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Hua-shan Zhang

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Organization: Wuhan University
Department: Department of Chemistry
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1,3,5,7-Tetramethyl-8-aminozide-difluoroboradiaza-s-indacene as a new fluorescent labeling reagent for the determination of aliphatic aldehydes in serum with high performance liquid chromatography
Co-reporter:Xu-Jie Xiong, Hong Wang, Wan-Bing Rao, Xiao-Feng Guo, Hua-Shan Zhang
Journal of Chromatography A 2010 Volume 1217(Issue 1) pp:49-56
Publication Date(Web):1 January 2010
DOI:10.1016/j.chroma.2009.11.003
A BODIPY-based fluorescent derivatization reagent with a hydrazine moiety, 1,3,5,7-tetramethyl-8-aminozide-difluoroboradiaza-s-indacene (BODIPY-aminozide), has been designed for aldehyde labeling. An increased fluorescence quantum yield was observed from 0.38 to 0.94 in acetonitrile when it reacted with aldehydes. Twelve aliphatic aldehydes from formaldehyde to lauraldehyde were used to evaluate the analytical potential of this reagent by high performance liquid chromatography (HPLC) on C18 column with fluorescence detection. The derivatization reaction of BODIPY-aminozide with aldehydes proceeded at 60 °C for 30 min to form stable corresponding BODIPY hydrazone derivatives in the presence of phosphoric acid as a catalyst. The maximum excitation (495 nm) and emission (505 nm) wavelengths were almost the same for all the aldehyde derivatives. A baseline separation of all the 12 aliphatic aldehydes (except formaldehyde and acetaldehyde) is achieved in 20 min with acetonitrile–tetrahydrofuran (THF)–water as mobile phase. The detection limits were obtained in the range from 0.43 to 0.69 nM (signal-to-noise = 3), which are better than or comparable with those obtained by the existing methods based on aldehyde labeling. This reagent has been applied to the precolumn derivatization followed with HPLC determination of trace aliphatic aldehydes in human serum samples without complex pretreatment or enrichment method.
Selective spectrofluorimetric determination of glutathione in clinical and biological samples using 1,3,5,7-tetramethyl-8-phenyl-(2-maleimide)-difluoroboradiaza-s-indacene
Co-reporter:Xiao-Feng Guo, Hong Wang, Yue-Hong Guo, Hua-Shan Zhang
Analytica Chimica Acta 2009 Volume 633(Issue 1) pp:71-75
Publication Date(Web):2 February 2009
DOI:10.1016/j.aca.2008.11.028
This work reports the development of a selective, sensitive and rapid spectrofluorimetric method for the determination of reduced glutathione (GSH) in the presence of relatively high levels of cysteine (Cys) in clinical and biological samples using 1,3,5,7-tetramethyl-8-phenyl-(2-maleimide)-difluoroboradiaza-s-indacene (TMPAB-o-M). The fluorescence from TMPAB-o-M is strongly quenched by its maleimide moiety, but after reaction with thiol, the fluorescence is restored with a 350-fold intensity increase (fluorescence quantum yield from 0.002 to 0.73). In H3Cit–Na2HPO4 buffer (pH 7.40), the derivatization is completed in just 5 min under 37 °C. The linear range is 0.005–0.2 μmol L−1, with detection limit of 1.1 × 10−10 mol L−1 (signal-to-noise ratio = 3). Almost all amino acids, including Cys, impose no interference even if present at relatively high concentrations (amino acids:GSH = 100:1, Cys:GSH = 1:1, molar ratio, CGSH = 3 × 10−7 mol L−1). The sample can be used directly without further treatment after the protein is removed. The developed method is precise with a relative standard deviation (R.S.D.) lower than 5.0% (n = 6) and has been applied to the determination of GSH in human blood and pig’s liver with recoveries between 94.4 and 105.6%.
