Simultaneous determination of thiamine and its phosphate esters by a liquid chromatographic method based on post-column photolysis and chemiluminescence detection.

A sensitive method for the post-column detection of thiamine (T) and its phosphate esters is described. The procedure is based on the on-line photolysis of the analytes into photoproducts which have a strong enhancing effect on the CL permanganate-luminol reaction. The complete separation of the thiamines was obtained on a RP-amide C(16) column in isocratic elution with an analysis time of less than 7 min.

A sensitive post-column photochemical derivatization/fluorimetric detection system for HPLC determination of bisphosphonates.

A new reversed-phase ion-pair high-performance liquid chromatographic (HPLC) method has been developed for the determination of the following bisphosphonic acids: alendronic acid (ALEN), etidronic acid (ETID), ibandronic acid (IBAN) and risedronic acid (RISE). Separation was achieved on a C(18) column using a mixture of 50 mmol L(-1) borate buffer pH 9.0 containing 0.

Flow injection chemiluminescent method for the successive determination of l-cysteine and l-cystine using photogenerated tris(2,2'-bipyridyl) ruthenium (III).

Flow injection configurations were developed for the individual determination of l-cysteine and l-cystine and for the mixture of both analytes. The method is based on the reaction of l-cysteine with tris(2,2'-bipyridyl) ruthenium (II) and peroxydisulphate under UV irradiation to produce chemiluminescence. Cystine is determined after reduction to cysteine in a copper-coated cadmium reductor mini-column in the flow system.

Simultaneous determination of amiodarone and its metabolite desethylamiodarone by high-performance liquid chromatography with chemiluminescent detection.

A novel method was developed for the determination of amiodarone and desethylamiodarone by high-performance liquid chromatography (HPLC) coupled with chemiluminescent (CL) detection. The procedure is based on the post-column photolysis of the analytes into photoproducts which are active in the tris(2,2'-bipyridyl)ruthenium(III) [Ru(bpy)(3)(3+)] CL system. Ru(bpy)(3)(3+) was on-line generated by photo-oxidation of the Ru(II) complex in the presence of peroxydisulfate.

Chemiluminescent determination of EDTA and related compounds using tris(2,2'-bipyridyl)ruthenium(III) photogenerated on-line.

A rapid and sensitive chemiluminescence method using flow-injection has been developed for the determination of EDTA. The method is based on the chemiluminescent reaction of EDTA with tris(2,2'-bipyridyl)ruthenium(III), which is generated on-line through the photooxidation of tris(2,2'-bipyridyl)ruthenium(II) with peroxydisulfate. After optimizing the different experimental parameters, a calibration graph was obtained over the concentration range of 7 x 10(-8) M to 3 x 10(-6) M, with a minimum detectability of 7.

High-performance liquid chromatography-post-column chemiluminescence determination of aminopolycarboxylic acids at low concentration levels using tris(2,2'-bipyridyl)ruthenium(III).

A simple, selective and sensitive method for the determination of aminopolycarboxylic acids [diethylenetriaminepentaacetic acid (DTPA), S,S-ethylenediamine N,N'-disuccinic acid (EDDS), ethylenediaminetetraacetate (EDTA) and nitrilotriacetate (NTA)] has been developed using high-performance liquid chromatography with chemiluminescence detection. The aminopolycarboxylic acids were separated on a C18 reversed-phase column with an aqueous sulfuric acid mobile phase at a pH lower than 1.5.

Determination of N-methylcarbamate pesticides in environmental samples by an automated solid-phase extraction and liquid chromatographic method based on post-column photolysis and chemiluminescence detection.

An automated solid-phase extraction-high performance liquid chromatography method has been developed to determine trace concentration of N-methylcarbamate pesticides in water and fruits. The method is based on the post-column conversion of the pesticides into methylamine by irradiation with UV light. The resultant methylamine was subsequently detected by chemiluminescence using tris(2,2'-bipyridyl)ruthenium(III), which was on-line generated by photo-oxidation of the ruthenium(II) complex with peroxydisulfate.

Determination of propoxur in environmental samples by automated solid-phase extraction followed by flow-injection analysis with tris(2,2'-bipyridyl)ruthenium(II) chemiluminescence detection.

