Simultaneous determination of carbaryl and azinphos-methyl in water by first-derivative synchronous spectrofluorimetry

A method is proposed for the simultaneous determination of the pesticides carbaryl (CBL) and azinphos-methyl (AZM) in water by first-derivative synchronous spectrofluorimetry. It is based on the alkaline hydrolysis of both pesticides to their metabolites 1-naphthol (from CBL) and anthranilic acid (from AZM). The constant wavelength difference chosen to optimize the determination is Δλ=λ_em?λ_ex=103 nm. CBL is measured at 302/405 nm and AZM at 333/436 nm. The calibration graphs are linear between 2.0 and 500.0 ng/ml for CBL and between 1.2 and 500.0 ng/ml for AZM with detection limits of 0.62 ng/ml and 0.35 ng/ml, respectively. The precision of the method (RSD) is 2.4% at the 80.0 ng/ml level for CBL and 2.5% at the 80.0 ng/ml level for AZM. The method is applied to the determination of both analytes in samples of natural waters.     

Enhancement of the fluorescence of the beryllium-morin complex by non-ionic surfactants

The effect of surfactants on the fluorescence of the beryllium-morin system has been studied. Non-ionic surfactants strongly enhance the fluorescence intensity of the beryllium complex. The addition of Triton X-100 makes possible the fluorimetric determination of submicrogram quantities of beryllium in feebly acidic media (pH 5.8-6.2, hexamine buffer). The fluorescence is excited at 440 nm and measured at 530 nm. The calibration graph is linear up to 10 ng/ml Be and the detection limit is 0.04 ng/ml. The relative standard deviation is 2.2% for beryllium at 0.5 ng/ml concentration and 0.7% for 5.0 ng/ml. The effects of 25 ions commonly found in water have also been studied; Zn(2+) and F(-) give the main interference. The method has been applied to the determination of beryllium in water pollution quality-control samples with satisfactory results.     

Enhanced Fluorimetric Determination of Europium(III) With Thenoyltrifluoroacetone and 4,7-Diphenyl-1,10-Phenanthroline by Gadolinium(III)

Abstract

A sensitive fluorimetric method was developed for the determination of trace amount of europium in rare earth oxides. In the presence of gadolinium, the fluorescence of the europium complex with thenoyltrifluoroacetone and 4,7-diphenyl-1,10-phenanthroline was increased by a factor of about 2; the excitation and emission wavelengths were 346 and 613nm, respectively;the fluorescence was linear up to 1.59ng/ml of europium;and the detection limit was found to be 0.6pg/ml of europium. A general mechanism of fluorescence enhancement was proposed.     

Kinetic Spectrophotometric Determination of Trace Amounts of Nitrite Ion Using Its Reaction With Neutral Red

Abstract

A rapid, simple, sensetive and selective method for the determination of trace amounts of nitrite ion(30-800 ng/ml) is developed. It depends on the reaction of nitrite with Neutral Red. The reaction is monitored spectrophotometrically by measuring the decrease in absorbance at 530 nm by a fixed time method. The limit of detection is 14 ng/ml. The method is used for the determination of nitrite ion in waste water.     

Fluorometric Determination of Iron(Iii) with O-Hydroxyhydroquinonephthalein in the Presence of Brij 58

Abstract

A highly sensitive fluorescence reaction of iron(III) with o-hydroxyhydroquinonephthalein (Qnph) in the presence of various surfactants, and its application to the fluorophotometry of trace amounts of iron(III) is described. the method is based on the fluorescence quenching reaction between Qnph and iron(III) in the presence of Brij 58 at pH 3–4. the quenching calibration graph was linear over the range 0 – 300 ng per ml iron(III) by using fluorescence reaction at Em 525 nm with Ex 470 nm, and the iron(III) detection limit was 5 ng/ml. the proposed method is simple, rapid and does not involve heating or solvent extraction.     

Determination of Bendroflumethiazide in Plasma by High Performance Liquid Chromatography and Fluorescence Detection

Abstract

An accurate, precise, and specific assay is described for the determination of bendroflumethiazide (BFTZ) in plasma. The procedure employs a C18 column, a mobile phase consisting of 35% acetonitrile in 0.015M phosphoric acid, and a fluorescence detector with a 254nm excitation filter and a 400nm emission filter. Furosemide is used as the internal standard. Using lml of plasma, this method can detect 10ng/ml of BFTZ.     