Simultaneous analysis of plasma thiols by high-performance liquid chromatography with fluorescence detection using a new probe, 1,3,5,7-tetramethyl-8-phenyl-(4-iodoacetamido)difluoroboradiaza-s-indacene
Co-reporter:Xiao-Feng Guo, Hong Wang, Yue-Hong Guo, Zi-Xing Zhang, Hua-Shan Zhang
Journal of Chromatography A 2009 Volume 1216(Issue 18) pp:3874-3880
Publication Date(Web):1 May 2009
DOI:10.1016/j.chroma.2009.02.083
The design, synthesis and properties of a new derivatizing reagent, 1,3,5,7-tetramethyl-8-phenyl-(4-iodoacetamido)difluoroboradiaza-s-indacene (TMPAB-I), for thiol groups are presented. Using the derivatization of TMPAB-I with thiols, a new high-performance liquid chromatographic method for measuring low-molecular-weight thiol-containing compounds, including coenzyme A (CoA), glutathione, N-acetylcysteine, cysteine, homocysteine (HCys) and 6-mercaptopurine has been developed. The reaction of TMPAB-I with thiols is specific, fast and stable for both TMPAB-I and the derivatives. A baseline separation of all the six derivatives is achieved by isocratic elution on reversed-phase column within 20 min with detection wavelengths of 500 and 510 nm for the excitation and emission, respectively, and the limits of detection (signal-to-noise ratio = 3) are from 1.8 fmol (CoA) to 14.0 fmol (HCys), respectively, per 20 μL injection. The utility of the proposed method has been validated by measuring thiol-containing compounds in human plasma samples from healthy persons and patients with hypertension, with recoveries of 94.2–106.8%.
Trace determination of short-chain aliphatic amines in biological samples by micellar electrokinetic capillary chromatography with laser-induced fluorescence detection
Co-reporter:Ying-Hua Deng, Hong Wang, Lu Zhong, Hua-Shan Zhang
Talanta 2009 Volume 77(Issue 4) pp:1337-1342
Publication Date(Web):15 February 2009
DOI:10.1016/j.talanta.2008.09.013
In this study, a new capillary electrophoresis (CE) method is described originally for the sensitive and selective determination of short-chain aliphatic amines in biological samples. These amines were converted into their N-hydroxysuccinimidyl fluorescein-O-acetate (SIFA) derivatives and measured by micellar electrokinetic capillary chromatography with laser-induced fluorescence detection. The derivatization conditions and separation parameters for the aliphatic amines were optimized in detail. The SIFA-labeled amines were fully separated within 8.5 min using 25 mM pH 9.6 boric acid electrolyte containing 60 mM sodium dodecyl sulfate (SDS). The parameters of validation such as linearity of response, precision and detection limits were determined. The detection limits were obtained in the range from 0.02 to 0.1 nM, which was the lowest value reported by CE methods. The developed method was successfully employed to monitor aliphatic amines in serum and cells samples. After comparison of other CE methods using different fluorescent probes, the present method represents a powerful tool for the trace determination of aliphatic amines in complex biological samples.
Determination of primary biogenic amines in various food products using isocratic HPLC with 3-(4-chlorobenzoyl)-quinoline-2-carboxaldehyde as a new precolumn fluorogenic reagent
Co-reporter:Niu Zhang;Hong Wang;Xiao-Feng Guo
Journal of Separation Science 2008 Volume 31( Issue 15) pp:2804-2812
Publication Date(Web):
DOI:10.1002/jssc.200800247

Abstract

A simple HPLC approach has been successfully established for the sensitive determination of six biogenic amines (BAs) in food samples. The method involves derivatization with 3-(4-chlorobenzoyl)-quinoline-2-carboxaldehyde newly synthesized as a new fluorogenic reagent followed by LC isocratic elution mode. The optimization of both derivatization and separation conditions is carefully studied. Related analyses of the eluted compounds, in the presence of MeOH/THF/H2O (78:2.5:19.5 v/v/v) as a mobile phase containing 8 mM, pH 6.0 phosphate buffer solution, have been carried out on a C18 column. The LOD (S/N = 3) of 2.5 nM, RSD value from 1.0 to 5.1% in peak areas, and good response linearity (R2 >0.9936) are provided with fluorescence detection at λex/λem = 480/545 nm. Obviously, recovery ranging from 95 to 107% in this method demonstrates its accuracy for determination of histamine, tyramine, 2-phenylethylamine, putrescine, cadaverine, and spermidine in the storage fish sample. Thus, the present method could be developed to monitor BAs in fish, cucumber, and spinach samples.

