Determination of the plant growth regulator chlormequat in food by liquid chromatography-electrospray ionisation tandem mass spectrometry

A confirmatory method for the determination of trace levels of chlormequat in a variety of different food matrices was developed. It entails a single clean-up step over a solid-phase cation exchange resin and subsequent liquid chromatography-electrospray ionisation tandem mass spectrometry using a stable isotopically labelled internal standard. Mass spectral acquisition was done in selected reaction monitoring mode, selecting the transitions from both the 35Cl and the 37Cl isotope of chlormequat. Recoveries after extraction and clean-up, determined with radio-labelled chlormequat and averaged over the spiking range (16-65 microg kg(-1)) in four different commodities, were within 88-96%, with a coefficient of variation better than 8%. The method can be applied to pears, pear juice concentrates, fruit purées, and cereal products, with typical limits of detection for chlormequat estimated at 2-5 microg kg(-1). A survey of different food commodities revealed that chlormequat was detectable--albeit at very low levels--in many of the food samples analysed, with the highest concentration recorded in pears purchased in Switzerland and of South African origin (5.5 mg kg(-1)). Measurements were also conducted on two LC-MS instruments and demonstrate the versatility and robustness of the method and its applicability to instruments of different ion source design.     

Analysis of OSPAR priority pharmaceuticals using high-performance liquid chromatography-electrospray ionisation tandem mass spectrometry

The occurrence and potential adverse effects of pharmaceutical compounds in the aquatic environment have received much scientific interest. Presented are analytical methodologies for the determination of 10 of the pharmaceuticals listed on the Oslo and Paris Commission for the protection of the Marine Environment of the North East Atlantic (OSPAR) hazardous substances website. In addition to these 10 substances, the chemical fluoxetine (Prozac) was also investigated. The performance characteristics of a combined solid phase extraction (SPE) isolation and high-performance liquid chromatography-electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS) procedure have been determined. Extraction efficiencies were obtained for a variety of SPE sorbents, following this initial investigation. Strata-X (Phenomenex, UK) was selected for further development. The extraction method performed satisfactorily for the majority of the 11 compounds analysed, with recoveries of over 60% for most of the compounds and relative standard deviations of between 4 and 13%. The recoveries of chloroquine and closantel were below 50% but the method provides semi-quantitative information regarding the occurrence of these compounds. Separation of the analytes was made using a C18 Luna analytical column (Phenomenex, UK) and mass spectra were obtained using an ion trap mass spectrometer operated in both positive and negative electrospray ionisation modes. Limits of detection for all compounds ranged from 1 to 20 ng/l, making the method suitable for low level environmental analysis. Of the selected surface water and treated sewage effluent samples (n = 6) analysed, chlorpromazine, fluoxetine and miconazole were detected in concentrations ranging from 7 to 34 ng/l. The chemicals determined using this procedure fall into a variety of pharmaceutical classes including antipsychotics and tranquilisers resulting in an analytical method that contains compounds from diverse chemical classes.     

超高效液相色谱-电喷雾电离串联质谱联用法检测茶叶中阿维菌素类药物残留

建立了采用超高效液相色谱-电喷雾电离串联质谱同时检测茶叶中爱比菌素、甲胺基阿维菌素、乙酰胺基阿维菌素、伊维菌素、多拉菌素、莫西丁克残留的方法。试样经饱和氯化钠溶液浸润后,用乙腈提取,C18固相萃取小柱净化,超高效液相色谱-电喷雾串联质谱法(UPLC/ESI-MS/MS)测定。对流动相、监测离子、校正曲线等进行了优化和探讨。6种分析物在2.0～50 μg/L范围内线性关系良好,相关系数均大于0.9920。莫西丁克在5,10,20 μg/kg,其余分析物在2,5,10 μg/kg加标水平的平均回收率为61.7%～85.4%,相对标准偏差为9.37%～17.19%。该方法可靠、稳定,可满足茶叶中阿维菌素类药物残留检测与确证的需要。     

Analysis of estrogens in river sediments by liquid chromatography-electrospray ionisation mass spectrometry. Comparison of tandem mass spectrometry and time-of-flight mass spectrometry

