Specificity commercial assay kits

The assay microorganisms in Polytox are a blend of bacterial strains originally isolated from wastewater [48]. The Polytox kit (Microbiotest Inc., Nazareth, Belgium), specifically designed to assess the effect of toxic chemicals on biological waste treatment, is based on the reduction of respiratory activity of rehydrated cultures in the presence of toxicants. The commercially available kit is specihcally designed for testing wastewaters. Quantative results can be obtained in just 30 minutes. 

Depending on the isotype (i.e. class/subclass and kind of light chain), immunoglobulin molecules will display a particular biological property and will require an appropriate method for purification. The identification of mAb isotypes generally employs the culture supernatants of hybridomas and commercially available kits for the specific immunoenzymatic assays. This knowledge about the specific isotype facilitates the selection of the purification process in the next step. 

Beta-endorphin is a frequently measured opioid peptide. Immunoassay is the method of choice for the analysis of plasma (3-endorphin. Both RIAs and direct IRMAs have been developed for this purpose. Commercial reagent kits are widely available, and many commercial reference laboratories offer P-endorphin assays. The concentrations of P-endorphin are usually very low to undetectable in normal subjects, and it may be necessary to use extraction procedures to detect meaningful concentrations in plasma. The specificity of commercial antibodies for p-endorphin relative to p-LPH varies widely in some immunoassays, 50% cross-reactivity is seen with p-LPH. With polyclonal antibodies, results may be spuriously high owing to crossreactivity with serum immunoglobulin G (e.g., in patients with immunoglobulin G myeloma). 

Several uptake kits are commercially available, Tg uptake values for individual subjects depend on specific assay conditions such as incubation time and temperature, quantity and avidity of the binding material, and specific activity and choice of the label. To compensate for variations in uptake values, the percent uptake for each unknown should be determined by comparison with a calibrator, reference material, or euthyroid reference serum of Imown percent uptake. Almost aU commercial assays determine the percent uptake... 

Even if a kit is not specifically designed for animal usage, or is specifically designed for a particular species, it is possible that the manufacturers have data to support the use of their kit with different species. Some suppliers do provide information on species cross-reactivity and some also provide a complete list of their kits that can be used in other species. When selecting a kit for different species, it may be advisable to search for a species-specific kit. The main reason for using a species-specific kit is that it ensures reactivity of the analyte with assay key reagent(s) and it is likely that there will be fewer problems with matrix effects. Ifa species-specific kit is not available, a search of the literature can be performed to investigate whether other researchers have used specific commercial kits, that is, to obtain information on potential cross-reactivity and so on. 

A wide variety of commercial LFIA kits for the detection of antibiotic residues is available and the most well-characterised of these are summarized in Table 5.4, including the rapid one-step assay (ROSA) range from Charm Sciences Inc., and the Tetrasensor, Twinsensor, Trisensor, and Sulfasensor from Unisensor SA and the Betastar from Neogen Corporation. Other LFIA assays have been reported in the scientific literature for the detection of antimicrobial residues, including a lateral-flow device for nicarbazin detection in animal feedstuffs. However, at present these are not commercially available. These LFIA tests incorporate either a receptor protein or an antibody as the specific capture molecule and operate in the competitive assay format (most applicable for small-molecule detection). The sample preparation protocols are based on either direct analysis of the liquid sample (e.g., milk) or a simple extraction step for solid or complex matrices using buffer(s) supplied in the test kit. In general, the time required to perform these tests is less than 30 min with only basic laboratory equipment, if any, required. 

Calculation The isomers of lactic acid are quantified using commercially available assay kits that rely on enzymes specific for either D- or L-lactic acid and a spectrophotometer. 

The intensive research carried out to achieve good stability and easy handling of the BL reagents allowed development of many simple, rapid, highly sensitive and specific assays, many of which are available as commercial kits. More recently application of the newest techniques of molecular biology greatly accelerated the continuous improvement of BL assay performance. 

Finally, MAbs and an immunoassay kit for LAS have been commercialized (see Table 3). The working range of the assay is between 20 and 500 pg L1. The antibodies are highly specific for LAS with alkyl chains between C8 and C12, whereas other anionic and nonionic surfactants tested showed no cross-reactivity. 

Finally, there are custom two-step quantitation methods such as chromatography or ELISA that require a capture step for isolating the protein and then a quantitation step based on a standard curve of the purified target protein. The preliminary capture step may also concentrate the protein for increased sensitivity. These techniques are typically not available in a commercial kit form and may require extensive method development. They are more labor intensive and complex than the colorimetric or absorbance-based assays. In addition, recovery of the protein from and reproducibility of the capture step complicate validation. Despite these disadvantages, the custom two-step quantitation methods are essential in situations requiring protein specificity. 

Hapten-labeled DNA probes for FISH assays can be used for BISH assays and those probes can be purchased from various vendors. If commercial hapten-labeled DNA probes are not available, DNA probes can be labeled with haptens by nick translation or by PCR in a laboratory. Nick translation kit can be utilized for labeling DNAprobes with hapten (10976776001, Roche Applied Science, Germany). New probes must be analyzed for the specificity by FISH or BISH assays using a comparative genomic hybridization metaphase control slide. 

---