Determination of amino acid neurotransmitters in human cerebrospinal fluid and saliva by capillary electrophoresis with laser-induced fluorescence detection
Co-reporter:Ying-Hua Deng;Hong Wang
Journal of Separation Science 2008 Volume 31( Issue 16-17) pp:3088-3097
Publication Date(Web):
DOI:10.1002/jssc.200800339

Abstract

A CE–LIF detection method has been developed to identify and quantitate six amino acid neurotransmitters including glutamic acid, aspartic acid, γ-aminobutyric acid, glycine, taurine, and glutamine. N-Hydroxysuccinimidyl fluorescein-O-acetate, a fluorescein-based dye, was employed for the derivatization of these neurotransmitters prior to CE–LIF analysis. Different parameters which influenced separation and derivatization were optimized in detail. Under optimum conditions, linearity was achieved within concentration ranges of up to three orders of magnitudes for those analytes with correlation coefficients from 0.9989 to 0.9998. The LODs ranged from 0.06 nM to 0.1 nM, and are thus superior or equivalent to those previously reported in the literature using CE–LIF detection. The proposed method has been successfully applied to the determination of amino acid neurotransmitters in biological samples such as human cerebrospinal fluid and saliva with satisfactory recoveries.

6-Oxy-(acetyl ethylenediamine) fluorescein, a novel fluorescent derivatization reagent for carboxylic acids and its application in HPLC
Co-reporter:Xiao-Lan Du;Hong Wang;Ming Ma;Ying-Hua Deng
Journal of Separation Science 2008 Volume 31( Issue 6-7) pp:999-1006
Publication Date(Web):
DOI:10.1002/jssc.200700456

Abstract

A novel fluorescent derivatization reagent for carboxylic acids, 6-oxy-(acetyl ethylenediamine) fluorescein (AEF), was well designed, synthesized, and applied to HPLC. The derivatization reaction with 12 fatty acids, including n-valeric acid (C5), n-hexanoic acid (C6), n-heptanoic acid (C7), n-octanoic acid (C8), n-nonanoic acid (C9), n-decanoic acid (C10), lauric acid (C12), myristic acid (C14), palmitic acid (C16), stearic acid (C18), oleic acid (C18:1), and linoleic acid (C18:2), was completed at 55°C within 40 min. The derivatives of fatty acids were separated on a C18 RP column and detected by fluorescence detection. The LODs attained were 0.4–1.2 nM (S/N of 3). It has been demonstrated that AEF is a prominent derivatization reagent for carboxylic acids which is suitable for HPLC.

Sensitive determination of biogenic amines by capillary electrophoresis with a new fluorogenic reagent 3-(4-fluorobenzoyl)-2-quinolinecarboxaldehyde
Co-reporter:Niu Zhang, Hong Wang, Zi-Xing Zhang, Ying-Hua Deng, Hua-Shan Zhang
Talanta 2008 Volume 76(Issue 4) pp:791-797
Publication Date(Web):15 August 2008
DOI:10.1016/j.talanta.2008.04.027
An effective approach was proposed to the derivatization of seven biogenic amines using 3-(4-fluorobenzoyl)-2-quinolinecarboxaldehyde (FBQCA) as a fluorogenic reagent. The sensitive determinations of these derivatives were achieved by micellar electrokinetic capillary chromatography (MEKC) with laser-induced fluorescence (LIF) detection. The derivatization and electrophoretic conditions have been optimized. A running buffer was composed of mixtures of 25 mM pH 9.5 boric acid, 25 mM SDS, and 27% ACN. At 25 °C and 22.5 kV, the baseline separation of the derivatives was accomplished in 13 min. The detection limit (S/N = 3) was found as low as 0.4 nM. The proposed method was validated by the linearity of two orders magnitude and correlation coefficient in the range 0.9969–0.9998. Also, the procedure was successfully applied to the determination of biogenic amines in soy sauce, fish and wine samples.
