UPLC-MS/MS Determination of 18 Typical Pharmaceutical and Personal Care Products in Drinking Water with Enrichment by Separation on Solid Phase Extraction

1.0 L of drinking water sample was taken and filtered through 0.22 μm filtering membrane, and the filtrate was passed through the activated HLB SPE column at a flow-rate of 5 mL·min^-1 to have the 18 typical pharmaceutical and personal-care products (PPCPs) enriched and separated on the SPE column. The column was then rinsed with 10 mL of water and 10 mL of 15% (φ_HCOOH) methanol solution successively. The 18 analytes were eluted from the SPE column with 15 mL of methanol and the eluate was collected and evaporated to ca. 200 μL by N₂-blowing at 30℃. Water was added to the residue to make its volume to 1.0 mL, and after centrifugation for 10 min, the supernatant was taken and filtered through an injection filter, and the filtrate was used for UPLC-MS/MS analysis under the instrumental working conditions. Waters UPLC^TM BEH C₁₈ column was used for chromatographic separation with mobile phase mixtures composing of (A) 8 mmol·L^-1 HCOONH₄ solution0.1% formic acid (volume fraction, the same below) and (B) mixture of CH₃OH-CH₃CN at a volume ratio of 1:1 (1% formic acid) in various proportions, to elute the 18 analytes from the chromatographic column by gradient elution. The 18 analytes were well saparated within 34 min. ESI⁺ mode and MRM mode were adopted in MS/MS determination. Linear relationships between values of peak areas and mass concentration of the 18 analytes were found in the same range within 15 μg·L^-1. Values of detection limit (3S/N) found were in the range from 5 to 50 pg·L^-1. Recovery tests were made by standard addition method using extrapure water and tap water as matrixes, giving results of recovery in the ranges of 64.4%-113% and 78.2%-116% respectively, and values of RSDs (n=5) found were ranged from 1.6% to 19% (for extrapure water) and from 2.8% to 18% (for tap water). Drinking water samples were collected from 7 water works in various regions of our country, and were analyzed by the proposed method. 4-Acetylaminoantipyrine with contents over 1 ng·L^-1 were found in 3 of the 7 samples; carbamazepine and praziquantel in amounts lower than 1 ng·L^-1 were found in all the 7 samples; and imidazole, sulfamethoxazole, sulfathiazole, sulfamethazine etc. in amounts less than 1 ng·L^-1 were found in 3 to 5 among the 7 samples.