The development of sequential injection analysis with lab-at-valve (LAV) semi-automated system on-line liquid-liquid extraction is demonstrated for spectrophotometric determination of solasodine in various Solanum species fruits. The main proposed is semi-automated extractive determination of solasodine using methyl orange as colorimetric reagent. After optimization of the system, sample, reagent and organic solvent were sequentially aspirated into an extraction coil connected to the center of a selection valve, where extraction took place by flow reversal. The aqueous and organic phases were separated in a lab-at-valve unit attracted to one of the ports of the selection valve. The absorption of ion-pair solasodine-methyl orange complex in the organic phase was measured spectrophotometrically at 420 nm. The method performances, including reproducibility, linearity, sensitivity and accuracy, were also evaluated. The proposed method is simple, reproducible and accurate. It was successfully applied to the determination of solasodine in Solanum aculeatissimum Jacq., Solanum violaceum Ortega., Solanum melongena Linn. and Solanum indicum Linn. fruits in Solanaceae family. Results obtained were in good agreement with those obtained by batch wise spectrophotometric method. It is also suitable and useful for determination of solasodine in other medicinal plants.
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