Study on the inclusion interactions of berberine hydrochloride and cucurbit[7] by spectrofluorimetry

The inclusion interaction between berberine hydrochloride （BRH） and cucurbit[7] （CB[7]） has been studied by spectrofluorimetry. The result showed that CB[7] interaction with BRH to form a stable inclusion complex with an association constant of 9.57 × 10^4 L/mol and the fluorescence intensity of the complex was enhanced in 17 times higher than that of the studied drug itself. Based on the significant enhancement of fluorescence intensity of BRH in inclusion complex, a spetrofluorimetric method with high sensitivity and selectivity was developed for the determination of BRH in aqueous solution. The linear range of the method was 3.2- 2 × 10^3 ng/mL with a detection limit of 1.1 ng/mL. The proposed procedure could be applied successfully to determination of BRH remained in pharmaceutical dosage forms, spiked human plasma and urine with satisfactory results.

Study on the inclusion interaction of methylated-β-cyclodextrins with albendazole by spectrofluorimetry and its application

The inclusion interaction between three types of methylated-β-cyclodextrins （Me-β-CDs） and albendazole （ABZ） was studied by spectrofluorimetry. The result showed that Me-β-CDs reacted with ABZ to form an inclusion complex, 1： 1 stoichiometry for Me- β-CDs-ABZ complex was established and its association constant have been determined from fluorescence data by Benesi- Hildebrand＇s method （double reciprocal plots）. It was noted that 2,6-DM-β-CD exhibited stronger binding ability than other Me-β- CDs. Based on the significant enhancement of fluorescence intensity of inclusion complex, a simple and highly sensitive fluorimetric method is proposed for the determination of ABZ in the presence of 2,6-DM-β-CD. The proposed method was successfully applied to the determination of ABZ in tablets and human urine.

Prediction of Concentration of Animal Fat in Mixture with Vegetable Oil by Multivariate Calibration Associated with Spectrofluorimetry

Total spectrofluorimetry associated with Principal Component Analysis (PCA) was used to discriminate samples of vegetable oil and animal fat. In addition, a multivariate calibration model was developed that combines spectroflurimetry with Partial Least Squares (PLS) for prediction of concentration of animal fat in mixture with vegetable oil. The multivariate calibration model had an R2 value of 0.98098, which indicates the accuracy of the model. This method has potential application in the control of quality of raw material for production of biodiesel. The control of the concentration of animal fat is important because animal fat is more susceptible to oxidation than vegetable oil. Furthermore, high concentrations of animal fats may increase electricity costs for biodiesel production due to the high melting points of saturated fats that solidify at room temperature and cause the fouling and clogging of pipes.

O-(β-hydroxyethyl)rutosides determination by micellar flow injection(FI)-spectrofluorimetry

A simple,eco-friendly.sensitive and economic flow injection spectrofluorimetric method was developed for the determination of O-（β-hydroxyethyl）rutosidcs.The procedure was based on the use of an anionic surfactant such as sodium dodecyl sulfate to provide an appreciable O-（β-hydroxyethyl）rutosides fluorescence enhancement,increasing considerably the sensitivity of detection.All the variables affecting the fluorescence intensity were studied and optimized.The flow rate was 5 mL/min with detection at 450 nm（after excitation at 346 nm）.A linear correlation between drug amount and peak area was established for 0-（β-hydroxyethyl）rulosides in the range of 0.01-200 μg/mL with a detection limit of0.001 μg/mL（s/n = 3）.Validation processes were performed by recovering studies with satisfactory results.The new methodology can be employed for the routine analysis of 0-（P-hydroxyethyl）rutosides in bulks as well as in commercial formulations.

