Simultaneous determination of gallium and aluminium in biological samples by conventional luminescence and derivative synchronous fluorescence spectrometry

The simultaneous determination of gallium and aluminium by using conventional fluorimetry and derivative synchronous fluorescence spectrometry has been studied. These determinations are based on the formation of fluorescent complexes of gallium and aluminium with salicylaldehyde carbohydrazone (SACH). In the conventional method, two samples are analysed under different analytical conditions, and the results are evaluated by solving a system of two simultaneous equations. In the derivative synchronous method (at pH = 2.6, in an ethanol-water medium containing 72% of ethanol), the following conditions are used: a constant wavelength difference of 20 nm between the monochromator settings, a time-constant of 1.5 sec, a scan-speed of 120 nm/min, and a derivative wavelength difference of 10 nm; gallium can be determined in the range 7-38 ng/ml, and aluminium between 6 and 45 ng/ml. The synchronous method shows more advantages, and has been used in the determination of both metal ions in diverse biological samples (animal tissues and human serum) with good results.     

Determination of propranolol concentration in small volume of rat plasma by HPLC with fluorometric detection.

A simple, rapid and sensitive fluorescence high performance liquid chromatographic method was developed to determine propranolol concentration in the small volume of rat plasma without the solvent extraction step using pronethanol as the internal standard. The analysis was accomplished using a 5 microm CAPCELL PAK analytical cyano column at room temperature and a mobile phase consisted of 1% aqueous acetic acid containing 0.2% triethylamine and acetonitrile (65:35, v/v; pH 3.8). The flow-rate was kept at 0.5 mL/min and column effluent was monitored with a fluorescence detector at an excitation wavelength of 230 nm and an emission wavelength of 340 nm. Retention times for pronethalol and propranolol were 8.5 min and 10.5 min, respectively. Linear regressions for the standard curves were linear in the range 2-800 ng/mL, giving correlation coefficients above 0.998. The detection limit was 1.34 ng/mL. No analytical interference was observed from endogenous components in rat plasma. This simple and sensitive assay method was feasibly applied to the pharmacokinetic study of propranolol after intravenous administration of 2 mg/kg of propranolol to normal and carbon tetrachloride-induced liver cirrhotic rats.     

Simple and extractionless high-performance liquid chromatographic determination of rosiglitazone in human plasma and application to pharmacokinetics in humans

A simple and extractionless HPLC method using fluorescence detection was developed for the determination of rosiglitazone in human plasma. After deproteinization using perchloric acid the plasma samples were directly injected onto the HPLC system. The mobile phase was composed of acetonitrile (52%) and 20 mm ammonium acetate (48%, pH 7.5), and analysis was run at a flow rate of 0.2 mL/min with the detector operating at 247 nm for excitation wavelength and at 367 nm for emission wavelength, respectively. The method has a mean recovery of 97%, while the intra-day and inter-day precisions were all less than 7%. This method is simple, specific, sensitive and requires only a small plasma volume with short analytical time, and is suitable for the determination of plasma rosiglitazone in routine measurements for pharmacokinetic studies.     

Automated high-performance liquid chromatographic assay for the determination of 7-ethoxycoumarin and umbelliferone.

An improved high-performance liquid chromatographic assay is presented for the determination of 7-ethoxycoumarin O-deethylase activity. Following a 30-min microsomal incubation, 7-ethoxycoumarin, 4-methylumbelliferone (internal standard), and the metabolite umbelliferone were extracted with chloroform. Separation was achieved with an isocratic mobile phase using a microBondapak phenyl (300 mm x 3.9 mm I.D.) analytical column. The effluent was monitored by fluorescence detection with an excitation wavelength of 360 nm and an emission wavelength of 470 nm. The intra- and inter-assay coefficients of variation were 10 and 6%, respectively. A detection limit of 0.07 micrograms/ml was achieved, making this method suitable for characterizing P-450 activity of human livers.     

