Simultaneous determination of honokiol and magnolol in Magnolia officinalis by liquid chromatography with tandem mass spectrometric detection

An optimized high-performance liquid chromatographic method coupled with tandem mass spectrometric detection (LC-MS/MS) was developed for the simultaneous determination of honokiol and magnolol in Magnolia officinalis. Honokiol and magnolol were separated from the extracts using a reversed-phase C(18) column with a mobile phase consisted of acetonitrile and water (75:25, v/v) at a flow-rate of 0.8 mL/min. Selected reaction monitoring (SRM) mode was used for all sample quantification by the precursor-ion/product ion pair m/z 265 --> m/z 224 for honokiol and m/z 265 --> m/z 247 for magnolol. Validation data showed that this method has good linearity (r(2) > 0.995) over the concentration range of 0.0025-0.5 microg/mL for honokiol and magnolol, and both intra- and inter-day variability were acceptable within 15% at the lowest concentrations for this method. This proposed method provides excellent specificity, higher sensitivity and shorter run time than conventional methods and was applied successfully to determine the contents of honokiol and magnolol in M. officinalis.     

Liquid chromatographic determination of 6-, 8-, 10-gingerol, and 6-shogaol in ginger (Zingiber officinale) as the raw herb and dried aqueous extract

The determination of 6-, 8-, 10-gingerol, and 6-shogaol in dried ginger (Zingiber officinale) and in the dried aqueous extract of ginger is reported. This is the first study to report a validated method for the determination of these 4 analytes. Several extraction solvents and methods were examined, and the optimum combination was determined. The samples were extracted at room temperature by sonication with methanol, and the extract was analyzed by liquid chromatography with photodiode array detection. A C18 column was used with a water-acetonitrile gradient mobile phase. Quantification was at 200 nm. The levels of 6-, 8-, 10-gingerol, and 6-shogaol in the raw herb were 9.3, 1.6, 2.3, and 2.3 mglg, respectively. The levels of gingerols found in the dried aqueous extract were between 5 and 16 times lower than those in the raw herb, but the level of 6-shogaol was higher. Analyte identity was confirmed by negative-ion electrospray ionization tandem mass spectrometry, in which 2 daughter ions were obtained for each analyte. The average recovery was 97% with a relative standard deviation of <8%. The limits of detection for 6-, 8-, 10-gingerol, and 6-shogaol in the raw herb were 0.22, 0.04, 0.09, and 0.07 mglg, respectively, and in the dried aqueous extract, 0.11, 0.02, 0.02, and 0.14 mg/g, respectively.     

Direct determination of the ethanol metabolites ethyl glucuronide and ethyl sulfate in urine by liquid chromatography/electrospray tandem mass spectrometry

A liquid chromatography/electrospray tandem mass spectrometry (LC/ESI-MS/MS) method for the determination in urine samples of two ethanol metabolites, ethyl glucuronide (EtG) and ethyl sulfate (EtS), was developed and validated. Pentadeuterated EtG was used as internal standard for both EtG and EtS. In addition to the surviving ions, two MS/MS reactions were monitored for each analyte, with the deprotonated molecule as precursor ion: m/z 221 --> 75, m/z 221 --> 85 (EtG), and m/z 125 --> 97, m/z 125 --> 80 (EtS). Sample pretreatment, though very simple and rapid (1:50 water dilution and centrifugation of 50 muL of urine), was found to contain the occurrence of matrix effects. The method was accurate and precise over the linear dynamic range (0.05-10 mg/L). The analytes were stable in frozen urine for at least 1 month. The assay was applied to several authentic urine samples from social drinkers and to alcoholic beverages.     

Mass spectrometric characterization of toremifene metabolites in human urine by liquid chromatography-tandem mass spectrometry with different scan modes