The Determination of a New Trifluorinated Quinolone,Fleroxacin, Its N-Demethyl,and N-Oxide Metabolites in Plasma and Urine by High Performance Liquid Chromatography with Fluorescence Detection

Abstract

A liquid chromatographic method is described for the determination of the new fluoroquinolone Ro 23–6240 and its N-demethyl and N-oxide metabolites in plasma and urine. The three substances were extracted from aqueous solution with dichloromethane/isopropanol containing sodium dodecyl sulphate. After evaporation and reconstitution, samples were analysed on a reversed-phase column using ion pair chromatography and fluorescence detection. The limit of quantification was 10–20 ng/ml (RSD 4%) using a 0.5 ml plasma sample, and the inter assay precision was 3–10% over the concentration range 50 ng/ml to 20 μg/ml. Recovery from plasma was 81% (RSD 10%) over the range 10 ng/ml to 5 μg/ml. The method has been applied successfully to the analysis of several thousand samples from human pharmacokinetic studies. Care has to be taken to avoid exposure of samples to direct sunlight, and the use of opaque vessels for sample storage and handling is recommended.     

Determination of Trace Amounts of Acetaldehyde Using a Novel Chemiluminescence Reaction

Abstract

The chemiluminescent reaction of iso-propyl alcohol with C10^?-H₂O₂ is enhanced by acetaldehyde. This provides a new method for the determination of trace amounts of acetaldehyde. The detection limit is 0.08ng/ml acetaldehyde and the linear dynamic range is 0.5ng/ml to 1000 ng/ml. The method results in good selectivity and has been satisfactorily applied to the determination of traces of acetaldehyde in waste water samples.     

Spectrofluorimetric Determination of Chlorpromazine Hydrochloride and Thioridazine Hydrochloride

Abstract

Fluorescence spectroscopy was applied to the development of a sensitive and simple method for the determination of chlorpromazine HCl and thioridazine-HCl. The method is based upon development of an intense fluorescence using N-bromosuccinimide as the fluorogenic reagent. The produced fluorescence has very characteristic excitation and emission spectra and was stable for at least one hour. The results were reproducible and as little as 5 ng/ml chloropromazine HCl and 1 ng/ml thioridazine-HCl could be determined. The method was applied successfully to the analysis of various commercially available dosage forms. The obtained results were in good agreement with those of the official BP 93 procedures.     

Sodium Coumarin 6-Sulfonate,A Fluorometric Ion-Pairing Reagent for Tertiary Amines. Application to the Determination of Chlorpheniramine Maleate

Abstract

A study of sodium coumarin 6-sulfonate as a fluorescent ionpair reagent indicated that it could be useful in the analysis of tertiary amines such as chlorpheniramine maleate. The physical properties of the coumarin sulfonate that make it suitable as a fluorescent ion-pair reagent for basic drugs are its high relative quantum yield (0.76) and its acidity (pKa of ?7.66). Methylene chloride containing 5% n?pentanol was used to extract the coumarinchlorpheniramine ion-pair from aqueous solution. It was found that a 10^?2 M coumarin concentration yielded a 92% recovery of chlorpheniramine at pH 5. Following phase separation, the coumarin species was completely ionized by the addition of tetrabuty1 ammonium hydroxide to the organic phase. After irradiation for 30 min using long wavelength ultraviolet light (365 nm), the fluorescence intensity of the sample was measured using excitation and emission wavelengths of 400 and 540 nm, respectively. Comparison of fluorescence data of spiked aqueous samples to that of a chlorpheniramine maleate standard curve performed concurrently gave drug concentration in the samples. The calibration curve was linear in the 50–1000 ng/ml range (0.13 ? 2.6 × 10 ^?6 M). The procedure allowed the determination of chlorpheniramine maleate with an accuracy of 4–6% and a precision of 2–6% RSD (relative standard deviation). The minimum detectable concentration of drug (S/N = 2) that can be assayed by this method is 50 ng/ml of the maleate salt (35.3 ng/ml of chlorpheniramine free base).     

