Liquid-chromatographic determination of sulfadimidine in milk and eggs

A method for the determination/identification of residual sulfadimidine (SDD) in milk and eggs by high-performance liquid chromatography (HPLC) with a photo-diode array detector was developed. The sample preparation was performed by shaking with a mixture of 20% (w/v) trichloroacetic acid-methanol (4:1, v/v) followed by ultra-filtration using Molcut II^®. A LiChrospher^® 100 RP-8 (e) column and a mobile phase of 4% (v/v) acetic acid solution-acetonitrile (6:4, v/v) were used. The average recoveries from spiked SDD samples were 80.8–88.0% with coefficients of variation of 2.8–5.5%. The limits of detection in milk and eggs were 0.01 μg/mL and 0.01 μg/g, respectively. The total time required for the analysis of one sample was less than 20 min.     

High-performance liquid chromatographic methods for the determination of sulfonamides in tissue, milk and eggs.

In the last decade, significant research has been done to improve the existing high-performance liquid chromatographic (HPLC) methods and also towards developing simple, reliable and sensitive HPLC methods for sulfonamides in meat, milk and eggs. The replacement of solvent extraction with solid-phase extraction or matrix solid-phase dispersion techniques is a step forward. Significant improvements in sensitivity have been achieved. This review concentrates on HPLC methods for the determination of sulfonamides in foods of animal origin published after 1980. The existing methods are critically evaluated and suggestions for future research are made.     

Multiresidue determination of fluoroquinolones in eggs

A multiresidue method was developed for the determination of fluoroquinolones in eggs. Extraction of eggs with ammoniacal acetonitrile was followed by liquid-liquid defatting, solvent evaporation, and redissolution in a small volume of buffer. The fluoroquinolones were further purified by on-line microdialysis, concentrated on a trace enrichment column, and separated by reversed-phase liquid chromatography with fluorescence detection. Norfloxacin (NOR), ciprofloxacin (CIP), and sarafloxacin (SAR) were extracted from fortified eggs over a range of 2-200 microg/kg, with recoveries of 65.7-78.9%, 65.6-77.1%, and 67.6-110%, respectively. Enrofloxacin (ENRO) was extracted over a range of 1-100 microg/kg, with recoveries of 71.5-86.7%, whereas desethylene ciprofloxacin (DCIP) and danofloxacin (DANO) were extracted over a range of 0.2-20 microg/kg, with recoveries of 68.7-90.7% and 76.0-93.8%, respectively. The limits of quantitation for the 6 fluoroquinolones were as follows: DCIP and DANO, 0.3 microg/kg; ENRO, 1 microg/kg; NOR and CIP, 2 microg/kg; and SAR, 3 microg/kg. Both SAR and ENRO incurred eggs were also successfully analyzed using this method.     

Sample preparation followed by HPLC under harmless 100% aqueous conditions for determination of oxytetracycline in milk and eggs

A simple and hazardous chemical-free method for the high-performance liquid chromatographic determination of oxytetracycline (OTC) residues in milk and eggs has been developed. Sample preparation consists in homogenization with an aqueous solution by means of a handheld ultrasonic homogenizer followed by centrifugal ultrafiltration. HPLC is performed with an isocratic aqueous mobile phase and a photodiode array detector. Average recoveries of OTC (0.05, 0.1, and 0.2 microg mL(-1) for milk; 0.1, 0.2, and 0.4 microg mL(-1) for eggs) were > or =84% with relative standard deviations of < or =2.3%. The total time required for the analysis of one sample and LOQs were <30 min and <0.1 microg mL(-1), respectively. In all the processes, no organic solvents or hazardous reagents were used.     

Simultaneous determination of seventeen glucocorticoids residues in milk and eggs by ultra-performance liquid chromatography/electrospray tandem mass spectrometry

