Liquid chromatography–UV diode-array detection method for multi-residue determination of macrolide antibiotics in sheep's milk

Effect of theophylline on serum and milk pharmacokinetics of tylosin following intramuscular administration in lactating goats

AIM OF THE WORK

The study was conducted to evaluate the influence of theophylline pre-treatment on serum pharmacokinetics and milk elimination of tylosin following single intramuscular (IM) administrations in lactating goats.

METHODS AND RESULTS

In a cross-over study, tylosin was injected via intramuscular (IM) at a single dose of 15 mg/kg b.wt. After a one-month washout period goats received theophylline at a daily IM dose of 2 mg/kg b.wt. for seven consecutive days then tylosin was injected IM dose of 15 mg/kg b.wt. two hours after the last theophylline dosing. Blood samples were collected before and at 0.25, 0.5, 0.75, 1, 2, 4, 6, 8, 10, 12, and 24 h post-injection. Samples were left to clot and then centrifuged to yield serum. Milk samples were collected before and at 0.5, 1, 2, 4, 6, 8, 10, 12, 24, 48, and 72 h post-injection from each goat by hand milking. Tylosin serum concentrations were determined by high-performance liquid chromatography (HPLC). Tylosin concentrations versus time were analyzed by a noncompartmental method. Tylosin Cmax significantly declined from 1.73 ± 0.10 to 1.01 ± 0.11 µg/ml, and attained Tmax values of 2 and 1 h, respectively in theophylline-pretreated goats. Moreover, theophylline pretreatment significantly shortened the elimination half-life (t1/2el) from 6.94 to 1.98 h, t1/2ka from 0.62 to 0.36 h and the mean residence time (MRT) from 8.02 to 4.31 h, also Vz/F and AUCs decreased from 11.91 to 7.70 L/kg and from 12.64 to 4.57 µg*h/ml, respectively, consequently, theophylline enhanced the clearance (Cl/F) of tylosin from the body. Similarly, tylosin milk concentrations were significantly lower in theophylline-pretreated goats than in goats that received tylosin alone and were detected up to 24 and 72 h in both groups, respectively. Moreover, the t1/2el and AUCs were significantly decreased from 14.68 ± 1.97 to 4.72 ± 0.48 h, and from 181 to 67.20 µg*h/ml, respectively.

CONCLUSIONS

The withdrawal period for tylosin in goat milk is at least 72 h. Theophylline pretreatment significantly decreases serum and milk tylosin concentrations to subtherapeutic levels, which could have serious clinical consequences such as failure of therapy. This means that after administering tylosin to goats, milk from these animals should not be consumed for at least 96 h to ensure that the milk is free from residues of the antibiotic.

Recovery of flavor compounds from vanilla bagasse by hydrolysis and their identification through UPLC-MSE

Vanilla is a globally treasured commodity, and the consequences of its unstable value affect social, environmental, economic, and academic ambits. The extensive range of aroma molecules found in cured vanilla beans is crucial to the complexity of this natural condiment and knowledge about their recovery is of the essence. Many strategies aim on reproducing the chemical intricacies of vanilla flavor, such as biotransformation and de novo biosynthesis. Few studies, however, aim at the exhaustion of the cured pods, of which the bagasse, after the traditional ethanolic extraction, might still bear a highly valued flavor composition. An untargeted liquid chromatography coupled with mass spectrometry (LC-MS^E) approach was applied to elucidate if sequential alkaline-acidic hydrolysis was effective in extracting flavor related molecules and chemical classes from the hydro-ethanolic fraction. Important vanilla flavor related compounds present in the hydro-ethanolic fraction were further extracted from the residue through alkaline hydrolysis, such as vanillin, vanillic acid, 3-methoxybenzaldehyde, 4-vinylphenol, heptanoic acid, and protocatechuic acid. Acid hydrolysis was effective on further extracting features from classes such as phenols, prenol lipids, and organooxygen compounds, though representative molecules remain unknown. Finally, sequential alkaline-acidic hydrolysis rendered natural vanilla's ethanolic extraction residues as an interesting supplier of its own products, which could be used as a food additive, and many other applications.

