title: Sequential injection analysis with chemiluminescence detection for rapid monitoring of commercial Calendula officinalis extractions.
abstract: BACKGROUND
  Plant extracts containing high levels of antioxidants are desirable due to their reported health benefits. Most techniques capable of determining the antioxidant activity of plant extracts are unsuitable for rapid at-line analysis as they require extensive sample preparation and/or long analysis times. Therefore, analytical techniques capable of real-time or pseudo real-time at-line monitoring of plant extractions, and determination of extraction endpoints, would be useful to manufacturers of antioxidant-rich plant extracts.
  
  
  OBJECTIVE
  To develop a reliable method for the rapid at-line extraction monitoring of antioxidants in plant extracts.
  
  
  METHODS
  Calendula officinalis extracts were prepared from dried flowers and analysed for antioxidant activity using sequential injection analysis (SIA) with chemiluminescence (CL) detection. The intensity of CL emission from the reaction of acidic potassium permanganate with antioxidants within the extract was used as the analytical signal. The SIA-CL method was applied to monitor the extraction of C. officinalis over the course of a batch extraction to determine the extraction endpoint. Results were compared with those from ultra high performance liquid chromatography (UHPLC).
  
  
  RESULTS
  Pseudo real-time, at-line monitoring showed the level of antioxidants in a batch extract of Calendula officinalis plateaued after 100 min of extraction. These results correlated well with those of an offline UHPLC study.
  
  
  CONCLUSIONS
  SIA-CL was found to be a suitable method for pseudo real-time monitoring of plant extractions and determination of extraction endpoints with respect to antioxidant concentrations. The method was applied at-line in the manufacturing industry.
authors.affiliation: Flinders University, School of Chemical and Physical Sciences, Bedford Park, South Australia, 5042, Australia.
authors.forename: Rachel R
authors.initials: RR
authors.lastname: Hughes
authors.affiliation: Jurlique International, Mount Barker, South Australia, 5251, Australia.
authors.forename: David
authors.initials: D
authors.lastname: Scown
authors.affiliation: Flinders University, School of Chemical and Physical Sciences, Bedford Park, South Australia, 5042, Australia.
authors.forename: Claire E
authors.initials: CE
authors.lastname: Lenehan
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D020838:Calendula / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D049449:Luminescence; D010936:Plant Extracts / Q000737:chemistry*
chemical_list: D000975:Antioxidants; D010936:Plant Extracts
keywords: Plant extract; chemiluminescence; extraction monitoring; process analysis; sequential injection analysis