LC-Fluorescence Detection of Abamectin, Ivermectin, Doramectin, and Eprinomectin in Rabbit Feces

A simple multi-residue method was developed for the simultaneous determination of abamectin, ivermectin, doramectin, and eprinomectin in rabbit feces. Samples were extracted with acetonitrile, cleaned up with a C18 solid-phase extraction cartridge, and analysed by LC with fluorescence detection after derivatization. Abamectin, ivermectin, doramectin, and eprinomectin were detected at levels of 2–500 ng g^?1; the average recoveries ranged from 73.2 to 99.6% with relative standard deviations of 2.5–11.3%. The limits of detection were 0.1–0.4 ng g^?1.     

Multiresidue analysis of avermectins in bovine liver by immunoaffinity column cleanup procedure and liquid chromatography with fluorescence detector

A multiresidue liquid chromatography (LC) method was developed to detect avermectin, ivermectin, doramectin, and eprinomectin simultaneously in bovine liver. The extracted samples were cleaned up by an immunoaffinity column, which was prepared by coupling anti-avermectin polyclonal antibody with CNBr-activated Sepharose 4B. The dynamic column capacities of avermectin, ivermectin, doramectin, and eprinomectin were 3531, 3542, 3543, and 3284 nglmL gel, respectively. The eluate was evaporated to dryness, and residues were derivatized and determined by LC with fluorescence detector set at 365 nm excitation and 465 nm emission wavelengths. Recoveries ranged from 79.3 to 115.9% with coefficients of variation of 1.1-19.4% when avermectin, ivermectin, doramectin, and eprinomectin were spiked at levels of 5-100 ng/g. The limit of quantitation of the method was 2 ng/g for each drug.     

Confirmation of eprinomectin, moxidectin, abamectin, doramectin, and ivermectin in beef liver by liquid chromatography/positive ion atmospheric pressure chemical ionization mass spectrometry

A liquid chromatographic (LC) multiresidue screening procedure was developed for determination of eprinomectin, moxidectin, abamectin, doramectin, and ivermectin in beef liver at 0, 25, 50, and 100 ppb levels. A procedure using low resolution LC/atmospheric pressure chemical ionization (APCI) mass spectrometry (MS) was developed with further purification steps added to the quantitative LC method to confirm residues. Acetonitrile extracts of liver, prior to derivatization for LC analysis, were further purified by using a C8 solid-phase extraction cartridge and an alumina-B cartridge. The purified extract was analyzed by injection into an LC/positive ion APCI MS. Identity of the compound was confirmed by comparison of its retention time and relative intensity data with those of a standard or recovery from a fortified control liver sample. Anthelmintic drugs in acetonitrile extracts of liver containing eprinomectin, moxidectin, abamectin, doramectin, and ivermectin at 25 ppb, the lowest level of fortification used in the LC determinative method, were successfully confirmed.     

Simultaneous determination of eprinomectin, moxidectin, abamectin, doramectin, and ivermectin in beef liver by LC with fluorescence detection

Eprinomectin, moxidectin, abamectin, doramectin, and ivermectin are drugs used to control parasitic infections in both meat-producing and nonmeat-producing animals. A number of analytical methods are available to analyze these anthelmintic drugs individually. A multiresidue screening method was developed for these drugs; however, the initial attempt to derivatize eprinomectin following the method published by Merck scientists was unsuccessful because the eprinomectin derivatization reaction was temperature- and time-dependent. The optimum time and temperature for the completion of eprinomectin derivatization were 90 min and 65 degrees C, respectively, without appreciable effect on the remaining 4 drugs. Beef liver samples were fortified with 0, 25, 50, and 100 ppb mixed standards of eprinomectin, moxidectin, abamectin, doramectin, and ivermectin. Each set of 4 levels of recoveries was repeated 10 times with all 5 compounds. The average of 10 recoveries of 5 compounds at all 4 levels of fortification was > 70%; the coefficient of variation was < 20%.     