The metabolism and excretion of toremifene were investigated in one healthy male volunteer after a single oral administration of 120 mg toremifene citrate. Different liquid chromatographic/tandem mass spectrometric (LC/MS/MS) scanning techniques were carried out for the characterization of the metabolites in human urine for doping control purposes. The potential characteristic fragmentation pathways of toremifene and its major metabolites were presented. An approach for the metabolism study of toremifene and its analogs by liquid chromatography-tandem mass spectrometry was established. Five different LC/MS/MS scanning methods based on precursor ion scan (precursor ion scan of m/z 72.2, 58.2, 44.2, 45.2, 88.2 relative to five metabolic pathways) in positive ion mode were assessed to recognize the metabolites. Based on product ion scan and precursor ion scan techniques, the metabolites were proposed to be identified as 4-hydroxy-toremifene (m/z 422.4), 4'-hydroxy-toremifene (m/z 422.4), α-hydroxy-toremifene (m/z 422.4), 3,4-dihydroxy-toremifene (m/z 404.2), toremifene acid (m/z 402.2), 3-hydroxy-4-methoxy-toremifene (m/z 456.2), dihydroxy-dehydro-toremifene (m/z 440.2), 3,4-dihydroxy-toremifene (m/z 438.2), N-demethyl-4-hydroxy-toremifene (m/z 408.3), N-demethyl-3-hydroxy-4-methoxy-toremifene (m/z 438.3). In addition, a new metabolite with a protonated molecule at m/z 390.3 was detected in all urine samples. The compound was identified by LC/MS/MS as N-demethyl-4,4'-dihydroxy-tamoxifene. The results indicated that 3,4-dihydroxy-toremifene (m/z 404.2), toremifene acid (m/z 402.2) and N-demethyl-4,4'-dihydroxy-tamoxifene (m/z 390.3) were major metabolites in human urine.     

Mass spectrometry for the characterization of unsulfated chondroitin oligosaccharides from 2-mers to 16-mers. Comparison with hyaluronic acid oligomers

This study reports for the first time the complete liquid chromatography/electrospray ionization mass spectrometry (LC/ESI-MS) and tandem mass spectrometry (MS/MS) analyses performed in negative ion mode of saturated unsulfated chondroitin oligosaccharides up to 16-mers and comparison with hyaluronic acid (HA) oligomers differing only in the nature of the hexosamine residue. MS/MS of the chondroitin disaccharide on the singly charged precursor at m/z 396.1 afforded a glycosidic cleavage C1 product ion at m/z 192.9. In the tetrasaccharide, C2 (m/z 396.0) and C3 (m/z 572.0) product anions were generated by glycosidic cleavage. A C5 [M-2H]2- product ion at m/z 475.1 was generated by the glycosidic cleavage of the hexasaccharide, and a C7 ion (m/z 664.6, charge state of -2) was produced from the octasaccharide. The same fragmentation pattern of deprotonated oligomers was observed for the largest oligosaccharides, from 10- to 16-mers. There has been no previous report of MS/MS spectra for unsulfated chondroitin oligomers of these sizes. Unsulfated saturated chondroitin oligosaccharides with x-mer units and larger than a tetrasaccharide dissociate to almost exclusively form CX-1-type ions. Saturated HA oligomers also afforded the same fragmentation pattern as deprotonated oligomers by ESI-MS and MS/MS analyses. Thus, under the experimental conditions used in the current study, we were unable to distinguish between unsulfated chondroitin and HA.     

Preparative purification of gentamicin components using high-speed counter-current chromatography coupled with electrospray mass spectrometry

We developed a useful and preparative method based on high-speed counter-current chromatography with mass spectrometry (HSCCC/MS) to purify gentamicin C1a, C2/2a and C1 from standard powder. The analytes were purified on the HSCCC model CCC-1000 (multi-layer coil planet centrifuge) with a volatile two-phase solvent system composed of n-butanol/10% aqueous ammonia solution (50:50, v/v) and detected on an LCMS-2020EV quadrupole mass spectrometer fitted with an electrospray ionization (ESI) source system in positive ionization following scan mode (m/z 100-500). The HSCCC/ESI-MS peaks indicated that gentamicin C1a (m/z 450: [M+H](+)), C2/2a (m/z 464: [M+H](+)) and C1 (m/z 478: [M+H](+)) have the peak resolution values of 1.3 and 1.7 from 30 mg of loaded gentamicin powder. The HSCCC yielded 3.9 mg of gentamicin C1a, 12.6 mg of gentamicin C2/2a and 12.0 mg of gentamicin C1. These purified substances were analyzed by LC/MS with scan positive-mode. Based on the LC/MS chromatograms and spectra of the fractions, analytes were estimated to be over 95% pure. These gentamicin isomers of C1a, C2/2a and C1 were evaluated for their antibacterial activities. The overall results indicate that this approach of HSCCC/MS is a powerful technique for the purification of gentamicin components.     

