Semicarbazide – from state-of-the-art analytical methods and exposure to toxicity: a review

Synthesis, crystal structure and Hirshfeld surface analysis of catena-poly[[bis(semicarbazide-κ2 N,O)copper(II)]-μ-sulfato-κ2 O:O′]

The title polymer, [Cu(SO4)(CH5N3O)2] n , has been synthesized from aqueous solutions of CuSO4 and semicarbazide. In the crystal structure, the CuII atoms are chelated by two neutral semicarbazide molecules through the oxygen atom and a nitrogen atom of the amino group. The remaining two positions of the Jahn–Teller-distorted octahedral coordination sphere are occupied by oxygen atoms of two sulfate anions in the axial positions. The coordination bonds of the latter associate the polyhedra into polymeric chains running parallel to the c axis. There is a weak intramolecular hydrogen bond between the N—H group and an oxygen atom of the SO4 2– anion. Thirteen relatively weak intermolecular hydrogen-bonding interactions link the chains into a three-dimensional network. Hirshfeld surface analysis revealed that 64.7% of the intermolecular interactions are from O...H/H...O contacts and 20.1% from H...H contacts. Other interactions such as N...H/H...N or C...H/H...C contribute less to the crystal packing.

Survey of Meat Collected from Commercial Broiler Processing Plants Suggests Low Levels of Semicarbazide Can Be Created during Immersion Chilling

ABSTRACT

Semicarbazide (SEM) is routinely employed as an indicator for the use of nitrofurazone, a banned antimicrobial. The validity of SEM as a nitrofurazone marker has been scrutinized because of other possible sources of the compound. Nonetheless, a U.S. trade partner rejected skin-on chicken thighs because of SEM detection and suspected nitrofurazone use. Because nitrofurazone has been banned in U.S. broiler production since 2003, we hypothesized that incidental de novo SEM formation occurs during broiler processing. To assess this possibility, raw leg quarters were collected from 23 commercial broiler processing plants across the United States and shipped frozen to our laboratory, where liquid chromatography-mass spectrometry was used to quantitatively assess for SEM. Leg quarter samples were collected at four points along the processing line: hot rehang (transfer from the kill line to the evisceration line), prechill (before the chilling process), postchill (immediately following chilling), and at the point of pack. Thigh meat with skin attached was removed from 535 leg quarters and analyzed in triplicate for SEM concentrations. The concentrations ranged from 0 to 2.67 ppb, with 462 (86.4%) of 535 samples below the regulatory decision level of 0.5 ppb of SEM. The 73 samples over the 0.5-ppb limit came from 21 plants; 53 (72.6%) of positive samples were in meat collected after chilling (postchill or point of pack). The difference in both prevalence and concentration of SEM detected before and after chilling was highly significant (P < 0.0001). These data support our hypothesis that SEM detection in raw broiler meat is related to de novo creation of the chemical during processing.

HIGHLIGHTS

Determination of semicarbazide residue in human urine samples using liquid chromatography-tandem mass spectrometry

An ultra-performance liquid chromatography coupled with electrospray ionisation tandem mass spectrometry (UPLC-ESI-MS/MS) with pre-column derivatisation was developed and validated for the determination of semicarbazide in human urine. Urine samples were derivatised with 2-nitrobenzaldehyde and subsequently extracted with acetonitrile. Extracts were concentrated and then analysed by UPLC-MS/MS. The time per run was 7 min. Good results were observed for the linearity of matrix-matched calibration curves (R² > 0.99) in the concentration range of 1-100 µg/L. The absolute recovery ranged from 98.7% to 108.6%, with the relative standard deviations (RSDs) of 2.2%-3.6%. The limit of detection and quantification for the semicarbazide was 0.5 µg/L and 1 µg/L, respectively. The method showed good extraction efficiency, high sensitivity, and good reproducibility. It was suitable for the detection of semicarbazide in human urine. Residues of semicarbazide were between 1.0 and 41.5 μg/L in children's 24-h urine. This work is the first report on the quantitative analysis of SEM in 24-h human urine samples.

A simplified modification to rapidly determine the residues of nitrofurans and their metabolites in aquatic animals by HPLC triple quadrupole mass spectrometry

A simplified method is described for reducing the analysis time of nitrofurans (NFs) and nitrofuran metabolites (NFMs) in the aquatic animals. Most existing HPLC-MS/MS methods are intended only for NFMs and are based on their fast metabolic transformations. We optimized a method for simultaneously detecting major NFs and their metabolites, including nitrovin (NV) that imply use of an optimized buffer solution. The novel method was validated by six different aquatic animal matrices (loach, catfish, shrimp, lobster, scallop, and eel) spiked with the analytes at 0.5, 1.0, and 2.0 μg kg^-1. Recovery rates and %RSDs (relative standard deviations) of 82-97% and 1-8% were observed for NFMs, respectively, with values of 70-96% and 1-8% obtained for furazolidone, furaltadone, nitrofurazone, nitrofurantoin, and NV, respectively. Linearity was observed in the 0.1-20 μg L^-1 range, with correlation coefficients greater than 0.99 recorded for all compounds. The developed method is sensitive, accurate, easier to use, and faster than previous methods when applied to real samples. To the best of our knowledge, this is the first method that can simultaneously determine NFs and their metabolites, as well as NV, using a single-step extraction process.