Determination of isoliquiritigenin and its distribution in mice by synchronous fluorescence spectrometry

The aim of the present work was to develop a new method using synchronous fluorescence spectrometry (SFS) to determine the concentration of isoliquiritigenin (ISL) in mouse blood and tissues, and to investigate ISL's distribution among organs after an intraperitoneal (IP) dose of ISL. The synchronous fluorescence method was optimized with the sample pH, stability, metal ions, concentration of Al(3+), and surfactants. The proposed method was used to determine the ISL concentration in mouse blood, brain, heart, kidney, liver, spleen and lung after an IP injection of ISL. The optimal conditions for the determination of ISL using SFS were found to be: excitation and emission wavelengths of 469 and 557 nm, respectively; the use of 3% AlCl(3) as a fluorescence intensity enhancer; measuring samples within 1 h of collection, sample pH 7-8, isolation of samples from surfactants; and wavelength interval (Δλ) = 70 nm. After IP injection, the distribution of ISL in mouse organs was: liver > kidney > spleen > blood > lung > brain > heart. The blood concentration of ISL peaked at 60 min; concentrations of ISL in liver, kidney and spleen achieved maxima at 120 min. SFS provides a simple, but effective analytical method that will benefit the study of in vivo biological effects of ISL, including absorption, distribution, metabolism, and excretion.     

高效液相色谱法测定大鼠组织中双酚A和4-壬基酚浓度

建立了大鼠组织中双酚A和4-壬基酚的提取和含量测定方法。大鼠组织样品经甲醇-乙酸铵缓冲液匀浆、 正己烷-乙醚混合溶剂提取、氮气吹干后用流动相溶解,以乙腈-0.01 mol/L乙酸铵缓冲液(pH 4.5)(体积比为75∶25)为流动相,经C18色谱柱分离,在激发波长227 nm、发射波长313 nm下进行荧光检测。大鼠心、脑、肝和肾脏组织样品中,双酚A的检出限为3.2~4.6 ng/g,4-壬基酚的检出限为11.8~15.6 ng/g;日内检测精密度为0.89%~4.50%,日间检测精密度为3.10%~12     

未衍生高效液相法测定烤鳗和活鳗中噁喹酸的残留量

 研究了快速测定烤鳗和活鳗中口恶 喹酸残留的高效液相方法。捣碎后的样品用二氯甲烷提取 ,提取液浓缩后再用一定量的流动相溶解残渣 ,并用正己烷去除杂质 ,然后进行高效液相分离及荧光检测。口恶喹酸的最低检出限为 0 0 1mg/kg ,标准添加回收率大于 80 % ,相对标准偏差小于 3 8%。     

Analysis of abamectin residues in avocados by high-performance liquid chromatography with fluorescence detection

In this work an analytical method for the determination of abamectin residues in avocados is developed using high-performance liquid chromatography (HPLC) with fluorescence (FL) detection. A pre-column derivatization with trifluoroacetic anhydride (TFAA) and N-methylimidazole (NMIM) was carried out. The mobile phase consisted of water, methanol and acetonitrile (5:47.5:47.5 v/v/v) and was pumped at a rate of 1 mL/min (isocratic elution). The fluorescence detector was set at an excitation wavelength of 365 nm and an emission wavelength of 470 nm. Homogenized avocado samples were extracted twice with acetonitrile:water 8:2 (v/v) and cleaned using C(18) solid-phase extraction (SPE) cartridges. Recovery values were in the range 87-98% with RSD values lower than 13%. The limits of detection (LODs) and quantification (LOQs) of the whole method were 0.001 and 0.003 mg/kg, respectively. These values are lower than the maximum residue limit (MRL) established by the European Union (EU) and the Spanish legislation in avocado samples.     

Determination of fluoroquinolones in edible animal tissue samples by high performance liquid chromatography after solid phase extraction

