A simple and rapid assay based on hot water extraction and liquid chromatography–tandem mass spectrometry for monitoring quinolone residues in bovine milk

A rapid, specific and sensitive procedure for determining residues of eight widespread used quinolone antimicrobials in bovine milk is presented. The method is based on the matrix solid-phase dispersion technique with hot water as extractant followed by LC/MS/MS. The entire sample treatment did not take more than 40 min. Hot water appeared to be an efficient extracting medium, since absolute recoveries of the analytes in milk were 77–90%. The method proved to be robust as matrix effects did not affect significantly the accuracy of the method, as evidenced by analyzing six different batches of milk. Using norfloxacin as surrogate analyte, the accuracy of the method at three different spike levels of the analytes in milk was 93–110% with RSDs not larger than 10%. On the basis of a S/N of 10, estimated LOQs of this method range from 0.3 to 1.5 ng/ml, well below the tolerance levels of quinolones in milk set by the European Union.     

Magnetic molecularly imprinted polymer extraction of chloramphenicol from honey

A rapid and selective method was successfully developed using magnetic molecularly imprinted polymer (MMIP) as sorbent for the extraction of chloramphenicol from honey samples. The extraction process was carried out in a single step by blending and stirring the sample, extraction solvent and polymers. When the extraction was completed, the MMIPs adsorbing the analyte were separated from the sample matrix by an external magnet. The analyte eluted from the MMIPs by methanol under ultrasound assisted was analysed by liquid chromatography–tandem mass spectrometry. Various parameters affecting the extraction efficiency were evaluated for achieving optimal recovery and reducing non-specific interactions. Under optimal conditions, the detection limit of CAP was 0.047 ng g⁻¹. The relative standard deviations of intra- and inter-day ranging from 4.1% to 5.3% and from 2.9% to 7.1% were obtained, respectively. The method was applied to determine CAP in six honey samples. The recoveries of CAP in these samples from 84.3% to 90.9% were obtained.     

Liquid chromatography–tandem mass spectrometry for the determination of chrysoidine in yellow-fin tuna

A high performance liquid chromatography (HPLC) coupled to electrospray ionisation tandem mass spectrometry (MS/MS) method was described for the residue detection of chrysoidine in yellow-fin tuna in the present study. Samples were cleaned up with solid phase extraction (SPE) cartridge, and then injected into HPLC for separation. Multiple-reaction monitoring (MRM) was applied for quantitative determination. Results showed that the low limit of detection (LOD) of the method was 1.25 × 10⁻¹² g, and the low limit of quantification (LOQ) was 0.42 μg/L. The standard calibration curve was y = 2333.9x −845 (r² > 0.99) with the linear range of 0.63–100 μg/L. The average recoveries of chrysoidine ranged from 86.0% to 108.0% when the spiked concentration was from 0.5 μg/kg to 20 μg/kg. And the developed method also showed the good test precisions (RSD%: 4.38–14.27%).     

High performance liquid chromatographic determination of aflatoxins in chilli,peanut and rice using silica based monolithic column

A simple and rapid high performance liquid chromatographic with fluorescence detection method for the determination of the aflatoxin B₁, B₂, G₁ and G₂ in peanuts, rice and chilli was developed. The sample was extracted using acetonitrile:water (90:10, v/v%) and then purified by using ISOLUTE® multimode solid phase extraction. After the pre-column derivatisation, the analytes were separated within 3.7 min using Chromolith® performance RP-18e (100–4.6 mm) monolithic column. To assess the possible effects of endogenous components in the food items, matrix-matched calibration was used for the quantification and validation. The recoveries of aflatoxins that were spiked into food samples were 86.38–104.5% and RSDs were <4.4%. The method was applied to the determination of aflatoxins in peanut (9), rice (5) and chilli (10) samples. Liquid chromatography–tandem mass spectrometry analysis using triple quadruple analyser and operated in the multiple reaction monitoring modes on the contaminated samples was performed for confirmation.     