Liquid chromatography/tandem mass spectrometry analysis of chloramphenicol in cooked crab meat

A liquid chromatography/tandem mass spectrometry (LC/MS/MS) method is described for the extraction, cleanup, determination, and confirmation of chloramphenicol (CAP) in cooked crab meat. The method involves pulverization of cooked crab meat with dry ice; extraction of the CAP into ethyl acetate (EtOAc); evaporation (by N2) of the EtOAc; addition of methanol, aqueous NaCl, and heptane; extraction of the lipids into the heptane, followed by extraction of the aqueous phase with EtOAc; evaporation (by N2) of the EtOAc; dissolution into methanol-water; filtration; and separation/detection/confirmation using LC/MS/MS. Crab meat was fortified at 0.25, 0.50, and 1.0 ng/g (ppb) chloramphenicol. Average absolute recoveries were 67, 84, and 86%, respectively, with relative standard deviation values all less than 1%. Four daughter ions (m/z 152, 176, 194, and 257) were monitored off the m/z 321 precursor ion. Determination was based on a standard curve using the peak areas of the m/z 152 daughter ion (the base peak) for standard solutions equivalent to 0.10, 0.20, 0.50, and 1.0 ppb in tissue (made with control crab extract). A set of 6 matrix controls (unfortified crab meat) was also analyzed, in which no chloramphenicol was detected. For identification purposes, the ion ratios (of each daughter ion versus the base daughter ion) of the fortified crab versus those of the chloramphenicol standards agreed within 10% (relative) at fortified chloramphenicol concentrations of 0.25-1.0 ppb.     

Quantitative determination of ochratoxin A in kidneys by liquid chromatography/mass spectrometry

A sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for the quantitative determination of ochratoxin A (OTA) in kidney samples was developed. Ochratoxin B (OTB) was used as internal standard. Extraction of homogenized kidney samples was done by adding a chloroform/phosphoric acid mixture. Due to restriction of the sample size, less chloroform could be used than in previously described methods. Two different columns for clean-up were compared: strong anion exchange (Bond Elut SAX) and Extrelut NT columns. The high-performance liquid chromatography (HPLC) was used with gradient elution consisting of variable mixtures of formic acid (0.3%) in acetonitrile and formic acid (0.3%) in water. The mass spectrometer was operated in the positive ESI mode using multiple reaction monitoring. For OTA the precursor ion was m/z 404 while the product ions were at m/z 239 and m/z 341. For OTB the precursor ion was m/z 370 while the product ions were at m/z 205 and at m/z 324. A calibration curve of fortified kidney samples was used to quantify OTA. Method validation was performed according to Commission Decision 2002/657/EC. Decision limit (CCalpha), detection capability (CCbeta), precision, bias, trueness, specificity and measurement uncertainty were determined. In general, the best results were obtained using SAX clean-up. CCalpha and CCbeta were 0.11 and 0.25 microg kg(-1), respectively. Within-laboratory reproducibility (% CV) was 9, 9, and 5% for OTA-fortified kidney samples of 0.5, 1, and 2.5 microg kg(-1), respectively. Trueness (%) was 75, 69, and 57% for OTA-fortified kidney samples at 0.25, 0.5, and 1 microg kg(-1), respectively. Measurement uncertainty and expanded uncertainty were 14.85 and 29.70%, respectively. All criteria as laid down in Commission Decision 2002/657/EC were fulfilled. Therefore, this LC/ESI-MS/MS method can be used to monitor kidneys for OTA in the framework of Council Directive No. 96/23/EC.     

Synthesis of 4-[2-(N,N-dimethylamino)ethylaminosulfonyl]-7-N-methylhydrazino-2,1,3-benzoxadiazole (DAABD-MHz) as a derivatization reagent for aldehydes in liquid chromatography/electrospray ionization-tandem mass spectrometry

Benzofurazan derivatization reagent, 4-[2-(N,N-dimethylamino)ethylaminosulfonyl]-7-N-methylhydrazino-2,1,3-benzoxadiazole (DAABD-MHz), for aldehydes in liquid chromatography/electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS), was synthesized. DAABD-MHz reacted with aliphatic aldehydes under mild conditions. The generated derivatives were separated on a reversed-phase column and detected by ESI-MS/MS with detection limits of 30-60 fmol on-column. Upon collision-induced dissociation, a single and intense fragment ion at m/z 151 was observed. These results suggested that DAABD-MHz was suitable as a derivatization reagent in LC/ESI-MS/MS.     