In the present work, a rapid, accurate, and sensitive method has been developed for the quantitative determination of five fluoroquinolones (enoxacin, ofloxacin, norfloxacin, ciprofloxacin, and enrofloxacin) in edible animal tissues (muscle tissue, liver, kidney, and eggs). The separation was accomplished on an Inertsil (250 x 4 mm) C8, 5 microm, analytical column, at ambient temperature within 15 min. The mobile phase consisted of a mixture of citric acid (0.4 mol L(-1))-CH3OH-CH3CN (87:9:4% v/v). UV detection at 275 nm yielded the following limits of detection: 100 pg per 20 microL injected volume for enoxacin, norfloxacin, and ciprofloxacin, 20 pg for ofloxacin, and 200 pg for enrofloxacin. Peaks in real samples were identified by means of a photodiode array detector. The method was validated in terms of intra-day (n = 8) and inter-day (n = 8) precision and accuracy. Tissue samples were purified from endogenous interference by solid-phase extraction using Oasis HLB cartridges. The solid-phase extraction protocol was optimized in terms of retention and elution. Recovery rates at fortification levels of 40, 60, and 80 ng/g ranged from 82.5% to 111.1%. The applicability of the method was examined using real samples from a chicken treated orally with the five studied fluoroquinolones.     

Determination of pyrimethamine in animal tissue and egg by liquid chromatography with fluorescence detection

A sensitive and selective liquid chromatographic (LC) assay was developed to determine the concentration of pyrimethamine in animal tissue and egg by fluorescent derivative. Animal samples were extracted with acetonitrile, centrifuged, and purified by hexane. Fluorescent derivatization was performed by reacting pyrimethamine with chloroacetaldehyde and subjected to LC with fluorescence detection (excitation wavelength 300 nm, emission wavelength 420 nm). The limit of detection was 10 ng/g (10 ppb) and the standard calibration curve was linear in the range of 1-100 ppb (0.01-1 ng/10 microL). Recoveries from samples fortified at levels of 0.1 and 1 ppm (microg/g) were 61.0-77.4 and 65.5-81.2%, respectively. The method was applied to the monitoring of marketed samples. Pyrimethamine was not determined in any of the 70 samples: 20 swine muscle; 20 chicken muscle; 10 chicken liver; and 20 egg.     

Determination of urinary free cortisol by high performance liquid chromatography with sulphuric acid-ethanol derivatization and column switching.

A rapid and highly sensitive determination method for urinary free cortisol has been developed using reversed phase high performance liquid chromatography (HPLC) with a precolumn for sulphuric acid-ethanol fluorescence derivatization and column switching. Urinary cortisol, eluted from the octadecylsilane-bonded silica (ODS) minicolumn with 90% aqueous ethanol, was derivatized with the addition of sulphuric acid only at ambient temperature. Cortisol derivatives injected directly onto the ODS precolumn were purified on-line. After switching the columns, the cortisol derivative was separated on an ODS analytical column with a retention time of 15.3 min and monitored at an emission wavelength of 520 nm (exitation wavelength of 365 nm) to decrease the detection limit to 0.26 microgram/dL (signal-to-noise ratio = 3). The automated HPLC operation resulted in good reproducibility and recovery of the stable cortisol derivative at 5 degrees C.     

Measurement of epidoxorubicin and its metabolites by high-performance liquid chromatography using an advanced automated sample processor.

A sensitive and rapid method for measuring epidoxorubicin and its six metabolites by high-performance liquid chromatography using an advanced automated sample processor is described. Plasma samples (1 ml) were extracted using C2 cassettes, and reversed-phase chromatography was performed with an Apex II ODS column. The isocratic mobile phase of acetonitrile-0.019 M NaH2PO4 (pH 4.0) had a flow-rate of 1 ml/min and the fluorescence detector an excitation wavelength of 480 nm with an emission at 580 nm. Linear calibration curves were obtained which were reproducible both within-day and day-to-day (coefficients of variation less than 10%). The extraction efficacy of epidoxorubicin was 88% and ranged from 51 to 88% for the metabolites. This method has been successfully applied to measure the plasma levels of these compounds in patients receiving epidoxorubicin over a wide dose range (12-120 mg/m2) and in patients with disturbed liver biochemistry.     