Microwave-assisted extraction and determination of cyanuric acid residue in infant formula samples by liquid chromatography–tandem mass spectrometry

In the present work, microwave-assisted extraction method in combining with liquid chromatography–tandem mass spectrometry (LC–MS/MS) was proposed for the determination of cyanuric acid (CYA) in infant formula samples. The separation was performed on a MERCK ZIC HILIC column (150 × 2.1 mm i.d., 5 μm) with gradient elution of 20 mM ammonium acetate solution – acetonitrile. The method could respond linearly with cyanuric acid at concentrations from 1.0 to 50 ng mL⁻¹ with a quantification limit of 0.25 mg kg⁻¹. The intra- and inter-day precision was less than 4% and the recovery of the assay was in the range of 86.7–93.1%. In the analysis of practical spiked infant formula samples, the new method yielded satisfactory results. Due to its simplicity and accuracy the straightforward method is particularly suitable for routine cyanuric acid detection.     

Quantitative analysis of acrylamide in tea by liquid chromatography coupled with electrospray ionization tandem mass spectrometry

An effective sample preparation procedure was optimized and a liquid chromatography–tandem mass spectrometry (LC–MS/MS) was developed for the quantitative analysis of acrylamide in tea. [¹³C₃]-acrylamide was used as internal standard. Acrylamide was extracted at 25 °C for 20 min by 10 ml water followed by 10 ml acetonitrile, and then 4 g of magnesium sulfate and 0.5 g of sodium chloride were added to the above mixture under stirring thoroughly. In order to increase the response of acrylamide, 9 ml acetonitrile layer was taken and concentrated to 0.5 ml. Solid-phase extraction with an Oasis MCX cartridge was carried out for clean-up. The limit of detection (LOD) and limit of quantification (LOQ) were 1 and 5 ng/ml, respectively. The recovery efficiency of the extraction procedure ranged between 74% and 79%. The levels of acrylamide in 30 tea samples were less than 100 ng/g. Black, oolong, white and yellow tea samples had quite low acrylamide contents (<20 ng/g). Higher acrylamide levels occurred in baked, roasted, and one sun-dried green tea samples (46–94 ng/g).     

The fate of fungicide and insecticide residues in Australian wine grape by-products following field application

Pesticides applied to grape vines before harvest may concentrate in the grape seed due to their high oil solubility. Twenty-four samples of grape marc, representing a range of red and white wine grape varieties, were collected and analysed for selected fungicides and insecticides. Fifteen of the 24 samples were matched with insecticide and fungicide application diaries. Residue concentrations of the fungicides, procymidone, iprodione, cyprodinil, fenhexamid, fludioxinil, pyrimethanil and trifloxystrobin, and the insecticides, indoxacarb and tebufenozide, were higher in grape seed oil and grape seed meal than in the fruit and the marc. The relative concentrations were approximately proportional to the octanol to water partition coefficients, log K_ow. A range of other fungicides and insecticides were detected but were not significantly concentrated in the oil and seed meal relative to fruit and marc. The presence of pesticide residues in grape seed oil and grape seed meal will impact on the possibility of producing these wine by-products.     

Determination of Gibberellin A3 residue in fruit samples by liquid chromatography–tandem mass spectrometry

A fast, simple, low cost, and high throughput method has been developed for the determination of Gibberellin A3 residue in fruit samples (apple, orange, peach, pear and grape). Analysis is performed by LC–MS/MS operated in the multiple reaction monitoring (MRM) mode, acquiring two specific precursor-product ion transitions per target compound. The method has been validated showing good linearity and selectivity. Limits of quantification (LOQs) were 10 μg kg⁻¹ for apple, orange, peach, pear and grape samples. The average recoveries, measured at three concentration levels (10, 20 and 200 μg kg⁻¹) were in the range 77.8–96.2% for the compound tested with relative standard deviations below 13.7%. The proposed method is rapid, simple and could be utilised for the routine analysis of Gibberellin A3 in fruit samples.     

Simultaneous determination of 22 residual steroid hormones in milk by liquid chromatography–tandem mass spectrometry

Food safety and consumers’ health are paramount; therefore, it is essential to establish a novel method to determine hormone content in milk. Herein, a novel method was developed that can simultaneously determine 22 residual steroid hormones in milk. To obtain the maximum detection sensitivity, the preparation method of sample, mass spectrometer parameters and liquid chromatography conditions were optimised. The samples were concentrated using Oasis HLB solid‐phase extraction cartridge, followed by quantification via liquid chromatography (C18 column)–tandem mass spectrometer (LC‐MS). Determination of oestrogens and glucocorticoids was conducted in negative mode, whereas androgens and progesterone were in positive multiple reaction monitoring mode. The limit of detection (LOD) and limit of quantification (LOQ) of the target compounds were 0.10–1.20 μg/kg and 0.33–3.96 μg/kg, respectively. The average extraction recoveries of 22 steroid hormones were generally high (82.6–95.3%). The proposed method can be an effective alternative to measure hormonal compounds in milk.     