A Fluorescence Synergistic Method for the Determination of Stilboestrol

Abstract

A simple, highly sensitive and selective fluorescence synergistic method has been developed for rapid determination of stilboestrol with Triton × — 100 (λ_ex = 318nm, λ_em = 415nm) at pH 8.80 ～ 10.20. The calibration graph is linear over the range of 0.0 ～ 30.0μg/10ml. The detection limit is 0.03μg/ml stilboestrol. The method has been successfully applied for the determination of stilboestrol in tabellae stilboestrol and injectio stilboestrol with satisfactory results. It can also be applied for the determination of stilboestrol in body fluid of special patients.     

A Fluorescence Quenching Method for the Determination of Iodide Ion with Salicylfluorone and Hydrogen Peroxide

Abstract

A highly sensitive and selective fluorescence quenching method has been developed for rapid determination of iodide ion with salicylfluorone (SAF) as fluorogenic reagent (λ_ex = 495 nm, λ_em = 520 nm) at pH 2.5-3.0. The calibration graph is linear over the range 0.05-300 μg/25 ml. The detection limit is 0.05 μ/25 ml iodide. Other halide ions do not interfere with the determination even when present in large excess. The method is rapid and was successfully applied for the determination of iodide ion in sodium chloride, table salt and low sodium salt.     

A Rapid and Sensitive Method for The Determination of Diclofenac Sodium in Plasma By High-Performance Liquid Chromatography

Abstract

A rapid and sensitive high-performance liquid chromatographic method for the determination of diclofenac sodium in plasma has been developed. The method is specific and free of interference from metabolites and common anti-inflammatory agents. The UV detector (215 nm) response was linear over a range of 5-1000 ng/ml. Day-to-day and within-day calibration curves were reproducible. The method was validated by analysis of spiked human plasma samples, partly in a blind fashion. The accuracy and precision of the method are satisfactory over the range of 5-1000 ng/ml. The method was cross-checked with the GC method. Results show a correlation coefficient of 0.983 and a slope of 1.04. The method is suitable for the routine analysis of large numbers of plasma samples usually obtained in bioavailability and pharmacokinetic studies.     

Improved High Pressure Liquid Chromatographic Method for Phenylpropanolamine in Human Plasma

Abstract

A high-pressure liquid chromatographic analysis of phenylpropanolamine in plasma following extraction, back extraction and pre-column derivitization with O-phthalaldehyde is presented. The method is improved by the use of phenylethanolamine as internal standard. Using fluorescence detection, the method is sufficiently sensitive to quantitate 5 ng/ml in 0.5 ml plasma with a standard error of estimate of 2.7 ng/ml when calibrated over the O to 240 ng/ml range. Analysis of over 2000 clinical samples have shown the method to be highly specific and reliable.     

Spectrofluorimetric determination of BrO 3 − by oxidation of 1,2,4-trihydroxyanthraquinone-3-carboxylic acid

Summary A method is described for the fluorimetric determination of BrO₃, at the nanogram level, based on the oxidation of 1,2,4-tri-hydroxyanthraquinone-3-carboxylic acid in sulfuric acid medium. The fluorescence emission is monitored at 585 nm (wavelength of excitation 521 nm). The method shows a detection limit of 5 ng/ml, being the most sensitive of all the established methods for the determination of this anion by photometry and fluorimetry.

---

Spektrofluorimetrische Bestimmung von Bromat durch Oxydation von 1,2,4-Trihydroxyanthrachinon-3-carbonsäure

Zusammenfassung Die fluorimetrische Bestimmung von Bromat im Nanogrammbereich auf der Grundlage der Oxydation von 1,2,4-Trihydroxyanthrachinon-3-carbonsäure in schwefelsaurer Lösung wurde beschrieben. Die Fluoreszenz wird bei 585 nm gemessen (Anregung bei 521 nm). Die Erfassungsgrenze liegt bei 5 ng/ml. Das Verfahren ist somit das empfindlichste unter allen bekannten Methoden zur photometrischen bzw. fluorimetrischen Bestimmung dieses Anions.

