Novel magnetic SPE method based on carbon nanotubes filled with cobalt ferrite for the analysis of organochlorine pesticides in honey and tea

A novel magnetic SPE method based on magnetic cobalt ferrite filled carbon nanotubes ( MFCNT s) coupled with GC with electron capture detection was developed to determine organochlorine pesticides ( OCP s) in tea and honey samples. The MFCNT s were prepared through the capillarity of carbon nanotubes for drawing mixed cobalt and iron nitrates solution into their inner cavity followed by heating to 550°C under A r to form the cobalt ferrite nanoparticles. SEM images provided visible evidence of the filled cobalt ferrite nanoparticles in the multiwalled nanotubes. X ‐ray photoelectron spectroscopy indicated no adhesion of cobalt ferrite nanoparticles and metal salts on the outer surface of the MFCNT s. Eight OCP s were extracted with the MFCNT s. The enrichment factors were in the range of 52–68 for eight OCP s. The LOD s for the eight OCP s were in the range of 1.3–3.6 ng/L. The recoveries of the OCP s for honey and tea samples were 83.2–128.7 and 72.6–111.0%, respectively. The RSD s for these samples were below 6.8%. The new method is particularly suited to extract nonpolar and weakly polar analytes from a complex matrix and could potentially be extended to other target analytes.