The determination of vitamin D3 in bovine milk by liquid chromatography mass spectrometry

A renewed international interest in vitamin D status has revealed significant deficiencies in several populations, including Australia. Vitamin D exists in two forms, cholcalciferol (D₃) and ergocalciferol (D₂). The main source of vitamin D₃ is from exposure of 7-dehydrocholesterol present in the skin to UV irradiation. However, there is an absolute requirement for vitamin D through proper dietary intake if humans live in the absence of sunlight or exclusively indoors. Bovine milk is considered to be a good dietary source of vitamin D₃, even though the levels are quite low. This paper describes robust methods using liquid chromatography–linear ion trap mass spectrometry (LC–MSⁿ) and liquid chromatography–tandem mass spectrometry (LC–MS/MS) to measure the levels of vitamin D₃ in fresh bovine milk (0.05 μg/100 ml), commercial (natural and fortified) milk samples (0.01–2 μg/100 ml) and a dairy based infant formula (8 μg/100 g), without the need for extensive clean-up procedures. The limits of quantification (LOQ) are 0.01 μg/100 ml and 0.02 μg/100 ml for LC–MSⁿ and LC–MS/MS, respectively. Recoveries of vitamin D₃ added to the samples prior to saponification were satisfactory (range 60–90%). 25-Hydroxyvitamin D₃ was not present in any of the samples analysed (LOQ = 0.01 μg/100 ml, recovery range 30–40%).     

Determination of ionophores in raw bovine milk using LC–MS/MS: Application to residue surveillance

Residues of four ionophores (lasalocid, monensin, narasin, and salinomycin) in raw milk samples were extracted with acetonitrile and subsequently determined using liquid chromatography–tandem mass spectrometry. Ionophores could be determined down to 0.1 ng g⁻¹ level, without additional cleanup or concentration of the resulting extract. The analysis of a series of raw milk samples fortified at analyte concentrations ranging from 1 to 20 ng g⁻¹ yielded average accuracies ranging from 60.7% to 118.3% with percent relative standard deviations below 13%. During six months of a surveillance program, 1072 raw milk samples were collected from the transport chain of dairy producers in Alberta and analysed. Monensin was detected in 736 of 1072 samples tested at concentrations ranging from 0.10 to 0.53 ng g⁻¹ which is well below the current Canadian maximum residue limit of 10 ng g⁻¹.     

Development and validation of a quantitative spectrophotometric method to detect the amount of carbon monoxide in treated tuna fish

In recent years carbon monoxide (CO) has been employed by the fishery industry to preserve the fresh appearance of fish products during frozen storage, particularly in vacuum packaged products. CO reacts with oxy-myoglobin to form a stable cherry coloured carboxy-myoglobin complex. We propose a method that allows the quantitative determination of CO in the meat drip of tuna fish by UV–Vis spectroscopy. It consists of: (i) preparations of CO secondary standard solutions titrated against horse heart Mb primary standard solutions; (ii) determination of calibration curves to measure CO concentration in treated and untreated samples. The accuracy of the spectrophotometric method has been evaluated in terms of trueness and precision by using fortified tuna fish samples. The spectroscopic results have been compared with those obtained using a head space gas chromatographic technique (HS-GC–MS). The CO levels measured in tuna fish samples by UV–Vis are substantially lower than those revealed by HS-GC–MS. The origin of this discrepancy is discussed.     

Determination of tetracyclines in multi-specie animal tissues by pressurized liquid extraction and liquid chromatography–tandem mass spectrometry