Sensitive determination of S-nitrosothiols in human blood by spectrofluorimetry using a fluorescent probe: 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacene
Co-reporter:Ke-Jing Huang, Wan-Zhen Xie, Hong Wang, Hua-Shan Zhang
Talanta 2007 Volume 73(Issue 1) pp:62-67
Publication Date(Web):15 August 2007
DOI:10.1016/j.talanta.2007.02.031
S-Nitrosothiols (RSNO) have been proved to be potent smooth muscle relaxants and inhibitors of platelet aggregation. It has been reported as the best candidate for the endogenous storage and transport of nitric oxide (NO) in vivo. Sensitive determination of RSNO in biosamples seems to be of great significance. In this work, a novel spectrofluorimetric method is proposed to determine RSNO. An excellent fluorescence probe 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacence (DAMBO) is used to label RSNO. The derivatization reaction performs in aqueous medium at 30 °C for 15 min in the presence of 1.0 × 10−4 mol L−1 Hg2+. The derivative is detected by fluorescence at an emission wavelength of 507 nm with excitation at 498 nm. The response is a linear function of concentration in the range of 6.0–400.0 × 10−9 mol L−1. The detection limit is 1.2 × 10−10 mol L−1 (S/N = 3). The method is applied to determine RSNO in the blood of healthy persons and patients suffering from cardiovascular diseases. Recoveries of RSNO from spiked blood samples are between 97.52 and 102.81%. The studies indicate that the method presented here is rapid, simple, sensitive and feasible.
Investigation of the effect of tanshinone IIA on nitric oxide production in human vascular endothelial cells by fluorescence imaging
Co-reporter:Ke-Jing Huang, Hong Wang, Wan-Zhen Xie, Hua-Shan Zhang
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 2007 Volume 68(Issue 5) pp:1180-1186
Publication Date(Web):31 December 2007
DOI:10.1016/j.saa.2007.01.029
Nitric oxide (NO) has been proved to be a potent vasodilator that played an important role in regulating vascular tones. Tanshinone, one of the active components of Radix Salvia miltiorrhiza, was used widely in clinics in China for treating cardiovascular diseases. The objective of this study was to sensitively and specifically investigate the effects of tanshinone IIA, one important pharmacological constituent of tanshinone, on the release of NO from human vascular endothelial cells (HVECs) by fluorescence imaging with an excellent fluorescent probe 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacence (TMDCDABODIPY). After cells were incubated with tanshinone IIA, TMDCDABODIPY was employed to label NO. Following the tagging, real-time imaging of NO release from the cells was performed with inverted fluorescence microscope. The results of the experiments showed that tanshinone IIA could induce NO production significantly enhanced in HVECs. The activation of NO by tanshinone IIA may be employed therapeutically in modulating NO production in HVECs.
