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

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 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

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%.     

Ultra-trace level determination of nitrite in human saliva by spectrofluorimetry using 1,3,5,7-tetramethyl-8-(3,4-diaminophenyl)-difluoroboradiaza-s-indacene

A rapid, highly sensitive and selective fluorogenic method for the determination of traces of nitrite is described. It is based on the reaction of weakly fluorescent 1,3,5,7-tetramethyl-8-(3,4-diaminophenyl)-difluoroboradiaza-s-indacence (DAMBO) and nitrite in acidic aqueous solution to give 1,3,5,7-tetramethyl-8-(5-benzotriazolyl)-difluoroboradiaza-s-indacene (DAMBO-T), which is highly fluorescent. The optimum reaction conditions and other analytical parameters are investigated to enhance the sensitivity of the method. The fluorescence enhancement at 507 nm is linearly related to the concentration of nitrite in the range of 6.0 × 10⁻⁹–5.0 × 10⁻⁷ mol L⁻¹ with a correlation coefficient of R = 0.9995 (n = 10) and a detection limit of 1.0 × 10⁻¹⁰ mol L⁻¹. The R.S.D. is 1.12% (n = 10). The method is applied to the determination of nitrite in human saliva samples with the recoveries of 96. 24–105.30%. Correspondence: Ke-Jing Huang, Department of Chemistry, Wuhan University, Wuhan 430072, P.R. China     

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

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%.     

Determination of primary and secondary aliphatic amines with high performance liquid chromatography based on the derivatization using 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene

In this article, the simultaneous determination of primary and secondary aliphatic amines including dimethylamine (DMA), diethylamine and eleven primary aliphatic amines by high performance liquid chromatography (HPLC) with fluorescence detection has been achieved using a BODIPY-based fluorescent derivatization reagent, 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene (TMBB-Su). The derivatization reaction of TMBB-Su with aliphatic amines was optimized with orthogonal design experiment and the derivatization reaction proceeded at 15 °C for 25 min. The baseline separation of these derivatives was carried out on a C₈ column with methanol-tetrahydrofuran-50 mM pH 6.50 HAc-NaAc buffer (55/5/40, v/v/v) as a mobile phase. Detected at the excitation and emission of 490 and 510 nm, respectively, the detection limits were obtained in the range of 0.01-0.04 nM (signal-to-noise ratio = 3). The proposed method has been applied to the determination of trace aliphatic amines in viscera samples from mice without complex pretreatment or enrichment method. The recoveries ranged from 95.1% to 106.8%, depending on the samples investigated.     

Determination of trace biogenic amines with 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene derivatization using high-performance liquid chromatography and fluorescence detection

A reversed-phase high-performance liquid chromatographic method based on chemical derivatization with fluorescence detection has been developed for analyzing biogenic amines in food and environmental samples. A BODIPY-based fluorescent reagent, 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene (TMBB-Su), was employed for the derivatization of these biogenic amines at 20 °C for 20 min in pH 7.20 borate buffer after careful investigation of the derivatization conditions including reagent concentration, buffer solution, reaction temperature and reaction time. Separation of biogenic amines with gradient elution was conducted on a C8 column with methanol-tetrahydrofuran-water as mobile phase. The detection limits were obtained in the range from 0.1 to 0.2 nM (signal-to-noise=3). This procedure has been validated using practical samples. The study results demonstrated a potential of employing high-performance liquid chromatography (HPLC) with 1,3,5,7-tetramethyl-8-(N-hydroxysuccinimidyl butyric ester)-difluoroboradiaza-s-indacene labeling as a tool for quantitative analysis of biogenic amines involved in various matrices.     

Direct spectrofluorimetric determination of glutathione in biological samples using 5-maleimidyl-2-(m-methylphenyl) benzoxazole

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%     

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

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.     