A liquid chromatography coupled to tandem mass spectrometry method for the quantification of spiramycin and its active metabolite neospiramycin in milk of major and minor species: Validation using the accuracy profile

A liquid chromatography with tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous quantification of residues of spiramycin, a macrolide antibiotic, and its active metabolite neospiramycin in cow's milk as well as in minor species 'milk, goat and ewe. Spiramycin-d3 was used as internal standard for quantification of both analytes. This analytical method was validated using a global accuracy profile as a graphical decision tool built according to the trueness and the precision of the method. A unique and optimal linear model with logarithm transformation (with a determination coefficient of 0.9991) allowed the measurement of both analytes in the milks of the three animal species, in a wide range from 0.2 to 10 times the Maximal Residue Limit (MRL) (40-2000 µg.kg^-1). The limits of detection and quantification were 13 µg.kg^-1 and 40 µg.kg^-1, respectively. The accuracy profile was established to get 80% of future measurements in routine assays that will fall within the acceptance limits. Trueness of the method, expressed as relative bias, was comprised between -1.6% and 5.7% over the whole range of concentrations. The mean relative standard deviation for repeatability and intermediate precision were comprised between 1.1% and 2.7%; 2.5 and 4.2%, respectively, in all levels of concentration for the three milks. Moreover, a two-order polynomial function was used to model the relative expanded uncertainty with a determination coefficient of 0.834. This function aimed to determine the uncertainty of the future quantifications within the validated dosing range. Overall, the global accuracy profile highlighted the reliability of the method for the routine assays of spiramycin and neospiramycin even in milk from minor species (goat, ewe) by using the most accessible milk (often from cow), while guaranteeing a very high proportion of samples within the fixed acceptance limits. The applicability of this method was tested during a depletion study of spiramycin and neospiramycin in the milk of cow, goat and ewe. The developed analytical method will be useful to assess the distribution profile of the antibiotic and its metabolite in milk of minor species where few studies are available.

An Easy Efficient Method of Veterinary Drug Residue Analysis in Raw Milk by RP-HPLC-UV with Application to Raw Milk

Background:

This study reports an easy method of a veterinary drug investigation in raw milk, based on QuECHERS extraction followed by RP-HPLC-UV analysis. Use of this benchtop system was motivated by its availability and moderate cost relatively to other sophisticated methods such as LC-MS which are more efficient.

Methods:

This developed method has been optimized and then after validation according to EU legislation, it demonstrated good linearity with R²>0.997, acceptable peak resolution within a short time (<9.5 min) and good recovery of the analyzed drugs (OXY, ALZ and IVR, respectively 87.08, 99.02 and 92.01 %). Additionally, we applied the method to the analysis of cow milk, collected in Nouakchott, capital of Mauritania.

Results:

The obtained results indicated a mixed level of drug use according to targeted molecules. In 42% of sampled farms, the anti-parasitics IVR and ALZ were detected whereas the antibiotic OXY was detected in 50%.

Conclusion:

This investigation shows that 17% of the sampled farms exceeded European standards for IVR drug.

Antibiotic residues in milk: Past, present, and future

Now-a-days, various types of antibiotics are being used worldwide in veterinary sector indiscriminately for promotion of growth and treatment of the livestock. Significant portions of antibiotics are released through milk of dairy animals unaltered and exert serious harmful effects on human health. This review evaluates and compare researches on antibiotic residues in milk in published literatures from Pubmed, CrossRef, CAB direct, DOAJ, JournalTOCs, AGRICOLA, ScientificGate, Electronic Journals Library, CAB abstracts, Global Health Databases, Global Impact Factor, Google Scholar, Park Directory of Open Access Journals, BanglaJOL and ISC E-Journals. Antibiotics residue in milk was first detected in 60s and then with an increasing trend with highest after 2,000 (188). The highest no. of works, 49 (21.87%) were accomplished in China, followed by Spain, 30 (13.39%); Germany, 11 (4.91%); and USA, 10 (4.46%). Continent-wise highest researches are published from Europe, 105 (46.88%), followed by Asia, 77 (34.38%); South America, 18 (8.04%); North America, 16 (7.14%); and Africa, 8 (3.57%). For detection, Bovine milk sample is mostly used, 193 (86.16%), followed by ovine, 19 (8.48%); and caprine, 14 (6.25%). Acetonitrile was used in maximum cases (77) for processing the samples. Chromatographic technique was the highest, 115 (51.34%) for detection. Residue of β-lactam group have been detected mostly 133 (36.54%), followed by tetracyclines, 51 (14.01%); fluoroquinolones, 49 (13.46%); sulfonamides, 46 (12.64%); and aminoglycosides, 38 (10.44%). This review observe that antibiotics residues are more common in milk samples that are being manifested in increasing researches on antibiotic detection and measures should adopt to cease this residue.

