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OBJECTIVE:To establish a method for the concentration determination of catecholamines in human urine. METH-ODS:After extracted by aluminum oxide,using 3,4-dihydroxybenzylamine as internal standard,HPLC-electrochemistry was per-formed on the column of Shim-Pack C18 with mixed solution [every 500 ml mixed solution containing ion-pairing reagents(octane sulfonate) 0.5 mmol,methanol 10 ml,0.06 mmol/L Di-n-butylamine 50 μl,sodium acetate anhydrous 2.0 g,citric acid 5.5 g, EDTA-Na2 60 mg and sodium chloride 584.4 mg,pH=3.5] at a flow rate of 0.8 ml/min,column temperature was 30 ℃,detection voltage was 750 mV,and injection volume was 40 μl. RESULTS:The linear ranges were 3.125-100 ng/ml for both norepinephrine (r=0.998 5)and epinephrine(r=0.999 2),lower limits of quantitation were 3.125 ng/ml;RSDs of within days and daytime were lower than 10%,method recoveries were 99.2%-101.6% and 98.9%-100.5%,extraction recoveries were 63.8%-66.8% and 60.5%-62.6%. CONCLUSIONS:The method shows strong specificity,high sensitivity and low detection cost,and can be used for the concentration determination of catecholamines in human urine.
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OBJECTIVE: To determine the content of the related substances in azithromycin tablet by HPLC-electrochemical detector.METHODS: The column was Gamma ARP-1/P.The mobile phase consisted of 0.014 mol?L-1 dipotassium hydrogen phosphate/0.020 mol?L-1 sodium hydroxide(pH was adjusted to 11 by phosphoric acid and sodium hydroxide)-acetonitrile(71∶29) at a flow rate of 0.7 mL?min-1.The column temperature was 40 ℃.The injection volume was 50 ?L.Glass carbon working electrode was set at +900 mV.RESULTS: The linear ranges of erythromycin peroxide,deoxyazithromycin,azithromycin impurity A,and N-demethlation azithromycin were 0.15～1.80 ?g(r=0.999),0.09～1.08 ?g(r=0.999),0.23～2.76 ?g(r=0.998) and 0.30～3.60 ?g(r=0.998),respectively.The average recoveries were 98.9%(RSD=1.1%),94.6%(RSD=5.4%),103.4%(RSD=3.4%) and 96.2%(RSD=4.3%),respectively.The contents of the related substances were all below 0.7%.CONCLUSION: The established method is reproducible,sensitive and reliable,and applicable for the detection of the related substances in azithromycin tablets.
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Objective To develop a nonaqueous electrolyte electrochemical detector in order to solve the problems of shorter average life span and operating temperature range in aqueous electrolyte electrochemical detector for unsymmetrical dimethyl hydrazine(UDMH).Methods Nonaqueous electrolyte was utilized in this kind of electrochemical detector comprised of n-mehyl-2-pyrrolidone with conductive compatible salts,such as tetrabutyl ammonium tetrafluoroborate,which had much lower evaporating pressure and freezing point than aqueous electrolyte ones.Three-electrode potential electrochemical system was also used,composing a sensing electrode,a counter electrode and a reference electrode.The three electrodes were all teflon-bonded diffusion electrodes which were prepared by spraying the noble metal catalyst dispersion onto the Teflon film.Results The experiment result showed that the average life span could be over two years compared with the aqueous electrolyte electrochemical detector of one year life span.Operating temperature range was expanded to-20 ℃～+40 ℃.However,the response time was nearly five minutes.Conclusion The detector can be used for leakage checking in the places where a large quantities of UDMH are used or stored.
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0.05).Conclution After at a time sampling the levels of hydroxyl free radical and monoamines neurotransmitters and their metabolites from brain micronilysis of freely moving rats during salicylate sodium-Ringer's solusion perfusion can be simultaneously measured by HPLC-ED.
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Aim To establish the rapidly detecting method of glucose concentration in brain microdialysate.Method Using high-performance liquid chromatography (HPLC) with electrochemical detector (ED) and Nano-Copper screen-printed electrode (NCSE100)-Flow injection analysis the glucose concentration in brain microdialysate were detected.Result The related coefficient (r) of glucose standard curve was 0.9995. The variation coefficient (CV) within a day was 4%~7%. The striatum extracellular glucose concentration in rats was(2.4?0.8) mmol?L-1. These results indicated that our method was reliable.Conclusion Using HPLC with ED, NCSE100, and flow injection analysis the glucose concentration in brain microdialysate were detected, which has certain applied worth.