Sensitive determination of positional isomers of benzenediols in human urine by boronate affinity capillary electrophoresis with chemiluminescence detection

A boronate ACE coupled with chemiluminescence (CL) detection was developed for sensitive determination of three isomeric benzenediols, which was based on the principle of an inhibited effect of borate complexation on the CL reaction between luminol and potassium hexacyanoferrate (K3Fe(CN)(6)) in alkaline solution. The effects of some important factors on CE separation and CL intensity were systemically investigated. Baseline separation of isomeric benzenediols including o-benzenediol, m-benzenediol, and p-benzenediol was achieved by using a mobile phase of 40 mmol/L glycine-NaOH buffer at pH 9.4 containing 0.8 mmol/L luminol and 0.4mol/L 4-iodophenylboronic acid. The calibration curves of the analytes by plotting the peak height against corresponding concentration were linear over the range of 4.5 x 10(-8) approximate to 4.5 x 10(-5)mol/L for p-benzenediol, 6.8x10(-8)approximate to 2.7x10(-5)mol/L for m-benzenediol, and 9.0x10(-8) approximate to 4.5x10(-5)mol/L for o-benzenediol. The corresponding detection limits for p-, m-, and o-benzenediols were 2.8x10(-8)mol/L (68 amol), 3.2 x 10(-8)mol/L (108.4amol), and 3.7 x 10(-8)mol/L (125.8 amol; S/N= 3), respectively. The proposed method has been successfully applied to the analysis of trace benzenediols in spiked human urine sample and the recoveries were >97.2%. Our primary result demonstrated the proposed CE-CL method has great potential for biomarker determination in clinical diagnosis.