Screening method for the determination of tetracyclines and fluoroquinolones in animal drinking water by liquid chromatography with diode array detector

A liquid chromatography - diode array detector (HPLC-DAD) procedure has been developed for the determination of oxytetracycline (OTC), tetracycline (TC), chlorotetracycline (CTC), doxycycline (DC), enrofloxacin (ENR), ciprofloxacin (CIP), sarafloxacin (SAR) and flumequine (FLU) residues in animal drinking water. This method was applied to animal drinking water. Solid-phase extraction (SPE) clean-up on an Oasis HLB cartridge allowed an extract suitable for liquid chromatographic analysis to be obtained. Chromatographic separation was carried out on a C18 analytical column, using gradient elution with 0.1% trifluoroacetic acid - acetonitrile - methanol at 30°C. The flow-rate was 0.7 mL/min and the eluate was analysed at 330 nm. The whole procedure was evaluated according to the requirements of the Commission Decision 2002/657/EC, determining specificity, decision limit (CCα), detection capacity (CCβ), limit of detection (LOD), limit of quantification (LOQ), precision and accuracy during validation of the method. The recoveries of TCs and FQs from spiked samples at the levels of 10, 100 and 1000 μg/L were higher than 82%. The developed method based on HPLC-DAD has been applied for the determination of four tetracyclines and four fluoroquinolones in animal drinking water samples.

Milk and blood pharmacokinetics of tylosin and tilmicosin following parenteral administrations to cows

The aim of this study is to determine the pharmacokinetics of tylosin and tilmicosin in serum and milk in healthy Holstein breed cows (n = 12) and reevaluate the amount of residue in milk. Following the intramuscular administration of tylosin, the maximum concentrations (C_max) in serum and milk were found to be 1.30 ± 0.24 and 4.55 ± 0.23 µg/mL, the time required to reach the peak concentration (t_max) was found to be 2nd and 4th h, and elimination half-lives (t_1/2β) were found to be 20.46 ± 2.08 and 26.36 ± 5.55 h, respectively. Following the subcutaneous administration of tilmicosin, the C_max in serum and milk were found to be 0.86 ± 0.20 and 20.16 ± 1.13 µg/mL, the t_max was found to be 1st and 8th h, and the t_1/2β were found to be 29.94 ± 6.65 and 43.02 ± 5.18 h, respectively. AUC_milk/AUC_serum and C_max-milk/C_max-serum rates, which are indicators for determining the rate of drugs that pass into milk, were, respectively, calculated as 5.01 ± 0.72 and 3.61 ± 0.69 for tylosin and 23.91 ± 6.38 and 20.16 ± 1.13 for tilmicosin. In conclusion, it may be stated that milk concentration of tylosin after parenteral administration is higher than expected like tilmicosin and needs more withdrawal period for milk than reported.

Simultaneous determination of tylosin and josamycin residues in muscles, liver, eggs and milk by MLC with a monolithic column and time-programmed UV detection: application to baby food and formulae

Background

Tylosin and Josamycin are macrolide antibiotics. They are used in the treatment of pneumonia, arthritis and mastitis in cattle, and mycoplasma infections in poultry. The incorrect use of antibiotics has lead to the presence of antibiotic residues in foods. The residues cause toxic effects on consumers.

Results

A simple and sensitive method was optimized and validated for the analysis of tylosin and josamycin residues in food samples. Analytical separation was performed in less than 10 min using a RP C₁₈ monolithic column with time-programmed UV detection at 287 nm and 232 nm and a micellar solution of 0.17 M sodium dodecyl sulphate, 14% methanol and 0.3% triethylamine in 0.02 M phosphoric acid buffered at pH 4 as the mobile phase. The method was fully validated in accordance with ICH guidelines. The micellar method was successfully applied to quantitatively determine tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae. The compounds were separated by a monolithic column which, on account of its particular structure, could bear higher flow rates than usually found for this kind of analysis. High extraction efficiency for tylosin and josamycin was obtained without matrix interference in the extraction process and in the subsequent chromatographic determination. No organic solvent was used during the pretreatment step. Hence, it is considered an interesting technique for “green” chemistry.

