Determination of t,t-muconic acid in urine samples using a molecular imprinted polymer combined with simultaneous ethyl chloroformate derivatization and pre-concentration by dispersive liquid-liquid microextraction.
The present communication describes the preparation and evaluation of a molecularly imprinted polymer (MIP) as a solid-phase extraction (SPE) sorbent and simultaneous ethyl chloroformate (ECF) derivatization and pre-concentration by dispersive liquid-liquid microextraction (DLLME) for the analysis of t,t-muconic acid (t,t-MA) in urine samples using gas chromatography-mass spectrometry. The imprinting polymer was prepared using methacrylic acid as a functional monomer, ethylene glycol dimethacrylate as a cross-linker, 2,2-azobisisobutyronitrile as the initiator and t,t-MA as a template molecule. The imprinted polymer was evaluated for its use as a SPE sorbent by comparing both imprinted and non-imprinted polymers in terms of the recovery of t,t-MA from urine samples. Molecular modelling studies were performed in order to estimate the binding energy and efficiency of the MIP complex formed between the monomer and the t,t-MA. Various factors that can affect the extraction efficiency of MIP, such as the loading, washing and eluting conditions, were optimized; other factors that can affect the derivatization and DLLME pre-concentration were also optimized. MIP in combination with ECF derivatization and DLLME pre-concentration for t,t-MA exhibits good linearity, ranging from 0.125 to 2 μg mL(-1) (R(2) = 0.9971), with limit of detection of 0.037 μg mL(-1) and limit of quantification of 0.109 μg mL(-1). Intra- and inter-day precision was found to be <6%. The proposed method has been proven to be effective and sensitive for the selective pre-concentration and determination of t,t-MA in urine samples of cigarette smokers.
Analytical Chemistry Section, CSIR-Indian Institute of Toxicology Research, MG Marg, Lucknow 226 001, Uttar Pradesh, India. mmudiam@iitr.res.in
Mohana Krishna Reddy
MK
Mudiam
Abhishek
A
Chauhan
Krishna P
KP
Singh
Shailendra K
SK
Gupta
Rajeev
R
Jain
Ratnasekhar
R
Ch
R C
RC
Murthy
D002138:Calibration; D004305:Dose-Response Relationship, Drug; D005563:Formic Acid Esters / Q000737:chemistry*; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods; D006801:Humans; D059627:Liquid Phase Microextraction / Q000379:methods*; D008958:Models, Molecular; D054802:Molecular Imprinting / Q000379:methods*; D011108:Polymers / Q000737:chemistry; D011485:Protein Binding; D015203:Reproducibility of Results; D012907:Smoking / Q000652:urine; D012997:Solvents / Q000737:chemistry; D013011:Sorbic Acid / Q000031:analogs & derivatives / Q000737:chemistry; D062789:Tobacco Products; D016482:Urinalysis / Q000379:methods*
D005563:Formic Acid Esters; D011108:Polymers; D012997:Solvents; C007658:ethyl chloroformate; C005939:muconic acid; D013011:Sorbic Acid