A specific, sensitive and robust pressurized liquid extraction (PLE) and liquid chromatography tandem mass spectrometry (LC–MS/MS) method for determining tetracycline, chlortetracycline, oxytetracycline and doxycycline in bovine, swine, poultry and lamb muscle tissues is presented. PLE was performed using an ASE^® 200 from Dionex and water as extractant, followed by solid-phase extraction (SPE) using an Oasis HLB cartridge. The method was validated for beef, chicken, pork and lamb meat in compliance with the requirements set by Commission Decision, 2002/657/EC [Commission Decision 2002/657/EC (2002). Implementing Council Directive 96/23/EC concerning the performance of analytical methods and interpretation of results. Official Journal of European Communities, L239, 66–98. (Available at: <http://europe.eu.int>)]. The average recoveries of the different meat samples, spiked with the four tetracyclines at three levels (1, 100 and 200 μg kg⁻¹ of each tetracycline), were always higher than 89% with intraday and interday precision lower than 15% and 17%, respectively. A good linearity was established for the four tetracyclines in the range from 5 to 10,000 μg kg⁻¹ with r > 0.995. The limits of quantification (LOQs) were between 0.5 and 1 μg kg⁻¹, which are well below the tolerance levels set by the European Union. The decision limit (CCα) and the decision capability (CCβ) were in the range 101–116 and 112–130 μg kg⁻¹, respectively. Compared with previous methods, sample preparation time required for the analysis and LOQs, are reduced. The method demonstrated its successful application for the analysis of 100 meat samples. Two samples of beef and one sample of chicken out of 25 of each type tested positive while none of 25 samples of either, lamb or pork, tested positive.     

超高效液相色谱-串联质谱法检测小龙虾中7种有机磷酸酯类阻燃剂

目的 建立超高效液相色谱-串联质谱法测定小龙虾中7种有机磷酸酯类阻燃剂(organophosphate flame retardants, OPFRs),探究湖北省不同地区小龙虾中的OPFRs污染水平。方法 以二氯甲烷为提取溶剂,采用超声辅助提取以及固相萃取和QuEChERS技术进行前处理,利用超高效液相色谱-串联质谱法(ultra-performance liquid chromatography-tandem mass spectrometry, UPLC-MS)定量分析小龙虾中7种OPFRs的含量。结果 该方法线性系数r2>0.999;各物质定量限在0.08~4.68 μg/kg;回收率在62.39%~113.3%;精密度RSD < 9.70%。7种OPFRs在样品中检出率为100%,∑OPFRs范围在34.09~41.45 μg/kg。其中磷酸三乙酯（Triethyl Phosphate, TEP）和磷酸三（2-氯丙基）酯（Tris(1-Chloro-2-Propyl) Phosphate, TCPP）总体占比最多,达到13.43~18.14 μg/kg和9.72~13.67 μg/kg;磷酸三（2-氯乙基）酯(Tris(2-chloroethyl) Phospate, TCEP)、磷酸三苯酯（Triphenyl Phosphate, TPHP）和磷酸三丁酯（Tributyl Phosphate, TnBP）次之,达到3.08~3.83 μg/kg、2.86~5.3 μg/kg和2.63~3.63 μg/kg,磷酸三丙酯（Tripropyl Phosphate, TPP）和磷酸三（2-丁氧基乙基）酯(Tris(2-butoxyethyl) Phosphate, TBEP)含量最少,0.17~0.2 μg/kg,1.28~1.75 μg/kg。结论 该方法准确、可靠、简便,可用于小龙虾中有机磷酸酯类阻燃剂检测。湖北省小龙虾中OPFRs污染现象普遍存在。因OPFRs市场使用前景广阔, 后续仍需持续关注其含量变化。     

液相色谱-串联质谱法测定茶叶中二氰蒽醌残留量

目的建立液相色谱-串联质谱法(liquidchromatographytandemmassspectrometry,LC-MS/MS)测定茶叶中二氰蒽醌残留。方法茶叶用乙腈(含0.1%甲酸)提取,经固相萃取柱(HC-C18 SPE)净化后采用多反应监测(multiplereactionmonitoring,MRM)模式进行检测,外标法定量。结果目标化合物在一定范围内(0.391～12.5μg/L)线性关系良好,相关系数(r2)大于0.995。样品中二氰蒽醌的定量限(limitofquantification,LOQ)和检出限(limitofdetection,LOD)分别为10.0、5.00μg/kg;不同加标浓度样品10.0μg/kg(LOQ)、20.0μg/kg(2×LOQ)、50.0μg/kg(5×LOQ)的平均回收率为84.1%～103%,相对标准偏差(RSDs)为3.18%～4.62%。25份市售茶叶中均未检出二氰蒽醌。结论该方法简便、快速,准确。各项性能参数均能符合技术规范的要求,已应用于市售茶叶的检测。     

Simplified pesticide multiresidues analysis in fish by low-temperature cleanup and solid-phase extraction coupled with gas chromatography/mass spectrometry

