Pectin characterisation using size exclusion chromatography: A comparison of ELS and RI detection

• Published in: Food chemistry 2018-06, Vol.252, p.271-276
• Main Authors: Muñoz-Almagro, Nerea, Rico-Rodriguez, Fabián, Villamiel, Mar, Montilla, Antonia
• Format: Article
• Language: English
• Subjects: Light scattering; Molecular mass; Pectin; Refraction index; Response Surface Methodology
• ISSN: 0308-8146; 1873-7072
• DOI: 10.1016/j.foodchem.2018.01.087

•An optimisation of ELSD was done maximizing the detector response by RSM.•The air flow rate had the highest impact in the response ELSD.•Pectin characterisation with HPSEC-ELSD exhibited better results than HPSEC-RID. A high-performance size-exclusion chromatography (HPSEC) method coupled to Evaporative Light Scattering (ELS) and Refractive Index (RI) detectors were evaluated and compared for the molecular mass (Mw) estimation of pectin in a wide range (0.342–805 kDa). Instrumental parameters of the ELSD were optimised by Response Surface Methodology (RSM) being 73 °C the evaporator temperature and 0.9 mL/min the air flow rate. The linear range for the ELSD concentration response was wider (10–2250 mg/L) and better (R2 = 0.985) than RID (10–1500 mg/L; R2 = 0.875). The limits of detection (LOD) and quantitation (LOQ) for all pullulans hardly changed in ELSD (LOD: 1.22–1.99 mg/L; LOQ: 4.07–6.63 mg/L); however, RID showed huge variations (LOD: 0.49–10.41 mg/L; LOQ: 1.64–34.70 mg/L), which increased with the Mw. In general, responses of both detectors were similar for the Mw estimation, although pectin characterisation with HPSEC-ELSD exhibited better results in the lowest Mw compounds.