Mimi Coffey in a Gas Chromatography Lab 2023 Everyone knows you can’t compare apples to oranges yet this is what many Texas forensic laboratories are doing. ANSI/ANAB standards (who accredit Texas crime labs) are very specific on both quality control and method validation requiring some whole blood samples to be tested to adjust for the matrix effects that blood samples introduce in gas chromatography testing. Yet, most north Texas labs still ignore these “shall” (not optional) mandates opting to use aqueous samples (water based). Blood has compounds that interfere in analytical readings that water based calibrators and controls go not have. Does this affect the result? 100%. Absolutely. One study in Austin estimated an increase in alcohol (ethanol) by 20%. This is just one Texas government lab’s findings. Bottom line- don’t trust the blood result. The State must do better.
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