ALBERT

All Library Books, journals and Electronic Records Telegrafenberg

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 2
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 3
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 4
    ISSN: 1618-2650
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A determination method for traces of copper by Solid-Phase Spectrophotometry (SPS) has been developed. It is based on the fixation of copper(II) as 4-(2-pyridylazo)resorcinol complex on a styrene-divinylbenzene anion-exchange resin. The resin phase absorbances at 525 and 800 nm are measured directly, and the determination of copper (with a RSD of 1.8%) is possible in the range of 0.3–4.5 μg L−1. The method has been applied to the determination of copper in different samples, i.e. mushrooms, tea, drugs and waters.
    Type of Medium: Electronic Resource
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 5
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
  • 6
    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
    Location Call Number Expected Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...