改良的QuEChERS结合高效液相色谱-串联质谱同时测定水产品中7种阿维菌素类药物残留

建立了改良的QuEChERS结合高效液相色谱-串联质谱(HPLC-MS/MS)同时测定水产品中7种阿维菌素类药物(阿维菌素、伊维菌素、多拉菌素、塞拉菌素、乙酰氨基阿维菌素、莫西菌素和埃玛菌素)的分析方法。样品经0.2%(v/v)氨化乙腈提取,3 g无水硫酸镁和2 g无水硫酸钠除水剂和沉淀蛋白质,100 mg十八烷基硅烷(C18)和500 mg无水硫酸镁净化。以0.1%(v/v)甲酸乙腈(含5 mmol/L乙酸铵)-0.1%(v/v)甲酸水溶液(含5 mmol/L乙酸铵)为流动相,采用Varian Pursuit ULTRA C8色谱柱(100 mm×2.0 mm,2.8μm)进行分离。在加热电喷雾离子(HESI)源、正离子模式下采用多反应监测模式检测,基质匹配标准曲线外标法定量。阿维菌素、伊维菌素、多拉菌素、塞拉菌素、乙酰氨基阿维菌素和莫西菌素在2~200μg/L范围内、埃玛菌素在0.2~20μg/L范围内呈线性相关,相关系数(r)均≥0.997 2,水产品中阿维菌素类药物的加标回收率为71.6%~112.8%,相对标准偏差(RSD)为4.7%~13.1%,不同水产品的基质效应均小于15%。阿维菌素、伊维菌素、多拉菌素、塞拉菌素、乙酰氨基阿维菌素和莫西菌素的定量限均为5μg/kg,埃玛菌素的定量限为0.25μg/kg。该法操作简便,重复性好,适用于水产品中7种阿维菌素类药物残留量的同时测定。     

Simultaneous determination of residual antiparasitic lactones in bovine muscle and liver by liquid chromatography with fluorescence detection

Abamectin, doramectin, eprinomectin, ivermectin, milbemectin, and moxidectin in bovine muscle and liver were extracted with acetonitrile. The extracts were partitioned with n-hexane and then evaporated to dryness. The residue was cleaned up on Bond Elute NH2 cartridge, and the drugs were eluted from the cartridge with methanol-ethyl acetate (3 + 7). The eluate was evaporated to dryness, and residues were derivatized with N,N-dimethylformamide-acetic anhyride-1-methylimidazole. The derivatives were determined by liquid chromatography with fluorescence detection. Recoveries of the 6 drugs were 79.6-63.8% in muscle and 71.6-60.6% in liver at 0.01 ppm levels. The quantitation limits were 5 ppb for each drug.     

高效液相色谱-串联质谱法测定猪肉中的阿维菌素类、地克珠利、妥曲珠利及其代谢物残留

建立了猪肉中阿维菌素、伊维菌素、多拉菌素、莫西菌素、乙酰氨基阿维菌素等5种阿维菌素类药物以及地克珠利、妥曲珠利、妥曲珠利砜、妥曲珠利亚砜等4种均三嗪类药物及其代谢物残留的高效液相色谱-串联质谱分析方法。样品采用乙腈提取,ODS粉分散固相萃取净化,经Venusil ASB C18色谱柱(150 mm×2.1 mm, 3.0 μm)分离,电喷雾串联四极杆质谱多反应离子监测方式测定。9种分析物在0.005～0.2 mg/L范围内线性关系良好,相关系数均大于0.990。猪肉基质中9种分析物在0.005、0.01、0.02 mg/kg加标水平下,回收率为73.2%～91.5%,相对标准偏差为12%～17%。该方法稳定、可靠,可满足猪肉中阿维菌素类、均三嗪类药物残留的检测与确证。     

Simultaneous Analysis of Avermectins in Bovine Tissues by LC-MS-MS with Immunoaffinity Chromatography Cleanup

A rapid, simple and sensitive LC-MS-MS method was developed to simultaneously measure residues of avermectin, ivermectin, doramectin, and eprinomectin in bovine liver and muscle. The extracted samples were cleaned by an immunoaffinity column which was prepared by coupling anti-avermectin polyclonal antibodies with CNBr-activated Sepharose 4B. The residues eluted from the column were analyzed by high-performance liquid chromatography with tandem mass spectrometry. Recoveries fortified at levels 5?50 ng g^?1 ranged from 62.93 to 84.03%, with relative standard deviations from 6.02 to 17.39% for all four compounds in liver tissue. The limits of quantification were 5 ng g^?1, and limits of detection were 2.5 ng g^?1 in liver for the four drugs. The procedure was also applied to bovine muscle, giving similar results.     

