Magnetic solid‐phase extraction based on magnetic carbon particles from coffee grounds for determining phthalic acid esters in plastic bottled water

Newly developed magnetic carbon particles prepared from coffee grounds were used as the sorbent for the magnetic solid‐phase extraction of eight phthalic acid esters (PAEs) from plastic bottled water prior to their analysis by GC‐MS. The method, which uses coffee‐ground particles coated with iron oxide, was validated, and exhibited linearities for the eight PAEs, with coefficients of determination above 0.998 in the 0.005 to 0.1 mg/L concentration range. Limits of detection and limits of quantification of 0.00003 to 0.002 mg/L and 0.0001 to 0.005 mg/L, respectively, were achieved, with recoveries (%) ranging between 77% and 120%, and relative standard deviations for intra‐ and interday precisions below 16.3% at three fortification levels. No PAE residues were detected when the developed and validated method was applied to 10 real plastic bottled water samples. Taken together, the developed magnetic solid‐phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples. Practical Application The development of a new, inexpensive, and efficient magnetic sorption material derived from spent coffee grounds, and its ability to determine phthalate esters in aqueous solutions was described by GC‐MS/MS. The developed magnetic solid‐phase extraction method is a useful tool for monitoring phthalate esters in aqueous samples.