The OvuQUICK Self-Test ovulation prediction kit uses a technique known as ELISA, enzyme-linked immunosorbent assay, to detect luteinizing hormone, LH, in your urine. This is a relatively new technology which can detect very small amounts of LH, as well as other hormones, in the urine.
LH is always present in the body but about 20-44 hours prior to ovulation, there is an increased release of LH from the pituitary gland. By detecting this increased release, or surge, of LH we can determine when ovulation will occur within a day. This increases a couple's chances of conceiving. The Reference Spot on the test pad is a color which indicates a low surge in LH. Thus, by comparing the Reference spot to the Test Result spot, the LH surge can be detected when it begins.
For more information on ELISA, click here.