A comprehensive analytical method has been developed and validated for the simultaneous determination of seventeen glucocorticoid residues in eggs and milk. The mass spectrometer parameters, the composition of the mobile phase and the sample preparation method were firstly optimized to obtain maximum sensitivity. The samples were deconjugated with beta-glucuronidase/arylsulfatase enzyme and concentrated using an Oasis HLB solid-phase extraction cartridge, followed by cleanup with a dual Sep-pak silica and aminopropyl cartridge. The analytes were quantified by ultra-performance liquid chromatography (using a C18 column)/electrospray ionization tandem mass spectrometry (UPLC/ESI-MS/MS) operating in the negative ion mode. The assay for the 17 glucocorticoids was linear over the range of 1-200 microg/L for milk and egg samples with a high correlation coefficient (>0.99). The limits of quantification (LOQs) for the target analytes were 0.04-1.27 microg/kg for the egg samples and 0.03-0.73 microg/kg for the milk samples. The average extraction recoveries of the glucocorticoids from eggs and milk at two concentration levels (spiked at 0.40 and 2.00 microg/kg) were 65.6-118.7% and 61.5-119.6%, respectively, with relative standard deviations between 1.8-17.0% and 2.4-18.4%, respectively. Because of its high sensitivity, good precision and specificity, the method was found to be suitable for trace analysis of synthetic and natural glucocorticoids in complex biosamples such as eggs and milk.     

Simultaneous determination of aminopyrine and antipyrine in porcine muscle,milk, and eggs using liquid chromatography with tandem mass spectrometry

The concentrations of residual aminopyrine and antipyrine in porcine muscle, milk, and egg samples were analyzed using liquid chromatography with tandem mass spectrometry after undergoing a series of sample pretreatment steps. Owing to an ion suppression effect, matrix‐matched calibrations were used for analyte quantitation with determination coefficients (R²) ≥ 0.9931. The recovery rates for aminopyrine and antipyrine in various matrices at two spiking levels (5 and 10 ng/g) fell in the range of 60.96–68.87 and 61.87–66.99%, respectively. Meanwhile, the intra‐ and inter‐day precisions (expressed as relative standard deviation) were 1.02–12.95 and 1.71–5.50%, respectively. The method's detection limit (1 ng/g) was very low, thus enabling the detection of low residue levels. The applicability of the developed method was demonstrated with actual market samples and none of the tested analytes was detected in any of the samples.     

溴取代紫外光度法同时测定痕量磺胺嘧啶和磺胺二甲嘧啶

提出了同时测定痕量磺胺嘧啶(SD)和磺胺二甲嘧啶(SM2)的溴取代紫外光度分析法, 实验结果表明: 在6×10-5 mol/L Br2, 2.5×10-3 mol/L KI溶液和体积分数40%乙醇溶液中, 测定SD和SM2的线性范围分别为: 0～2.25 mg/L, 和0～1.125 mg/L, 摩尔吸光系数(L·moL-1·cm-1)分别为: 在水中9.66×104和8.16×104, 在乙醇水溶液中1.25×105, 1.99×105. 用此法对猪肉中SD和SM2进行测定, 猪肉中SD和SM2的质量分数分别为7.53、7.35 mg/kg, 回收率在91.4%～104.4%, SD和SM2的相对标准偏差分别为0.5%、1.5%.     

Characterization and determination of piperine and piperine isomers in eggs

A new analytical method for the determination of piperine and its isomers in egg yolk and albumen is described here. All four isomers were separated by HPLC and detected using UV, DAD and electrochemical detection. The absolute detection limit (UV detection, S/ N=3) of a standard solution of piperine was 370 pg piperine. The correlation coefficients for the linear calibration graphs (concentration range: c=100 ng-10 micro g piperine isomer/mL) are generally better than 0.996. The piperine isomers were characterized and identified by spectroscopy (MS, (1)H-NMR, FT-IR). The method was successfully applied to the determination of piperine deposits in eggs (egg yolk and albumen) after feeding hens with piperine-spiked feed. The detection limit for piperine (24.8(+/-0.2) ng/g egg yolk and 37.9(+/-4.9) ng/g albumen) and the recoveries (70.3(+/-7.7)% (egg yolk) and 75.7(+/-1.9)% (albumen)) of piperine were determined.     

