IVDT_In Vitro Diagnostics Technology

IVD Technology, Fall 2013

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MANUFACTURING High assay reproducibility Average peak area Low assay reproducibility 6 6 5 5 4 4 3 3 2 2 1 1 0 700 7 0 0 1 2 3 4 5 Avg. Peak Area 7 800 600 500 400 FF120HP (7A/R) 300 FF120HP (7A/S) 200 FF120HP (7A/Q) 100 0 0 0 1 2 3 4 5 2 4 6 8 10 [Myoglobin] ng/ml Figure 2. Effect of reproducibility on assay detection limit. Figure 4. Intra-lot variability of FF120HP based on testing of The high reproducibility assay (left) has a lower detection limit than a low reproducibility assay (right). three rolls from the same casting lot. High assay reproducibility not only improves the distinction between clinically relevant results and assay variability, but also has an efect on an assay detection limit. A common practice is to establish the limit of detection at a point that is three standard deviations above normal assay variability. Figure 2 shows the efect of assay reproducibility on assay detection limit. Tere are many factors that can infuence the performance of a test. Temperature diferences can alter the assay kinetics; procedural errors, such as those associated with timing and dispensing, contribute to assay variability. Other factors including assay components, manufacturing processes, and reagent variation also contribute to assay precision. It is important to note that assay reproducibility is the cumulative efect of individual sources of variability. Technological advances have enabled manufacturers to develop assays with improved reproducibility and simplicity since the early days of diagnostic testing. Tests that once required hours or days to complete can now generate results in minutes. Today, automated assay platforms have replaced repetitive manual operations and eliminated many causes of procedural errors. Engineering advances, combined with components developed specifcally for diagnostic applications, have not only contributed to increased assay performance, but have also enabled tests to Average peak height (mV) Average peak heights 900 800 be performed in a variety of settings ranging from central laboratory environments to in-home testing to remote feld locations. Under ideal situations, a developer would assess test reproducibility under the actual conditions of fnal use. However, in many instances, assessing test reproducibility under conditions of actual use is neither practical nor possible. Tis is especially true for tests intended for in-home and feld use. Instead, manufacturers rely on a combination of robust assay design, manufacturing methods, and multiple inprocess and fnal quality control procedures to assess and ensure reproducibility. Assays intended for decentralized analysis, such as inhome and remote test settings, have an additional simplicity requirement as they are often performed by individuals with little or no technical training. One test platform especially suited for use by nonprofessionals is the lateralfow assay (LFA). LFA reproducibility is not only infuenced by design and manufacturing, but also by the components used in the assembly of the test. Te most critical component in these types of assays is the reaction membrane, which is typically a nitrocellulose membrane. With the need for more-sensitive assays and the reporting of quantitative results, the consistency of the LFA reaction membrane has a signifcant impact on the performance of the fnal test. Nitrocellulose membranes are manufactured by dissolving the raw materials in a mixture of organic solvents and 700 500 FF120HP (7A/Q) 400 Membrane 300 200 FF120HP (7A/Q) 100 0 0 2 4 6 8 10 [Myoglobin] ng/ml Figure 3. Average peak heights of FF120HP (roll 7A/Q). [Myoglobin] ng/ml Average peak height SD % CV 0 600 0 0 N/A 0.25 107 11 10.5% 2.5 10 579 822 28 33 4.9% 4.1% Table I. ESEQuant reader results of colloidal gold myoglobin assay using a constant amount of anti-human myoglobin antibody per test. 16 IVD TEC HNOLO G Y | FA L L 2013 magenta cyan yellow black ES323919_IV1309_016.pgs 09.24.2013 06:18 UBM

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