Sensitive and specific liquid chromatographic–tandem mass spectrometric assay for atropine and its eleven metabolites in rat urine
Co-reporter:Huaixia Chen, Yong Chen, Peng Du, Fengmei Han, Hong Wang, Huashan Zhang
Journal of Pharmaceutical and Biomedical Analysis 2006 Volume 40(Issue 1) pp:142-150
Publication Date(Web):23 January 2006
DOI:10.1016/j.jpba.2005.06.027
A sensitive and specific method is described for the simultaneous determination of atropine and its metabolites in rat urine by combining liquid chromatography and tandem mass spectrometry (LC–MSn). Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of atropine. After extraction procedure the pretreated samples were separated on a reversed-phase C18 column using a mobile phase of methanol/ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70: 30, v/v) and detected by an on-line LC–MSn system. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (ΔM), retention-times and full scan MSn spectra with those of the parent drug. The results revealed that at least eleven metabolites (N-demethyltropine, tropine, N-demethylatropine, p-hydroxyatropine, p-hydroxyatropine N-oxide, glucuronide conjugates and sulfate conjugates of N-demethylatropine, p-hydroxyatropine and the parent drug) and the parent drug existed in rat urine after ingesting 25 mg/kg atropine. p-Hydroxyatropine and the parent drug were detected in rat urine for up 106 h after ingestion of atropine.
2,6-Dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester: A fluorogenic hydrophilic derivatizing reagent for liquid chromatographic analysis of aliphatic amines
Co-reporter:Hong Wang;Niu Zhang;Xin Liu;Li-Wei Cao
Journal of Separation Science 2006 Volume 29(Issue 5) pp:635-640
Publication Date(Web):14 MAR 2006
DOI:10.1002/jssc.200500508

The use of a fluorogenic, hydrophilic, and amine-reactive reagent, 2,6-dimethyl-4-quinolinecarboxylic acid N-hydroxysuccinimide ester (DMQC-OSu) has been investigated in the procolumn derivatization for the LC separation of aliphatic amines. In pH 8.0 aqueous medium, DMQC-OSu reacted with amines at 50°C within 20 min to form highly fluorescent carboxamides and the excess reagent hydrolyzed to the corresponding carboxylic acid. The separation of representative amine derivatives with DMQC-OSu has been performed using a C18 column with the fluorescence detection at 326/409 nm. The detection limits reached nanomolar level. The proposed method has been applied to the analysis of real samples with recoveries of 94–108%. Compared with other succinimidyl esters used in the derivatization of amino compounds, DMQC-OSu and its hydrolysate had negligible fluorescence (ϕ fl = 0.09 and 0.02, respectively), which implied that small peaks appeared in chromatograms and slight interference was introduced to the determination.

Spectrofluorimetric determination of trace nitrite in food products with a new fluorescent probe 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacene
Co-reporter:Ke-Jing Huang, Hong Wang, Yue-Hong Guo, Rong-Li Fan, Hua-Shan Zhang
Talanta 2006 Volume 69(Issue 1) pp:73-78
Publication Date(Web):15 March 2006
DOI:10.1016/j.talanta.2005.08.062
A new fluorescent probe 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacene (TMDCDABODIPY) has been developed to detect nitrite in meat products and vegetables. The fluorescence of TMDCDABODIPY is very weak, but when it reacts with nitrite, a strong fluorescent triazole forms in aqueous medium at room temperature, which offers the advantage of specificity and sensitivity for the determination of nitrite. The fluorescence intensity was linear over a nitrite concentration of 9–300 nmol l−1 with a detection limit of 0.21 nmol l−1 (S/N = 3). The proposed method has been used for the determination of trace nitrite in food products with the recoveries of 94.62–105.48%.