Cu~(2+)络合萃取FAAS法间接测定磺胺二甲嘧啶钠

在pH为5.0~6.5的溶液中,磺胺二甲嘧啶盐与Cu2+结合形成2:1络合物,此络合物用氯仿萃取,火焰原子吸收光度法测定络合萃取后水相中剩余Cu2+的吸光度A。发现试剂空白溶液与试样溶液的萃余液之间Cu2+吸光度差ΔA随磺胺二甲嘧啶含量增大而线性增大。据此,我们建立了一种Cu2+络合萃取FAAS法间接测定磺胺二甲嘧啶新方法。优化条件下,方法线性范围为14.6~144mg/L,线性回归方程为ΔA=0.0025ρ-0.0046(r=0.9991)。检出限为5.6mg/L,方法回收率为99.3%~99.6%。     

Separation and determination of radioactive caesium in milk

A method is given for the separation and determination of radiocaesium in fluid milk. Caesium is separated from organic material and interfering ions by passage of the milk sample through a cation-exchanger in the lithium form. It is eluted from this column with 6M hydrochloric acid. Two methods are given for the recovery of radiocaesium from the eluate. It may be precipitated with silico-tungstic acid and then converted into caesium perchlorate for counting or weighing. Alternatively, the eluate is passed through a small column of ammonium phosphomolybdate, which quantitatively sorbs the radiocaesium, the activity of which is determined by putting the column in a well-type scintillation counter and measuring the activity. Approximately 90% of the radiocaesium is recovered.     

Normal-phase high-performance liquid chromatographic determination of spiramycin in eggs and chicken

A precise method is presented for determination of residual spiramycin (SP) in chicken eggs and tissues by high-performance liquid chromatography (HPLC). The sample preparation was performed by homogenizing with a mixture of acetonitrile and n-hexane (5:4, v/v) to minimize the fat amount followed by ultra-filtration using a MolCutII(R). The extracts containing SP were free from interfering compounds when examined by the normal-phase HPLC using a LiChrosorb(R) NH(2) column and a mobile phase of acetonitrile-water (85:15, v/v) with a photo-diode array detector. The average recoveries from spiked SP (0.1, 0.5 and 1.0 ppm) were in excess of 89.0% with coefficients of variation between 1.4 and 2.4%. The limit of detection was 0.1 ppm.     

气相色谱-质谱联用法同时测定乳及乳制品中的三聚氰胺及肌酐

建立了同时测定乳制品中三聚氰胺及肌酐的气相色谱-质谱联用方法。样品经1%三氯乙酸溶液萃取,混合型阳离子交换固相萃取净化,提取液用氮气吹干后加入N,O-双(三甲基硅基)三氟乙酰胺-三甲基氯硅烷(BSTFA-TMCS)硅烷化试剂,于75 ℃下衍生60 min,最后采用选择离子模式下的气相色谱-质谱测定。三聚氰胺和肌酐的定量限分别为0.10 mg/kg和0.20 mg/kg;在0.1～50 mg/L范围内的线性相关系数均大于0.99。实际样品中,肌酐在10～100 mg/kg和三聚氰胺在0.1～5.0 mg/kg添加范围内的回收率分别为80.7%～116.8%和77.6%～107.5%,相对标准偏差分别小于9.4%和8.5%。该方法能有效除去干扰,灵敏度高,回收率较好,可用于乳制品中三聚氰胺和肌酐的同时测定。     

Direct copper determination in whole milk, non-fat milk and whey milk by electrothermal atomic absorption spectrometry

A method for the direct determination of copper in samples of whole milk, non-fat milk and whey milk by electrothermal atomic spectrometry (ETAAS) was studied. The fat separation by centrifugation at 3200 rpm and the separation of casein mycelles to obtain the whey milk by ultracentrifugation at 31 000 g were investigated. In all cases Mg(NO₃)₂ was used as chemical modifier and Triton X-100 (0.2% w/v) as emulsifying agent. The optimum pyrolysis temperature was 1500° C. The detection limit was 0.4 μg/l of copper. The precision was studied for the whole milk and the coefficients of variation (CV) were 5.7, 4.0, 2.4 and 2.8% for 0, 5, 10 and 20 μg/l of copper added. The accuracy was determined by using the Reference Material Milk A-11 (IAEA) with a certified content of 378.4 ± 24 ng Cu/g; 359 ± 16 ng/g were found. The method was applied to ten cow milk samples, the levels of copper being determined for whole milk, non-fat milk and whey milk. A statistical study was applied and it was concluded that the majority of copper is in the non-fat milk. Received: 29 February 1996 / Revised: 19 April 1996 / Accepted: 28 April 1996     

Single‐step extraction followed by LC for determination of (fluoro)quinolone drug residues in muscle,eggs, and milk