超高效液相色谱-电喷雾电离串联质谱联用法检测茶叶中阿维菌素类药物残留

建立了采用超高效液相色谱-电喷雾电离串联质谱同时检测茶叶中爱比菌素、甲胺基阿维菌素、乙酰胺基阿维菌素、伊维菌素、多拉菌素、莫西丁克残留的方法。试样经饱和氯化钠溶液浸润后,用乙腈提取,C18固相萃取小柱净化,超高效液相色谱-电喷雾串联质谱法(UPLC/ESI-MS/MS)测定。对流动相、监测离子、校正曲线等进行了优化和探讨。6种分析物在2.0～50 μg/L范围内线性关系良好,相关系数均大于0.9920。莫西丁克在5,10,20 μg/kg,其余分析物在2,5,10 μg/kg加标水平的平均回收率为61.7%～85.4%,相对标准偏差为9.37%～17.19%。该方法可靠、稳定,可满足茶叶中阿维菌素类药物残留检测与确证的需要。     

A liquid-liquid extraction procedure followed by a low temperature purification step for the analysis of macrocyclic lactones in milk by liquid chromatography-tandem mass spectrometry and fluorescence detection

In this work a method is proposed and demonstrated for the analysis of the macrocyclic lactones abamectin, doramectin, eprinomectin, ivermectin and moxidectin in bovine milk by liquid chromatography coupled to mass spectrometry (LC-MS/MS) and liquid chromatography with fluorescence detection (LC-FL). The method is based on liquid-liquid extraction followed by a low temperature purification (LLE-LTP) step. Moreover, the proposed method was validated according to the Commission Decision 2002/657/EC, using LC-MS/MS and LC-FL for confirmatory and quantitative analysis, respectively. For LC-MS/MS the recovery rates observed ranged from 101.2 to 141.6% with coefficient of variation from 2.6 to 19.8%. For LC-FL the recovery rates observed ranged from 100.2 to 105% and coefficient of variations from 2.9 to 8.8%. Matrix effects were negligible due to the low temperature purification step. The quantification limits were far below the maximum limits established by regulations of all countries consulted. The proposed method proved to be simple, easy, and adequate for high-throughput analysis of a large number of samples per day at low cost.     

Development and optimisation of an improved derivatisation procedure for the determination of avermectins and milbemycins in bovine liver

A robust procedure has been developed to overcome the instability problems experienced with the fluorescent derivative of eprinomectin. The procedure involves addition of acetic acid, together with the typical reagents methylimidazole and trifluoroacetic anhydride, to produce a fluorescent molecule that can be determined by high performance liquid chromatography (HPLC) with fluorescence detection. Derivatisation is completed in 30 min at 65 degrees C. This derivatisation procedure was shown to be suitable, also, for the related compounds, moxidectin, abamectin, doramectin and ivermectin. A multi-residue method for these compounds in bovine liver has been developed using the derivatisation procedure. Samples are extracted with acetonitrile; followed by clean-up on deactivated alumina and C18 solid phase extraction (SPE) cartridges. The method was validated using bovine liver fortified at levels of 4 and 20 micrograms kg-1 with the drugs. The mean recovery ranged between 73 and 97%. The intra- and inter-assay variations showed relative standard deviations typically of < 6% and < 14%, respectively. The limit of quantitation of the method is 2 micrograms kg-1 (ppb).     

Multi-Residue Analysis of Avermectins in Bovine Liver and Muscle by Liquid Chromatography–Fluorescence Detector

A simple multi-residue analysis method for the quantitative determination of eprinomectin, abamectin, doramectin and ivermectin in bovine tissues was developed. The tissue sample was extracted with acetonitrile, followed by clean-up on a C₁₈ solid phase extraction cartridge. The eluate was derivatised before being analyzed by HPLC coupled to a fluorescence detector. The method was validated using bovine liver and muscle fortified with the drugs at 0, 5, 10 and 50 ng g⁻¹. The mean recoveries of the four drugs were 70.31–87.11% in liver and 79.57–93.65% in muscle, with relative standard deviations below 17.84% in liver and 14.68% in muscle. The limits of detection were between 0.5 and 1.0 ng g⁻¹ and the limits of quantification were 1–2 ng g⁻¹ in bovine tissues for the four drugs.     