A method has been developed and optimised for the determination of two natural estrogens, estrone (E1) and 17beta-estradiol (E2), and one synthetic estrogen, 17alpha-ethynylestradiol (EE2), in river sediments at the sub-ng/g level. This procedure includes microwave-assisted solvent extraction (MASE), solid-phase extraction and high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionisation. Using sediments spiked with the three estrogens at 10 ng/g wet weight, efficient extraction (>92%) of all the three analytes was achieved by MASE, and whole-procedure recoveries ranged from 82 to 98%. Optimisation of the LC separation allowed for substantial reduction of ionisation suppression in the electrospray source to a final level of <18% suppression. Time-of-flight mass spectrometry (TOF-MS) and MS/MS were compared for the analysis of sediment extracts, with the latter technique proving to be the most selective. The method detection limits achieved by LC-MS/MS were 15, 30 and 40 pg/g for E1, E2 and EE2, respectively, which were 13-fold lower than those obtained by LC-TOF-MS. Analysis of river sediments collected from the River Ouse, UK, showed the presence of the natural estrogens at sub-ng/g level. E1 levels ranged from 0.40 ng/g (dry weight) to 3.30 ng/g while E2 levels ranged from <0.03 to 1.20 ng/g and EE2 was never detected (<0.04 ng/g).     

Quantitative determination of five ergot alkaloids in rye flour by liquid chromatography-electrospray ionisation tandem mass spectrometry

A confirmatory method for detecting five ergot alkaloids, ergocristine, ergotamine, ergonovine, ergocornine and alpha-ergokryptine, in rye flour is described using high performance liquid chromatography coupled to tandem mass spectrometry detection by monitoring two transition reactions per analyte. The procedure entails a liquid-liquid extraction followed by a clean-up step using a C18 solid-phase extraction (SPE) cartridge. An analogue compound, methysergide hydrogen maleinate, was used to assess both repeatability sample preparation and potential MS response fluctuations. The method was fully validated according to the European Union (EU) criteria. Detection and quantification limits of all analytes were calculated ranging from 7 to 11 microg/kg and from 23 to 37 microg/kg, respectively. Fifteen rye flour samples were investigated with the newly developed method, and none of them were above the current Swiss limits of 200mg/kg for total ergot alkaloids.     

Analysis of oak tannins by liquid chromatography-electrospray ionisation mass spectrometry

Extractable tannins were analysed by liquid chromatography-electrospray ionisation mass spectrometry in two oak species, North American white oak (Quercus alba) and European red oak (Quercus robur). They mainly included various glucose gallic and ellagic acid esters. The structures were partially determined, and they included grandinin/roburin E, castalagin/vescalagin, gallic acid, valoneic acid bilactone, monogalloyl glucose, digalloyl glucose, trigalloyl glucose, ellagic acid rhamnose, quercitrin and ellagic acid.     

分散固相萃取净化液相色谱-质谱联用快速检测糙米中的多种残留农药

建立了同时检测糙米中多种农药残留的分析方法.采用乙腈提取,使用N-丙基乙二胺键合固相吸附材料(PSA)和C18硅胶胶联吸附剂分散固相萃取(dispersive-SPE)净化,高效液相色谱-电喷雾串联质谱,正离子模式检测,内标法定量.30种农药在0.05～2mg/kg范围内线性良好,方法检出限和定量限分别为0.5～20 μg/kg和2～60 μg/kg,30种农药平均回收率在73%～109%之间,相对标准偏差<10%,均能够满足农药残留分析的要求.     

Determination of abamectin and azadirachtin residues in orange samples by liquid chromatography-electrospray tandem mass spectrometry

A rapid and sensitive LC-ESI-MS-MS method has been developed for the determination of azadirachtin and abamectin residues in orange samples. Samples were extracted with acetonitrile, in a high-speed blender. After the addition of sodium acetate, an aliquot of extract was directly injected into the LC-ESI-MS-MS system. The highest sensitivity of the method was achieved under MS-MS conditions using [M+Na]+ adducts as precursor ions. Recoveries for both compoundsfrom spiked orange samples at 0.01 and 0.1 mg/kg were above 80%, with good repeatability (<10%). Method detection limits achieved (<0.007 mg/kg) were adequate for the determination of these pesticides in this kind of sample from the regulatory point of view. The importance of the solvent used for extraction, as well as the addition of sodium acetate to the extracts and the selection of adequate chromatographic conditions are discussed.     

