Determination of Eprinomectin in Bovine Urine and Feces Using HPLC with Fluorescence Detection

Eprinomectin is a novel and potent antiparasitic animal health drug. An analytical procedure for the determination of EPR in bovine urine and feces has been developed. The urine sample was centrifuged and alkalized with ammonia following solid phase extraction. The fecal sample was extracted with acetonitrile, defatted with hexane, cleaned-up using C18 cartridge. All samples were analyzed by high performance liquid chromatography with fluorescence detection after derivatization with N-methylimidazole. The limits of detection are 0.5 ng mL⁻¹ and 0.5 ng g⁻¹, respectively. Fortified at 2, 10, 50, and 100 ng mL⁻¹(ng g⁻¹), inter-assay recoveries of EPR in cattle urine and feces were in the range of 87.9–91.5% and 78.6–86.3%, with coefficients of variation of 5.4–10.2% and 1.4–7.2%, respectively. Intra-assay mean recoveries of the analytes were 82.2–86.5% and 79.6–87.3%, with coefficients of variation of 7.8–11.5% and 6.3–7.8%, respectively. The method was used to study the excretion of eprinomectin in bovine urine and feces after subcutaneous administration at a dose of 0.5 mg kg⁻¹.     

Monitoring Farmed Fish Welfare by Measurement of Cortisol as a Stress Marker in Fish Feces by Liquid Chromatography Coupled with Tandem Mass Spectrometry

The aquaculture industry has become a sustainable source of food for humans. Remaining challenges include disease issues and ethical concerns for the discomfort and stress of farmed fish. There is a need for reliable biomarkers to monitor welfare in fish, and the stress hormone cortisol has been suggested as a good candidate. This study presents a novel method for measurement of cortisol in fish feces based on enzymatic hydrolysis, liquid–liquid extraction, derivatization, and finally instrumental analysis by liquid chromatography coupled with tandem mass spectrometry. Hydrolysis and extraction conditions were optimized. Cortisol appeared to be mostly conjugated to sulfate and less conjugated to glucuronic acid in the studied samples of feces from farmed Atlantic salmon. The method was suitable for quantification of cortisol after enzymatic deconjugation by either combined glucuronidase and sulfatase activity, or by glucuronidase activity alone. The limit of detection was 0.15 ng/g, the limit of quantification was 0.34 ng/g, and the method was linear (R² > 0.997) up to 380 ng/g, for measurement of cortisol in wet feces. Method repeatability and intermediate precision were acceptable, both with a coefficient of variation (CV) of 11%. Stress level was high in fish released into seawater, and significantly reduced after eight days.     

A pre-column derivatization high-performance liquid chromatography method for simultaneous determination of short-chain and medium-chain fatty acids in a fecal sample

Short-chain and medium-chain fatty acids have plentiful biological functions, which play a crucial role in the diagnosis and therapy of many diseases. Herein, a new method for simultaneous quantifying 17 short-chain and medium-chain fatty acids with high-performance liquid chromatography coupled with an ultraviolet detector was developed and the pre-column derivatization by indole-3-acetic acid hydrazide was performed to improve the separation and detection. The conditions of the derivatization reaction were systematically investigated. Subsequently, the method was validated and the results showed a satisfactory linearity (linear regression coefficients > 0.9969), the limit of detection (4.0×10⁻³–1.9×10⁻² μmol/L), precision (0.9%–7.3% for intra-day and 2.0%–9.8% for inter-day), recovery (90.0%–109.1% with relative standard deviation <7.7%) and stability (0.1%–3.3% for standard solution and 0.2%–3.9% for fecal sample). Finally, the established method was successfully applied to quantify short-chain and medium-chain fatty acids in the feces of healthy control and diabetic rats. Eleven kinds of short-chain and medium-chain fatty acids were detected and six of them showed a significant difference between the control group and the model group.     

