Biomedical subjects

Zhao-lun Fang

Publications and source records attributed to Zhao-lun Fang.

3 recordsLinked to original sources

PubMed2004

[Studies on sequential injection spectrophotometric system using a reflective flow cell for process analysis].

A reflective flow cell was developed and coupled to a sequential injection system and optical fiber photometric detection system based on emitting diode light source. A multistrand bifurcated optical fiber was coupled with incident light, detector and flow cell. Optical fibers were used to carry light from the electronics unit to a reflective flow-through cell and back. The liquid flow path through the cell is linear with a large exit aperture such that bubbles are not trapped in the optical path. The optical arrangement is such that the incident light crosses the liquid flow orthogonally and is reflected back to the receiver fiber. This arrangement reduces the reflective index sensitivity by an order of magnitude relative to a conventional flow cell. The cell showed good immunity to refractive index and air bubble effects. The chromogenic reaction of chloride ion with mercury thiocyanate-iron(III) was used as a model reaction to optimize the experiment system and check the optical system. The reflectance of the reaction was monitored with blue emitting diode. The linear range was 0-100 mg x L(-1) Cl-. A detection limit (3sigma) of 1.2 mg x L(-1), precision of 1.5% (n = 11), and a throughput of 30 samples per hour were achieved.

English Abstract↗

PubMed2003

[Progress in techniques of interfacing capillary electrophoresis with inductively coupled plasma mass spectrometry].

The coupling of capillary electrophoresis (CE) with inductively coupled plasma mass spectrometry (ICP-MS) has demonstrated multiple advantages, including high separation efficiency, sensitivity and resolution, as well as low sample consumption and detection limit. The technique has been widely used for the speciation of environmental and biological samples. The interface between CE and the nebulizing system of ICP-MS plays a key role in the hyphenation of CE and ICP-MS. The most important factors in the interface design were reviewed in this paper, including electrical connections, nebulizer designs and flow compensation in the nebulizer system. Methods for achieving stable electrical current within the capillary were discussed, including the employment of concentric sheath flow, stainless steel components, platinum wire and silver paint. The structures and performance of various nebulizer designs were reviewed and compared, including the concentric pneumatic nebulizer (CPN), micro concentric nebulizer (MCN), high efficiency nebulizer (HEN), ultrasonic nebulizer (USN) and direct injection nebulizer (DIN). To eliminate nebulizer suction, four compensations systems were suggested, including applying a negative pressure at the inlet of the capillary, putting a sol-gel frit at the outlet of the capillary, pumping an appropriate make-up flow to the interface and adjusting the height of the make-up flow. 35 papers were cited.

Electrophoresis, Capillary↗

PubMed2002

[Studies on a sequential injection renewable surface reflectance spectrophotometric system using a microchip flow cell].

A microchip flow cell was developed for flow injection renewable surface assay by reflectance spectrophotometry. The flow cell was coupled to a sequential injection system and optical fiber photometric detection system. The flow cell featured a three-layer structure. The flow channel was cut into a silicone rubber membrance which formed the middle layer, and a porous filter was inlayed across a widened section of the channel to trap microbeads introduced into the flow cell. The area of the detection window of the flow cell was approximately 3.6 mm2, the volume of the bead trapped in the flow cell was 2.2 microL, the depth of the bead layer was 600 microns. A multistrand bifurcated optical fiber was coupled with incident light, detector and flow cell. The chromogenic reaction of Cr(VI) with 1,5-diphenylcarbohydrazide (DPC) which was adsorbed on trapped Polysorb C-18 beads was used as a model reaction to optimize the flow cell design and the experimental system. The reflectance of the renewable reaction surface was monitored at 540 nm. With 100 microL sample loaded and 1.0 mL.min-1 carrier flow rate, the linear response range was 0-0.6 microgram.mL-1 Cr(VI). A detection limit (3 sigma) of 6 ng.mL-1, precision of 1.5% RSD(n = 11), and a throughput of 64 samples per hour were achieved. Considerations in system and flow cell design, the influence of depth of the bead layer, weight of beads used, and the flow rates of carrier stream on the performance were discussed.

Chromium↗