QTest Photometer – Step-by-Step Guide

You can, but with caution. The reagents in the detection solution may stain or damage the cuvettes over time since, especially if they’re not cleaned immediately and the detection solution may contain acids that can damage them. If you decide to reuse them, we recommend the class cuvettes, rinse them with destilated water and dry them thoroughly as soon as you're done with the reading. Make sure they’re completely clear and show no traces of color, as leftover stains can interfere with your results. For beginners, we recommend using fresh cuvettes for each sample until you feel confident in your technique.

The blank prepared during the testing procedure may be reused if handled and stored appropriately.
⚠️ Under no circumstances should the used blank solution be returned to the original stock vial. After performing the blank measurement, pour any leftover solution into a clean glass container (not plastic), seal it tightly, and keep it in the fridge, protected from light. Under these conditions, the blank can be reused for up to one month.

However, over time, the color of the blank may shift slightly — especially if stored for several days. This change can lead to small variations in your results, usually around 1–3%, which may appear as a mild false positive.

If the stored blank becomes darker than it was originally, the photometer will treat this darker color as the new “zero.” When you later measure your real sample — which is dissolved in a fresher and slightly lighter detection solution — the photometer might interpret that difference as if your sample contains less active compound than it actually does.

This variation is not representative of your true sample — it's simply a result of using a blank that no longer matches the background of the test solution. Whether this affects you depends on how precise you want to be. If you need high accuracy (e.g., for dose comparisons or consistency), we recommend preparing a fresh blank each time. For general use or learning, reusing the stored blank is fine — just monitor the storage time and check that the color hasn’t changed noticeably.

No — never return any used solution to the original bottle from the Bulk Kit. Once the blank has been in contact with air or equipment, it may carry contaminants or traces of active compounds, which can spoil the rest of the reagent and compromise future tests. Always store reused blank solutions separately in a clean, labeled glass container. Keeping your reagents uncontaminated is key for getting reliable and consistent results.

Yes! You can perform a blank measurement as many times as you like. Just insert the blank cuvette again and press the “zero” or “blank” button on the device.

Each cuvette has a small triangle marking — this triangle must point toward you and be aligned parallel to the photometer screen when inserted. This is important because the cuvettes are not perfectly symmetrical — the light path must go through the correct flat sides for accurate results. Misalignment can lead to errors in absorbance readings.

Yes, you can. Just make sure to use a clean cuvette for each sample and follow the same steps: blanking if needed, inserting the sample, and recording the result. This way, you can run multiple tests in a row without restarting the device.

Yes! The photometer works with MDMA, LSD and Psilocybin QTes. However, each test requires its own specific detection solution and blank, so: test one substance at a time, perform the blank for each substance, and do not mix detection solutions or blanks across different QTests. We recommend finishing all measurements for one substance before starting with the next.

Because using the QTest Photometer is not just about following steps — it’s a hands-on learning process. These methods are built to be robust and reliable, so small variations (like slight differences in pipetting or timing) won’t ruin your results. But over time, you’ll start to notice patterns and build confidence in your technique.

Just like in any scientific experiment, precision comes from a combination of practice, attention, and curiosity. The more tests you perform, the more naturally you’ll recognize clean sample preparation, stable readings, and how to interpret your data accurately. It becomes a skill — and like any skill, it improves with experience and care.

And remember, you’re not doing this alone. We’re here to help. If you ever have doubts, want a second opinion, or simply want to share your progress, feel free to email us. You’re also warmly invited to join our Signal Photometer Community Chat, where users share insights, solve issues together, and grow as a community.

Yes – the QTest Photometer is fully compatible with our QTest reagents, making it easy to upgrade without switching products.

Yes – gently mix the contents by swirling or flicking the cuvette to ensure even distribution of the reagent and sample before measuring.

No calibration is needed before each test. Just make sure to use a fresh or valid blank before starting a new session.

Check for residue in the cuvette, bubbles, the color of the detection reaction isn´t homogeneous or improper blanking. Clean the cuvette, re-blank if needed, and try again.