Determination of phytohormones in plant samples based on the precolumn fluorescent derivatization with 1,3,5,7-tetramethyl-8-aminozide-difluoroboradiaza-s-indacene by HPLC for routine use

Six phytohormones including indole butyric acid (IBA), naphthalene acetic acid (NAA), 2,4-dichloro-phenoxy acetic acid (2,4-D), indole-3-acetic acid (IAA), abscisic acid (ABA), and salicylic acid (SA) in crude plant extractions have been quantitated by means of high-performance liquid chromatography (HPLC) with fluorescence detection based on the precolumn derivatization using 1,3,5,7-tetramethyl-8-aminozide-difluoroboradiaza-s-indacene (BODIPY-aminozide), a fluorescent reagent synthesized in our lab recently. The optimization of derivatization conditions was carefully studied by an L(25) (5(6)) orthogonal array design (OAD) with five factors at five levels that are important influence parameters in the improvement of derivatization efficiency. The separation conditions were also studied in detail. Under the optimal conditions, the detection limits (S/N=3) of the six phytohormones were found from 0.12 to 0.75 nM. The proposed method was the first investigation of aminozide for the analysis of phytohormones and has been successfully applied to the determination of phytohormones in plant samples such as cucumber and tomato with recoveries of 94-105%.     

Determination of D-penicillamine and tiopronin in human urine and serum by HPLC-FLD and CE-LIF with 1,3,5,7-tetramethyl-8-bromomethyl-difluoroboradiaza-s-indacene

Two rapid and sensitive analytical methods are developed for the determination of D-penicillamine (D-PEN) and tiopronin (TP) through high-performance liquid chromatography with fluorescence detection (HPLC-FLD) and capillary electrophoresis with laser-induced fluorescence detection (CE-LIF). A boron-dipyrrolemethene (BODIPY) fluorescence labeling reagent, 1,3,5,7-tetramethyl-8-bromomethyl-difluoroboradiaza-s-indacene (TMMB-Br) was successfully applied to derivatize these two thiol drugs. Fluorescein was used as the internal standard (IS) for the quantification of D-PEN and TP in CE-LIF. The derivatization and separation conditions were optimized carefully. Under the optimum conditions, the HPLC and CE separation of D-PEN and TP could be achieved within 12?min. The limits of detection were as low as 2.0 nmol/L for HPLC-FLD and 0.47 nmol/L for CE-LIF. The drugs in human urine and serum samples were determined successfully, and the recoveries were 95.0–06.7% and 95.2–104.3%, respectively.     

8-Phenyl-(4-oxy-acetic acid N-hydroxysuccinimidyl ester)-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene as a new highly fluorescent-derivatizing reagent for aliphatic amines in disease-related samples with high-performance liquid chromatography

A novel fluorescent-activated ester, 8-phenyl-(4-oxy-acetic acid N-hydroxysuccinimidyl ester)-4,4-difluoro-1,3,5,7-tetramethyl-4-bora-3a,4a-diaza-s-indacene (TMPAB-OSu) has been designed and synthesized for amine labeling in HPLC. Being used 11 aliphatic amines as the models, the derivatization conditions were optimized. In 0.2 mol/l borate buffer (pH 8.8), amines reacted with TMPAB-OSu at 30 °C to form the derivatives in 10 min. The fluorescent quantum yield of TMPAB-OSu and its amine derivatives are high even compared with fluorescein. The separation of these amine derivatives was achieved with a C₈ column and gradient elution by using 0.1 mol/l sodium acetate buffer (pH 5.0) and methanol. With fluorescence detection at an emission wavelength of 509 nm and an excitation wavelength of 497 nm, the detection limits of aliphatic amines were 2–18 fmol, at a signal-to-noise ratio of 3:1. The proposed TMPAB-OSu-based HPLC method has been applied to the analysis of urine samples of health, hepatic and renal patients and lake water. Recoveries from different matrices are from 96 to 104%, depending on the sample investigated.     

A facile synthesis of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl)acetamidines

<正>A series of novel unsymmetrical N-(4-oxo-2-phenyl-3(4H)-quinazolinoyl)-N-(aryl) acetamidines was synthesized by reacting ethyl(1H)-N-(4-oxo-2-phenylquinazolin-3(4H)-y1)ethanimidoate(2) and suitable reactive aromatic amines.Structures' determination of the synthesized compounds was carried out using spectroscopic techniques including IR,~1H NMR,and mass spectrometry. Structural effects on reactivity were also studied.     

