Detecting Dimetridazole in Chicken Eggs and Tissue with HPLC-MS/MS

A recent study conducted by the Guangdong Key Laboratory for Veterinary Drug Development and Safety Evaluation part of the College of Veterinary Medicine at South China Agricultural University, in Guangzhou, China (1), reported on the development of a high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method for the precise detection of dimetridazole (DMZ) and its metabolite 2-hydroxymethyl-1-methyl-5-nitroimidazole (HMMNI). The results of the study demonstrate a strong linear relationship between the concentrations of DMZ and HMMNI in tissues and egg within the range of 1~100 ng/g.

DMZ is a widely used nitroimidazoles drug, exhibiting broad-spectrum anti-anaerobic and antiprotozoal activity, as well as potent inhibition of spirochetes, which is commonly used in the treatment of histomonosis (blackhead or infectious enter hepatitis). DMZ is also commonly employed with other antibiotics in clinical settings for the treatment of mixed infections involving both anaerobic and aerobic bacteria. While DMZ premix has been used as a feed additive due to its efficacy, convenience, and cost-effectiveness, previous animal studies have found that the potential of genotoxicity could not be judged while carcinogenicity was suggested. Therefore, DMZ has been banned from use in food-producing animal in some countries or has only been approved for use in the treatment of disease.

As a result of the limited data to establishing a safe level of residues of DMZ or its metabolites in food, the Joint FAO/WHO Expert Committee on Food Additives (JECFA) are currently demanding that DMZ should not be detected in all animal foods (2), imposing higher requirements on the protocols for the use of DMZ in food-producing animals. The authors of the study, hoping to establish a scientific basis for the safe and rational application of DMZ in poultry farming, developed their HPLC–MS/MS method for simultaneous analysis of DMZ and HMMNI concentrations in broiler tissues and egg. They also investigated the elimination pattern of DMZ in broiler and laying hens using SanHuang chicken and Hy-line Gray laying hens as experimental subjects, as well as proposed corresponding withdrawal times and egg abandonment periods.

While the authors cite that the current main methods for the detection of nitroimidazoles in animal tissues are thin-layer chromatographic (TLC), gas chromatography (GC), high performance liquid chromatography (HPLC), the HPLC-MS/MS method they utilize offers high sensitivity, good separation, and conservation. Their study indicates that residues of HMMNI were consistently higher than those of DMZ in both broiler tissues and egg samples. Sebum (an oily substance that protects and hydrates the skin's surface [3]) was the accumulating tissue for DMZ and HMMNI and had the slowest elimination rate. In egg, residues of DMZ and HMMNI reached a peak on the first day after withdrawal, followed by slow elimination with elimination half-lives of 0.45 and 0.66 days.

Under the conditions of this study, WT1.4 software was used to determine that the withdrawal time for broilers is 262.97 h (10.96 days) and the egg abandonment period for laying hens is 13.45 days after withdrawal. Therefore, for practical purposes, the authors recommend a withdrawal time of 11 days in broilers, and 14 days after withdrawal for egg abandonment period in laying hens.

Chicken and eggs. © GrafitiRex - stock.adobe.com

References

1. Mo, K.; Wei, C.; Bai M.; Long X.; Liu, X.; Ding, H. Elimination Patterns of Dimetridazole in Egg of Laying Hens and Tissues of Broiler After Oral Administration. Frontiers in Veterinary Science, 2024, 11. DOI: 10.3389/fvets.2024.1451904

2. World Health Organization. Residue Evaluation of Certain Veterinary Drugs: Joint FAO/WHO Expert Committee on Food Additives, 94th Meeting (Virtual), May 16–27, 2022. Food and Agriculture Organization, 2023.

3. What is Sebum? Medical News Today website. https://www.medicalnewstoday.com/articles/sebum#function (accessed 2024-08-07).