REVERSE VARIABLE-ANGLE SYNCHRONOUS SPECTROFLUORIMETRY FOR RAPID SIMULTANEOUS DETERMINATION OF CHLOROPHYLL A AND CHLOROPHYLL B

Rapid simultaneous determination of chlorophyll a and chlorophyll b by reverse variable-angle synchronous spectrofluorimetry has been studied on a laboratory-constructed microcomputer-controlled versatile spectrofluorimeter.A method in estimation of scan parameters for the determination of two-component system by variable-angle synchronous spectrofluorimetry has been suggested

Spectrofluorimetry and High-Performance Liquid Chromatography in the Detection of Aflatoxins in Chinese Medicinal Materials

Objective: To analyze the effect of spectrofluorimetry and highperformance liquid chromatography in the detection of aflatoxin in Chinese medicinal materials. Methods: The content of aflatoxin in Chinese medicinal materials was determined by spectrofluorimetry and high-performance liquid chromatography respectively, and the effects of the two detection methods were compared. Results: The results of sample detection by spectrofluorimetry showed that except for Angelica and Sophora flavescens with "detection dada error", the other 25 kinds of Chinese medicinal materials were positive for aflatoxin, but the types of aflatoxin derivatives could not be distinguished, and the tested content was generally high. The recovery experiment of mixed reference substance based on the concentration levels showed that the recovery rate of aflatoxin was 93.60%-99.70% in the case of high-performance liquid chromatography,and the RSD was 1.83%-6.70%. The sample detection results by high-performance liquid chromatography showed that among the 18 kinds of Chinese medicinal materials,only Radix Peucedani, almond, barley, raw Jianqu and aflatoxin were positive, and the types of aflatoxin derivatives could be accurately differentiated. Conclusion: Compared with spectrofluorimetry, high-performance liquid chromatography is more accurate in the determination of aflatoxin content in Chinese medicinal materials, which can distinguish the types of aflatoxin derivatives.

Fluorescence enhancement and cofluorescence in complexes of terbium(III) with trimellitic acid

The fluorescence of terbium （Ⅲ） was enhanced by about three orders of magnitude in the presence of trimellitic acid （benzene-1, 2, 4-tricarboxylic acid （TLA）） in aqueous solution at pH 6. The fluorescence intensity could be greatly increased when the system of Tb^3＋-TLA was treated with La^3＋ （or Gd^3＋） and TritonX- 100. The addition of La^3＋ （or Gd^3＋） enhanees the fluorescence of the system by about two orders of magnitude due to cofluorescenee, and the TritonX-100 micellar medium plays an important role for stabilization of the system. Both the intermolecular energy transfer mode and intramolecular energy transfer mode are responsible for the mechanism of fluorescence enhancement. In the optimum condi- tions, the fluorescence intensity is a linear function of Tb3~ concentration in the range of 7.8 × 10^-9-3.6 × 10^4 mol/L for the system Tb^3＋-La^3＋-TLA and 1.0 × 10^-8-4.7 × 10^-5 mol/L for the system Tb^3＋-Gd^3＋-TLA, and the limits of detection are 4.6 × 10^-10 mol/L and 6.0 × 10^-10 mol/L, respectively.

Highly Sensitive Spectrofluorimetric Determination of Trace Amounts of Indium(Ⅲ) with Salicylaldehyde Salicyloylhydrazone

The fluorescent reaction of salicylaldehyde salicyloylhydrazone(SASH) with indium(Ⅲ) was studied in detail. Based on this chelation reaction, a sensitive spectrofluorimetric method was developed for the determination of indium in a water ethanol(volume ratio 3∶7) medium at pH 4 0. Under the condition, the In SASH complex displays an excitation and emission maxima at 396 and 461 nm, respectively. The linear range of the method is from 4 7 to 1000 ng/mL and the detection limit is 0 94 ng/mL. The molar ratio of indium to the reagent is 1∶1. The interferences of other ions were studied. The method was successfully applied to the determination of indium in the chemical reagents of lead, tin, zinc, zinc chloride and geological samples by standard addition method.