Validation and robustness testing of a HPLC method for the determination of avermectins and moxidectin in animal liver samples using an alumina column clean-up

A multi-residue method has been developed for the quantitative determination of moxidectin, abamectin, doramectin and ivermectin in liver samples, with capability for qualitative identification of the presence of eprinomectin. Liver samples are extracted with isooctane, followed by clean-up on alumina-N solid phase extraction (SPE) cartridges. Extracts are derivatised and determined by high-performance liquid chromatography (HPLC) with fluorescence detection. The method was validated using bovine liver fortified at levels of 4 and 20 micrograms kg-1 with the drugs. The mean recovery from bovine liver ranged between 90 and 96%. The intra and inter-assay variations showed RSD typically of < 5% and < 10%, respectively. The procedure was applied also to ovine and porcine liver, giving similar results. A robustness study, carried out on the alumina clean-up step, indicated that the step is relatively insensitive to method changes. However, significant differences overall were found for the type of alumina and/or commercial SPE cartridge used. The limit of quantitation of the method is 2 micrograms kg-1 (ppb).     

Trace analysis of endectocides in milk by high performance liquid chromatography with fluorescence detection

An analytical method has been developed for the simultaneous determination of the following endectocide drugs in milk: ivermectin, abamectin, doramectin, moxidectin, eprinomectin, emamectin and nemadectin. Samples were extracted with acetonitrile, purified with solid-phase extraction on a reversed phase C₈, derivatised with N-methylimidazole, trifluoroacetic anhydride and acetic acid to a stable fluorescent derivative, and were further analysed by gradient high performance liquid chromatography (HPLC) on an endcapped reversed phase Supelcosil LC-8-DB. The derivatisation step was mathematically optimised and the method was validated according to the requirements of Commission Decision 2002/657/EC, using fortified raw bovine milk. Mean recovery was between 78 and 98%. The repeatability (CV_r) and within-laboratory reproducibility (CV_W) ranged from 4.6 to 13.4% and from 6.6 to 14.5%, respectively. Decision limits (CCα) for analytes with MRL values, namely eprinomectin and moxidectin, were determined to be 24.8 and 50.6 μg kg⁻¹, respectively. CCα values for unauthorised endectocides ranged from 0.1 to 0.2 μg kg⁻¹. Due to high acceptability regarding the required criteria and applicability to ovine and caprine milk, giving similar results, this multi-analyte method has been successfully implemented in pharmacokinetic research studies as well as statutory residue monitoring in Slovenia.     

Determination of abamectin, doramectin, emamectin, eprinomectin, ivermectin, and moxidectin in milk by liquid chromatography electrospray tandem mass specrometry

The avermectin and milbemycin families of compounds are derived from naturally occurring yeasts. They have proven to be potent preventatives against a variety of pests such as insects and parasites. Only eprinomectin and moxidectin are currently approved for use on lactating cattle with tolerances in milk of 12 microg/kg for eprinomectin and 40 microg/kg for moxidectin. Detection of misuse or inadvertent contamination in milk requires a sensitive and definitive analytical method. A method has been developed for the determination of 5 avermectins and 1 milbemycin in milk using a simple liquid-liquid extraction and liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis. Ivermectin (IVR), doramectin (DOR), abamectin (ABA), eprinomectin (EPR), emamectin (EMA), and moxidectin (MOX) were extracted from whole milk by partitioning into acetonitrile with a subsequent solvent exchange into methanol-water. Simultaneous confirmation and quantification were achieved with LC separation, positive electrospray ionization (ESI+), and MS/MS. The limits of detection ranged from 16 pg/g (ppt) for EMA to 1.7 microg/g (ppb) for MOX.     

A monoclonal antibody-based ELISA for multiresidue determination of avermectins in milk

Due to the widespread use and potential toxicity of avermectins (AVMs), multi-residue monitoring of AVMs in edible tissues, especially in milk, has become increasingly important. With the aim of developing a broad-selective immunoassay for AVMs, a broad-specific monoclonal antibody (Mab) was raised. Based on this Mab, a homologous indirect enzyme-linked immunosorbent assay (ELISA) for the rapid detection of AVMs in milk was developed. Under the optimized conditions, the IC?? values in assay buffer were estimated to be 3.05 ng/mL for abamectin, 13.10 ng/mL for ivermectin, 38.96 ng/mL for eprinomectin, 61.00 ng/mL for doramectin, 14.38 ng/mL for emamectin benzoate. Detection capability (CCβ) of the ELISA was less than 5 ng/mL and 2 ng/mL in milk samples prepared by simple dilution and solvent extraction, respectively. The optimized ELISA was used to quantify AVMs in milk samples spiked at different amounts. The mean recovery and coefficient of variation (CV) were 95.90% and 15.42%, respectively. The Mab-based ELISA achieved a great improvement in AVMs detection. Results proved this broad-selective ELISA would be useful for the multi-residue determination of AVMs in milk without purification process.     