Conclusion

The proposed method was validated and successfully applied for the determination of tylosin and josamycin residues in spiked chicken muscles, chicken liver, bovine muscles, liver, milk and eggs. It was also extended to the determination of tylosin and josamycin residues in chicken-based baby food and baby formulae.

Monoclonal antibody production and the development of an indirect competitive enzyme-linked immunosorbent assay for screening spiramycin in milk

To monitor spiramycin (SP) residue in milk, a monoclonal antibody (mAb)-based indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed. This study described the preparation of three immunogens and the production of a high-affinity mAb. After optimization, the 50% inhibition concentration (IC50) for the developed icELISA was estimated as 0.97 ng/mL in the assay buffer, and the limit of detection and limit of quantitation were 2.51 and 4.40 μg/L in the milk matrix. The newly developed assay demonstrated negligible cross-reactivity with 15 other macrolide antibiotics, but not with kitasamycin (23.4%). The mean recoveries ranged from 81 to 103% for the spiked samples (5, 10, and 50 μg/L), and the coefficient of variation ranged from 5.4 to 9.6%. The icELISA was validated by LC-MS/MS method, and all results demonstrated that it was a suitable screening method for detecting SP residue in milk without requiring a cleanup process.

Tylosin content in meat and honey samples over a two-year period in Croatia

A total of 646 meat and 96 honey samples were examined over a 2-year period for the presence of tylosin residues. ELISA method used was validated according to the criteria of Commission Decision 2002/657/EC established for qualitative screening methods. The CCβ values were 32.1 µg kg⁻¹ in muscle and 24.4 µg kg⁻¹ in honey. The recoveries from spiked samples ranged from 66.4-118.6%, with a coefficient of variation between 12.6% and 18.6%. All the investigated samples showed no presence of tylosin. Calculated estimated daily intakes show exposure levels lower than the acceptable daily intakes set by World Health Organization.

QuEChERS-HPLC-DAD method for sulphonamides in chicken breast

The development of a QuEChERS-HPLC-DAD method using a Lichrospher 60 RP-Select B column (250 x 4.6 mm x 5 µm) at 40ºC, mobile phase constituted by phosphate buffer:acetonitrile (75:25, v/v) at a initial flow rate of 0.5 mL min-1, increased by 1.2 mL min-1 and at 265 nm is presented for simultaneous determination of sulphadiazine, sulphametoxipiridazine and sulphamethoxazole in chicken breast samples. QuEchERS is inexpensive, fast and easy, and the extraction of the analytes of the matrix was successfully employed. In addition, the method presented linearity, in the range of 25, 50, 100, 150, 175, and 200 µg kg-1, precision, selectivity and sensitivity. The intraday precision (RSD %) for QuEChERS method was between 3.6-10.8 (SDZ), 6.9-14.1 (SPZ) and 1.9-10.9 (SMX) and interday precision (RSD%) was between 1.5-9.7, 1.7-4.1 and 2.1-10.2, respectively. Results of accuracy (bias) were in the range of -8.6 to +11.9 %. Therefore, the validated method is clearly useful for the practical residue monitoring of the drugs evaluated in chicken samples, as all the values were within the acceptable criteria used for food safety. Of 6 samples analyzed, none of them showed contamination of the sulphonamides studied at detectable levels.

Dispersive liquid-liquid microextraction for the determination of macrocyclic lactones in milk by liquid chromatography with diode array detection and atmospheric pressure chemical ionization ion-trap tandem mass spectrometry

Eprinomectin (EPRI), abamectin (ABA), doramectin (DOR), moxidectin (MOX) and ivermectin (IVM) were determined in milk samples using dispersive liquid-liquid microextraction (DLLME) and liquid chromatography with diode array detection (LC-DAD) coupled to atmospheric pressure chemical ionization in negative ion mode ion-trap tandem mass spectrometry (APCI-IT-MS/MS). Milk proteins were removed by precipitation with trichloroacetic acid and the analytes were preconcentrated using 2mL of acetonitrile containing 200μL of chloroform as extraction mixture. The effect of several parameters for the liquid-liquid microextraction efficiency was evaluated. Standard additions method was used for quantification purposes, the correlation coefficients were better than 0.9970 in all cases and the quantification limits ranged from 1.0 to 4.7ngg(-1) and from 0.1 to 2.4ngg(-1) when using DAD and MS, respectively. The DLLME-LC-APCI-IT-MS/MS optimized method was successfully applied to different milk samples and none of the studied analytes was detected in the samples studied. The recoveries for milk samples spiked at concentration levels ranging between 0.5 and 50ngg(-1), depending on the compound, were between 89.5 and 105%, with relative standard deviations lower than 9% (n=135). Simplicity, rapidity and reliability are important advantages of the proposed method, while the sample preparation step can be regarded as environmentally friendly.

