Assays, tests, assessment methods selectivity

Adoption of standard methods also allows gathering of extensive knowledge and validation of the methods. The method validation can initially be comprehensive including long-term buffer shelf life, instrument-to-instrument type transfer, analyst-to-analyst repeatability and extensive robustness testing. If the standard method is applied to a new solute then validation is limited and may only need to include assessment of injection precision, linearity, sensitivity, etc., which can be obtained relatively quickly and simply. Internal standards are widely used in CE to improve injection precision and to compensate for solution viscosity differences, which may unduly affect assay results. Standard internal standards can be used for specific methods, which avoids additional work selecting an appropriate choice. 

Plants also have potential for demographic testing. Sheppard et al. (1993) proposed a 35-day test with Brassica rapa. Comparison of the results with a suite of assays in metal-spiked soils indicated that bloom initiation was more sensitive than lettuce emergence or earthworm survival for zinc but not mercury. Saterbak et al. (1999) used this test for the assessment of hydrocarbon-contaminated soil. The study, which used Brassica rapa selectively bred to reduce generation time, proved unsuccessful due to low germination in the control soil, suggesting that there is still a need for further method development. 

The in vitro assessment of NM toxicity mechanisms requires a careful selection of the test method, and it is generally agreed that the conventional and well-established protocols used to test chemical or pharmaceutical compounds should be employed with caution and often adapted when applied for NMs. There are several problems that can arise when using these conventional in vitro assays, including ... 

To validate SOP 123 for measuring mass of Product W, the quantitative method performance characteristics of accuracy, precision, linearity, and range will be assessed using the validation assays shown in the design matrix over two days and using two operators. As per ICH guideline Q2A, the validation experiments will be run from 40 pg to 180 jUg. The test lot will be diluted out and concentrated up to specific expected masses using the mass cited on certificate of analysis for the lot of Product W selected for the validation. The points on the Product W curve will be as follows 40 /xg, 50 /xg, 70 /xg, 90 /xg, 110 /xg, 130 pg, 150 pg, and 180 pg. 

The antiviral activities of the test compounds/extracts are measured with the CPE inhibition assay (Liu et al. 2008b). Viral suspension (200 TCIDj ml, 100 pi) is added to each well of a 96-well plate containing a confluent cell monolayer. After incubation at 37°C for 2 h, the virus solution is removed, and 100 pi of consecutive threefold serial dilutions of the test compounds/extracts and reference compounds are added to each well, using the MNCC as the highest concentration. An infection control without samples is also included. The plates are incubated at 37°C in a humidified CO atmosphere (5% CO ) for 24 h, after which the CPE is assessed. The virus-induced CPE is scored as follows 0=no CPE, 1=0-25% CPE, 2=25-50% CPE, 3 = 50-75% CPE, and 4 = 75-100% CPE. The reduction in virus multiplication is calculated as a percentage of the virus control (% virus control = CPE Z 100). The IC, of the CPE with respect to the virus control is estimated using the Reed-Muench method. The selective index (SI) is calculated as the ratio CC /IC... 

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