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Background and Objectives: Food quality and safety control is an important part of the public health assessment of food adulteration has been a key issue in recent years. Cream is a product containing milk fat and is one of the most expensive and widely consumed edible fats, which is often targeted for cheating by mixing various vegetable oils with natural milk fats. A way to detect this type of fraud is to assess phytosterols in this dairy product.
 Materials & Methods: In this study, homogeneous liquid-liquid extraction method combined with dispersive liquid-liquid microextraction method was used for the extraction of stigmasterol, brassicaestrol, compesterol and β-sitestrol from animal cream samples. Samples were analyzed using gas chromatography-flame ionization detection method. To achieve high efficiency, effects of various factors in each extraction step, including type and volume of the extraction solvent, volume of the separating agent, speed and duration of centrifugation in the homogeneous liquid-liquid extraction step were investigated and optimized. Moreover, type and volume of the extraction solvent and salting effects in the dispersive liquid-liquid microextraction step were investigated and optimized as well.
Results: The suggested method was successfully carried on on cream samples. Limit of detection and limit of quantification of the method were in ranges of 0.92–2.1 and 2.1–6.4 ng/g, respectively. Method included a proper precision with relative standard deviation of less than ≤ 8.8 for intra and inter-day precisions. Results showed that the total phytosterol content in 21 samples (70%) was more than 3%, contrary to the legal limits by the Institute of Standards and Industrial Research of Iran.
Conclusion: Results of this study have verified that the suggested method is simple and reliable, including short analysis time and high ability to extract and measure phytosterols from animal cream samples.

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Background and Objectives: Antibiotics are chemical compounds, which are extensively used in the treatment of diseases in animals worldwide. Ignorance or negligence of the withdrawal time and use of antibiotics more than that prescribed have resulted in the presence of antibiotic residues in food products such as eggs that can include adverse effects on the consumer health. The aim of this study was to develop an appropriate method to assess antibiotics in eggs.
 Materials & Methods: In the present study, an efficient method called homogeneous liquid-liquid extraction in combination with deep eutectic solvent-based dispersive liquid–liquid microextraction was developed for the extraction of penicillin G, oxytetracycline, chloramphenicol and doxycycline from egg samples and then analyses were carried out using high performance liquid chromatography. To achieve high extraction recoveries, effects of various parameters including concentration and volume of the zinc acetate solution, salt quantity, type and volume of the extraction/dispersive solvent and vortexing time were investigated and optimized in HLLE step as well as type and volume of the extraction solvent, ionic strength and rate and time of the centrifuging procedure in DLLME step.
Results: Under the optimum extraction conditions, extraction recoveries were in the ranges of 59–75%. Detection limits of the method for analytes were in the range of 3.7–4.4 ng g^–1.  Consumption of small volumes of the organic solvents has been addressed as another advantage of this method. Moreover, 35 egg samples were analyzed with the highlighted method and results indicated that 28.58% of the investigated egg samples were contaminated by at least one of the listed antibiotics.
Conclusion: The developed method is well capable of measuring the mentioned antibiotics in eggs, so this method can be used with the aim of increasing food safety in various industries, including poultry
 

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Background and Objectives: Different types of antibiotics are used indiscriminately in animal husbandry for the growth and treatment of livestock, which cause accumulation of antibiotic residues in livestock products such as milk. Long-term consumption of milk contaminated with antibiotic residues above the permissible limits is harmful to human health, causing antibiotic resistance problems. Therefore, monitoring of antibiotic residues in milk and dairy products is particularly important.
Materials and Methods: In this study, temperature-controlled ionic liquid-assisted dispersive liquid-liquid microextraction  method was developed for the extraction of amoxicillin, cloxacillin and erythromycin residues from cow milk and their assessment were carried out using high-performance liquid chromatography equipped with a diode array detector. Furthermore, effects of various parameters on the extraction efficiency such as volume of precipitating agent and vortexing time, type and quantity of extracting solvent, effects of salt addition and temperature of aqueous solution were optimized.
Results: Analysis of milk samples showed presence of amoxicillin in eight milk samples, all of which included values greater the permissible limits. No other antibiotics were detected in the milk samples. The suggested method included high efficiencies in extracting the target antibiotic residues from milk samples. Therefore, repeatability of the method based on relative standard deviation proportion included 3–4.5. Under optimal conditions, extraction recoveries were in range of 78–87% and the limits of detection and quantification less than 1.1 and 3.7 ng/ml were reported, respectively.
Conclusion: The developed method is appropriate for the determination of selected analytics in cow milk and its detection limit is lower than the maximum residue limits for the residues of these antibiotics.