A new liquid chromatographic method for routine determination of oxytetracycline marker residue in the edible tissues of farm animals

A simple, rapid, and specific ion-pair liquid chromatographic method for routine determination of the marker residue of oxytetracycline (OTC), namely OTC and 4-epi-oxytetracycline (4-epiOTC), in edible animal tissues (muscle, liver, kidney, and fat) has been developed. Minced tissue samples were acidified at pH 2.7 with 2 mol L(-1) sulfuric acid and extracted with acetonitrile. The extracts were purified by treatment with ammonium sulfate solution and concentrated into 0.1 mol L(-1) phosphoric acid. Baseline separation was carried out isocratically on a Nucleosil 100-5 C(18), 5-microm column using an acetonitrile-0.01 mol L(-1) disodium hydrogen phosphate (20:80, v/v) mobile phase that contained both positively (tetrabutylammonium) and negatively (octanesulfonate) charged pairing ions and EDTA, and was adjusted to pH 3.8. Detection was by UV at 370 nm. The method was fully validated according to Commission Decision 2002/657/EC. Overall recoveries were better than 82.6% and overall relative standard deviation was better than 6% for all the tissues examined. The good analytical characteristics of the method allowed limits of quantification as low as 30 ng g(-1) for muscle and fat and 50 ng g(-1) for liver and kidney, for both OTC and 4-epiOTC, to be realized. The method was successfully used to determine the OTC marker residue in tissues of two sheep intramuscularly administered a commercial OTC formulation.     

离子对高效液相色谱法同时测定鱼类中四种喹诺酮类药物的残留

采用离子对高效液相色谱法同时测定了鱼类中4种喹诺酮类药物(FQS)的残留。检测条件为:采用Waters μBondapakTM C18柱,以11 mmol/L的四丁基溴化铵溶液-乙腈(体积比为94∶6)为流动相(用冰乙酸调pH为3.0,流速1.0 mL/min),柱温40 ℃;采用荧光检测器检测,激发波长280 nm,发射波长460 nm。测定结果表明,该方法对FQS的最低检测限为1 μg/kg,在6～100 μg/kg线性范围内,溶液含量与峰面积的相关系数达0.9995以上。在高、中、低3种含量水平下对所测鱼组织中4种喹诺酮类药物进行回收率测定,结果为76%～100%,相对标准偏差小于7%。该法简便、准确,灵敏度高,符合痕量测定的要求。     

高效液相色谱-荧光检测法测定罂粟籽和火锅汤料中的罂粟碱

用所建立的高效液相色谱-荧光检测法测定了罂粟籽和火锅汤料中的罂粟碱。采用的色谱柱为RP-C18柱(250 mm×4.6 mm i.d.,5 μm);检测激发波长为285 nm,发射波长为355 nm;流动相为甲醇-0.02 mol/L乙酸铵(体积比为70∶30),流速0.8 mL/min。实验结果表明,罂粟碱的进样量为1×10-4~0.1 μg时其质量浓度与相应峰面积有良好的线性关系,最低检测限(以信噪比大于3计)达到0.02 ng。罂粟籽中罂粟碱的回收率为99.0%～100.8%。方法快速准确,简便灵敏,分离度高,能够满足有关食品中罂粟碱的检测要求。     

Determination of serum cortisol by reversed-phase liquid chromatography using precolumn sulphuric acid-ethanol fluorescence derivatization and column switching.

An assay method for serum cortisol, using precolumn sulphuric acid-ethanol fluorescence derivatization and reversed-phase liquid chromatography with a column-switching technique, has been developed. The crude precolumn fluorescence cortisol derivative was prepared by the addition of sulphuric acid to serum deproteinized with ethanol, and directly injected onto an octadecylsilane-bonded silica gel (ODS) precolumn for concentration and purification. After switching columns the samples were separated using an ODS analytical column and monitored fluorimetrically. When the pH of the mobile phase in the analytical separator decreased to 1.85, the emission wavelength of the cortisol derivative changed to 520 nm (excitation of 365 nm) and the fluorescence intensity increased. Among the sulphuric acid-ethanol derivatives of various steroids, cortisol, corticosterone and testosterone emitted fluorescence. However, their retention times differed from those of the cortisol derivatives (12.5 min). The detection limit of cortisol was 0.3 micrograms/dl (signal-to-noise ratio of 3). Use of the fully automated column-switching system contributed to good reproducibility and recovery.     