Determination of macrolide antibiotics in meat and fish using pressurized liquid extraction and liquid chromatography-mass spectrometry

We developed a method for determining the quantities of seven macrolide antibiotics in meat and fish by using pressurized liquid extraction (PLE) and liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The PLE was optimized with regard to solvents, temperature, pressure, extraction time and number of cycles. The optimum conditions were: methanol as the extraction solvent; a temperature of 80 degrees C; a pressure of 1500psi; an extraction time of 15min; 2 cycles; a flush volume of 150% and a purge time of 300s. All recoveries for macrolide antibiotics were over 77% at 200mug/kg, except for erythromycin, which was 58%. The repeatability and reproducibility on days in between, expressed as %RSD (n=12), were lower than 10% and 12%, respectively. The quantification limits of all compounds were 25mug/kg of dry weight of animal muscle except for troleandomycin (50mug/kg). The method was applied to determine the pharmaceuticals in real samples taken from 18 meat and fish samples. The results showed that PLE is quantitative short time consuming technique, with use of smaller initial sample sizes. Greater specificity and selectivity in extraction and increased potential for automation were shown.

Validation of a confirmatory method for the determination of macrolides in liver and kidney animal tissues in accordance with the European Union regulation 2002/657/EC

This study proposes a simple multiresidue liquid chromatography-diode array detector (LC-DAD) method capable of determining seven macrolide antibiotics in samples of liver and kidney animals at concentrations lower than those allowed by current legislation. Samples were prepared by homogenizing the tissue with EDTA-McIlvaine's buffer and extracted with an Oasis HLB cartridge. The consumption of organic solvent during extraction was minimum. The analytes were detected by LC-DAD and also by liquid chromatography-mass spectrometry with electrospray ionization (LC-(ESI)MS). The method was specific, stable and robust enough for the required purposes. The DAD method was validated in accordance with the European Commission Decision 657/2002. Recovery data were also satisfactory with values higher than 67% for most macrolide antibiotics extracted from liver and kidney samples spiked at 200 microg/kg, the lowest MRL established for the macrolides studied. The relative standard deviations (RSD (%), (n=3)) were lower than 13% and 15% for intra-day and inter-day assays. The method was applied to investigate the occurrence of the studied macrolides in 31 beef and kidney animal samples. The results obtained by LC-DAD for positive samples were compared to those obtained by LC-(ESI)MS. Therefore, the method with simpler instrumentation than a LC-(ESI)MS can be used as a control method and the results of the validation process demonstrate that this method is suitable for application in a European Union program for monitoring residues of veterinary drugs.

A preliminary study on the occurrence and behavior of sulfonamides, ofloxacin and chloramphenicol antimicrobials in wastewaters of two sewage treatment plants in Guangzhou, China

Wastewater samples collected from two sewage treatment plants (STPs) in Guangzhou, China were acidified, solid-phase extracted (SPE) with Oasis HLB cartridges, followed by instrumental measurement by high performance liquid chromatography (HPLC) coupled with a diode array UV detector (DAD) and a fluorescence detector (FLD) for the occurrence and fate of antimicrobial compounds sulfadiazine (SDZ), sulfamethoxazole (SMX), ofloxacin (OFX) and chloramphenicol (CAP). Antimicrobials have been detected at 5.10-5.15, 5.45-7.91, 3.52-5.56 and 1.73-2.43 microg L(-1) for SDZ, SMX, OFX and CAP in the raw sewages of the two STPs, respectively. The concentrations of antimicrobials do not show substantial changes after preliminary mechanical sedimentation. No quantifiable sulfonamides and chloramphenicol have been identified, and >85% of ofloxacin has been removed in the effluents after activated sludge treatment in the two STPs, indicating that activated sludge treatment is effective and necessary to remove antimicrobial substances in municipal sewage.