Liquid chromatography–tandem mass spectrometry analysis of anisodamine and its phase I and II metabolites in rat urine
Co-reporter:Huaixia Chen, Hong Wang, Yong Chen, Huashan Zhang
Journal of Chromatography B 2005 Volume 824(1–2) pp:21-29
Publication Date(Web):25 September 2005
DOI:10.1016/j.jchromb.2005.07.036
A sensitive and specific method for the analysis of anisodamine and its metabolites in rat urine by liquid chromatography–electrospray ionization tandem mass spectrometry (LC–MS/MS) was developed. Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of anisodamine. After extraction procedure the pretreated samples were injected on a reversed-phase C18 column with mobile phase (0.2 ml/min) of methanol/0.01% triethylamine solution (adjusted to pH 3.5 with formic acid) (60:40, v/v) and detected by MS/MS. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (ΔM), retention-times and full scan MSn spectra with those of the parent drug. At least 11 metabolites (N-demethyl-6β-hydroxytropine, 6β-hydroxytropine, tropic acid, N-demethylanisodamine, hydroxyanisodamine, anisodamine N-oxide, hydroxyanisodamine N-oxide, glucuronide conjugated N-demethylanisodamine, sulfate conjugated and glucuronide conjugated anisodamine, sulfate conjugated hydroxyanisodamine) and the parent drug were found in rat urine after the administration of a single oral dose 25 mg/kg of anisodamine. Hydroxyanisodamine, anisodamine N-oxide and the parent drug were detected in rat urine for up 95 h after ingestion of anisodamine.
Analysis of scopolamine and its eighteen metabolites in rat urine by liquid chromatography-tandem mass spectrometry
Co-reporter:Huaixia Chen, Yong Chen, Hong Wang, Peng Du, Fengmei Han, Huashan Zhang
Talanta 2005 Volume 67(Issue 5) pp:984-991
Publication Date(Web):31 October 2005
DOI:10.1016/j.talanta.2005.04.026
A rapid and sensitive method is described for the determination of scopolamine and its metabolites in rat urine by combining liquid chromatography and tandem mass spectrometry (LC–MS/MS). Various extraction techniques (free fraction, acid hydrolyses and enzyme hydrolyses) and their comparison were carried out for investigation of the metabolism of scopolamine. After extraction procedure, the pretreated samples were injected into a reversed-phase C18 column with mobile phase of methanol/ ammonium acetate (2 mM, adjusted to pH 3.5 with formic acid) (70:30, v/v) and detected by an on-line MS/MS system. Identification and structural elucidation of the metabolites were performed by comparing their changes in molecular masses (ΔM), retention-times and full scan MSn spectra with those of the parent drug. The results revealed that at least 18 metabolites (norscopine, scopine, tropic acid, aponorscopolamine, aposcopolamine, norscopolamine, hydroxyscopolamine, hydroxyscopolamine N-oxide, p-hydroxy-m-methoxyscopolamine, trihydroxyscopolamine, dihydroxy-methoxyscopolamine, hydroxyl-dimethoxyscopolamine, glucuronide conjugates and sulfate conjugates of norscopolamine, hydroxyscopolamine and the parent drug) and the parent drug existed in urine after ingesting 55 mg/kg scopolamine to healthy rats. Hydroxyscopolamine, p-hydroxy-m-methoxyscopolamine and the parent drug were detected in rat urine for up 106 h after ingestion of scopolamine.
3-Iodoacetylaminobenzanthrone as a fluorescent derivatizing reagent for thiols in high-performance liquid chromatography
Co-reporter:Hong Wang, Shu-Cai Liang, Zhi-Min Zhang, Hua-Shan Zhang
Analytica Chimica Acta 2004 Volume 512(Issue 2) pp:281-286
Publication Date(Web):11 June 2004
DOI:10.1016/j.aca.2004.03.002
A new thiol-reactive derivatizing reagent, 3-iodoacetylaminobenzanthrone (IAB) has been developed for thiol analysis in liquid chromatography. In aqueous methanol containing 15 mM pH 8.3 H3BO3–KCl–Na2CO3 buffer, IAB reacted with thiols at 35 °C for 15 min. The derivatives of IAB with glutathione (GSH), cysteine (Cys), homocysteine (Hcy) and N-acetylcysteine (Nac) were well separated on a C18 column with the mobile phase of methanol–water (50:50, v/v) containing 15 mM pH 2.7 H3cit–Na2HPO4 buffer. At λex/λem=420/540 nm, the detection limits were 20, 20, 55 and 40 fmol (1, 1, 2.3 and 2 nM), respectively, with a signal-to-noise ratio of 3. Owing to the preferential selectivity of iodoacetamidyl moiety to SH group, amino acids, aliphatic amines, phenol and alcohols had no obvious interference with the determination. The proposed method has been applied to the determination of thiols in human blood with recoveries of 98.5–105.3%.
