LAUSR

Abstract Since 2010 many countries do not permit the use of sibutramine for obesity treatment owing to risks of heart attack or stroke. However, it is still found adulterated in some slimming products. A distance-based paper device was developed for quantitative measurement of sibutramine by visual inspection. The device is a filter paper printed with a thermometer-shaped pattern but having circular zones at both ends. A small volume of sample, loaded at one end, flows along the channel, reacting with the pre-deposited Dragendorff’s reagent to form orange–red precipitate of sibutramine-tetraiodobismuthate complex. The length of the orange-red complex is directly proportional to amount of sibutramine in the sample. A ruler scale printed parallel to the channel allows the length of the orange-red precipitate to be directly observed and recorded. The measurement takes approximately five minutes. The device has a linear range of 0.22 to 0.90 mmol L–1 sibutramine, with coefficient of determination (r2) > 0.9868. The limit of quantification of the device (10SD intercept/slope calibration) is 0.22 mmol L–1 sibutramine, with intra-day and inter-day precisions