Blog | quantitativeanalysis

May 22, 2018
2 min

Maybe the Instrument Is No Longer Linear Enough to Be An "8000C"

Purpose: To explore the analytical variability of the 8000C as determined by the Alcohol Test Committee during evaluation of the 8000C prior to type approval. To compare the analytical variability of the individual 8000C used in the subject tests for the client with the analytical variability of the type or class 8000C determined by the Alcohol Test Committee. To suggest that the instrument in the matter before the Court may no longer be a member of that class or type because

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BAC Analysis in a Lab Without Bracketing Controls is at Best Qualitative not Quantitative

Stephen Biss

Apr 27, 2018
1 min

BAC Analysis in a Lab Without Bracketing Controls is at Best Qualitative not Quantitative

Purpose: To obtain an admission that when government scientists conduct a quantitative analysis to determine blood alcohol concentration using blood, urine, or serum, they use positive and negative controls. To obtain an admission from the government scientist that when they conduct such quantitative analysis they use a low control, an expected midpoint control, and a high control. To obtain an admission from the government scientist that they would never use just one control

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Stephen Biss

Apr 13, 2018
1 min

Change at One Point but Not at Another Point that is Equivalent

Purpose: To suggest that there is empirical evidence in the matter before the Court of change in response by the approved instrument at the lower end of the measuring interval (reading much lower) and at the upper end of the measuring interval (reading slightly higher) without corresponding change in response at the single data point control test level. To suggest that linearity has therefore changed, and in other words, the calibration curve programmed into the instrument, a

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Stephen Biss

Mar 29, 2018
1 min

Police Fail to Correct a Linearity Problem on In-House Annual Inspection

Purpose: To obtain an admission from the CFS scientist that the disclosed annual maintenance records indicate that the police failed to take any steps to correct control tests on inspection that indicated the instrument's response had shifted well beyond not only a 3 mg% tolerance, but well beyond a 10mg% tolerance. To suggest to the CFS scientist that the calibration curve has shifted. To suggest to the CFS scientist that the instrument's response is no longer as accurate an

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Stephen Biss

Mar 25, 2018
1 min

Why Does the ATC Say Single Point Control Tests are Good Enough?

Purpose: To explore the differences between a measurement instrument that has a linear relationship between the thing measured and the result v. a measuring instrument that has a calibration curve. To search for an admission that the calibration curve can shift up or down, left or right, or rotate around a point over time. To cross-examine the CFS expert on the lack of empirical study supporting the ATC/CFS hypothesis that a single point control test can always detect drift.

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Stephen Biss

Jan 13, 2018
1 min

Control Tests do not displace Formal Calibration Intervals

Purpose: To separate conceptually control tests from calibration To obtain an admission that there are no "assessors" in the province of Ontario To obtain an admission that the historical maintenance records show a deterioration of performance - deterioration of linearity in this particular instrument The strategy of using control tests as indication of reliability depends upon completeness of records and transparency To obtain an admission that at the bottom of the valley in

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Stephen Biss

Jan 11, 2018
1 min

Instrumental Deviations from Beer-Lambert Law

Purpose: To explore the reasons why measurement instruments in the field may deviate from the linearity alleged by the Beer-Lambert law To introduce a university textbook dealing with inter alia: External Calibration Creating a Calibration Curve Limits to Beer's law No longer linear when the molar absorptivities differ Instrumental Deviations from Beer-Lambert law Polychromatic Radiation rather than Monochromatic IR #BeerLambert #polychromatic #linearity #calibrationcurve #ca

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Stephen Biss

Jan 11, 2018
2 min

Bandwidth of Filters Changes Over Time

Purpose: To explain the basic methodology of IR quantitative analysis using an approved instrument. To explain calibration. To explain the function of the linearizer. To explain drift over time. To explain calibration curve. The pencil is the sample in the sample chamber. The paperclips are the instrument's electronic response to the transmittance of IR light through the sample chamber. An electrical signal is produced by the detector at the end of the sample chamber that has

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Stephen Biss

Jan 10, 2018
1 min

Beer-Lambert Law as Stated in Training Aid is Over-Simplified and Inadequate

Purpose: To obtain admissions that the concept of single point control test(s) at time of use is adequate, to verify calibration has not changed over time, is not good measurement science. To obtain admissions that checks of linearity during annual maintenance or other periodic inspection are necessary to confirm linearity, to confirm that the instrument is still calibrated across the whole measuring interval. To obtain an admission that although the Beer-Lambert Law suggests

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Maybe the Instrument Is No Longer Linear Enough to Be An "8000C"

BAC Analysis in a Lab Without Bracketing Controls is at Best Qualitative not Quantitative

Change at One Point but Not at Another Point that is Equivalent

Police Fail to Correct a Linearity Problem on In-House Annual Inspection

Why Does the ATC Say Single Point Control Tests are Good Enough?

Control Tests do not displace Formal Calibration Intervals

Linearity Studies are Done on New Instruments not Aging Instruments

Instrumental Deviations from Beer-Lambert Law

Bandwidth of Filters Changes Over Time

Beer-Lambert Law as Stated in Training Aid is Over-Simplified and Inadequate