A simple and fast method for the simultaneous analysis of thiobencarb, deltamethrin and 19 organochlorine pesticide residues in fish by gas chromatography–mass spectrometry was investigated in this study. Samples are extracted with acetonitrile. Most of lipids in the extract are eliminated by low-temperature cleanup, prior to solid-phase extraction cleanup. The lipids extracted from the fish samples were easily removed without any significant losses of the pesticides. Aminopropyl (NH₂) cartridge was effective to eliminate the remaining interference. Spiked experiments were carried out to determine the recovery, precision and limits of detection (LODs) of the method. The method detection limits ranged from 0.5 μg kg⁻¹ to 20 μg kg⁻¹, whilst recoveries of the pesticides were in the range of 81.3–113.7% with relative standard deviations ?13.5% at a spiked concentration of 0.05 mg kg⁻¹, 0.02 mg kg⁻¹ and 0.1 mg kg⁻¹. The newly developed method is demonstrated to give efficient recoveries and LODs for detecting pesticide multiresidues in fish.     

Sensitive determination of domoic acid in shellfish by on-line coupling of weak anion exchange solid-phase extraction and liquid chromatography–diode array detection–tandem mass spectrometry

An automated method based on the use of on-line solid-phase extraction (SPE) coupled to liquid chromatography with diode array detection and tandem mass spectrometry (LC–DAD–MS/MS) has been developed for the determination of domoic acid in shellfish. The on-line coupling of SPE and liquid chromatography was accomplished by a column switching approach. A weak anion exchange (WAX) sorbent was selected for the SPE procedure, allowing a selective cleanup of shellfish extracts. High sensitivity was achieved by on-line pre-concentration of large volume injections (50–1000 μL). A simple protein precipitation cleanup with acetone was used to efficiently remove proteins from shellfish extracts, preventing possible column clogging during chromatographic separation.     

分散固相萃取-液相色谱-串联质谱法测定植源性油料油脂中67种除草剂

目的 建立分散固相萃取结合液相色谱-串联质谱同时测定油料油脂中 67 种除草剂残留的检测方法。方法 选取花生、大豆、油菜籽、花生油、大豆油及菜籽油为典型基质试样,经 1% 甲酸-乙腈提取,通过乙二胺基-N-丙基和无水 MgSO₄分散固相萃取净化。以甲醇和 5 mmol/L 乙酸铵(含 0. 1% 甲酸)为流动相梯度洗脱,采用 C₁₈色谱柱分离,ESI 离子源正负离子模式同时进行多反应监测(MRM),基质标准曲线外标法定量。结果 基质加标试验结果表明,0. 000 5～0. 08 mg/L 浓度范围内 67 种除草剂线性良好,决定系数(R²)均>0. 992,定量限(LOD)为 0. 005～0. 02 mg/kg。3 个加标水平下(LOD、2LOD、10LOD)的回收率为 62. 3%～118. 1%,RSD(n=6)均<15%。结论 本方法稳定性高、特异性强、灵敏、准确、高效,可以用于油料油脂中多种除草剂残留的定性定量检测。     

Development and validation of a quantitative UHPLC-MS/MS method for selected brominated flame retardants in food

An ultra-high performance liquid chromatography – tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated (in-house) for the quantification of selected brominated flame retardants (BFRs), including tetrabromobisphenol A (TBBPA), hexabromocyclododecanes (HBCDs), tetrabromobisphenol S (TBBPS) and bromophenols (BPs), in various food matrices. The sample preparation consisted of extraction of TBBPS with acidified acetonitrile followed by a fast dispersive solid-phase extraction (dSPE) clean-up and extraction of the other BFRs with a mixture of hexane and dichloromethane (1:1, v/v) with subsequent clean-up using acidified silica (44%, w/w). The limits of quantification of the method varied widely for the types of food matrices and the different classes of BFRs from 4 pg g^?1 wet weight (ww) to 8 ng g^?1 ww. For most of the analytes the apparent recovery was in the range 70–120%, and the method precision (under repeatability conditions) was below 20%. The method was successfully applied in proficiency testing exercises as well as for analysis of various food items. Only 25% of the collected food samples contained BFRs, with 4-bromophenol and α-HBCD as the only detected compounds. The contaminated foodstuffs were fish and eggs with concentrations in the range from 48 to 305 pg g^?1 ww.