Spectrofluorimetric Determination of Trace Amounts of Gallium with Salicylaldehyde Benzoylhydrazone

The fluorescent reagent salicylaldehyde benzoylhydrazone(SABH) was synthesized and its ionization constants were estimated spectrophotometrically. The fluorescent reaction of this reagent with gallium was studied. Based on this chelation reaction, a spectrofluorimetric method was developed for the determination of gallium in a water medium at pH 3.2. Under these conditions, the Ga SABH complex has excitation and emission maxima at 372 and 455 nm, respectively. The linear range of the method was 0~150 μg/L and the detection limit was 0.36 μg/L of gallium when a standard addition method was used in the assay. The molar ratio of gallium to the reagent was 1∶3. The interference of other ions was studied. The extraction with n butyl acetate from a 6 mol/L hydrochloric acid medium was used to separate Ga from the interfering elements in semiconductor silicon and geological samples, and themethod has been successfully applied to the determination of gallium in these samples.

Spectrofluorimetric method for determination of some angiotensin II receptor antagonists

A simple, rapid, accurate and highly sensitive spectrofluorimetric method has been developed for determination of some angiotensin II receptor antagonists (AIIRA’s), namely Losartan potassium (Los-K), Irbesartan (Irb), Valsartan (Val) and Candesartan cilexetil (Cand) in pure forms as well as in their pharmaceutical dosage forms. All the variables affecting the relative fluorescence intensity (RFI) were studied and optimized. Under the optimum conditions, linear relationships with good correlation coefflcients (0.9982–0.9991) were obtained over the concentration range from 0.006 mg/mL to 1.7 mg/mL. Good accuracy and precision were successfully obtained for the analysis of tablets containing each drug alone or combined with hydrochlorothiazide (HCTZ) without interferences from the co-formulated HCTZ or the additives commonly present in tablets.

Spectrofluorimetric determination of gallium with calon-carboxyli cacid

A simple and sensitive spectrofluorimetric procedure for the analysis ofmicroquantities of gallium in alloy was described. The method is based on the formation ofGa(III)-CCA (calon-carboxylic acid) complex. The emission of the fluorescent complex was measured atlambda = 620 nm with excitation at lambda = 584 nm. A good linearity was found in the gallium rangeof 0.7-280 ng/mL. The precision of the method is good and the relative standard deviation is 1.9percent for a gallium standard solution of 70 ng/mL. The procedure was proved to be suitable interms of accuracy and selectivity for the microamount of gallium in alloy.

Spectrofluorimetric determination of terbium with terephthalic acid

A Spectrofluorimetric method has been developed for the determination ofterbium(Ⅲ) based on the formation of a complex with terephthalic acid [benzene-1, 4-dicarboxylicacid (TPA)] in slightly acidic aqueous solution in the presence of gelatin. Terbium ion can form astable complex with TPA with the stoichiometry of 1:2. The best excitation and maximum emissionwavelengths are observed at 260 nm and 545 nm, respectively. The fluorescence intensity of terbiumcomplex gets the strongest within 20 min and remains stable up to 10 h, and it is proportional toterbium(Ⅲ) concentration in the range of 4.0x10^(-5)-1.6x10^(-7) mol·L^(-1) under the optimumconditions. The fluorescence system has good selectivity, sensitivity and stability. The relativestandard deviation is still within +-4% in the presence of 1200-fold amounts of the other lanthanideions when the concentration of terbium(Ⅲ) is 1.0x10^(-6) mol·L^(-1) and common co-existing ionshardly interfere the determination. It has been applied to the direct fluorimetric determination oftrace terbium (Ⅲ) in rare earth ores and oxides.

Development and Validation of a Spectrofluorimetric Method for the Assay of Tetracycline in Capsules

The purpose of this study is to develop and validate a method for the analysis of tetracycline capsules by spectrofluorimetry. A pH 9 borate buffer was used as diluent of tetracycline after reaction with magnesium salt at the excitation wavelength of 372 nm and 516 nm of emission. A linear response was observed between 0.25 μg/mL and 1.5 μg/mL with a correlation coefficient (R) of 0.9998. The detection and quantification limits found are 0.0125 μg/mL and 0.0412 μg/mL respectively. The proposed method proved trueness with a recovery between 99.88% and 101.10%. The relative standard deviations of repeatability and intermediate precision found ≤2.88% reflected a good precision of the method. The proposed method is therefore valid within the limits of 90% to 110%. The proposed method was applied to the quality control of 9 tetracycline samples from market and gave results in accordance with the pharmacopoeia standards.

