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  • 1
    Electronic Resource
    Electronic Resource
    Solid-phase spectrophotometric microdetermination of iron with ascorbic acid and ferrozine (1997)
    Springer
    Fresenius' journal of analytical chemistry 357 (1997), S. 44-49 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract  A very sensitive and selective method for the determination of trace amounts of iron has been developed, based on the reduction of Fe(III) to Fe(II) by ascorbic acid, followed by chromogenic chelation of Fe(II) with ferrozine. The complex Fe(II)-ferrozine is easily sorbed on a dextran-type anion-exchange gel packed in a 1 mm cell, and the absorbance of the gel is measured directly at 569 and 800 nm. The extended linear range of the determination is 0.5–10 ng ml-1 of iron (apparent molar absorptivity=4.4×107 l mol-1 cm-1) and the precision (RSD) 1.3% for a concentration of 5 ng ml-1 of iron (n=10). The detection limit for a sample volume of 1000 ml, using 0.040 g of anion-exchanger, corresponds to 0.12 ng ml-1. The method has been successfully applied to the determination of iron in natural and waste waters, wine, soil extract and previously digested vegetal tissues, drugs and human hair.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160050108
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  • 2
    Electronic Resource
    Electronic Resource
    Determination of traces of aluminium with chrome azurol S by solid-phase spectrophotometry
    Amsterdam : Elsevier
    Talanta 40 (1993), S. 1059-1066 
    Details
    ISSN: 0039-9140
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0039-9140(93)80166-O
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  • 3
    Electronic Resource
    Electronic Resource
    Spectrophotometric extractive determination of Ti in mineral samples and aluminium alloys as a mixed-ligand Ti(IV)-salicylhydroxamic acid-thiocyanate complex (1990)
    Springer
    Microchimica acta 100 (1990), S. 305-311 
    Details
    ISSN: 1436-5073
    Keywords: titanium determination ; spectrophotometry ; extraction ; liquid ionexchanger ; ores and aluminium alloys analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A sensitive method for the determination of titanium, based on the formation of a mixed-ligand Ti (IV)-salicylhydroxamic acid-thiocyanate complex and extraction of this into a liquid ion-exchanger phase has been developed. The extract has maximum absorbance at 400–460 nm and the apparent molar absorptivity is 1.8 × 104l · mole−1 · cm−1 at 420 nm. The system obeys Beer's law at 420 nm in the range 0.16–3.20 mg/1 Ti, the detection limit being 0.1 mg/1. The method is found suitable for determination of titanium in aluminium alloys and silicate rocks.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242891
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  • 4
    Electronic Resource
    Electronic Resource
    A simple solid phase spectrofluorimetric method combined with flow analysis for the rapid determination of salicylamide and salicylic acid in pharmaceutical samples (1999)
    Springer
    Fresenius' journal of analytical chemistry 365 (1999), S. 619-624 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A new, sensitive and very simple spectrofluorimetric biparameter sensor is described for the determination of salicylamide and/or salicylic acid in pharmaceutical preparations. The method integrates the transitory retention and fluorescence detection of both compounds on Sephadex QAE A-25 resin packed into a conventional flow-through cell. A monochannel manifold with two alternative carriers is used. At pH 2.0 (first carrier) salicylic acid is selectively retained on the solid support and after developing the analytical signal it is desorbed. At pH 11.0 (second carrier) both salicylic acid and salicylamide are simultaneously and transitorily retained on the solid, the analytical signal now corresponding to both analytes. The monochromators were tuned at 260 (excitation) and 415 (emission) nm, respectively. The calibration graph for salicylamide is linear over the range 0.01 to 0.32 μg mL–1 and for salicylic acid from 0.04 to 1.0 μg mL–1 in the presence of each other. The relative standard deviation and the sampling frequency for the determination of salicylamide (0.20 μg mL–1) and salicylic acid (0.50 μg mL–1) were 1.1% and 35 h–1, and 0.9% and 45 h–1, respectively. Good results on application to individual determination or mixture resolution in pharmaceutical samples testify to the usefulness of the proposed sensor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051533
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  • 5
    Electronic Resource
    Electronic Resource
    Flow injection-solid phase spectrofluorimetric determination of pyridoxine in presence of group B-vitamins (1999)
    Springer
    Fresenius' journal of analytical chemistry 363 (1999), S. 265-269 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A flow-through optosensor has been prepared for the sensitive and selective determination of pyridoxine (vitamin B6) in aqueous solutions. The sensor was developed in conjunction with a monochannel flow-injection analysis system with fluorimetric detection using Sephadex SP-C25 resin as an active sorbent substrate. This method of determination is carried out without any derivatization. The wavelengths of excitation and emission were 295 and 385 nm, respectively. When a HCl (10–3 mol L–1) / NaCl (3 × 10–2 mol L–1) solution is used as carrier solution, the sensor responds linearly in the measuring range of 5–200, 10–400 and 50–1800 ng mL–1 with detection limits of 0.33, 0.67, and 5.70 ng mL–1 for 2000, 1000 and 200 μL of sample volume, respectively. The relative standard deviation for ten independent determinations is less than 0.75% for 0.2 and 1.0 mL of sample volumes used, and 1.31% for 2.0 mL of sample volume used. The method was satisfactorily applied to the determination of vitamin B6 in pharmaceutical preparations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051186
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  • 6
    Electronic Resource
    Electronic Resource
    Determination of ascorbic acid by use of a flow-through solid phase UV spectrophotometric system (1999)
    Springer
