Quantification of Paraquat, MPTP, and MPP+ in brain tissue using microwave-assisted solvent extraction (MASE) and high-performance liquid chromatography–mass spectrometry

Abstract

Animal models, consistent with the hypothesis of direct interaction of paraquat (PQ) and 1-Methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) with specific areas of the central nervous system have been developed to study Parkinson’s disease (PD) in mice. These models have necessitated the creation of an analytical method for unambiguous identification and quantitation of PQ and structurally similar MPTP and 1-Methyl-4-phenylpyridinium ion (MPP+) in brain tissue. A method for determination of these compounds was developed using microwave-assisted solvent extraction (MASE) and liquid chromatography-mass spectrometry. Extraction solvent and microwave conditions such as power and time were optimized to produce recoveries of 90% for PQ 78% for MPTP and 97% for its metabolite MPP+. The chromatographic separation was performed on a C8, column and detection was carried out using an ion trap as an analyzer with electrospray ionization. Mass spectrometer parameters such as heated capillary temperature, spray voltage, capillary voltage and others were also optimized for each analyte. Analysis was done in Selective Ion Monitoring (SIM) mode using 186 m/z for PQ, m/z 174 for MPTP, and m/z 170 for MPP+. The method detection limit for paraquat in matrix was 100 pg and 40 pg for MPTP and 20 pg MPP+.

Method for measurement of the quaternary amine compounds paraquat and diquat in human urine using high-performance liquid chromatography–tandem mass spectrometry

“…However, few laboratories are routinely measuring PQ or DQ as a part of their analytical or environmental programs. EOHSI has developed methods to measure PQ in a variety of matrices in support of its environmental and toxicology programs [34]. In tissue extracts that were analyzed by both laboratories, we found 94% agreement among quantified values, providing some assurance for our quantitative measurements (Fig.…”

“…The analytical core laboratory at the Environmental and Occupational Health Science Institute (EOHSI) at Rutgers University provided us with tissue extract samples that staff members had previously analyzed in their laboratory using established methods [34]. The percentage of agreement between the two platforms was calculated as the slope of a linear regression analysis of a plot of the values obtained from each method.…”

Quantification of paraquat in postmortem samples by gas chromatography–ion trap mass spectrometry and review of the literature

“…The drawback of most chromatographic and spectrophotometric methods is the high LOD (from 30 to 500 µg/L), which is unsuitable for analysis of biological samples with low PQ or DQ values, especially those that were obtained from patients having undergone hemodialysis, charcoal haemoperfusion or other depurative therapies (Dinis‐Oliveira et al , ). Therefore, chromatography‐electrospray ionization‐mass spectrometry (LC/ESI/MS) has been suggested as an alternative technique for quaternary amine herbicides (Taguchi et al , ; Castro et al , , , ; Grey et al , ; Lee et al , ; Vidal et al , ; Ariffin and Anderson, ; Winnik et al , ; Whitehead et al , ). LC/ESI/MS methods have also used mobile phases with ion‐pair reagents such as heptafluorobutyric (Lee et al , ; Ariffin and Anderson, ) or trifluoroacetic acids (Taguchi et al , ), conferring good chromatographic separation results for simultaneous analysis of PQ, DQ and difenzoquat (DF) on reverse‐phase silica‐based C 8 or C 18 columns.…”

Liquid chromatographic–electrospray mass spectrometric determination of 1-methyl-4-phenylpyridine (MPP+) in discrete regions of murine brain

“…For example, Hows et al (2004) used 0.4 M perchlorate containing sodium metabisulfite (0.1%), EDTA (0.01%), and cysteine (0.1%). Zhang et al (2008) homogenized 100 mg of brain tissue in 1 mL of 0.4 M perchloric acid, whereas Winnik et al (2009) homogenized 10–15 mg of brain tissue in 150 μL of 12% acetic acid. Whereas these procedures work well for analysis of MPP + , they are not optimal for concurrent neurotransmitter amine analysis.…”