Automated Solid-Phase Extraction and Liquid Chromatography Tandem Mass Spectrometry Determination of N-methyl-2-pyrrolidone and its Metabolites in Urine and Plasma

Metabolism of N-Methyl-2-Pyrrolidone in Honey Bee Adults and Larvae: Exploring Age Related Differences in Toxic Effects

In chronic feeding assays, the common agrochemical inert formulant N-methyl-2-pyrrolidone (NMP) is at least 20 times more toxic to honey bee larvae than to adults, but the underlying cause of this difference is unknown. In other taxa, NMP is primarily detoxified via a cytochrome P450 mediated pathway. Using a LC-MS method, putative cytochrome P450 metabolites of NMP were identified and quantified in adults and larvae following chronic exposure to NMP. Major differences in the identities and quantities of the generated metabolites were observed between adults and larvae. One major difference was the higher percentage of the administered NMP recovered as the parent compound in larvae compared to adults. To further explore the apparent difference in metabolic capacity, a spectrofluorometric method was used to compare general cytochrome P450 enzyme activity by monitoring the transformation of a 7-ethoxycoumarin substrate. Higher microsomal levels of 7-ethoxycoumarin-O-deethylase activity in adult fat bodies suggests that the higher percentage of unmetabolized NMP in larvae relative to adults may be due to lower cytochrome P450 enzyme activity in fat bodies. Taken together, these results suggest that larvae may be less able to detoxify xenobiotics encountered in diet than adults, and these findings will help inform future risk assessment.

Field Residues and Effects of the Insect Growth Regulator Novaluron and Its Major Co-Formulant N-Methyl-2-Pyrrolidone on Honey Bee Reproduction and Development

Owing to the recent declines in honey bee (Apis mellifera L.) populations, there is a need for field and laboratory studies to investigate threats to pollinator health. This study examines the hypothesis that the organophosphate alternative, Rimon 0.83EC, can have consequences to honey bee health by combining newly acquired field residue data, laboratory bioassays, and colony level feeding studies. Following label rate applications of Rimon 0.83EC to apple trees, average residue concentrations of the active ingredient, novaluron, were found to be 3.38 ppm in tree-collected pollen. Residues of the major co-formulant in Rimon 0.83EC, N-methyl-2-pyrrolidone (NMP), were below the limit of detection in the field, but a growth chamber study described here found that NMP can persist in pollen for up to 7 d with average concentrations of 69.3 ppm. Concurrent larval rearing studies found novaluron and NMP to be toxic to developing honey bees at doses as low as 100 ppb and 100 ppm, respectively. Nucleus colony feeding studies found that chronic exposure to Rimon 0.83EC at doses as low as 200 ppm (18.6 ppm novaluron) can result in interruptions to brood production that can last for up to 2 wk after exposure. Taken together, these data indicate the use of Rimon 0.83EC on blooming flowers is a significant threat to honey bee reproduction, and suggest the need for more strict and clear usage guidelines.

Determination of N-methyl-2-pyrrolidone and its metabolites in urine by micellar electrokinetic chromatography

A fast and accurate micellar electrokinetic capillary chromatography (MEKC) method was developed for monitoring N-methyl-2-pyrrolidone (NMP) exposure. Baseline separation of NMP and its main metabolites: 5-hydroxy-N-methyl-2-pyrrolidone (5HNMP), N-methylsuccinimide (MSI), 2-hydroxy-N-methylsuccinimide (2HMSI), and 2-pyrrolidone (2P) was obtained within 6 min in an uncoated fused silica capillary using 5 mM phosphate buffer and 140 mM sodium dodecyl sulfate (pH 7.1) as background electrolyte (BGE). On-line UV-detection was performed at 200 nm and the applied electric field was 400 V cm−1. Possible interference of BGE-induced system peaks on separation was investigated by computer simulation and no such interference was observed. The developed MEKC method combined with solid phase extraction for sample preparation was successfully applied to the analysis of urine of rats exposed to NMP. The urinary excretion was determined in 0–6 h and 6–24 h specimens collected after an intragastic administration of 308 mg NMP / kg rat body weight. The results of NMP disposition kinetics in rat urine are reported for NMP and metabolites.