Sensitized effect of β-cyclodextrin on the fluorescence in the determination of carbaryl

Based on the significant enhancement of fluorescence intensity of carbaryl in inclusion complex, a spetrofluorimetric method with high sensitivity was developed for the determination of carbaryl in aqueous solution. Under the optimum conditions, the complex had excitation and emission maxima at 278 nm and 332 nm, respectively. The linear range of the method was 7.0 ng/ml—1500 ng/ml with a detection limit of 1.2 ng/ml. The proposed method was successfully used to determine quantitatively of carbaryl in cottonseeds.

Spectrofluorimetric Determination of Magnesium (Ⅱ) with 7-(8-Hydroxy-3, 6-Disulfonaphthylazo)-8-Hydroxyquinoline-5-Sulfonic Acid

A new fluorescent reagent, 7 (8 hydroxy 3, 6 disulfonaphthylazo) 8 hydroxyquinoline 5 sulfonic acid (HDNHQ) for the determination of magnesium has been developed. It reacted with magnesium to form a 1∶1 fluorescent complex with λ ex / λ em =356/495 nm immediately at room temperature in ammonia ammonium chloride buffer (pH 10.7). A linear relationship was obtained in the magnesium concentration range of 0 160 ng·mL -1 with the detection limit of 0.04 ng·mL -1 . The proposed method was simple, rapid and sensitive. It has been successfully applied to the determination of trace magnesium in blood serum with recoveries of 103.75% and 98.16%, respectively.

Spectrofluorimetric Determination of Tetracycline Using Eu^(3+)Chelation and Cetyltrimethylammonium Bromide

The fluorescence of tetracycline was greatly enhanced by chelation with Eu 3+ in Tris HCl buffer (pH8.5). The addition of cetyltrimethylammonium bromide, a cationic surfactant, further enhanced the fluorescence of tetracycline Eu 3+ chelates.This spectrofluorimetric method for the determination of tetracycline yielded a linear responeses in the range of 10 nmol/L 10 μmol/L. The detection limit was 5 nmol/L (or 2.22 ng/mL).The recovery of tetracycline spiked in serum at levels of l and 0.09 μg/mL was 97.9% and 97.8%, respectively. This method is fast, sensitive and suitable for the determination of tetracycline in biological specimens.

Organic Media Enhanced Spectrofluorimetric Determination of L-Ascorbic Acid

A novel spectrofluorimetric method for the determination of L ascorbic acid is proposed. It is based on the inhibition of L ascorbic acid on the formation of 2,3 diaminophenazine, which is an oxidation product of o phenylenediamine catalyzed by laccase .The fluorescence (at λ ex /λ em =464 nm /530 nnm) was enhanced strongly in the presence of organic media . The mechanism of o phenylenediamine oxidation reaction catalyzed by laccase in the presence of L ascorbic acid is discussed .L ascorbic acid is determined in the ethanol, 1,4 dioxane and acetone over the linear range of 4.0×10 -7 ～1.2×10 -4 mol/L, 4.0×10 -7 ～ 8.0×10 -5 mol/L and 4.0×10 -7 ～1.0×10 -4 mol/L with a detection limit of 1.20×10 -8 mol/L,1.19×10 -8 mol/L and 1.24×10 -8 mol/L, respectively. The method has been successfully applied to the simple and rapid determination of L ascorbic acid in pharmaceuticals and milk powder.

