Synthetic urine has certain tracers that a lab will pick up . Yes you will pass the test , yes they will know it's fake .
Most commercial urine drug tests also measure creatinine (a common kidney-excreted metabolite of dietary protein/muscle breakdown to determine if it's been diluted, and with so-so precision, by how much) B vitamin supplements make your pee darker orange so can dilute and have light yellow pee, but if creatinine is below physiological range (there is a range), they can nullify the test. Nonetheless, a simple 5-analyte (most common) or 10-analyte ELISA (enzyme-linked immunosorbent assay--I've run thousands but not for drugs) test is the first (and most economical approach). Any positive result needs to be confirmed with much more expensive MS-GLC, mass spectroscopy/gas-liquid chromatography.
Synthetic urine is stupid and a joke. While there are many substances that will cross-react with drug tests and give false positives (poppy seeds on a bagel, or a Polish dessert dish that is like 80% poppy seeds will light you right up for opioids/opiates; there are others....), nothing sold today online will clean your pee for a test. Hard exercise, copious hydration, and time are your only reliable accelerators, though not by much.
Why is this on TRF anyways? Try erowid, ffs...
Sheesh
Final note: Potheads leave Doritos crumbs on the couch, are always late, and sound kinda stupid in normal conversation (unless daily smokers--then this does not apply). Drunks get inordinately angry over stupid ****, crash cars unnecessarily, and occasionally beat their wives....