Glycerides are first separated to classes of triglycerides(TGs), diglycerides(DGs) and monoglycerides(MGs) by normal phase HPLC on silica gel column. Individual triglyceride separation is then achieved by non-aqueous ...Glycerides are first separated to classes of triglycerides(TGs), diglycerides(DGs) and monoglycerides(MGs) by normal phase HPLC on silica gel column. Individual triglyceride separation is then achieved by non-aqueous reversed phase(NARP) HPLC on C_(18) column with UV detection at 215nm.展开更多
High Performance Liquid Chromatography (HPLC) experiments have been performed on nine steviol glycosides namely rebaudioside A, steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, r...High Performance Liquid Chromatography (HPLC) experiments have been performed on nine steviol glycosides namely rebaudioside A, steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A isolated from the leaves of Stevia rebaudiana using Reversed-Phase (RP) column. Using RP-HPLC method, the individual retention times for nine naturally occurring ent-kaurane diterpene glycosides of S. rebaudiana reported in JECFA have been determined at four different temperatures: 20℃, 40℃, 60℃, and 79℃. Also, calculated the relative retention times of the eight steviol glycosides steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A against the major steviol glycoside rebaudioside A. HPLC results suggested that temperatures 40℃ and 60℃ would be ideal conditions for better separation of steviol glycosides.展开更多
With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chro...With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chromatography (RPLC) was investigated by on line UV spectrometry and identified with nuclear magnetic resonance (NMR) spectrometry and mass spectrometry. The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis (FA). When the insulin concentration was limited to a certain range, the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten. The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components. The displaced methanol was quantitatively determined by NMR and on line UV spectrometries. TFA with high UV absorbance can not be used as an ion pairing agent for the investigation of the FP in RPLC, but it can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC. A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC. From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC, while solute can penetrate into it in FA of RPLC. The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.展开更多
A novel reserved\|phase ion\|pair liquid chromatographic method using hexadecyltrimethylammonium bromide(HTMAB) as an ion\|pair reagent for separating the complexes of metal and 8\|hydroxyquinoline\|5\|sulphonic aci...A novel reserved\|phase ion\|pair liquid chromatographic method using hexadecyltrimethylammonium bromide(HTMAB) as an ion\|pair reagent for separating the complexes of metal and 8\|hydroxyquinoline\|5\|sulphonic acid(HQS) coupled with on\|line fluorescence detection has been developed. The chromatographic behavior of metal\|HQS complexes in the proposed system was systematically investigated.When the C\-\{18\} column modified by HTMAB and the suitable mobile phase coupled with fluorescence detection(\%λ\%\-\{ex\}=388 nm; \%λ\%\-\{em\}=518 nm) were employed, the detection limit of cadmium is 7.72 ng/mL with an injection volume of 20 μL, and the linear range of calibration curve for cadmium is 50\800 ng/mL. It was successfully applied to determination of bio\|available cadmium in polluted soils of China. Moreover, the possible species of Cd\|HQS on the column has been investigated by log\|log plot analysis.展开更多
A new method has been developed for separation and determination of zinc,copper,cobalt and nickel based on their colour chelates with 6,6″-dimethyl-4′-phenyl-2,2′:6′,2″-terpyridine(TPY) by ion pair high perform...A new method has been developed for separation and determination of zinc,copper,cobalt and nickel based on their colour chelates with 6,6″-dimethyl-4′-phenyl-2,2′:6′,2″-terpyridine(TPY) by ion pair high performance liquid chromatography in a reversed phase mode.The suitable conditions are the methanol-water(80:20,V/V) containing 10mmol/L NaH2PO4-H3PO4 buffer solution(pH=5.0) and 3.0mmol/L sodium dodecyl sulfonate as mobile phase,on a Symmetry C18 column(3.9mmID×150mm),the flow rate of the mobile phase is 1.0mL/min.Spectrophotometric detection was made at 340nm.The detective limits are 0.05,0.10,2.00 and 0.50ng/mL respectively.The method has good selectivity and sensitivity.It has been applied to the separation and determination of zinc,copper,cobalt and nickel in human hair and tobacco and the result is satisfied.展开更多
文摘Glycerides are first separated to classes of triglycerides(TGs), diglycerides(DGs) and monoglycerides(MGs) by normal phase HPLC on silica gel column. Individual triglyceride separation is then achieved by non-aqueous reversed phase(NARP) HPLC on C_(18) column with UV detection at 215nm.
