Ce And Immunoassay

Many drugs, such as tacrolimus and digoxin, remain far below the detection limits of CE or HPLC without extraction and subsequent concentration. In response to this limitation, Chen and Evangelista (79,80) described a method that has potential for better sensitivity along with simultaneous detection of several drugs. This method is based on a combination of immu-noassay, laser-induced fluorescence (LIF), and CE. In this system, fluorescent-labeled drug conjugates antibodies of known specificity and the unknown samples were mixed. After the reaction is completed, CE separates the free drug (including the fluorescent-labeled drug) from the bound. The quantity of drug in the unknown sample that can be estimated from a standard curve established using the same methodology. Cortisol, an endogenous substance and a drug, has also been quantitated using a similar approach (81,82).

Recently, Steinmann and Thormann (83) described an assay using MEKC, LIF, and commercial Fluorescence Polarization Assay reagents to separate a variety of drugs. The free and bound tracers for the different drugs were separated in phosphate-borate buffer containing SDS. The feasibility of simultaneous determination of several drugs was also demonstrated. A similar method was also described for the analysis of digoxin using the commercial reagent from an enzyme immunoassay kit (84). Additionally, Chiem and Harrison (85) described a microchip CE method to separate the reaction products of a reaction of an antibody and theophylline within approx 40 s. The buffer system consisted of tricine, pH 8.0, with 0.01% (w/v) Tween 20, and 40 mM NaCl, allowing adequate separation for theophylline and for the theo-phylline-antibody complex. Reproducibility of migration times was 1-1.5%.

Coping with Asthma

Coping with Asthma

If you suffer with asthma, you will no doubt be familiar with the uncomfortable sensations as your bronchial tubes begin to narrow and your muscles around them start to tighten. A sticky mucus known as phlegm begins to produce and increase within your bronchial tubes and you begin to wheeze, cough and struggle to breathe.

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