Commercial assay kits samples

Quality Control Acceptance Criteria Commercial assay kits that also have QC samples supplied will normally contain data on expected target value for each QC sample and usually also expected or acceptable ranges. The procedures used to produce these figures and reasoning behind them can vary widely between different manufacturers and so great caution is required, particularly with R D type kits. It is common to find that these ranges do not have any connection to the actual performance of the assay from a statistical standpoint, and also that they are usually much wider than one may want to accept (or achieve). 

Because of the possibility that the herbicide alachlor could adulterate food if either poultry or livestock consumed contaminated materials, Lehotay and Miller evaluated three commercial immunoassays in milk and urine samples from a cow dosed with alachlor. They found that milk samples needed to be diluted with appropriate solvents (1 2, v/v) to eliminate the matrix effect. One assay kit (selected based on cost) was also evaluated for use with eggs and liver samples from chickens. Egg and liver samples were blended with acetonitrile, filtered, and diluted with water. Linear calibration curves prepared from fortified egg and liver samples were identical... 

C9. Craig, W. Y., Poulin, S. E., Forster, N. R., Neveux, L. M., Wald, N. J., and Ledue, T. B., Effect of sample storage on the assay of lipoprotein(a) by commercial available radial immunodiffusion and enzyme-linked immunosorbent assay kits. Clin. Chem. (Winston-Salem, NC) 38, 550-553 (1992). 

The bead-based technology works not only for inflammatory mediators that have diagnostic/prognostic valne, bnt also for others (e.g., C-reactive protein, IL-6). This can make bead-based systems even more powerful. Kofoed et al. combined in-house and commercially available kits and used bead-based Luminex systems to assay biomarkers of potential interest in EDTA-plasma samples (70). A 3-plex assay for suPAR, sTREM-1, MIF was added to a commercially available human cytokine panel, IL-1P, IL-6, IL-8, GM-CSF, and TNF-a. Compared to healthy controls, all eight analytes were significantly higher in plasma from bacterial sepsis patients. 

LCAT acts preferentially on lipids transported by HDL (so-called a-LCAT activity), but also on lipids transported by apoB-containing lipoproteins (so-called jS-LCAT activity) [58, 85]. In practice, LCAT activity is measured either as the activity required to esterify radioactive cholesterol that has been exogenously incorporated into native HDL or into artificial HDL-like particles (a-LCAT activity) or which has been equilibrated with endogenous lipoproteins of the plasma sample (cholesterol esterification rate, CER) [21, 58, 85]. Several variations of these assays have been reported, some of which are available as commercial test kits (e.g., Roar Biomedical, New York, USA). In addition, LCAT concentration can be determined by either laboratory-made tests or by a commercial ELISA kits [57]. However, the decrease in LCAT concentration is difficult to judge since it also decreases secondary to HDL deficiency due to causes other than LCAT deficiency. Plasma from patients with LCAT deficiency fails to esterify radioactive cholesterol provided by any substrate. By contrast, plasmas of patients with fish-eye disease show a near-normal cholesterol ester-fication rate but have a selective inability to esterify radioactive cholesterol provided to plasma with native HDL or reconstituted HDL (a-LCAT activity) [58, 85]. 

For MG7-Ag, similar results were obtained [32] A direct comparison was carried out with commercially available kits for several tumor markers and an IPCR of MG7-Ag. The IPCR assay detected 81.4% seropositive samples, whereas other tests varied between 48.8% (MG7Ag with IRMA detection) and 33.7% (CEA-RIA) correct identifications of gastric carcinoma patients. IPCR additionally allowed for the discrimination between patients both with... 

Chemiluminescence of oxidized luminol has been the basis of several lumino-metric methods of estimation of TAC (Table 1). The mostcommon is to measure the induction time of the reaction. Often the chemiluminescence is first induced by an oxidant and then attenuated by addition of a sample, and the time to recover the initial fluorescence is measured. The enhanced chemiluminescent assay introduced a decade ago is based on the oxidation of luminol by perborate or by hydrogen peroxide in a reaction catalyzed by horseradish peroxidase. Enhancement (and stabilization) of luminescence is achieved by addition of p-iodophenol. The original procedure used a commercial reagent kit (ECL Anti-oxidant Detection Pack... 

Notes-. Concentrations of tl4 and tTs in sera were determined by radioimmunoassay (RIA) using commercial RIA kits for rat sera or human sera. The effect of a high bromide intake in the dams was more pronounced in their pups, as is evident from markedly decreased concentrations not only of tl4, but also of tTa in the sera of the young whose mothers drank water with the highest bromide concentration. Average values determined in duplicate in three repeated assays in samples from two independent experiments are shown. The values are means SD, n = 3-6. Modified with permission from Pavelka et at. (2002). 

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. 

The cytotoxicity tests were performed with the use of the direct contact method on the extracts obtained by an 8-d incubation of the polymer PSU and PSU/Ag composite samples, placed at the bottom of the well of a 24-well culture plate, in 2 ml of culture mediiun. The incubation was conducted at 37°C in air atmosphere with a 5% content of C02and 100% of relative air humidity. Next, 0.2 ml of ihe obtained extract and its fourfold dilution in a proper culture medium was dosed for the cultures of human osteoblasts (HTB-85 cell line, ATCC, USA) and human fibroblasts (CRL-7422 cell line, ATCC, USA) adhered to the bottom of the well of a 96-well culture plate. In the case of the control test, the extract of the examined samples was replaced by the proper volume of culture medium. The plates were incubated at 37°C in air atmosphere with a 5% content of CO and 100% of relative air humidity. The incubation time for two parallelly conducted experiments was 24 h and 48 h. The cytotoxicity of PSU and the PSU/Ag composites was measured by 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyltetrazolium (MTT) assay [9, 10] and by lactate dehydrogenase (LDH) activity measured with the use of a commercial cytotoxicity assay kit (Roche Diagnostics GmbH, Mannheim, Germany), [11]. Each of the indications was repeated three times. 

Radioassay kits are used extensively in clinical laboratories. Folate values obtained by using the dilferent commercially available kits fluctuate considerably and therefore no absolute values can be given to indicate folate deficiency. Each laboratory has to define its own lower limits based on a large number of sample assays from a representative population of normal subjects (Shane 2011). At present, the microbiological assay using L. casei is one of the best and most versatile methods for the determination of food folate. 

A comparison of the samples fiom southern Sweden using the microformat chemiluminescent assay and a commercially available 2,4-D assay kit from Millipore revealed that six of the samples were foimd to have 2,4-D concentrations in the range 0.06 and 0.1 ng mL and five of the six sanq)les were also positive with the Milhpore... 

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