A Study for the Validation of Spectrophotometric Methods for Detection, and of Digestion Methods Using a Flow Injection Manifold, for the Determination of Total Phosphorus in Wastewaters1

The construction and evaluation of a fully automated Flow Injection-Stopped Flow (FI-SF) spectrophotometric analyser is described. A microcomputer (Rockwell AIM 65) is used to control the analyser (sample injection, stop and start of the pump) through a suitable interface. Data acquisition is achieved using a 12 bit ADC card and a suitable subroutine in 6502 assembly language, allowing data sampling at a frequency of 7.5 kHz. The measurement interface and software were evaluated using a voltage ramp generator. A precision of 0.02-1.1% RSD (N =10) was obtained for voltage ramps in the range of 1-37 mVs-1. The FI-SF analyser was evaluated in routine analysis by developing FI-SF kinetic spectrophotometric methods for the determination of ammonia nitrogen (20-250 ppm, 0.4-2.5% RSD) based on the Berthelot reaction, creatinine (20-220 ppm, 0.9-3.6% RSD) based on the Jaffé reaction, and phosphate (5-30 ppm, 1.0-3.3% RSD) based on the phosphomolybdenum blue reaction. The reaction rate is measured by linear fitting of multiple absorbance readings vs time. Algorithms for automated estimation of the residence time, the linear range of the reaction curve, and data treatment are presented.

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Modifications of spectrophotometric methods for total phosphorus determination in meat samples

Chemical Papers ◽

10.2478/s11696-008-0091-2 ◽

2009 ◽

Vol 63 (1) ◽

Cited By ~ 6

Author(s):

Aneta Jastrzębska

Keyword(s):

Total Phosphorus ◽

Reducing Agents ◽

Statistical Parameters ◽

Molybdenum Blue ◽

Spectrophotometric Methods ◽

Hydrazine Sulphate ◽

Meat Samples ◽

Blue Reaction ◽

Better Than

AbstractSpectrophotometric determination of total phosphorus in meat samples was modified using the molybdenum blue reaction with the following reducing agents: ascorbic acid (AA), hydrazine sulphate (HS), and mixture of hydroquinone and hydrazine sulphate (HHS). Proposed methods were validated by evaluation of statistical parameters such as: linearity, sensitivity, limits of detection (DL) and quantification (QL), precision, and accuracy, against the standard and malachite green (MG) modified procedures and by applying food certified materials. The values of within-day and between-days precision in meat samples for all tested reducing agents were better than 3.4 % and 4.2 %, respectively. The recoveries for CRMs analyses were between 92 % and 102.3 %. Obtained results suggest usefulness of the hydroquinone and hydrazine sulphate mixture in the determination of phosphorus ions.

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Rapid spectrophotometric determination of total phosphorus in industrial wastewaters by flow injection analysis including a capillary digestor

Analytica Chimica Acta ◽

10.1016/s0003-2670(00)80380-3 ◽

1989 ◽

Vol 219 ◽

pp. 363

Author(s):

M. Aoyagi ◽

Y. Yasumasa ◽

A. Nishida

Keyword(s):

Spectrophotometric Determination ◽

Total Phosphorus ◽

Flow Injection ◽

Flow Injection Analysis ◽

Industrial Wastewaters

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Optimization of Two Flow-Injection Spectrophotometric Methods for the Determination of Indapamide in Pharmaceutical Dosage Forms

Journal of AOAC International ◽

10.1093/jaoac/88.4.1148 ◽

2005 ◽

Vol 88 (4) ◽

pp. 1148-1154 ◽

Cited By ~ 3

Author(s):

Juan C Rodríguez ◽

Julia Barciela ◽

Sagrario García ◽

Carlos Herrero ◽

Rosa M Peña

Keyword(s):

Flow Injection ◽

Screening Method ◽

Pharmaceutical Preparations ◽

Dosage Forms ◽

Response Surfaces ◽

Subsequent Formation ◽

Pharmaceutical Dosage Forms ◽

Spectrophotometric Methods ◽

Accuracy And Precision

Abstract Multivariate experimental design has been used to optimize 2 flow-injection spectrophotometric methods for the determination of indapamide in pharmaceutical dosage forms, both pure and commercial tablets. The methods are based on the oxidation of this drug with iron (III) in acidic medium and the subsequent formation of an intensive orange-red complex between the liberated iron (II) and 2,2′-bipyridyl or 1,10-phenanthroline reagents. Plackett-Burman designs were applied as a screening method to evaluate the most significant factors with few experiments. Central composite 23+ star designs were performed to evaluate the response surfaces. The methods have been fully validated and were applied successfully to the determination of indapamide in pure and pharmaceutical forms with good accuracy and precision. Therefore, the 2 proposed procedures are simple, inexpensive, and rapid flow methods for the routine determination of indapamide in pharmaceutical preparations.

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