A study of the Claisen rearrangement of 7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one derivatives

Summary The Claisen rearrangement of 7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (2 a) gave 7-hydroxy-8-(1-phenyl-2-propenyl)-3-phenyl-(4H)-1-benzopyran-4-one (3 a) and 2,3-dihydro-2,6-diphenyl-3-methyl-(7H)furo[2,3-h]-1-benzopyran-7-one (7 a). 2-Methyl-7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (2 b) afforded4 b and7 b. 8-Methyl-7-(3-phenyl-2-propenyloxy)-3-phenyl-(4H)-1-benzopyran-4-one (12) gave only the alkali soluble product 7-hydroxy-8-methyl-6-(1-phenyl-2-propenyl)-3-phenyl-(4H)-1-benzopyran-4-one (13).3 a,4 b, and13 were further cyclized in acidic medium to9 a,10 b, and14 followed by dehydrogenation.This paper is dedicated to Dr. F. M. Dean, Department of Organic Chemistry, Robert Robinson Laboratories, University of Liverpool, Liverpool, U. K., on his retirement     

Ultrasound-assisted liquid-phase microextraction and high-performance liquid chromatographic determination of nitric oxide produced in PC12 cells using 1,3,5,7-tetramethyl-2,6-dicarbethoxy-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacene

To reveal the function of nitric oxide (NO) that has been reported as an intracellular second messenger and a diffusible intercellular messenger, a novel ultrasound-assisted liquid-phase microextraction (ULPME) and high-performance liquid chromatographic method for the determination of NO produced in PC12 cells has been developed. 1,3,5,7-Tetramethyl-2,6-dicarbethoxy-8-(3',4'-diaminophenyl)-difluoroboradiaza-s-indacene (DAMBO-CO(2)Et) has been used for NO trapping to form corresponding triazole (DAMBO-CO(2)Et-T). The enrichment factor of DAMBO-CO(2)Et-T reached 150 in 2.5 min with the proposed ULPME method. NO produced in (200+/-5) PC12 cells has been determined directly with the detection limit (S/N=3) of 2.5 x 10(-13)mol/L (5a mol), which was the lowest in HPLC determination of NO reported yet. The proposed method was sensitive, selective, convenient and rapid, which has great prospect in the qualitative and quantitative determination of NO in minimal biological samples.     

Liquid chromatographic determination of vanadium in petroleum oils and mineral ore samples using 2-acetylpyridne-4-phenyl-3-thiosemicarbazone as derivatizing reagent

Liquid chromatographic method has been developed, based on precolumn derivatization of vanadium(V) with 2-acetylpyridine-4-phenyl-3-thiosemicarbazone (APPT). The complex is extracted in chloroform together with palladium(II), tin(II) and iron(III) and eluted and separated completely from Kromasil 100 C-18, 10 μm (25 cm × 4.6 mm i.d.) column with methanol:water:acetonitrile (60:30:10, v/v/v) with a flow rate of 1 ml/min. UV detection was at 260 nm. Linear calibration curve was obtained with 1-12.5 μg/ml vanadium(V) with detection limit of 8 ng/injection (20 μl). A number of metal ions tested did not affect the determination of vanadium. The test mixtures were analyzed for vanadium(IV) and vanadium(V) contents and relative% error was obtained ±1-8%. The method was applied for the determination of vanadium in petroleum oils and mineral ore samples with vanadium contents of 0.32-2.3 and 121.7-717.3 μg/g with R.S.D. of 1.5-4.5 and 0.38-4.7%, respectively. The results correlated with reported values and by atomic absorption spectrophotometry.     

2-R-6-ethyl-7-hydroxy-3-(5-phenyl-1,3,4-thiadiazolyl-2)chromones

-(5-Phenyl-1,3,4-thiadiazolyl-2)-6-ethyl-2,4-dihydroxyacetophenone was synthesized by the condensation of 4-ethylresorcinol with 2-cyanomethyl-5-phenyl-1,3,4-thiadiazole. Interaction of the former with carboxylic acid anhydrides and halides and subsequent hydrolysis gave 2-R-6-ethyl-7-hydroxy-3-(5-phenyl-1,3,4-thiadiazoyl)chromones.Translated from Khimiya Geterotsiklicheskikh Soedinenii, 1840–1847, December, 2004.     