超高效液相色谱法同时测定纺织品中18种荧光增白剂

建立了同时测定纺织品中18种荧光增白剂（FWAs）的超高效液相色谱-荧光检测（UPLC-FLR）法。试样由三氯甲烷-乙醇（6：4,v/v）超声提取,以ACQUITY UPLC HSS T3柱（100 mm×2.1 mm,1.8 μm）为分离色谱柱进行分析,以5 mmol/L乙酸铵水溶液和甲醇为流动相,梯度洗脱,流速为0.4 mL/min,荧光激发波长为350 nm,发射波长为430 nm,外标法定量。18种FWAs在各自范围内呈良好的线性关系,相关系数（R²）均≥ 0.9992;方法的定量限（LOQs,S/N=10）为0.002~0.1 mg/L。样品的平均加标回收率为88.3%~104.5%,相对标准偏差（RSD）为2.0%~5.5%（n=6）。该方法灵敏度高,精密度好,准确度高,适用于各种纺织品中FWAs的测定。     

The fluorescence study of the inclusion coordinated compound of beta-cyclodextrin and p-hydroxyphenolacetamide and its analytical applications

The inclusion coordinated compound fluorescence of p-hydroxyphenolacetamide (PHPA) with beta-cyclodextrin was studied and a high sensitive analytical method to determine the content of PHPA was established based on the increased fluorescence intensity of the coordinated compounds in Britton-Robinson buffer solution (pH 7). The wavelength of the excited emission are 282 and 310 nm, respectively. The enhanced coordinated compounds fluorescence intensity is proportional to the concentration of PHPA in the range 0.030-11.0 mg/l. The relative standard deviation (R.S.D.) were within 0.66-4.2%. Correlation coefficient and inclusion binding constant Kf are obtained within 0.9950-0.9996 and 4.67 x 10(2), respectively. Meanwhile, a linear increase of the resonance light scattering (RLS) with the inclusion coordinated compounds concentration was noticed at a synchronous wavelength of 584 nm. The forming reasons of inclusion coordinated compounds were investigated. The 1:1 molar ratio composition of inclusion compound was measured with DTA and elemental analysis. The method is simple, rapid and has a good reproducibility. The method was used for determination of PHPA in an artificial sample with satisfactory results.     

Development of an HPLC multi-residue method for the determination of ten quinolones in bovine liver and porcine kidney according to the European Union Decision 2002/657/EC

A sensitive multi-residue analytical method was developed for the determination of ten quinolones: enoxacin, ofloxacin, norfloxacin, ciprofloxacin, danofloxacin, enrofloxacin, sarafloxacin, oxolinic acid, nalidixic acid, and flumequine in bovine liver and porcine kidney. A simple liquid extraction step followed by a solid phase extraction clean up procedure was applied for the extraction of quinolones from liver and kidney tissues. Recoveries of the extraction varied between 82 and 88% for bovine liver and 92 and 95% for porcine kidney. Separation was performed on an ODS-3 PerfectSil Target (250 x 4 mm) 5 microm analytical column at 25 degrees C. The mobile phase consisted of a mixture of TFA 0.1%-CH(3)CN-CH(3)OH, delivered at a flow rate of 1.2 mL/min according to a gradient program. Elution of quinolones and the internal standard (caffeine, 7.5 ng/microL) was complete within 27 min. Photodiode array detection was used for monitoring the eluants at 275 and 255 nm. The method was fully validated according to the European Union Decision 2002/657/EC, determining linearity, selectivity, decision limit, detection capability, accuracy, and precision. The LODs of the specific method of quinolone determination in bovine liver varied between 3 and 7 microg/kg and in porcine kidney between 3 and 4 microg/kg.     

Synthesis of Fluorescent Carbon Quantum Dots from Dried Lemon Peel for Determination of Carmine in Drinks

Carbon quantum dots(CQDs) with a quantum yield of 11% were synthesized via a simple, low-cost and green hydrothermal treatment using dried lemon peel as carbon source. The obtained CQDs showed a strong emission at the wavelength of 505 nm with an optimum excitation of 425 nm. Carmine with maximum absorption wavelength at 508 nm could selectively quench the fluorescence of CQDs. Based on this principle, a fluorescence probe was developed for carmine determination. The quenching mechanism of CQDs was elucidated. A linear relationship was found in the carmine concentration range of 0.20—30.00 mg/L with the detection limit(3σ/k) of 0.16 mg/L. Satisfactory results were achieved when the method was applied for the determination of carmine in soft drinks.