ASTM D 6091 : 2007 : R2014

1.3.1Routinely Achievable IDE Value—Most laboratories are able to attain the IDE detection performance in routine analyses, using a standard measurement system, at reasonable cost. This property is needed for a detection limit to be practically feasible. Representative laboratories must be included in the data to calculate the IDE.

1.3.2Routine Sources of Error Accounted For—The IDE should realistically include sources of bias and variation which are common to the measurement process. These sources include, but are not limited to: intrinsic instrument noise, some typical amount of carryover error, plus differences in laboratories, analysts, sample preparation, and instruments.

1.3.3Avoidable Sources of Error Excluded—The IDE should realistically exclude avoidable sources of bias and variation, that is, those which can reasonably be avoided in routine field measurements. Avoidable sources would include, but are not limited to: modifications to the sample, measurement procedure, or measurement equipment of the validated method, and gross and easily discernible transcription errors (provided there was a way to detect and either correct or eliminate them).

1.3.4Low Probability of False Detection—The IDE is a true concentration consistent with a measured concentration threshold (critical measured value) that will provide a high probability, 99 %, of true nondetection (a low probability of false detection, α = 1 %). Thus, when measuring a blank sample, the probability of not detecting the analyte would be 99 %. To be useful, this must be demonstrated for the particular matrix being used, and not just for reagent water.

1.3.5Low Probability of False Nondetection—The IDE should be a true concentration at which there is a high probability, at least 95 %, of true detection (a low probability of false nondetection, β = 5 %, at the IDE), with a simultaneous low probability of false detection (see 1.3.4). Thus, when measuring a sample at the IDE, the probability of detection would be at least 95 %. To be useful, this must be demonstrated for the particular matrix being used, and not just for reagent water.

1.4.1Sample Preparation, and calibration standards do not have to go through sample preparation.

1.4.2Differences in Analysts, and analysts have little opportunity to affect calibration results (such as with automated calibration).

1.4.3Differences in Laboratories, for whatever reasons, perhaps difficult to identify and eliminate.

1.4.4Differences in Instruments(measurement equipment), which could take the form of differences in manufacturer, model, hardware, electronics, sampling rate, chemical processing rate, integration time, software algorithms, internal signal processing and thresholds, effective sample volume, and contamination level.