In this study, a simplified method for the extraction and determination of seven fluoroquinolone residues (danofloxacin, difloxacin, enrofloxacin, marbofloxacin, orbifloxacin, ofloxacin, and sarafloxacin) and three quinolones (oxolinic acid, flumequine, and nalidixic acid), in porcine muscle, table eggs, and commercial whole milk, which required no cleanup step, was devised. This procedure involves the extraction of analytes from the samples via liquid‐phase extraction, and the subsequent quantitative determination was accomplished via LC‐fluorescence detection. Analyte separation was successfully conducted on an XBridge‐C₁₈ column, with a linear gradient mobile phase composed of acetonitrile and 0.01 M oxalic acid buffer at pH=3.5. The one‐step liquid‐liquid extraction method evidenced good selectivity, precision (RSDs=0.26–15.07%), and recovery of the extractable analytes, ranging from 61.12 to 115.93% in matrices. The LOQs ranged from 0.3 to 25 μg/kg. A survey of ten samples purchased from local markets was conducted, and none of the samples harbored fluoroquinolone residues. This method is an improvement over existing methodologies, since no additional cleanup was necessary.     

Simplified liquid-chromatographic determination of residues of tetracycline antibiotics in eggs

Summary A high-performance liquid chromatographic (HPLC) procedure is described for the identification and quantification of residues of tetracycline antibiotics (TCA) (oxytetracycline, tetracycline, chlortetracycline, and doxycycline), in eggs. Spiked and blank samples were prepared by homogenization with 1∶1 (v/v) acetonitrile-mixed Mcllvaine buffer and EDTA solution (pH 4.0) then centrifugal ultrafiltration. HPLC was performed on a reversed-phase column with acetonitrile-5% (v/v) aqueous acetic acid, 35∶65 (v/v), as mobile phase and photo-diode array detection. Average recoveries (each drug spiked at 0.1, 0.2, 0.3, 0.5 and 1.0 μg g⁻¹) were >-77% with standard deviations (SD) between 1.5 and 3.5%. The inter-assay variabilities and theirSD were <3.4% and <0.7%, respectively, and intra-assay variability was between 2.0 and 3.9%. The limits of quantitation (LOQ) were 0.064 0.087, 0.121, and 0.131 μg g⁻¹ for OTC, TC, CTC, and DC, respectively. The total time required for the analysis of one sample was less than 30 min.     

Radiochemical determination of caesium-137 in liquid milk

Summary A simple and rapid method is described for the radiochemical determination of a caesium-137 in liquid milk. After the addition of caesium carrier the milk sample is deproteinized with nitric acid, filtered and alkaline earths removed by oxalate precipitation. From the decanted solution caesium is precipitated with sodium cobaltinitrite, separated from potassium as caesium silicotungstate and finally counted as dipicrylaminate by an anticoincidence beta counter. The radiochemical yields for caesium amount to about 65%. Good agreement is found between results obtained by the present method and by the gamma spectrometry. The results for caesium-137 content may be obtained within 6 hours.

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Zusammenfassung Es wird eine einfache und schnelle Methode zur radiochemischen Bestimmung von Caesium-137 in flüssiger Milch beschrieben. Die zu untersuchende Milch wird nach Zusatz des Caesiumträgers mit Salpetersäure enteiweißt. Aus der dekantierten Lösung werden die Erdalkalien als Oxalate abgeschieden. Das Radiocaesium wird mit Natriumnitritocobaltat gefällt, von Kalium mit Silicowolframsäure getrennt und endlich als Caesiumdipikrylaminat in einem Beta-Antikoinzidenzzähler gemessen. Die Caesiumträgerrückgewinnung beträgt durchschnittlich 65%. Die nach der beschriebenen Methode erhaltenen Resultate stehen in guter Übereinstimmung mit denen der gammaspektrometrischen Bestimmung. Der Radiocaesiumgehalt in Milch kann innerhalb von 6 Std bestimmt werden.

     

阻抑动力学光度法测定乳品中的痕量碘

研究了在稀H2SO4介质中,痕量I-对KBrO3氧化酸性品红的阻抑作用及其动力学条件,建立了测定痕量I-的阻抑动力学光度分析的新方法.测定I-的线性范围为0～0.04 μg/mL,检出限为1.1×10-9 g/mL.已用于乳品中痕量碘的测定.