title: Syringe needle-based sampling coupled with liquid-phase extraction for determination of the three-dimensional distribution of l-ascorbic acid in apples.
abstract: A novel syringe needle-based sampling approach coupled with liquid-phase extraction (NBS-LPE) was developed and applied to the extraction of l-ascorbic acid (AsA) in apple. In NBS-LPE, only a small amount of apple flesh (ca. 10mg) was sampled directly using a syringe needle and placed in a glass insert for liquid extraction of AsA by 80 μL oxalic acid-acetic acid. The extract was then directly analyzed by liquid chromatography. This new procedure is simple, convenient, almost organic solvent free, and causes far less damage to the fruit. To demonstrate the applicability of NBS-LPE, AsA levels at different sampling points in a single apple were determined to reveal the spatial distribution of the analyte in a three-dimensional model. The results also showed that this method had good sensitivity (limit of detection of 0.0097 mg/100g; limit of quantification of 0.0323 mg/100g), acceptable reproducibility (relative standard deviation of 5.01% (n=6)), a wide linear range of between 0.05 and 50mg/100g, and good linearity (r(2)=0.9921). This interesting extraction technique and modeling approach can be used to measure and monitor a wide range of compounds in various parts of different soft-matrix fruits and vegetables, including single specimens.
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore.
authors.forename: Sheng
authors.initials: S
authors.lastname: Tang
authors.affiliation: Department of Chemistry, National University of Singapore, 3 Science Drive 3, Singapore 117543, Singapore; National University of Singapore Environmental Research Institute, T-Lab Building#02-01, 5A Engineering Drive 1, Singapore 117411, Singapore; Tropical Marine Science Institute, National University of Singapore, S2S, 18 Kent Ridge Road, Singapore 119227, Singapore. Electronic address: chmleehk@nus.edu.sg.
authors.forename: Hian Kee
authors.initials: HK
authors.lastname: Lee
mesh_terms: D001205:Ascorbic Acid / Q000032:analysis*; D002853:Chromatography, Liquid / Q000379:methods; D005638:Fruit / Q000737:chemistry*; D059625:Liquid-Liquid Extraction / Q000379:methods*; D027845:Malus / Q000737:chemistry*; D013594:Syringes
chemical_list: D001205:Ascorbic Acid
keywords: Apple; Liquid-phase extraction; Needle-based sampling; Three-dimensional distribution; l-Ascorbic acid