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What about the positive and negative results? |
| POSITIVE: Reagent 1 is added to the urine sample, which contains the antibody that binds to the donor's drug metabolite. Reagent 2 is then added which contains the G6PD attached to the lab's metabolite. The antibody has been consumed by the donor's metabolite in the sample and cannot react with the lab's metabolite on the G6PD. The G6PD's active site is free allowing NAD+ to bind and subsequently be reduced to NADH. The NADH gives off a distinctive color, which is absorbed by light at the 340 nm wavelength. The spectrometer measures the change in absorbance per minute and determines whether the sample is positive based on a previous baseline of the urine being analyzed.
NEGATIVE: Reagent 1 is added to the urine sample, which contains the antibody. The antibody does not bind with anything because the sample is clean. Reagent 2, which contains the G6PD attached to the lab's metabolite, is then added. The antibody reacts with the lab's metabolite. The antibody attaches to the metabolite, which is attached to G6PD. The antibody binds the active site of G6PD. Because the site is blocked, the NAD+ cannot bind and be converted to NADH. With no NADH present, the spectrometer reads a nominal absorbance change, and the sample is negative.
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