    Fresenius' journal of analytical chemistry 363 (1999), S. 92-97 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A continuous flow-through solid phase spectrophotometric system was developed for the determination of ascorbic acid based on the measurement of its intrinsic absorbance in the UV region when retained on a 1 mm Sephadex QAE A-25 anion exchanger gel layer which is placed into an appropriate quartz flow-through cell, the absorbance exhibited by this solid phase being monitored at 267 nm. A monochannel manifold was used, the sample (300, 600 or 1000 μL) being injected into the carrier solution (acetate buffer). This solution also elutes the analyte after developing the analytical signal, and regenerates the resin layer which, therefore, remains ready for the next sample. The linear dynamic range and other analytical parameters vary according to the sample volume injected. Three calibration lines were established for 300, 600 and 1000 μL sample volume, which ranged from 1.0 to 20.0, 0.5 to 10.0 and 0.2 to 6.0 μg mL–1, respectively. The detection limits were 0.04 (300 μL), 0.03 (600 μL) and 0.02 μg mL–1 (1000 μL), the sampling rates 28, 24 and 21 h–1, and the RSDs (n = 10) 0.87%, 1.08% and 0.90%, respectively. The amount of ascorbic acid in various samples (pharmaceuticals, sweets and urine) were successfully determined with this method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051144
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  • 7
    Electronic Resource
    Electronic Resource
    An integrated reaction-retention and spectrophotometric detection flow system for the determination of nickel (1999)
    Springer
    Fresenius' journal of analytical chemistry 363 (1999), S. 59-63 
    Details
    ISSN: 1432-1130
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract An integrated flow-through photometric sensor for the determination of nickel in real samples of various origins has been developed. The sensor is based on the reaction of Ni(II) with 1-(2-pyridylazo)-2-naphthol (PAN) immobilized on a cationic resin which was placed in a flow-cell using a spectrophotometer tuned at 566 nm as detector. The Ni(II) ion from the sample injected into the carrrier stream (pH = 5.0) of a monochannel continuous flow system reacts with the immobilized chromogenic reagent to form a red chelate which remains on the active solid support and generates the analytical signal. When this reached its maximum value the Ni(II)-PAN chelate was destroyed using 1 M H2SO4 as eluents, leaving the sorbed PAN untouched. The response of the sensor was linear in the three concentration ranges assayed: 0.3–4.0, 0.1–1.6 and 0.05–0.8 μg mL–1 for sample volumes of 100, 400 and 800 μL, respectively, and the R.S.D.(%) (n = 10) were 1.80(100 μL), 3.04(400 μL) and 2.29(800 μL). The sensor showed an excellent selectivity which could also be increased with a simple on-line modification to avoid interference from copper. It was applied to a variety of real samples with very good results in all cases.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002160051138
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  • 8
    Electronic Resource
    Electronic Resource
    Sensitive Determination of Adrenaline by Means of a Flow-Through Solid Phase UV Spectrophotometric Sensing Device (2000)
    Springer
    Microchimica acta 134 (2000), S. 101-105 
    Details
    ISSN: 1436-5073
    Keywords: Key words: Adrenaline; flow-through optosensor; pharmaceuticals.
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract.  A very sensitive flow-through optosensor with solid phase UV spectroscopic detection is proposed for the direct determination of adrenaline without prior derivatization. Sample is transported by the carrier stream (0.05 M NaCl/0.01 M NaOH) to the sensing microzone composed of Sephadex QAE A-25 resin placed in a flow-through cell, and its intrinsic absorbance is monitored at 287 nm. After development of the analytical signal adrenaline is easily and quickly desorbed from the solid support by a 0.7 M NaCl/0.01 M NaOH eluting solution stream. Adrenaline can be determined in the range 1–12 μg/ml, the detection limit being 0.17 μg/ml. The RSD (10 replicates) and sample throughput are 1.4% and 12 per hour, respectively. The procedure has been successfully applied to the determination of adrenaline in different medical formulations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s006040070061
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  • 9
    Electronic Resource
    Electronic Resource
    Determination of tungsten with pyrocatechol violet by first-derivative solid-phase spectrophotometry (1994)
    Springer
    Microchimica acta 112 (1994), S. 225-235 
    Details
    ISSN: 1436-5073
    Keywords: solid-phase spectrophotometry ; derivative spectrophotometry ; pyrocatechol violet ; tungsten determination ; natural and industrial waters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Derivative spectrophotometry was applied to solid-phase spectrophotometry in order to enhance its sensitivity and remove the large background caused by the absorbance of the resin layer. Determination of micro-amounts of tungsten with pyrocatechol violet to form a 2∶1 green complex in acid medium which is fixed on a dextran-type anion-exchange resin (Sephadex QAEA-25) is described as an example for the application of this technique. The absorbance of the resin packed in a 1-mm spectrophotometric cell, was measured directly. The characteristic peak amplitude of the signal at 674 nm in the first-derivative spectrum is useful for quantitative determination of tungsten (3–16 μg 1−1; RSD 5.8%) in natural and industrial water samples.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01242838
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  • 10
    Electronic Resource
    Electronic Resource
    Extractive-spectrophotometric determination of manganese(II) using 3-bromobenzohydroxamic acid as chelating agent (1992)
    Springer
    Fresenius' Zeitschrift für analytische Chemie 344 (1992), S. 30-33 
    Details
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A new extractive spectrophotometric method is described for determining trace amounts of Mn(II) based on its reaction at pH 10.2 with 3-bromobenzohydroxamic acid (3BrHA) and subsequent extraction into Adogen 464 in toluene. The apparent molar absorptivity of the 1:3:1 (Mn:3BrHA:Adogen 464) complex is 8.7×103 l·mol−1 cm−1 at 450 nm. Beer's law is obeyed from 0.5 to 6.0 mg·1−1 of Mn(II) in the aqueous phase with a C.V. of 1.2%. The detection limit is 0.18 mg·1−1. The method has been successfully applied to the determination of manganese in standard steel samples, natural water samples and plant material.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00324837
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