双(8-乙氧羰甲氧基-2-亚甲喹啉基)缩连氮的合成及其选择传感性能

以水合肼和2-甲酰基-8-乙氧羰甲氧基喹啉为原料合成了希夫碱双(8-乙氧羰甲氧基-2-亚甲喹啉基)缩连氮(BEQA),经1HNMR、元素分析等进行了结构表征,在乙醇-水混合溶剂中采用UV-Vis光谱法研究了H+、Ca2+、Mg2+、Sr2+、Mn2+、Co2+、Ni2+、Cu2+、Zn2+、Cd2+及Hg2+对BEQA光谱的影响,结果表明,BEQA分子的UV-Vis光谱仅对体系中的H+、Cu2+和Cd2+有特殊的选择传感性,在体系中的pH值或Cu2+、Cd2+浓度增大时,BEQA在380 nm处的吸收峰强度会逐渐减小,并伴随有不同程度的蓝移;Job′s法测定Cu2+和Cd2+与BEQA形成配合物的化学计量比为1∶4。     

Rapid and sensitive spectrofluorimetric determination of trace amount of Cr(III) with o-vanillin-8-aminoquinoline

A novel fluorescent reagent o-vanillin-8-aminoquinoline(OVAQ) was synthesized, and its infrared spectrum, elemental analysis and acid-base dissociation constants were obtained. The fluorescent reaction of this reagent with Cr(III) was studied. In acetonitrile-water (1:1, (v/v)) medium of pH 6.00, Cr(III) could react with fluorescent reagent OVAQ (λ_ex/em=280/314 nm) to form a 1:1 non-fluorescent complex. The linear range of the spectrofluorimetric method proposed was from 8.2 to 130 μg l⁻¹, and the detection limit was 2.5 μg l⁻¹. The interferences of 25 foreign ions were also studied. This method could be easily performed and was successfully applied to the determination of Cr(III) and total chromium in domestic and industrial waste water samples.     

Development of a novel flow injection liquid-liquid microextraction method for the on-line separation and preconcentration for determination of zinc(II) using 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane as a sensitive and selective fluorescent chemosensor

A novel flow injection analysis (FIA) system based on liquid-liquid microextraction and fluorimetric determination was developed for the determination of traces of the Zn²⁺ ion using 5-(8-hydroxy-2-quinolinylmethyl)-2,8-dithia-5-aza-2,6-pyridinophane (L) as a sensitive and selective fluorimetric sensor, with λ_ex = 373 nm and λ_em = 530 nm, and hexanol as the extracting organic solvent. In the designed FIA system, the phase separation takes place via gravitation forces in the absence of any segmenter. The influence of pH and ionic strength of the solution, amount of ligand, nature of counter ion, volume of organic solvent, extraction time and coil length was investigated. Under optimized experimental conditions, the calibration curve found to be liner over a concentration range of 0.025-4.53 μg mL⁻¹ (R² = 0.9951) with a limit of detection of 2.3 ng mL⁻¹. The enrichment factor was 45 and relative standard deviation for 7 replicate determinations was 2.43%. The method is very fast and uses low levels of organic solvents. The proposed method was applied successfully to the determination of zinc(II) in human hair, human serum and two inorganic sludge samples.     

Direct determination of reduced glutathione in biological fluids by Ce(IV)-quinine chemiluminescence

A simple, sensitive and selective chemiluminescence (CL) method is proposed for the determination of reduced glutathione (GSH) in biological fluids. This method is based on the fact that the weak CL of GSH oxidized with cerium(IV) can be greatly enhanced by quinine. The optimum conditions for the CL emission were investigated. The calibration curve for GSH was linear over the concentration range of 4.0 × 10⁻⁹-4.0 × 10⁻⁵ M with a detection limit of 5 × 10⁻¹⁰ M (S/N = 3). The R.S.D. was found to be 4.0% by 11 replicate determinations of 1.0 × 10⁻⁷ M GSH. It was also found that GSH and cysteine, the two often-coexisting thiol compounds in biological samples, exhibited a different CL sensitivity in the Ce(IV)-quinine system (the sensitivity of GSH was higher than that of cysteine). This leads to the successful use of the proposed method for the direct and selective determination of GSH in rabbit whole blood and rat brain microdialysate in the presence of cysteine. Moreover, compared to the classical 5,5′-dithiobis(2-nitrobenzoic acid) method, the present one has the advantages of simplicity and high sensitivity.