Small-molecule analytes

Most GPC columns are provided with vendor estimates of the plate count of the column and a chromatogram of a series of test peaks. These plate count estimates are usually obtained using small molecule analytes that elute at the total permeation volume (Vp) of the column. The Gaussian peak shape model... 

Like FRET, today BRET is predominantly used in biological sciences, especially in the monitoring of protein-protein interactions such as hormone-receptor interaction [223, 224] and protein-DNA interaction in living systems. However, BL resonance energy transfer can also be applied in immunoassays by using for instance a peptide-tagged luciferase and a fluorescein-labeled antipeptide antibody [225]. The development of more BRET assays for small-molecule analytes is thus awaited. 

In some cases, the NMR signals of a small-molecule analyte might be broad and poorly resolved because of a chemical exchange process, for example,... 

CSP, CMPA Newly Designed Small Molecules analytical to preparative excellent to moderate... 

A modem TOF instrument may well provide adequate resolution to allow quantification of small-molecule analytes, but examples in the literature report limited dynamic range. The latest TOF instruments provide for improved dynamic range in quantitative applications, but there are still other critical obstacles. These include sample preparation, selection of an internal standard, instrumental protocol, and... 

For small molecule analytes (see Note 6) for which a radiotracer form is available, sequentially load a known quantity of tracer dissolved in buffer and determine the amount of analyte in the eluant. When the radioactivity not retained by the immunoaffinity column plateaus, the column binding sites are saturated. Wash the column, and elute the retained radioactivity. The mass of analyte in the eluted volume is the apparent column capacity. In many instances a radio-labeled analyte may not be available. In such cases, high-performance liquid chromatography, UV spectroscopy, or any other analytical tool capable of selectively quantifying the analyte may be used to determine column capacity. 

Linhares MC, Kissinger PT. Capillary ultrafiltration in vivo sampling probes for small molecules. Analytical Chemistry 1992, 64, 2831-2835. 

No examples for quantification in the product ion scan mode were found in the literature even though data processing would allow extraction of selected ions, integration of related signal areas, and summation for quantification. This procedure has been used by John et al. for the determination of the human haemoglobin derived peptide hHEM-y 130-146 in plasma [102], However, quantification especially of small molecule analytes is best performed in the MRM mode that is addressed below. 

Tiller PR, Romanyshyn LA, Neue UD (2003) Fast LC/MS in the analysis of small molecules. Analytical and Bioanalytical Chemistry 337 788-802... 

Number of antibodies that can be produced is practically unlimited, hence wide development of immunoassays not only for determination of macromolecules, which induce immunoreactions, but also for small molecule analytes inducing such reaction after binding into suitable conjugates. Besides immunoassays carried out in various formats and immunoaffinity liquid chromatography, since many years very broad studies are carried out on design of integrated immunosensors.127129 In principle their construction should simplify the immunochemical determination by elimination various steps necessary in conventional immunoassays based on the use of labels to monitor the immunochemical reaction. In immunochemical process, the... 

Chan LL, Cunningham BT, Li PY, Puff D (2007) Self-referenced assay method for photonic crystal biosensors application to small molecule analytes. Sensors Actuators B Chem 120 392-398... 

For small molecules, the immune response is often small or nonexistent [the immune system has evolved to deal with larger invaders such as bacteria]. However, the scientist can still use the immune system of a laboratory animal to produce antibodies to small molecule analytes (S) he need only first chemically couple the analyte to a larger molecule, a carrier protein. The analyte is now known as a hapten (Fig. 2). Only a minority of the antibodies produced may be selective for the hapten, rather than the carrier protein, but the number still usually exceeds that which can be obtained by injecting the analyte alone [13]. 

---