Multiresidue determination of abamectin, doramectin, ivermectin, and moxidectin in milk using liquid chromatography and fluorescence detection

Abamectin, doramectin, ivermectin, and moxidectin are macrocyclic lactones derived from soil dwelling actinomycetes, and are very effective against nematode, insect, and arthropod infestations. These compounds, known as endectocides, have been approved for use in beef cattle in the United States; however, they are currently not approved for use in dairy cattle. Abamectin, doramectin, ivermectin, and moxidectin residues were isolated from milk by a series of liquid-liquid extraction steps, derivatized with trifluoroacetic anhydride, and determined by liquid chromatography with fluorescence detection. Recovery studies were performed in 2 laboratories. Recoveries of > 80% (1-30 ng/mL) were achieved for all 4 compounds.     

The derivatisation of avermectins and milbemycins in milk: new insights and improvement of the procedure

Derivatisation of the avermectines ivermectin (IVM), doramectin (DOR), abamectin (ABA) and eprinomectin (EPR), and the milbemycin moxidectin (MOX) to fluorescent derivatives is commonly used for quantitative analysis at relevant levels using high performance liquid chromatography (HPLC) with fluorescence detection. Problems associated with the differences in reactivity towards derivatisation (EPM) and limited stability of the derived products (IVM, DOR, ABA) may seriously hamper the applicability of the method and the reliability of the obtained results. A study was performed to obtain more insight in this derivatisation process from an organic chemistry point of view. This study demonstrated the occurrence of two main fluorescent derivatives: the trifluoroacetyl esters (flu-TFA) and the derivatives with a free hydroxy group at the glycosidic ring (flu-OH). Optimisation of the derivatisation conditions resulted in a fast and reproducible formation of the fluorescent derivatives for all analytes including EPM. The improved procedure involves the addition of 1-methylimidazole (MI), trifluoroacetic anhydride (TFAA), triethylamine (TEA) and trifluoroacetic acid (TFA) with a subsequent incubation for 30 min at 70 °C. With this procedure for IVM, DOR and ABA flu-TFA derivatives are obtained instead of flu-OH derivatives as generally described in literature. The derivatisation is reproducible in different milk samples and the derivatives proved to be stable for at least 80 h at room temperature. Using the optimised procedure a limit of detection (LoD) of 0.1 μg kg⁻¹ in milk was readily obtained.     

液相色谱-质谱法测定饲料中阿维菌素类药物

建立了饲料中阿维菌素类药物(阿维菌素、多拉菌素、埃普菌素和伊维菌素)液相色谱-质谱(LC-MS)检测法. 用乙腈提取样品中的药物, 加水稀释, 加三乙胺调节pH, 经C18固相萃取柱净化, LC-MS法测定. 结果表明, 方法平均回收率为91.3%～99.8%, RSD为2.9%～15% (n=4), 配合饲料、浓缩饲料和预混合饲料中的检出限均为10 μg/kg; 定量限均为20 μg/kg. 方法可用于饲料样品中阿维菌素类药物残留量的确证检测.     

Validation study on avermectine residues in foodstuffs

Avermectines are antiparasitic agents widely used as veterinary drugs for food producing animals. The European Community, due to their side effects, limited the use of these molecules establishing maximum residue limits (MRLs) in some foods. A validated qualitative and quantitative high performance liquid chromatography method with fluorescence detection (HPLC-FL) is presented for the simultaneous determination of ivermectin (IVM), abemectin (ABA), moxidectin (MOX), eprinomectin (EPR), doramectin (DOR) and emamectin (EMA) in foodstuffs (muscle, eggs and milk). Samples were extracted with acetonitrile, purified with liquid-liquid extraction (LLE), and analysed by HLPC-FL previous derivatization with trifluoroacetic anhydride (TFAA) in presence of 1-methyl-imidazole (MI) and acetic acid. To date, the presented method is the first validated for the matrix eggs, and in accordance with the requirements set by Commission Decision 2002/657/EC. Recoveries of the methods, calculated spiking the samples in the range 5.0-100.0 μg kg(-1), were 64-83% for muscle, 65-89% for milk and 63-84% for eggs. The precision (CV) ranged between 9.2 and 17.1% for muscle, 9.9 and 16.6% for milk and from 9.4 to 17.4% for eggs. Linearity for the six analytes was calculated from 5.0 to 200.0 μg kg(-1). The main advantages of the presented method are its rapidity, the specificity, the good precision and recovery that make it very suitable to the detection and determination of avermectines.