文摘High Performance Liquid Chromatography (HPLC) experiments have been performed on nine steviol glycosides namely rebaudioside A, steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A isolated from the leaves of Stevia rebaudiana using Reversed-Phase (RP) column. Using RP-HPLC method, the individual retention times for nine naturally occurring ent-kaurane diterpene glycosides of S. rebaudiana reported in JECFA have been determined at four different temperatures: 20℃, 40℃, 60℃, and 79℃. Also, calculated the relative retention times of the eight steviol glycosides steviolbioside, stevioside, rubusoside, rebaudioside B, rebaudioside C, rebaudioside D, rebaudioside F, and dulcoside A against the major steviol glycoside rebaudioside A. HPLC results suggested that temperatures 40℃ and 60℃ would be ideal conditions for better separation of steviol glycosides.
文摘With insulin methanol water, and the ion pairing agent, hydrochloric acid and trifluroacetic acid (TFA), the character of the first plateau (FP) on the elution curve of frontal analysis in reversed phase liquid chromatography (RPLC) was investigated by on line UV spectrometry and identified with nuclear magnetic resonance (NMR) spectrometry and mass spectrometry. The profile of the FP is the same as that of a usual elution curve of methanol in frontal analysis (FA). When the insulin concentration was limited to a certain range, the height of the FP was found to be proportional to the insulin concentration in mobile phase and its length companying to shorten. The FP profile on the intersection of two tangents reflects the components of the microstructure in the depth direction of the bonded stationary phase layer and the desorption dynamics of the displaced components. The displaced methanol was quantitatively determined by NMR and on line UV spectrometries. TFA with high UV absorbance can not be used as an ion pairing agent for the investigation of the FP in RPLC, but it can be used as a good marker to investigate the complicated transfer process of components in the stationary phase in RPLC. A stoichiometric displacement process between solute and solvent was proved to be valid in both usual and FA in RPLC. From the point of view of dynamics of mass transfer, the solutes can only contact to the surface of stationary phase in usual RPLC, while solute can penetrate into it in FA of RPLC. The solvation of insulin in methanol and water solution as an example indicating the usage of the FP in the FA was also investigated in this paper.
文摘A novel reserved\|phase ion\|pair liquid chromatographic method using hexadecyltrimethylammonium bromide(HTMAB) as an ion\|pair reagent for separating the complexes of metal and 8\|hydroxyquinoline\|5\|sulphonic acid(HQS) coupled with on\|line fluorescence detection has been developed. The chromatographic behavior of metal\|HQS complexes in the proposed system was systematically investigated.When the C\-\{18\} column modified by HTMAB and the suitable mobile phase coupled with fluorescence detection(\%λ\%\-\{ex\}=388 nm; \%λ\%\-\{em\}=518 nm) were employed, the detection limit of cadmium is 7.72 ng/mL with an injection volume of 20 μL, and the linear range of calibration curve for cadmium is 50\800 ng/mL. It was successfully applied to determination of bio\|available cadmium in polluted soils of China. Moreover, the possible species of Cd\|HQS on the column has been investigated by log\|log plot analysis.
文摘A new method has been developed for separation and determination of zinc,copper,cobalt and nickel based on their colour chelates with 6,6″-dimethyl-4′-phenyl-2,2′:6′,2″-terpyridine(TPY) by ion pair high performance liquid chromatography in a reversed phase mode.The suitable conditions are the methanol-water(80:20,V/V) containing 10mmol/L NaH2PO4-H3PO4 buffer solution(pH=5.0) and 3.0mmol/L sodium dodecyl sulfonate as mobile phase,on a Symmetry C18 column(3.9mmID×150mm),the flow rate of the mobile phase is 1.0mL/min.Spectrophotometric detection was made at 340nm.The detective limits are 0.05,0.10,2.00 and 0.50ng/mL respectively.The method has good selectivity and sensitivity.It has been applied to the separation and determination of zinc,copper,cobalt and nickel in human hair and tobacco and the result is satisfied.