The linear range of escitalopram in blood and liver were 5.56-1 111.10 ng/mL and 0.025-5.00 mg/g, respectively. The correlation coefficient ï¼rï¼ were greater than 0.999, limit of detection ï¼LODï¼ were 4.00 ng/mL and 2.00 µg/g, limit of quantitation ï¼LOQï¼ were 14.00 ng/mL and 6.00 µg/g, respectively. The extraction recovery rates were all greater than 50%, the interday and intraday precision were less than 20%. Escitalopram was detected in blood and liver samples from the actual poisoning case by this method with a content of 1.26 µg/mL and 0.44 mg/g, respectively. Conclusion The ultrasound-assisted ionic liquid-dispersive liquid-liquid microextraction combined with GC-MS/MS is environment friendly, rapid, has good enriching effect and consumes less organic solvent and can be used for forensic determination of escitalopram related cases.
Asunto(s)
Microextracción en Fase Líquida , Citalopram , Cromatografía de Gases y Espectrometría de Masas , Límite de Detección , Espectrometría de Masas en TándemRESUMEN
ABSTRACT: Objective To develop a high performance liquid chromatography-tandem mass spectrometry ï¼HPLC-MS/MSï¼ method for the determination of the content of 4-fluoromethamphetamine ï¼4-FMAï¼ in rat plasma, and to provide a methodological basis for the study of the toxicokinetics of 4-FMA in rats. Methods Rat plasma samples were added into internal standard methamphetamine ï¼MAï¼. Its proteins were precipitated with methanol and then separated with Poroshell 120 EC-C18 chromatographic column. A 0.1% formic acid aqueous solution and a 0.1% formic acid acetonitrile solution were used as the mobile phase at the flow rate of 0.4 mL/min. Electrospray ionization source was used for detection in the multiple reaction monitoring ï¼MRMï¼ mode. Results The linear relationship was good when the mass concentration of 4-FMA in plasma samples was in the range of 5-1 000 ng/mL ï¼r>0.999ï¼. The limit of detection ï¼LODï¼ was 3 ng/mL and the limit of quantification ï¼LOQï¼ was 5 ng/mL. The accuracy was expressed as relative error ï¼REï¼, and in the range of ±5%, the intra-day precision and inter-day precision ï¼relative standard deviation, RSDï¼ less than 9%, and the extraction recovery rate was more than 90%. The analysis and detection of plasma samples were completed within 2.5 min. Conclusion This study developed a HPLC-MS/MS method for the determination of 4-FMA in rat plasma samples. This method is accurate, rapid, simple and sensitive and can be applied to the study of toxicokinetics of 4-FMA.
Asunto(s)
Cromatografía Líquida de Alta Presión , Metanfetamina/sangre , Espectrometría de Masas en Tándem , Animales , Límite de Detección , Metanfetamina/análogos & derivados , Ratas , Reproducibilidad de los Resultados , ToxicocinéticaRESUMEN
OBJECTIVES: To establish an analytical method of the endosulfan concentrations ï¼α-endosulfan and ß-endosulfanï¼ in biological samples by GC-MS/MS. To observe the distribution of endosulfan in aquatic animals and provide experimental evidence for forensic identification of relevant cases. METHODS: Acetonitrile was added to the blood and muscle samples for precipitating the protein. The endosulfan concentrations were determined by GC-MS/MS in multiple reaction monitoring mode. Qualitative analysis was performed according to the retention time and ion rate, and quantitative analysis was performed by external standard working curve method. RESULTS: In blood samples, the calibration curves of α-endosulfan and ß-endosulfan ranging from 0.062 5 to 10 µg/mL had good linear relationship, the correlation coefficients ï¼rï¼ of which were >0.99. The limits of detection ï¼LODï¼ were 1 ng/mL and 2 ng/mL and the limits of quantification ï¼LOQï¼ were 4 ng/mL and 8 ng/mL, respectively. In muscle samples, the calibration curves of α-endosulfan and ß-endosulfan ranging from 0.062 5 to 10 µg/g, the r of which were >0.98. The LOD were 1 ng/g and 4 ng/g and the LOQ were 4 ng/g and 16 ng/g, respectively. The accuracy of α-endosulfan and ß-endosulfan was 90.76%-108.91% both in blood and muscle samples, the interday and intraday precision were 2.35%-8.71% and 5.44%-10.29%, respectively. In poisoning cases, endosulfan were detected in all parts of fish and crab and the content difference was statistically significant. CONCLUSIONS: The endosulfan detection method based on GC-MS/MS established in the present study is rapid, sensitive and accurate, which can be applied to the endosulfan detection in traces biological samples. The distribution of endosulfan in fish and crab was different, which can provide evidence to the sample collection and analysis for toxicological analysis in relevant forensic identification.
Asunto(s)
Cromatografía de Gases/métodos , Endosulfano/análisis , Endosulfano/metabolismo , Cromatografía de Gases y Espectrometría de Masas/métodos , Espectrometría de Masas en Tándem/métodos , Animales , Endosulfano/química , Humanos , Límite de Detección , Reproducibilidad de los ResultadosRESUMEN
Studies of oxygen equilibrium properties of Mg(II)-Fe(II) and Zn(II)-Fe(II) hybrid hemoglobins (i.e. alpha2(Fe)beta2(M) and alpha2(M)beta2(Fe); M=Mg(II), Zn(II) (neither of these closed-shell metal ions binds oxygen or carbon monoxide)) are reported along with the X-ray crystal structures of alpha2(Fe)beta2(Mg) with and without CO bound. We found that Mg(II)-Fe(II) hybrids resemble Zn(II)-Fe(II) hybrids very closely in oxygen equilibrium properties. The Fe(II)-subunits in these hybrids bind oxygen with very low affinities, and the effect of allosteric effectors, such as proton and/or inositol hexaphosphate, is relatively small. We also found a striking similarity in spectrophotometric properties between Mg(II)-Fe(II) and Zn(II)-Fe(II) hybrids, particularly, the large spectral changes that occur specifically in the metal-containing beta subunits upon the R-T transition of the hybrids. In crystals, both alpha2(Fe)beta2(Mg) and alpha2(Fe-CO)beta2(Mg) adopt the quaternary structure of deoxyhemoglobin. These results, combined with the re-evaluation of the oxygen equilibrium properties of normal hemoglobin, low-affinity mutants, and metal substituted hybrids, point to a general tendency of human hemoglobin that when the association equilibrium constant of hemoglobin for the first binding oxygen molecule (K1) approaches 0.004 mmHg(-1), the cooperativity as well as the effect of allosteric effectors is virtually abolished. This is indicative of the existence of a distinct thermodynamic state which determines the lowest oxygen affinity of human hemoglobin. Moreover, excellent agreement between the reported oxygen affinity of deoxyhemoglobin in crystals and the lowest affinity in solution leads us to propose that the classical T structure of deoxyhemoglobin in the crystals represents the lowest affinity state in solution. We also survey the oxygen equilibrium properties of various metal-substituted hybrid hemoglobins studied over the past 20 years in our laboratory. The bulk of these data are consistent with the Perutz's trigger mechanism, in that the affinity of a metal hybrid is determined by the ionic radius of the metal, and also by the steric effect of the distal ligand, if present. However, there remains a fundamental contradiction among the oxygen equilibrium properties of the beta substituted hybrid hemoglobins.