Determination of N-methyl-1,3-propanediamine in bovine muscle by liquid chromatography with triple quadrupole and ion trap tandem mass spectrometry detection.

Morantel, pyrantel and their drug-related metabolites in food of animal-origin are regulated as sum of residues which may be hydrolysed to N-methyl-1,3-propanediamine (NMPA). In this study, an isotope dilution liquid chromatography tandem mass spectrometry (LC-MS/MS) method with pentafluoropropionic acid anhydride (PFPA) derivatization was developed for the determination of NMPA in bovine muscle. A stable isotope labeled internal standard N-methyl-d(3)-3,3'-d(2)-propane-1,3-diamine (NMPA-d(5)) was synthesized as internal standard. NMPA was derivatized with PFPA to form an N,N'-bis (pentafluoroacyl) derivative (NMPA-PFPA) and analyzed by liquid chromatography triple quadrupole mass spectrometry (LC-QqQ-MS/MS) and liquid chromatography ion trap mass spectrometry (LC-IT-MS/MS) using negative ion electrospray ionization (ESI). Chromatographic behavior of several perfluorocarboxylic acid anhydride derivatives of NMPA and other structurally related diamines on C-18 and perfluorophenyl (PFP) columns was studied. Conversion of the parent drugs to NMPA under various hydrolysis conditions was evaluated. In addition, comparison of the matrix effect and linearity with isotopically labeled internal standard (I.S.) and analogous I.S. were performed and investigated. The method was validated using fortified bovine muscle samples. The apparent recovery (obtained after correction with an isotopically labeled I.S.) was between 89% and 97% and repeatability was less than 10%. The lowest LOD and LOQ (0.42 and 1.39µg/kg, respectively) were obtained with LC-QqQ-MS/MS.

Determination of pyrantel in swine liver by flame ionization gas chromatography and confirmation by gas chromatography/mass spectrometry.

During an evaluation of the gas chromatography/mass spectrometry (GC/MS) confirmatory procedure of Lynch and Bartolucci for pyrantel residues in swine tissues, we developed a GC flame ionization method for quantitating pyrantel residues in extracts of swine liver. The method was subjected to trial principally in the laboratories of Biospherics, Inc., using control liver, fortified control liver, and incurred liver tissue samples. Although the method does not meet all of the current Food and Drug Administration criteria, it compares favorably to the official determinative method. Portions of the same extract can be used for quantitation and for GC/MS confirmation, true recoveries appear to be slightly higher, and an internal standard is not required. The precision of this method equals or exceeds that of the official determinative method.

High-performance liquid chromatographic determination of oxantel and pyrantel pamoate.

A method is described for the determination of oxantel and pyrantel pamoate in proprietary broad spectrum anthelmintic tablets. Quantitation is performed by using an octyl Spherisorb column with a mobile phase consisting of acetonitrile and water modified with butylamine. Carbaryl-(1-naphthyl methylcarbamate) is used as internal standard.

Liquid chromatographic determination and identification of morantel-related residues as precursors of 3-(3-methyl-2-thienyl) acrylic acid (CP-20,107) in bovine milk.

A simple liquid chromatographic (LC) method was developed to determine and identify incurred morantel-related residues in bovine milk by converting them to 3-(3-methyl-2-thienyl) acrylic acid (CP-20, 107). Key techniques in this method involve short-term digestion of milk in HCl to release residues convertible to CP-20, 107, isolation and alkaline hydrolysis of these precursors to CP-20, 107, and recovery of the product for LC analysis. Photochemical conversion of CP-20, 107 to its cis-isomer and separation by LC identifies the residue. A homolog (pyrantel), which is used as an internal standard, is hydrolyzed to 3-(2-thienyl) acrylic acid. These acrylic acid isomers are readily resolved by LC. The method was evaluated over the 1-4 ppb (ng/mL) range for accuracy and precision to assess its utility for withdrawal studies. Bovine milk supplemented with morantel at 1, 2, and 4 ppb and assayed in replicate (n = 7-8) over 4 trials gave mean values and standard deviations of 1.0 +/- 0.11, 2.0 +/- 0.24, and 4.0 +/- 0.44 ppb, respectively. A milk specimen containing physiologically incurred residues of morantel assayed 2.1 +/- 0.19 ppb in replicate (n = 5).

Identification and confirmation of pyrantel- and morantel-related residues in liver by gas chromatography-mass spectrometry with selected ion monitoring.

A gas chromatographic-mass spectrometric method with selected ion monitoring (GC/MS-SIM) is described for identification of pyrantel- and morantel-related residues in swine and beef liver. Alkaline hydrolysis of tissue liberates and converts pyrantel- and morantel-related residues to 3-(2-thienyl)-acrylic acid (TAA) and 3-(3-methyl-2-thienyl)-acrylic acid (MTAA), respectively. These thienyl acrylic acids are recovered by ion exclusion chromatography and converted to methyl ester derivatives (TAAE and MTAAE) for identification by GC/MS-SIM. When the relative intensities of the molecular ion, the base peak, and a third significant ion of the sample correspond to ion intensities of the preformed or processed standards, the identity of the residue is confirmed. The method was validated by analysis of swine and beef liver samples containing incurred residues of pyrantel and morantel under withdrawal conditions.