Sensitive Spectrofluorimetric Method for Determination of Fluoroquinolones through Charge-Transfer Complex Formation

A sensitive spectrofluorimetric method was developed for determination of ciprofloxacin (CPFX), levofloxacin (LEV), gatifloxacin (GAT) and moxifloxacin (MOX) in pure, commercial formulations, human urine and plasma. The method is based on charge-transfer (CT) complex with chloranilic acid. Fluorescence intensity of the complexes was measured at emission wavelength ranging from 445-492 nm with excitation wavelengths from 285-330 nm. At optimum experimental conditions, a linear calibration plot was obtained in the concentration range of 20-1000 ng·mL-1, 60-320 ng·mL-1, 20-800 ng·mL-1 and 20 -00 ng·mL-1 for CPFX, LEV, MOX and GAT, respectively with good correlation coefficient in the range of 0.9929-1.0 in methanolic medium. The limit of detection and limit of quantification were found to be 5 ng·mL-1 and 18 ng·mL-1 for CPFX, 12 ng·mL-1 and 40 ng·mL-1 for LEV, 8 ng·mL-1 and 19 ng·mL-1 for MOX, 6 ng·mL-1 and 19 ng·mL-1 for GAT, respectively. The method was found free of interferences from excipients used as additive in pharmaceutical preparations, some common cations and compounds present in urine and plasma as well as co-administered analgesic, vitamins and other drugs. The method was successfully applied for quantification of selected fluoroquinolones in commercial formulations and also in spiked human urine and plasma samples with percent recoveries of 100.0 ± 1.56 and 100.2 ± 1.29 respectively.

A Highly Sensitive and Selective Spectrofluorimetric Method for the Determination of Arsenic at Pico-Trace Levels in Some Groundwater, Real, Environmental, Biological, Food and Soil Samples Using 2-(<i>α</i>-Pyridyl)-Thioquinaldinamide

A very simple, ultra-sensitive, highly selective and non-extractive new spectrofluorimetric method for the determination of arsenic at pico-trace levels using 2-(α-pyridyl)-thioquinaldinamide (PTQA) has been developed. PTQA has been proposed as a new analytical reagent for the direct non-extractive spectrofluorimetric determination of Arsenic (V). This novel fluorimetric reagent, PTQA becomes oxidized in a slightly acidic (0.025 - 0.1 M H2SO4) solution with Arsenic (V) in absolute ethanol to produce highly fluorescent oxidized product (λex = 303 nm;λem = 365 nm). Constant and maximum fluorescence intensities were observed over a wide range of acidity (0.025 - 0.1 M H2SO4) for the period between 2 min and 24 h. Linear calibration graphs were obtained for 0.001 - 800-μgL-1 of As, having a detection limit of 0.1-ngL-1;the quantification limit of the reaction system was found to be 1-ngL-1 and the RSD was 0% - 2%. A large excess of over 60 cations, anions and complexion agents (like, chloride, phosphate, azide, tartrate, oxalate, SCN, etc.) do not interfere in the determination. The developed method was successfully used in the determination of arsenic in several Certified Reference Materials (alloys, steels, ores, human urine, hair, nails, bovine liver and sediments) as well as in some biological fluids (human blood, urine, hair, nail and milk), soil samples, food samples (vegetables, fruits, rice, corn and wheat), solutions containing both arsenic (III) and arsenic (V) speciation and complex synthetic mixtures. The results of the proposed method for assessing biological, food and soil samples were comparable with both ICP-OES & AHG-AAS and were found to be in excellent agreement.

Analytical and Stability Studies on Medical Cosmetics

Two simple and sensitive spectrofluorimetric (method Ι) and spectrophotometric (method ΙΙ) methods have been developed for the determination of some chloride containing toothpastes and panthenol-containing cosmetic preparations respectively. Method Ι is based on quantitative fluorescence quenching of (terbium-salicylate-hexamine ternary complex) by fluoride which could be measured at λem/λex of 547 nm/322 nm. The ΔF-concentration plot was rectilinear over the concentration range of 0.5 - 20 μg/ml. Method ΙΙ depends reaction of panthenol with nitrobenzoxadiazole chloride (NBD-Cl) and measuring the absorbance of the resultant product at 480 nm. The absorbance-concentration plot was rectilinear over the concentration range of 2 - 20 μg/ml.