Homogeneous methods

Homogeneous TR-FIAs have been reported in which proprietary lanthanide chelates are used. In a homogeneous immunoassay for T4, a fluorescent europium chelate coupled to thyroxine is quenched by antibody binding. 90 A similar approach is used for estrone-3-glucuronide. 91 TRFIAs based on homogeneous methods have not yet become widely used. 

Another effective, homogeneous method for the quantitation of kinase activity that requires neither antibodies nor solid phase is the use of a second adenosine triphosphate... 

Number/sex/group age at start of study Animal housing Formulation/vehicle Drug stability/homogeneity Methods Doses... 

Some researchers have used approximate microscopic descriptions to develop more rigorous macroscopic constitutive laws. A microstructural model of AC [5] linked the directionality of mechanical stiffness of cartilage to the orientation of its microstructure. The biphasic composite model of [6] uses an isotropic fiber network described by a simple linear-elastic equation. A homogenization method based on a unit cell containing a single fiber and a surrounding matrix was used to predict the variations in AC properties with fiber orientation and fiber-matrix adhesion. A recent model of heart valve mechanics [8] accounts for fiber orientation and predicts a wide range of behavior but does not account for fiber-fiber interactions. 

Extensive progress has been attained in determination techniques. Noteworthy is the broad applicability of a homogenic method known as the TRACE method (time-resolved amplified cryptate emission). Another interesting solution, TSA (tyramide signal amplification), employs a technique which amplifies the tyramide signal (Bednarski and Reps, 2003). 

The availability of anti-phosphotyrosine antibodies, anti-phosphopeptide antibodies, and antibodies to fluorescent ADP analogs enabled the performance of several homogeneous methods using fluorophores including TR-FRET and fluorescence polarization (FP). 

Base-catalysed reactions such as the Knoevenagel, Michael and aldol reactions continue to be of importance in industrial routes to synthetic chemicals and are often inherently clean, with water (or nothing) as the by-product. Traditional homogeneous methods of catalysis often require upwards of 40 mol% catalyst (such as piperidine) with the attendant difficulties in recovery and reuse of the catalyst. They often offer extremely poor selectivity to the desired products, either due to competing processes (side reactions) or further reaction of the first-formed product. 

In fact, it is worthwhile to note that all these homogeneous methods were developed in the 1970s and early 1980s with a targeted application in automated diag-... 

Asakuma, Y., Miyauchi, S., Yamamoto, T., Aoki, H., Miura, T. (2004). Homogenization method for effective thermal conductivity of metal hydride bed. Int.. Hydrogen Energy 29, 209-216. 

When 9-anthryldiazomethane and the polymer have a common solvent, the homogeneous method is the most convenient one, since it ensures the highest yield and leads to the most homogeneous distribution of LM in the polymer (in the case when the contents of carboxylic groups in macromolecules greatly exceeds the required amount of LM) ... 

The molecular size of an alcohol and the steric bulkiness around a hydroxyl group of the alcohol are expected to influence the rate of the benzylation reaction on zeolite. In this respect, the benzylation of five primary alcohols of different sizes was studied by use of K Y (heterogeneous conditions) in comparison with the results obtained by a conventional, homogeneous method [sodium hydride and benzyl bromide in tetrahydrofuran (THF)], as shown in Table III. The steric hindrance around the hydroxyl groups of the alcohols examined was estimated by use of Corey-Pauling-Koltun (CPK) molecular... 

Table XX clearly demonstrates that the catalytic function of Al-Mont is far superior to that of homogeneous acid systems. Table XXI shows that a variety of silyl ketene acetals and enoates are applicable to the montmoril-lonite-catalyzed reactions. In particular, successful additions of silyl ketene acetal to ot,p- or, -disubstituted acrylates should be noted because these disubstituted acrylates were reported to be unreactive to lithium enolates of esters (an existent homogeneous method) (79). The Michael addition to enones was also achieved by the use of Al-Mont as shown in Table XXII.

Enzyme-Multiplied Immunoassay Technique. EMIT is a homogeneous method for the quantitation of haptens, especially hormones, therapeutic drugs, and drugs of abuse. This method is a competitive assay, in which hapten and enzyme-labeled hapten compete for a fixed, insufficient quantity of antibody (Eq. 6.16). 

Most studies of interference have been fairly traditional and relatively modest.Evaluations indicate that triglycerides below 900mg/dL do not generally interfere with any of the methods and some methods are reportedly free of interference to nearly 2000mg/dL. Hemoglobin below 2g/L and bilirubin below lOmg/dL do not interfere appreciably with any of the homogeneous methods. 

---