Interference testing

Keywords reducing uncertainty, cost-effective information, ranking sources of uncertainty, re-processing seismic, interference tests, aquifer behaviour, % uncertainty, decision tree analysis, value of information, fiscal regime, suspended wells, phased development. 

In general, the attempt to retest every compound that passes a statistically defined threshold of activity for each assay and to implement a concomitant assay interference test has been rewarded by recovery of a full spectrum of biological activities and diverse chemotypes in the confirmed hit set. In many cases, the compounds that the medicinal chemists ultimately judge to be the best starting points for lead development exhibited only modest activity (e.g., IC50 values of 0.5-5 pM) in HTS. 

Table I. Compounds Selected for Interference Testing in the Development of Analytical Procedures for the Three Chlorocarbons...

Various direct and indirect methods are generally used to determine the permeability of a sedimentary basin. The direct methods include laboratory measurements on core samples wire-line formation tests, single-well tests and interference tests. The data from the different types of well test and interference test can be analysed and interpreted by well-established procedures (Da Prat, 1990 Earlougher, 1977 Kruseman et al., 1990 Matthews and Russel, 1967). The conventional, indirect methods are theoretical, semi-empirical and empirical procedures which are based on the relation between permeability, grainsize characteristics and porosity (e.g. the Kozeny-Carman method, Domenico and Schwartz, 1990 Van Baaren method. Van Baaren, 1979). The laboratory methods and the conventional indirect methods provide permeability values which are representative of only a very small portion of the subsurface (cm-scale). The single-well test and interference test provide information representative of a larger volume of the subsurface (m - km scale). 

Zung Huinong, 1984. Interference testing and pulse testing in the Kenli carbonate oil pool - a case history. J. Pet. Technol., 1009-1017. 

Kazemi, H., Seth, M.S. and Thomas, G.W. 1969. The interpretation of interference tests in naturally fractured reservoirs with uniform fracture distribution. SPEJ, 463-427. 

Interferences are of particular importance for devices destined for continuous use in very complex matrices. Biosensors are tested for interferences not just from species that are expected to bind to or react with the particular chemical recognition agent employed the end use of the biosensor is considered, and components of that sample matrix are examined for potential interference. Test assays are conducted in the sample matrix, and compared with results obtained in simple buffers in order to determine analyte recovery. 

NCCLS. Interference testing in cUnical chemistry Approved guideline. NCCLS document NCCLS-EP7-A. NCCLS, Wayne, PA, USA 2002. 

National Committee for Clinical Laboratory Standards (CLSI) Document EP5 A Evaluation of Precision Performance of Clinical Chemistry Devices Approved Guideline. 1999 Document EP6 P Evaluation of the Linearity of Quantitative Analytical Method Proposed Guideline. 1986 Document EP7 P Interference Testing in Clinical Chemistry Proposed Guideline. 1986 Document EP9 A Method Comparison and Bias Estimation Using Patient Samples Approved Guideline. 1995. 

A gas phase immunosensor for the detection of cocaine has also been reported [73]. The antibody-coated crystals were used to detect cocaine in air to 0.5 ppb. Responses were observed in 30 s and full recovery was observed in 30 s, indicating a full analysis time of less than 2 min, allowing for base line stabilisation between measurements. Negligible effects were seen from the interferents tested. Coated crystals lasted 3 days without detectable loss in activity. 

EP07-A2. 2005. Interference testing in clinical chemistry, 2nd ed. Approved guideline. EP09-A2. 2002. Method comparison and bias estimation using patient samples, 2nd ed. Approved guideline. 

Figure 4. External circuits of the inverter to the motor segment electromagnetic interference test results.

Generally there is far less evidence of stray current induced corrosion from external sources into atmospherically exposed reinforced concrete structures compared to buried structures generally and far less evidence of stray current induced corrosion in buried or submerged concrete compared to buried or submerged steel, as concrete has much higher electrical resistance. However, it can occur and can be tested for in the same manner as for other metalwork. There is discussion of interference testing for stray currents in NACE RP0169-2002 and in BSEN 13509 2000. 

Plasma collection tubes with a variety of additives are commercially available (e.g., heparin, EDTA, sodium citrate). These additives have the potential to cause interference with some analytical assays. Thus, interference testing should be performed prior to implementing sample collection procedures. It should be noted that the collection tubes intended to generate plasma contain the optimal amount of the appropriate additive for the indicated sample volume. If tubes are not filled to this indicated volume, the concentration of additive will be higher than recommended and could pose problems during downstream analysis. After collection, sample tubes should be mixed by gentle inversion several times to ensure proper mixing of additive with the blood. 

Bassen HI, Moore HJ, Ruggera PS. Cellular phone interference testing of implantable cardiac defibrillators in vitro. Pacing Clin Electrophysiol 1998 21 1709-1715. 

EPRI TR-102323, 1994, "Guidelines for electromagnetic interference testing in power plants. USNRC Generic Communications CR 77-06, IN 83-83, IN 92-01, IN 92-12, IN 93-33. 

To address these interferences, test specimens could be prepared with fatigue precracking and the measurements made at small, defined crack extensions. However, the additional effort is significant and was considered too substantial for the first version of the standard. Instead, the effort was focused upon consistency and accuracy between several methods for materials exhibiting little crack growth resistance. C 1421provides warnings to alert the user to this interference. 

Reservoir sand continuity (<400 m) Well to well connectivity Loss of injection benefits Use of tracer and better defined geoiogy. Tracer test. Monitor return production of oii and poiymer. BHP response, interference test... 

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