超高效液相色谱-串联四极杆质谱法测定水产品中氯霉素残留量

建立超高效液相色谱-串联四极杆质谱法测定水产品中氯霉素残留量的方法。样品均质后经乙酸乙酯提取,正己烷脱脂(或用固相萃取柱净化),超高效液相色谱分离,串联四级杆质谱检测,同位素内标法定量。方法在0.05～1.0μg/kg的添加范围内的平均回收率为84.9%～103.3%,相对标准偏差为3.2%～5.2%,定量检测限为0.02μg/kg。方法适用于各种水产品基质的氯霉素残留检测。     

超高效液相色谱-电喷雾串联质谱法同时分析鸡肉中7种氟喹诺酮类药物残留

建立了一种同时测定鸡肉中7种氟喹诺酮类药物残留的超高效液相色谱-电喷雾串联质谱确证分析方法(UPLC-ESI-MS/MS)。样品经酸化乙腈提取、正己烷脱脂和HLB固相萃取柱净化,采用ACQUITY UPLCTM BEH C18色谱柱(50 mm×2.1 mm,1.7 μm)分离,以0.1%甲酸水溶液和乙腈作为流动相进行梯度洗脱,电喷雾质谱检测,正离子多反应监测模式进行定性和定量分析。7种药物在5～100 μg/kg范围内线性关系良好,相关系数(r2)均大于0.99;以5,25,50 μg/kg3个浓度水平进行添加回收试验,7种药物的平均回收率在79.2%～108.6%之间,相对标准偏差为4.2%～8.9%,方法的检出限(LOD)为0.2～1.4 μg/kg。方法重现性好、灵敏度高、分析时间短、确证能力强,适用于鸡肉中氟喹诺酮类药物多残留的确证检测。     

Countering matrix effects in environmental liquid chromatography-electrospray ionization tandem mass spectrometry water analysis for endocrine disrupting chemicals

In recent years, despite the increasing success of liquid chromatography (LC) coupled to tandem mass spectrometry (MS), reports on matrix susceptibility have shown the limitations of the this powerful analytical technique. Matrix effects (MEs) result from co-eluting residual matrix components affecting the ionization efficiency of target analytes and can lead to erroneous results. The present work evaluates the matrix effect of environmental water samples on 35 endocrine disrupting chemicals (EDCs) in negative and positive LC-ESI-MS/MS. It was shown that mobile-phase additives could significantly influence matrix effects. Addition of acids resulted in a severe signal suppression (average ME%: <65%), and 1 mM ammonium formate increased the average ME% to 84%. The importance of an efficient sample clean-up and internal standardization also was demonstrated. Cleaner extracts resulted in reduced matrix effects (average ME%: 89%) and labeled internal standards proved to have a beneficial effect especially on signal reproducibility (average CV% 4.2% versus 2.6%). The results from the present work indicate that evaluation of matrix effects should become an integrated part of quantitative LC-ESI-MS/MS method development and validation.     

Phenolics in selected European hardwood species by liquid chromatography-electrospray ionisation mass spectrometry

The phenols in beech (Fagus sylvatica), birch (Betula pendula) and ash (Fraxinus excelsior) wood dusts were compared using a mass spectrometer fitted with an electrospray ionisation interface with liquid chromatographic separation. Hardwood dust is a carcinogen, and an analysis of the polyphenol profile is a useful method for identifying the dust source in workplace air. The mass spectrometer was operated in both the negative and positive ion modes. Phenolic compounds were identified by comparing mass spectra and retention times from liquid chromatography with those for standard compounds and data in the literature. The phenol contents of the studied wood species varied considerably, and only a few common compounds were found in them.     

高效液相色谱-串联质谱测定猪肉中3种β-受体激动剂残留量

建立一种同时测定猪肉中3种β-受体激动剂残留量的高效液相色谱-电喷雾串联质谱(HPLC-ESI-MS/MS)确证分析方法。样品经β-葡萄糖醛酸酶/芳基硫酸酯酶酶解、乙酸铵缓冲液提取和MCX固相萃取柱净化,采用Agilent ZorbaxSB-C18(2.1mm×150mm,3.5μm)色谱柱,0.1%的甲酸水溶液、甲醇和乙腈作为流动相进行洗脱,高效液相色谱分离,电喷雾离子源电离,正离子多反应监测模式进行检测,内标法定量。3种药物在0.05～1μg/kg浓度范围内线性良好,相关系数r均大于0.999,0.05、0.1、0.5μg/kg3个浓度水平的添加回收率在89.7%～106.7%之间,相对标准偏差为2.4%～8.6%,3种药物的定量限均为0.05μg/kg。方法适用于猪肉中β-受体激动剂残留的确证分析。     

Determination of deltamethrin residues in plant materials by liquid chromatography/tandem mass spectrometry with electrospray ionization