A sensitive method for the analysis of propoxur in environmental samples has been developed. It involves an automated solid-phase extraction (SPE) procedure using a Gilson Aspec XLi and flow-injection analysis (FI) with chemiluminescence (CL) detection. The FI-CL system relies on the photolysis of propoxur by irradiation using a low-pressure mercury lamp (main spectral line 254 nm).

High-performance liquid chromatography: photochemical reduction in aerobic conditions for determination of K vitamins using fluorescence detection.

The development and application of a post-column detection system for K vitamins based on their photoreduction to the hydroquinone form is reported. The photoreduction yield is practically quantitative and occurs in a PTFE tubing coiled around a 6-W low-pressure mercury lamp in the presence of sodium dodecylsulfate and methanol. Factors affecting the rate of the photochemical reaction were optimised so that its contribution to the total broadening was negligible.

Development and validation of a capillary electrophoresis method with laser-induced fluorescence detection for the determination of captopril in human urine and pharmaceutical preparations.

This study describes the development of a CE method for the analysis of the antihypertensive drug captopril using LIF detection. The method is based on the derivatization of captopril with the fluorescent label 5-iodoacetamidofluorescein. The optimization of the electrophoretic electrolyte composition together with other variables, such as applied voltage and injection time, resulted in a solution of 20 mM phosphate buffer adjusted to pH 12.

Flow injection chemiluminescent determination of amiodarone in pharmaceutical preparations using photogenerated tris(2,2'-bipyridyl)ruthenium(III).

A flow injection configuration was developed and evaluated for the chemiluminescent determination of amiodarone. The method is based on the reaction of the drug with tris(2,2'-bipyridyl)ruthenium(III), which was generated through the on-line photo-oxidation of tris(2,2'-bipyridyl)ruthenium(II) with peroxydisulfate. Under the optimum experimental conditions, a linear calibration graph was obtained over the range 3.

Automatic determination of phylloquinone in vegetables and fruits using on-line photochemical reduction and fluorescence detection via solid phase extraction and flow injection.

A very simple, rapid and highly sensitive flow injection fluorimetric method was developed for the determination of phylloquinone. The assay was based on the on-line reduction of phylloquinone in dodecylsulfate micelles after irradiation with UV light. The micellar medium enhanced the fluorescence and stability of the reduced phylloquinone.

Determination of omeprazole, hydroxyomeprazole and omeprazole sulfone using automated solid phase extraction and micellar electrokinetic capillary chromatography.

A sensitive method for the determination of omeprazole and its metabolites has been developed. It involves an automated solid phase extraction (SPE) procedure and capillary electrophoresis with UV detection. Omeprazole, hydroxyomeprazole and omeprazole sulfone could be separated by micellar electrokinetic capillary chromatography using a background electrolyte composed of 20 mM borate buffer and 30 mM sodium dodecyl sulfate, pH 9.

Automated solid-phase extraction and high-performance liquid chromatographic determination of nitrosamines using post-column photolysis and tris(2,2'-bipyridyl) ruthenium(III) chemiluminescence.

A sensitive and selective post-column detection system for nitrosamines is described. The principle upon which the detector works is that UV irradiation of aqueous solutions of nitrosamines leads to cleavage of the N-NO bond. The amine generated is subsequent detected by chemiluminescence using tris(2,2'-bipyridyl) ruthenium(III), which is on-line generated by photo-oxidation of the ruthenium(II) complex in the presence of peroxydisulfate.

Migration behaviour and separation of acetaminophen and p-aminophenol in capillary zone electrophoresis: analysis of drugs based on acetaminophen.

The migration behaviour of acetaminophen and p-aminophenol was investigated by capillary electrophoresis. The influence of different parameters (pH, nature and concentration of the running buffer and applied voltage) on the migration time, peak symmetry, efficiency and resolution was systematically investigated. The two analytes can be well separated within 4 min in a 57 cm fused-silica capillary at a separation voltage of 18 kV in a 50mM borate buffer adjusted to pH 9.

An ultrasensitive method for the determination of thiouracil and phenylthiouracil using capillary zone electrophoresis and laser-induced fluorescence detection.

This paper reports the development of a method based on capillary electrophoresis with laser-induced fluorescence detection for the simultaneous determination of thiouracil (TU) and phenylthiouracil (PhTU) with high sensitivity (nanomolar range, i.e., attomoles detected).

