Abstract: A reagent useful in immunoassays, comprising a direct particulate level co-sensitised with a specific binding agent having specificity for an analyte or analyte analogue and with a non-specific protein which can participate in a control reaction with another specific binding agent which does not bind to the first specific binding agent nor participate in the formation of a complex by means of which detection of the analyte or analyte analogue is accomplished. Preferably the first specific binding agent is an antibody raised in a first species and the non-specific protein is an immunoglobulin from another species. Optionally, the reagent additionally comprises a second population of the direct particulate label sensitised solely with the non-specific protein.

Abstract: A method for determining the time of maximum fertility in the mammalian ovulation cycle, for the purpose of assisting conception, wherein testing is conducted over a period of days in the current ovulation cycle on samples of body fluid obtained from an individual human subject to detect an elevated concentration of first analyte, such as luteinising hormone (LH) indicative of the event of ovulation, and additionally testing is conducted over a period of days in the current ovulation cycle on samples of body fluid obtained from the individual subject to detect an elevated concentration of a second analyte, such as estradiol or a metabolite thereof, especially estradiol-3-glucuronide (E3G), to provide advance warning of ovulation.