A single molecule analyzer for determining the concentration of an analyte of interest comprising: (a) an electromagnetic radiation source for providing electromagnetic radiation to a microwell of a microtiter plate for confining a processing sample; (b) a system for directing the electromagnetic radiation from the electromagnetic radiation source to an interrogation space comprising a detection volume in a processing sample; (c) a translating system for moving at least one of the electromagnetic radiation source or the microtiter plate with respect to one another to translate the interrogation space through at least a portion of the sample, thereby forming a moveable interrogation space; (d) a detector for detecting photons emitted from the interrogation space; characterized in that the analyzer has (e) a processor operatively coupled to the detector, wherein the processor determines the presence or amount of an analyte specific photon emitting label comprising a fluorescent moiety in a processing sample, wherein the label comprises or corresponds to the analyte, by determining a threshold photon value corresponding to a background signal in the processing sample, determining the presence of a photon emitting label in the interrogation space in each time bin of a plurality of time bins by identifying time bins having a photon value greater than the threshold value, wherein each individual time bin having a photon value greater than the threshold value represents an individual detection event, determining a detection event value as the sum of detection events for a given time period, and determining the concentration of analyte from a standard curve of analyte concentration against detection event value. (a) an electromagnetic radiation source for providing electromagnetic radiation to a microwell of a microtiter plate for confining a processing sample; (b) a system for directing the electromagnetic radiation from the electromagnetic radiation source to an interrogation space comprising a detection volume in a processing sample; (c) a translating system for moving at least one of the electromagnetic radiation source or the microtiter plate with respect to one another to translate the interrogation space through at least a portion of the sample, thereby forming a moveable interrogation space; (d) a detector for detecting photons emitted from the interrogation space; characterized in that the analyzer has (e) a processor operatively coupled to the detector, wherein the processor determines the presence or amount of an analyte specific photon emitting label comprising a fluorescent moiety in a processing sample, wherein the label comprises or corresponds to the analyte, by determining a threshold photon value corresponding to a background signal in the processing sample, determining the presence of a photon emitting label in the interrogation space in each time bin of a plurality of time bins by identifying time bins having a photon value greater than the threshold value, wherein each individual time bin having a photon value greater than the threshold value represents an individual detection event, determining a detection event value as the sum of detection events for a given time period, and determining the concentration of analyte from a standard curve of analyte concentration against detection event value.