Separation of short and medium-chain fatty acids using capillary electrophoresis with indirect photometric detection: Part I: Identification of fatty acids in rat feces

Short and medium-chain fatty acids (SMCFAs) are known as essential metabolites found in gut microbiota that function as modulators in the development and progression of many inflammatory conditions as well as in the regulation of cell metabolism. Currently, there are few simple and low-cost analytical methods available for the determination of SMCFA. This report focuses on SMCFA analysis utilizing CE with indirect photometric detection (CE-IPD). A ribonucleotide electrolyte, 5’-adenosine mono-phosphate (5’-AMP), is investigated as an IPD reagent due to its high molar absorptivity and dynamic reserve compatible with separation and detection of SMCFA. The operating parameters like the composition of organic solvent, millimolar concentrations of the complexing agent (alpha-cyclodextrin), 5’-AMP and non-absorbing electrolyte (boric acid), as well as the applied voltage, are optimized for resolution, efficiency, and signal-to-noise ratio. A baseline resolution of all nine SMCFAs is achieved in less than 15 min. Additionally, the developed CE-IPD method shows promising potential to identifying SMCFA in rat fecal supernatant. The presented analytical assay is simple, economical, and has considerably good repeatability. The intraday and interday RSD of less than 1 and 2% for relative migration time, as well as less than 14 and 15% for peak area, respectively, were obtained for SMCFA in fecal solution.     

蚕沙替代精料对黑山羊瘤胃细菌数量及多样性的影响

旨在研究蚕沙替代精料对黑山羊瘤胃细菌多样性及瘤胃产甲烷杆菌、产琥珀酸杆菌和黄色瘤胃球菌数量的影响.试验选用35只体重相近(20±1.3 kg)且健康的3月龄乐至黑山羊阉公羊,随机分为5个处理组,每组7只山羊,单栏单饲,对照组饲喂基础精料,试验组(Ⅰ、Ⅱ、Ⅲ和Ⅳ组)分别以25%、50%、75%、100%蚕沙替代基础精料,粗料各组相同,预试期20 d,试验期90 d.试验结束时每个处理组选择4头接近组内平均体重的羔羊屠宰取瘤胃液用于检测瘤胃微生物;采用Real Time-PCR法检测产甲烷杆菌、产琥珀酸杆菌和黄色瘤胃球菌的数量,采用PCR/DGGE法检测瘤胃细菌的多样性.结果表明:(1)蚕沙替代不同水平精料影响瘤胃产甲烷杆菌、产琥珀酸杆菌和黄色瘤胃球菌数量,其中随着蚕沙替代水平增加,产甲烷杆菌有减少趋势,而产琥珀酸杆菌有先减少后增加趋势,黄色瘤胃球菌先增加,而后降低再增加;(2)蚕沙替代不同水平精料影响瘤胃细菌多样性,其中随着蚕沙替代水平增加,瘤胃细菌多样性有减少趋势,若继续增加,几乎无变化.综上,蚕沙替代精料影响黑山羊瘤胃细菌数量和多样性,其中产甲烷杆菌、产琥珀酸杆菌和黄色瘤胃球菌数量变化趋势不尽相同,而细菌多样性有减少趋势.     

高效液相色谱/挥发激光散射检测器测定奶粉和鸟粪中的甾体化合物

利用反相高效液相色谱／挥发激光散射检测器发展了分析甾体化合物的新方法,采用甲醇和水溶液为冲洗体系,梯度淋洗,12种甾体类化合物在35min内得到很好的分离。方法简单快速,不需衍生,样品经固相萃取预处理,回收率介于84.0％～102.8％之间,响应值和浓度不呈简单的线性关系,在5～50mg／L浓度范围内对峰面积与浓度进行对数线性回归分析,得回归系数大于0.99。     

Methylation and Demethylation of Dimethylarsinic Acid in Rats Following Chronic Oral Exposure