     

An HPLC Method for Determination of Atropine in Human Plasma

Abstract

A development of a high performance liquid chromatographic method for the determination of atropine in human plasma is presented. Atropine is extracted from plasma basified with 0. 1N sodium hydroxide using chloroform, subsequently subjected to base hydrolysis, followed by derivatization of the generated tropic acid with 4-bromomethyl-7-methoxycoumarin (Br-Mmc). The derivative produced has a strong blue fluorescence at excitation wavelength of 328 nm and emission cutoff filter of 389 nm. d1-Mandelic acid as internal standard (I. S.) was added after hydrolysis. The chromatographic separation was achieved on a reversed phase ODS column with a mobile phase of 33% acetonitrile in 0. 01M ammonium phosphate buffer (pH 5). The minimum quantitative limit was 125 ng/ml of plasma.     

Rapid Determination of Bupropion in Human Plasma by High Performance Liquid Chromatography

Abstract

A high performance liquid chromatographic (HPLC) technique has been developed for the determination of bupropion hydrocloride (Bup) in human plasma, using a reversed-phase method, with UV detection at 250 nm.

The internal standard 5-(P-methylphenyl)-5-phenylhydantoin (MPPH), was used as an aid to quantitation. The plasma was deprotemized with acetonitrile and the clear supernatant was directly injected in the chromatographic system. The lower limit of quantitation was 5.0 ng/ml using only 100 μl of plasma sample.

Linear regression analysis for the calibration plots obtained on five different days over a two-week period for the the two ranges used (10–250 ng/ml and 250–2000 ng/ml) in plasma indicated excellent linearity and reproducibility. The mean recovery of spiked Bup in plasma samples over the concentrations studied was found 96.5 ± 3.14%.

The method revealed that more than 30% of Bup was lost when the supernatant was stored at room temperature for 24 hrs.     

Spectrofluorimetric Determination of Germanium Traces Using 1,2,4-Trihydroxyantraquinone

ABSTRACT

A new spectrofluorimetric method for determination of germanium traces based on its reaction with 1,2,4-Trihydroxyantraquinone, at an apparent pH 8.8 provided by an ammonia/ammonium chloride buffer, in a 80:20(v/v) ethyleneglycol water medium is proposed. The calibration graph is linear over the range 70–725 ng/ml and features a detection limit of 2.5 ng/ml. The effect of potential major interferences has been investigated and the proposed method was successfully applied to the determination of germanium in synthetic samples and industrial concentrates, after extraction with CCl₄, in an 9 M HCl medium.     

An Improved HPLC Method for the Determination of Furosemide in Plasma and Urine

Abstract

A sensitive HPLC method with minimal sample preparation and good reproducibility for the determination of furosemide in plasma and urine is described. Acidified plasma samples were extracted using CH₂Cl₂ containing desmethylnaproxen as internal standard (IS). Fresh urine samples were incubated with β-gluc-uronidase for 15 minutes and then treated with CH₃CN containing IS.

Chromatography was performed on a C18 column with 10 mcl sample injection, Mobile phases were: a) for plasma: 0.01 M NaH₂PO₄, pH 3.5 - CH₃OH (65:35), and b) for urine: acetic acid, pH 3.5 - CHS3OH (60:40) at 3 ml/min and fluorescence detection at Ex 235/Em 389 nm. The plasma standard curve was linear from 0.01 to 15.0 mcg/ml and the urine from 0.5 to 200.0 mcg/ml. The within run CV's were 3,2% at 0.74 mcg/ml plasma and 2.0% at 10.7 mcg/ml urine. Recovery from plasma was 69.9% at 2.0 mcg/ml and 98.6% from urine at 5.0 mcg/ml. The stability of furosemide and its glucuronide were studied. Both methods have been applied to the analysis of plasma and urine samples obtained from human volunteers.     

Rapid Determination of Propranolol and 4-Hydroxypropranolol in Plasma by High Pressure Liquid Chromatography

Abstract

The resolving power of high pressure liquid chromatography has been combined with the sensitivity of fluorescence detection to develop a method for the determination of propranolol and 4-hydroxypropranolol in plasma. A single selective extraction step precedes chromatography on a high efficiency bonded phase column. The limits of quantitation are approximately 2 ng/ml of plasma for each drug. The analysis of a number of clinical samples has demonstrated the application of the method in pharmacokinetic studies, but the possible interference of other drugs and their metabolites is still under investigation.