Selective determination of mandelic acid in urine using molecularly imprinted polymer in microextraction by packed sorbent

Abstract

Mandelic acid (MA) is a major metabolite of ethylbenzene and styrene. For the first time, a selective, fast, and easy-to-use procedure was developed for the determination of MA in urine samples. The new procedure is based on MIMEPS, the combination of a molecularly imprinted polymer (MIP) and microextraction by packed sorbent (MEPS). High-performance liquid chromatography with ultraviolet detection (HPLC-UV) was used for the separation and determination of MA. The bulk polymerization method was used to synthesize the MIP, and the MIP and non-imprinted polymer (NIP) were characterized by Fourier transform infrared spectroscopy. The selectivity of the MIP was investigated in the presence of interferents. In addition, we investigated the various parameters that affect the performance of the MEPS, including the pH of the sample, the number of extraction cycles, sample volume, and the types and volumes of the washing and elution solvents. A six-point calibration curve was obtained in the range of 0.2-20 µg/mL (R = 0.9994). The extraction recovery was more than 88.8%. The limit of detection and the limit of quantitation were 0.06 and 0.2 µg/mL, respectively. The intra- and inter-day precisions were in the range of 3.6-4.7% and 3.8-5.1%, respectively. The accuracy was -8.4 to -11.1%. The optimized procedure was selective, sensitive, and rapid, and it was both user friendly and environmentally friendly. The sample preparation process took only about 5 min, so the MIMEPS-HPLC-UV procedure is recommended as an alternative for the biomonitoring of workers exposed to ethylbenzene and/or styrene.

Benzene, toluene, ethylbenzene, and xylene: Current analytical techniques and approaches for biological monitoring

“…[97][98][99][100][101][102], HPLC with photodiode array detector (HPLC-PAD) [103,104], gas chromatography (GC) with mass spectrometry (GC-MS) [105][106][107][108][109][110][111], GC with flame ionization detector (GC-FID) [112,113] or electron-capture detector (GC-ECD) [113], liquid chromatography/hybrid quadrupole time-of-flight mass spectrometry (LC-QqTOFMS) [114], and ion chromatography (IC) [115]. Some of these methods are develop specifically to measure only one of the BTEX metabolites [14,60,[81][82][83][84]86,88,[94][95][96][97][98][99]106,107], whereas others were developed to simultaneous determination of two or more metabolites of BTEX [85,89,90,105,[108][109][110][111]114]. Most of these analytical methods use liquid-liquid extraction (LLE)…”

“…Most of these analytical methods use liquid-liquid extraction (LLE) [14,87,88,109,110,113] or conventional solid phase extraction (SPE) [86,92,103,105,106,112] for sample preparation. However, microextraction techniques (METs) such as hollow-fiber liquid-phase microextraction (LPME) [91,93], single drop liquid-liquid-liquid microextraction (LLLME) [81], partitioned dispersive liquid-liquid microextraction (PDLLME) [96], solid phase microextraction (SPME) [111] and microextraction by packed sorbet (MEPS) [82][83][84]99] are also used in recent years. In addition, the "dilute-and-shoot" approach without need for a sample preparation step is used [97,98,100,102].…”

Developing a Method for Determination of Urinary Delta-Amino-Levulinic Acid using Molecularly Imprinted Polymers

“…There are various methods for preparing MIP. In this study, the bulk polymerization method was used to prepare MIP for ALA on the basis of previously described procedure by Soleimani et al [15]. To do this, we used 4 vials.…”

“…Various absorbents such as C2, C8, C18, SCX, SAX, APS, SDVB, HDVB are used in MEPS, but the lack of selectivity, the main disadvantage of these adsorbents, has led researchers to use high-selectivity adsorbents such as MIPs [14]. Therefore, considering the advantages of the MEPS compared to conventional SPE sorbents, as well as the highly selective and low cost of producing MIPs, their combination can be described as a simple, fast, selective, high-sensitivity and environmentfriendly method and for use in preparing environmental, pharmaceutical, toxicological, and food samples [15].…”

“…In the current study, we developed a novel approach based on MIP-MEPS to determine U-ALA. According to our knowledge, MIP-MEPS analysis has been carried out by analytical methods like GC, HPLC, LC-MS-MS, and GC-MS [14][15][16][17][18][19]. So far this method has not been performed with a spectrophotometer and for the first time, MIP-MEPS was combined with the spectrophotometric method with a microcell to analyze urinary U-ALA.…”