Behavior of new complexes of tetrakis(4-methoxyl phenyl)porphyrin with heavy rare earth elements in reversed-phase high performance liquid chromatography
Co-reporter:Jun-Feng Zhang;Hong Wang;Chang-Fa Wang;An-Xin Hou
Journal of Separation Science 2004 Volume 27(Issue 12) pp:1037-1041
Publication Date(Web):9 JUL 2004
DOI:10.1002/jssc.200201354

An HPLC method has been developed for the separation of new complexes of tetrakis(4-methoxylphenyl)porphyrin (TMOPP) with four heavy rare earth elements (RE = Y, Er, Tm, and Yb). The function of amine and acid in the mobile phase has been investigated and a reasonable explanation is presented. Successful separation of the RE-TMOPP-Cl complexes is accomplished in 10 min with a mobile phase consisting of methanol-water-acetic acid-triethanolamine. The detection limits (S/N = 3) for the four complexes are 0.01 μg/mL. This method is rapid, sensitive, and simple.

Spectrofluorimetric determination of total amount of nitrite and nitrate in biological sample with a new fluorescent probe 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacence
Co-reporter:Jin-Shu Li, Hong Wang, Xian Zhang, Hua-Shan Zhang
Talanta 2003 Volume 61(Issue 6) pp:797-802
Publication Date(Web):23 December 2003
DOI:10.1016/S0039-9140(03)00380-1
A new synthesized fluorescent probe, 1,3,5,7-tetramethyl-8-(3′,4′-diaminophenyl)-difluoroboradiaza-s-indacence (TMDABODIPY), has been used to detect nitrite. When TMDABODIPY reacted with nitrite, a weak fluorescent triazole formed in 0.2 mol l−1 HCl medium at room temperature. The fluorescence quenching intensity was linear over a nitrite concentration of 0.04–0.32 μmol l−1 with a detection limit of 0.3 nmol l−1 (S/N=3). The proposed method has been applied to the determination of total amount of nitrite and nitrate (reduced by Zn powder) in human serum and urine of health and hypertension persons with recoveries of 91.83–101.80%.
Spectrofluorimetric determination of aliphatic amines using a new fluorigenic reagent: 2,6-dimethylquinoline-4-(N-succinimidyl)-formate
Co-reporter:Li-Wei Cao, Hong Wang, Xin Liu, Hua-Shan Zhang
Talanta 2003 Volume 59(Issue 5) pp:973-979
Publication Date(Web):10 April 2003
DOI:10.1016/S0039-9140(03)00008-0
A new amino fluorescence probe, 2,6-dimethylquinoline-4-(N-succinimidyl) formate (DMQF-OSu) has been synthesized. Based on the selective reaction of DMQF-OSu with primary and secondary aliphatic amines to yield strong fluorescence, a new spectrofluorimetric method for the determination of total aliphatic amines has been developed. At λex/λem=324.4/416 nm, the linear calibration range was 6×10−8–6×10−6 mol l−1 with the detection limit (3σ) of 1.94×10−10 mol l−1 for the determination of aliphatic amines in weak basic media. The proposed method has been applied to the determination of aliphatic amines in tap water and lake water with the recoveries of 99–104%. Compared with the reported methods, the method presented here is rapid, simple, sensitive and feasible.