Successive determination of thiamine and ascorbic acid in pharmaceuticals by flow injection analysis.

A simple and rapid fluorimetric method for the determination of mixtures of thiamine and ascorbic acid is proposed. The procedure is based on the oxidation with mercury(II) of the B1 and C vitamins to form thiochrome (TC) and quinoxaline derivate, respectively. Both reaction products exhibit fluorescence at the same wavelengths (lambdaex = 356 and lambdaem = 440 nm).

Development and validation of a quantitative assay for raloxifene by capillary electrophoresis.

The migration behavior of raloxifene was investigated by capillary electrophoresis (CE). The influence of different parameters (nature and concentration of the running buffer, pH and applied voltage) on migration time, peak symmetry and efficiency was systematically investigated. A buffer consisting of 20mM acetate buffer of pH 4.

High-performance liquid chromatographic separation and quantification of citric, lactic, malic, oxalic and tartaric acids using a post-column photochemical reaction and chemiluminescence detection.

An HPLC method was developed for the determination of citric, lactic, malic, oxalic and tartaric acids by chemiluminescent detection following online irradiation with visible light. The organic acids were irradiated with visible light in the presence of Fe3+ and UO2(2+) to generate Fe2+, which was determined by measuring the chemiluminescence intensity in a luminol system in the absence of added oxidant. Factors affecting the photochemical and chemiluminescence reactions were optimised so that their contribution to the total band-broadening was negligible.

Development of a capillary electrophoresis method for the determination of allopurinol and its active metabolite oxypurinol.

A simple and sensitive capillary zone electrophoresis method with UV absorbance detection is described for the quantitation of allopurinol and its metabolite oxypurinol in aqueous solution. The influence of different parameters on migration times, peak symmetry, efficiency and resolution was systematically investigated; these parameters included the nature and concentration of the separation buffer, pH and applied voltage. A buffer consisting of 15 mM 2-[N-cyclohexylamino]ethanesulfonic acid (CHES) adjusted to pH 8.

Determination of ATP via the photochemical generation of hydrogen peroxide using flow injection luminol chemiluminescence detection.

The determination of ATP using the coupling between a photochemical reaction and a chemiluminescence reaction in a flow injection (FI) system is described. The method is based on the reaction of glucose with ATP catalyzed by hexokinase and Mg(2+) ions. The glucose that is not consumed by ATP is subsequently photooxidized using 9,10-anthraquinone-2,6-disulfonate as a sensitizer.

Determination of allopurinol by micelle-stabilised room-temperature phosphorescence in real samples.

A very simple, rapid and highly sensitive method has been developed for the determination of allopurinol. The method is based on the room temperature phosphorescence of allopurinol in sodium dodecylsulphate (SDS) micelles, with thallium (I) providing the external heavy atom and sodium sulphite acting as the oxygen scavenger. Under the optimum experimental conditions, the range of application is 0.

Chemiluminescence determination of carbofuran and promecarb by flow injection analysis using two photochemical reactions.

A flow injection-chemiluminescent method for the determination of carbofuran and promecarb is proposed. The assay was based on the on-line conversion of the pesticides into methylamine by irradiation with UV light. The methylamine generated was subsequently reacted with tris(2,2'-bipyridine)ruthenium(III), which was generated through the on-line photo-oxidation of tris(2,2'-bipyridine)ruthenium(II) with peroxydisulfate.

Direct determination of ranitidine and famotidine by CE in serum, urine and pharmaceutical formulations.

A simple and sensitive capillary electrophoresis method using UV detection has been developed for the direct determination of ranitidine (RANT) and famotidine (FAMT) in serum, urine and pharmaceutical formulations. A buffer consisting of 60 mM phosphate buffer adjusted to pH 6.5 was found to provide a very efficient and stable electrophoretic system for the analysis of both drugs.

Fluorimetric determination of arsanilic acid by flow-injection analysis using on-line photo-oxidation.

A flow-injection-fluorimetric method for the determination of arsanilic acid is proposed. The assay is based on the on-line decomposition of arsanilic acid in the presence of peroxydisulfate on irradiation with UV light. The arsenate generated in the photochemical reaction was reacted with molybdate in dilute nitric acid to form arsenomolybdic acid, which oxidised thiamine to thiochrome.