Metabolites of dimethylarsinic acid (DMA) were studied in rats chronically exposed to DMA in drinking water. The urine was collected by forced urination at the end of 8, 20 and 30 weeks and the feces at the end of 30 weeks. The samples were analyzed for arsenic species by a combined system of ion chromatography and inductively coupled plasma mass spectrometry (IC–ICP–MS). Increases in arsenite, DMA, trimethylarsine oxide and a still-to-be-identified arsenic compound (which was eluted immediately after monomethylarsonic acid on the chromatogram) were detected in both urine and feces. At the 100 mg l⁻¹ dose, DMA was the main component in the urine; arsenite was a main component in the feces. The results indicate that, besides undergoing methylation, DMA can be demethylated to inorganic arsenic, and demethylation of DMA may be associated with intestinal bacteria     

The biotransformation of oleuropein in rats

A highly sensitive and specific LC‐MS/MS method was developed to investigate the in vivo bio‐transformation of oleuropein in rat. Rat feces and urine samples collected after oral administration were determined by liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the negative‐ion mode. The assay procedure involves a simple liquid–liquid extraction of parent oleuropein and the metabolite from rat feces and urine with ethyl acetate. Chromatographic separation was operated with 0.1% formic acid aqueous and methanol in gradient program at a flow rate of 0.50 mL/min on an RP‐C₁₈ column with a total run time of 31 min. This method was successfully applied to simultaneous determination of oleuropein and its metabolites in rat feces and urine. De‐glucosylation, hydrolysis, oxygenation and methylation were found to comprise the major metabolic pathway of oleuropein in rat gastrointestinal tract and three metabolites were absorbed into the blood circulatory system within 24 h after oral administration. Copyright © 2013 John Wiley & Sons, Ltd.     

Validation of a Method for the Determination of Total Chromium in Rat Feces by Inductively Coupled Plasma Optical Emission Spectrometry

Abstract

The validation of a method for the determination of total chromium in Fischer-344 rat feces by inductively coupled plasma optical emission spectrometry following a rapid, atmospheric-pressure microwave digestion is described. The performance of the method was evaluated over the concentration range of 5.00 to 200 µg Cr/g feces. Data for method linearity, accuracy, precision, digest stability, and storage stability are presented along with limit of detection and limit of quantitation data. Data from a cross-validation method for B6C3F1 mouse feces are also presented. Following validation, the method was applied to analyze samples collected in support of two chronic toxicological investigations.     

Determination of a novel nonfluorinated quinolone,nemonoxacin, in human feces and its glucuronide conjugate in human urine and feces by high‐performance liquid chromatography–triple quadrupole mass spectrometry

Three methods were developed and validated for determination of nemonoxacin in human feces and its major metabolite, nemonoxacin acyl‐β‐ d ‐glucuronide, in human urine and feces. Nemonoxacin was extracted by liquid–liquid extraction in feces homogenate samples and nemonoxacin acyl‐β‐ d ‐glucuronide by a solid‐phase extraction procedure for pretreatment of both urine and feces homogenate sample. Separation was performed on a C₁₈ reversed‐phase column under isocratic elution with the mobile phase consisting of acetonitrile and 0.1% formic acid. Both analytes were determined by liquid chromatography–tandem mass spectrometry with positive electrospray ionization in selected reaction monitoring mode and gatifloxacin as the internal standard. The lower limit of quantitation (LLOQ) of nemonoxacin in feces was 0.12 µg/g and the calibration curve was linear in the concentration range of 0.12–48.00 µg/g. The LLOQ of the metabolite was 0.0010 µg/mL and 0.03 µg/g in urine and feces matrices, while the linear range was 0.0010–0.2000 µg/mL and 0.03–3.00 µg/g, respectively. Validation included selectivity, accuracy, precision, linearity, recovery, matrix effect, carryover, dilution integrity and stability, indicating that the methods can quantify the corresponding analytes with excellent reliability. The validated methods were successfully applied to an absolute bioavailability clinical study of nemonoxacin malate capsule. Copyright © 2014 John Wiley & Sons, Ltd.