This paper describes a selective and sensitive method that uses liquid chromatography/tandem mass spectrometry with positive electrospray ionization (ESI+) for the determination of deltamethrin in a variety of crops. Samples were extracted by conventional high-speed blending. Some samples required no further cleanup; others were cleaned up by gel permeation chromatography, strong cation-exchange cartridges, or partitioning with n-hexane. In the determinative step, the buffered neutral mobile phase, consisting of 10 mM ammonium acetate (pH 6.8) and methanol, and ESI+ provided strong ammonium adduct formation to [M+NH4]+ at m/z 523, and the multiple-reaction monitoring (MRM) transition at m/z 523/281 was used for the quantitation of deltamethrin. A second MRM transition at m/z 525/283 was used for confirmation. The limit of quantitation (LOQ) values were 0.01 mg/kg for edible materials and 0.05 mg/kg for nonedible materials. Mean overall recoveries at the LOQ and the 10-fold LOQ ranged from 73 to 96%, and the relative standard deviations were <10% for all samples materials analyzed.     

Determination of tridemorph and other fungicide residues in fruit samples by liquid chromatography-electrospray tandem mass spectrometry

A rapid and sensitive liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS) method for the determination of tridemorph and other pre- and post-harvest fungicides (carbendazim, thiabendazole, imazalil, propiconazole and bitertanol) in banana and orange samples has been developed and validated. The sample preparation was a simple extraction step with acetone using a high-speed blender prior to the injection of the five-fold diluted extract into the LC system with no other previous sample pre-treatment. Quantification was carried out using a matrix matched calibration curve which was linear in the range of 1-100 ng ml(-1) for all the compounds. The limit of quantification was 0.05 mg kg(-1) for all studied compounds, whereas limits of detection ranged between 0.005 and 0.025 mg kg(-1) (0.01 mg kg(-1) for tridemorph). Recoveries for tridemorph from spiked banana and orange samples at 0.05 and 1 mg kg(-1) were satisfactory, with values between 83 and 99% and relative standard deviations (R.S.D.s) lower than 13% (n = 5). For the other fungicides, recoveries between 75 and 95% with R.S.D.s lower than 12% were obtained. The developed method has been applied to the determination of selected fungicides in real samples of bananas and oranges from different origin. Thiabendazole and imazalil have been detected in almost all orange samples analyzed, and in around of 30% of banana samples. Bitertanol residues exceeded the maximum residue level (0.05 mg kg(-1)) in three banana samples while tridemorph was only detected in one sample.     

Separation and characterisation of sphingoceramides by high-performance liquid chromatography-electrospray ionisation mass spectrometry

We developed a simple and reliable analytical method for the quantification and the characterization of ceramides extracted from biological samples by high-performance liquid chromatography (HPLC) coupled to electrospray ionisation tandem mass spectrometry (ESI/MS/MS). The chromatographic separation of analytes was carried out in a RP8 column, eluting with a methanol-water mixture in gradient elution mode. The separated lipids were detected by total ion monitoring and characterised by MS/MS spectra; quantitative analysis was performed by integrating the extracted ion peaks obtained in the negative ion mode. Good repeatability was obtained for retention time (0.3-2%), peak area ratio (A(S)/A(IS), 2-8%), as well as limit of detection (LOD, 5-26 pg) and quantification (LOQ, 13-53 pg). The method was validated for the analysis of N-palmitoyl-D-erythro-sphingosine (Cer16), N-stearoyl-D-erythro-sphingosine (Cer18), N-tetracosanoyl-D-erythro-sphingosine (N24:0, lignoceric ceramide, Cer24:0), and N-tetracos-15'-enoyl-D-erythro-sphingosine (N24:1, nervonic ceramide, Cer24:1), giving good results. Lipid mixtures, extracted from skin and epidermal cells, were analysed for their content of the studied ceramides.     

Application of spectral libraries for high-performance liquid chromatography-atmospheric pressure ionisation mass spectrometry to the analysis of pesticide and explosive residues in environmental samples

The coupling of high-performance liquid chromatography (HPLC) and atmospheric pressure ionisation mass spectrometry (API-MS) seems to be the method of choice if good separation and selective detection of semi-volatile, thermolabile, and polar substances is required. Libraries of mass spectra will make the identification of unknown substances in complex environmental samples easier and more user-friendly. Unfortunately, existing GC-MS libraries are not applicable to HPLC-API-MS analysis. Thus, new and extensive mass spectral libraries were constructed. Several investigations of chromatographic (composition and salt concentration of the eluent) as well as mass spectrometric (orifice voltage) parameters and a few applications of real environmental samples are used to discuss the possibilities and limits of these libraries.     

