Use of a portable time-resolved fluorometer to determine oxytetracycline residue in four fruit crops

► Oxytetracycline (OTC) is quantified in-situ by europium-sensitised luminescence. ► A time-resolved analyser enables in-situ OTC quantitation for the first time. ► Sensitivity exceeds 350 ng g−1 tolerance in apple, pear, peach and nectarine. ► Liquid-liquid extraction is excluded saving both time and chemicals. ► Filtration replaces centrifugation to improve separation and deployability.