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Biomedical subjects

S N Tan

Publications and source records attributed to S N Tan.

8 recordsLinked to original sources
PubMed2001

Separation of kaempferols in Impatients balsamina flowers by capillary electrophoresis with electrochemical detection.

Capillary electrophoresis with wall-jet amperometric detection was used to detect kaempferol and its derivatives kaempferol-3-glucoside, kaempferol-3-glucosylrhamnoside and kaempferol-3-(p-coumaroyl)glucoside. The influence of buffer pH on separation was investigated and optimized. With a phosphate buffer at pH 7.5, nearly complete separation of the four kaempferols was achieved according to their different electrophoretic mobilities. The detection potential was also evaluated and optimized. At detection potential of +0.80 V vs. saturated calomel electrode, an amperometric response with high sensitivity and stability was obtained for these four compounds. Detection limit estimated for all the kaempferols examined was less than 1.4 fmol, based on S/N=3. The use of this method for the separation and detection of these compounds present in balsam flowers (Impatiens balsamina) is reported.

Electrochemistry↗
PubMed2000

Applications of a versatile sol-gel derived renewable electrode for capillary electrophoresis.

A new electrode has been developed and applied for amperometric detection in capillary electrophoresis (CE), comprised of carbon sol-gel composite material. The versatility of the sol-gel technique permits the flexible configuration of the electrode. The performance of such a sol-gel carbon composite electrode (CCE) is first evaluated in a typical CE application for the detection of purine-based compounds. Application of the CCE is also demonstrated for the detection of phenolic compounds in a micellar system. Separation resolution for non-ionic phenolic compounds can significantly be enhanced by introducing sodium dodecyl sulfate (SDS) at a concentration above its critical micelle concentration (cmc) to the buffer. Another design of the CCE incorporating the electrocatalyst Cu2O is employed for the analysis of sugars and organic acids based on dynamic modification with cetyltrimethylammonium bromide (CTAB). It has been found that the presence of surfactant in the separation buffer does not adversely influence the electrochemical detection using a sol-gel derived carbon electrode.

Journal Article↗
PubMed1998

Outlining the prostate boundary using the harmonics method.

In a computerised ultrasound image guidance for automated prostatectomy system, it is necessary to identify a smooth, continuous contour for the prostate (boundary) from the ultrasound image. The radial bas-relief (RBR) method, which has been reported previously, can extract a skeletonised image from an ultrasound image automatically. After this process the prostate boundary is clearly revealed. However, analysis of the image is far from complete, as there are many spurious branches that create too much ambiguity for the system to define the actual boundary. There are also sections missing from the prostate boundary. Therefore further post-processing is required to describe and define the prostate boundary. In the paper, the harmonics method is used to describe the prostate boundary. The harmonics method uses Fourier information for noise removal and encodes a smooth boundary. The results of using the harmonics method after application of the RBR method on ultrasound images are presented. Factors that affect the performance are also highlighted and discussed.

Fourier Analysis↗
PubMed1990

Voltammetric determination of platinum in inorganic complexes and in water, geological and biological matrices using laboratory- and field-based instrumentation.

The extremely sensitive catalytic hydrogen ion reduction wave observed after the formation of a platinum-formazone complex at a mercury electrode in a hydrazine-formaldehyde-H2SO4 medium has been utilised to determine platinum voltammetrically in well characterised platinum inorganic complexes (oxidation states O, II and IV) and in biological, geological and water samples. Experimental conditions have been optimised and sample-treatment procedures for various matrices have been critically evaluated for the quantification of platinum by the standard additions method. The determination of platinum in geological samples by this method has been compared with an inductively coupled plasma mass spectrometric method. Both conventional and portable field-based instrumentation have been used in the studies, and the possibility of developing a field-based method for the determination of platinum has been investigated. Despite the inherent sensitivity of the method, which enables concentrations down to 0.01 p.p.b. to be detected in simple matrices, natural levels in water and biological materials, where matrix effects suppress the voltammetric response, are often below the detection limit.

Animals↗