高效液相色谱-电喷雾串联质谱法同时测定鸡肉中残留的磺胺类和氟喹诺酮类兽药

建立了一种同时测定鸡肉中两类共10种兽药(3种磺胺和7种氟喹诺酮类药物)残留量的高效液相色谱-电喷雾串联质谱方法(HPLC -ESI-MS2)。样品经2%醋酸-乙腈提取,正己烷脱脂,过ENVI-18固相萃取柱净化,经氮气吹干后,残余物用流动相定容到1 mL。以乙腈和 0.05%甲酸溶液作为流动相,采用梯度洗脱程序进行液相色谱分离,用质谱检测器进行定性和定量分析,并对10种药物的二级质谱碎裂方 式进行分析。10种药物在0.02～2.0 mg/L范围内线性良好,相关系数均大于0.9988。检出限(LOD)为1.10～6.85 μg/kg,定量限(LOQ) 为3.68～22.85 μg/kg,样品的平均加标回收率为68.9%～102.6%,相对标准偏差均小于8.6%(n=3)。实验结果表明,该方法灵敏度高,重 现性好,确证能力强,分析时间短,可满足动物源性食品中磺胺和氟喹诺酮类药物的残留分析。     

Measurement of bile acid CoA esters by high-performance liquid chromatography-electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS)

The novel and rapid assay presented here combines high-performance liquid chromatography and electrospray ionisation tandem mass spectrometry (HPLC-ESI-MS/MS) to directly measure and quantify the CoA esters of 3alpha,7alpha,12alpha-trihydroxy- and 3alpha,7alpha-dihydroxy-5beta-cholestan-26-oic acid (THCA and DHCA). The latter are converted inside peroxisomes to the primary bile acids, cholic and chenodeoxycholic acids, respectively. Prior to MS/MS, esters were separated by reversed-phase HPLC on a C(18) column using an isocratic mobile phase (acetonitrile/water/2-propanol) and subsequently detected by multiple reaction monitoring. For quantification, the CoA ester of deuterium-labelled 3alpha,7alpha,12alpha-trihydroxy-5beta-cholan-24-oic acid (d(4)-CA) was used as internal standard. To complete an assay took less than 8 min.To verify the validity of the assay, the effect of peroxisomal proteins on the efficacy of extraction of the CoA esters was tested. To this end, variable amounts of the CoA esters were spiked with a fixed amount of either intact peroxisomes or peroxisomal matrix proteins and then extracted using a solid-phase extraction system. The CoA esters could be reproducibly recovered in the range of 0.1-4 micromol l(-1) (linear correlation coefficient R(2) > 0.99), with a detection limit of 0.1 micromol l(-1).In summary, electrospray ionization tandem mass spectrometry combined with HPLC as described here proved to be a rapid and versatile technique for the determination of bile acid CoA esters in a mixture with peroxisomal proteins. This suggests this technique to become a valuable tool in studies dealing with the multi-step biosynthesis of bile acids and its disturbances in disorders like the Zellweger syndrome.     

Multiresidue pesticide analysis of fruits by ultra-performance liquid chromatography tandem mass spectrometry

Ultra-performance liquid chromatography coupled to tandem mass spectrometry (UPLC–MS–MS) has been used for screening and quantification of 32 pesticides and metabolites in two fruit matrices. The compounds investigated belonged to different chemical families of insecticides, acaricides, fungicides, and herbicides; several metabolites were also included. Quantification was conducted using matrix-matched standards calibration; response was a linear function of concentration in the range tested (10–500 ng mL⁻¹). The method was validated with blank samples of lemon and raisin spiked at 0.01 and 0.1 mg kg⁻¹, and recoveries were satisfactory, between 70 and 110%, for most of the pesticides tested and relative standard deviations were below 15% (n = 5 at each spiking level). Excellent sensitivity resulted in limits of detection for all compounds well below 0.01 mg kg⁻¹, with the limit of quantification being validated at 0.01 mg kg⁻¹. The UPLC system generates narrow peaks (approx. 5 s), thus increasing peak height and improving sensitivity. This improved separation efficiency facilitates adequate resolution not only of the analytes but also of matrix interferences compared with conventional HPLC. The method developed could also resolve some geometric isomers. The main advantage of this approach is the high sample throughput achieved because of the short analysis time, which enables satisfactory separation of all the compounds in less than 5 min per sample.