Determination of amino acid neurotransmitters in cerebral cortex of rats administered with baicalin prior to cerebral ischemia by capillary electrophoresis–laser-induced fluorescence detection
Co-reporter:Hua Li, Hong Wang, Jin-he Chen, Li-hua Wang, Hua-shan Zhang, Yun Fan
Journal of Chromatography B 2003 Volume 788(Issue 1) pp:93-101
Publication Date(Web):5 May 2003
DOI:10.1016/S1570-0232(02)01032-2
An efficient, sensitive and rapid analysis of the amino acid neurotransmitters in the cerebral cortex of rats was developed by capillary electrophoresis with laser-induced fluorescence detection and fluorescein isothiocyanate (FITC) derivatization. This method was used to investigate the pharmacological effect of baicalin during cerebral ischemia. Different parameters which influenced derivatization and separation were optimized. The separation of amino acids was carried out in an uncoated fused-silica capillary (57 cm×75 μm I.D.) with a buffer of 15 mM borate at pH 9.2 and an applied voltage of 17.5 kV. The detection limits for six amino acids were in the range of 2.1×10−11–6.3×10−10M. The changes in the level of amino acid neurotransmitters in brain cortex of three experimental rat groups were studied by this capillary electrophoresis–laser-induced fluorescence detection method. The results show that cerebral ischemia can cause a significant elevation in the concentrations of Glu, Asp, GABA, and Gly in cerebral cortex. Baicalin administration can attenuate the elevations of Glu and Asp induced by cerebral ischemia. This research demonstrates that baicalin may act as a neuroprotectant during cerebral ischemia.
Direct spectrofluorimetric determination of glutathione in biological samples using 5-maleimidyl-2-(m-methylphenyl) benzoxazole
Co-reporter:Shu-Cai Liang, Hong Wang, Zhi-Min Zhang, Xian Zhang, Hua-Shan Zhang
Analytica Chimica Acta 2002 Volume 451(Issue 2) pp:211-219
Publication Date(Web):25 January 2002
DOI:10.1016/S0003-2670(01)01409-X
A new thiol fluorescence probe, 5-maleimidyl-2-(m-methylphenyl)benzoxazole (MMPB) has been developed for the direct determination of reduced glutathione (GSH) in real samples. Compared to the reported N-substituted maleimide type of thiol reagents, the main advantage of MMPB is its rather high selectivity for GSH to cysteine (Cys), which often coexists with GSH in biological samples. Under mild conditions similar to the physiological environment, MMPB reacted with GSH to give a highly fluorescent derivative with the excitation and emission wavelengths of 299.2 and 355.8 nm, respectively. In the presence of 0.40-fold (molar ratio) of Cys, a linear relationship was found in the range of 0–1.62×10−7 mol l−1 with the detection limit (3σ) of 3.23×10−10 mol l−1 for GSH determination. Many other amino acids (100-fold) did not interfere with the determination. Since the molar ratio of Cys to GSH in mammalian tissues and blood does not exceed the value of 0.40:1, the proposed method has been used in the direct determination of GSH in these kinds of biological samples, such as human blood, pig’s liver and heart with the recoveries of 94.3–104.5%
Spectrofluorimetric determination of nitric oxide at trace levels with 5,6-diamino-1,3-naphthalene disulfonic acid
Co-reporter:Xian Zhang, Hong Wang, Shu-Cai Liang, Hua-Shan Zhang
Talanta 2002 Volume 56(Issue 3) pp:499-504
Publication Date(Web):4 March 2002
DOI:10.1016/S0039-9140(01)00582-3
Based on the selective reaction that 5,6-diamino-1,3-naphthalene disulfonic acid (DANDS) traps nitric oxide (NO) in the presence of dioxygen to yield the highly fluorescent form, 1-[H]-naphthotriazole-6,8-disulfonic acid in moderately alkaline medium, a new spectrofluorimetric method for the determination of NO has been reported. The method offered the advantage of specificity, sensitivity and a simple protocol for the direct detection of NO in aqueous solution. The linear calibration range for NO was 0.04–1.44 μmol l−1 with a 3σ detection limit of 0.6 nmol l−1. The proposed method has been used to monitor the release of NO from S-nitrosocysteine, a NO-releasing agent.
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