Characterization and identification of steroidal alkaloids in the Chinese herb Veratrum nigrum L. by high-performance liquid chromatography/electrospray ionization with multi-stage mass spectrometry

Electrospray ionization multi-stage mass spectrometry (ESI-MS(n)) was performed to study the fragmentation behaviour of seventeen steroidal alkaloids (4 protoverine-type alkaloids, 10 germine-type alkaloids and 3 zygadenin-type alkaloids) from the Chinese herb Veratrum nigrum L. The MS(n) spectra of the [M+H](+) ions for steroidal alkaloids provided a wealth of structural information on the substituted groups. In positive ion mode, the three types of alkaloids showed very different characteristic ions: m/z 436 or 418 for protoverine-type alkaloids; m/z 438, 420 or 402 for germine-type alkaloids; m/z 440 or 422 for zygadenin-type alkaloids. These fragments were used to deduce their mass spectral fragmentation mechanisms. Furthermore, the primary compounds in methanolic extracts of the herb of Veratrum nigrum L. were investigated by using liquid chromatography (LC)/ESI-MS(n). As a result, 21 steroidal alkaloids (5 protoverine-type alkaloids, 14 germine-type alkaloids and 2 zygadenin-type alkaloids) were selectively identified from 27 determined peaks. Eleven compounds were unambiguously identified by comparing with standard compounds and ten compounds were tentatively identified or deduced according to their MS(n) data. Two of these compounds (xingangermine and deacetyl xinganveratrine) were found to be novel steroidal alkaloids. In addition, the chemical structures of two pairs of steroidal alkaloid isomers were deduced by comparing their fragment ions. Given the important structural information of known and unknown steroidal alkaloids in crude herbal extracts, this study is useful for identifying these types of steroidal alkaloids in crude materials rapidly and selectively.     

Quantitation of acrylamide in food products by liquid chromatography/mass spectrometry

A simple and inexpensive liquid chromatography/mass spectrometry (LC/MS) method was developed for the quantitation of acrylamide in various food products. The method involved spiking the isotope-substituted internal standard (1-C13 acrylamide) onto 6.00 g of the food product, adding 40 mL distilled/deionized water, and heating at 65 degrees C for 30 min. Afterwards, 10 mL ethylene dichloride was added and the mixture was homogenized for 30 s and centrifuged at 2700 x g for 30 min, and then 8 g supernatant was extracted with 10, 5, and 5 mL portions of ethyl acetate. The extracts were combined, dried with sodium sulfate, and concentrated to 100-200 microL. Acrylamide was determined by analysis of the final extract on a single quadrupole, bench-top mass spectrometer with electrospray ionization, using a 2 mm id C18 column and monitoring m/z = 72 (acrylamide) and m/z = 73 (internal standard). For difficult food matrixes, such as coffee and cocoa, a solid-phase extraction cleanup step was incorporated to improve both chromatography and column lifetime. The method had a limit of quantitation of 10 ppb, and coefficients of determination (r2) for calibration curves were typically better than 0.998. Acceptable spike recovery results were achieved in 11 different food matrixes. Precision in potato chip analyses was 5-8% (relative standard deviation). This method provides an LC/MS alternative to the current LC/MS/MS methods and derivatization gas chromatography/mass spectrometry methods, and is applicable to difficult food products such as coffee, cocoa, and high-salt foods.     

有机质谱学在蛇床子素、厚朴酚、和厚朴酚与鱼腥草素结构确定中的应用

有机质谱学在中药药效物质的结构确定中起到了至关重要的作用. 对中药药效物质质谱的确切解释需要对这些药效物质质谱的关键裂解规律有足够的了解. 应用有机质谱学规律对中药药效物质的结构确定进行了讨论. 这些中药的药效物质包括: 应用超临界二氧化碳从蛇床子中提取的蛇床子素和从厚朴中提取的厚朴酚与和厚朴酚; 应用水蒸汽蒸馏从鱼腥草中提取的鱼腥草素等. 具有较高丰度的质谱关键碎片峰 m/z 229 的出现是蛇床子素质谱的典型特征; 质谱关键碎片峰 m/z 169 的出现是鱼腥草素质谱的典型特征. 而质谱关键碎片峰 m/z 247 是否出现则是区分厚朴酚与和厚朴酚的质谱典型特征. 在此基础上, 尝试构建中药药效物质的有机质谱学平台.     

Analysis of testosterone and dihydrotestosterone from biological fluids as the oxime derivatives using high-performance liquid chromatography/tandem mass spectrometry

A sensitive liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) method for the simultaneous quantitative analysis of dihydrotestosterone (DHT) and testosterone (T) from biological fluids has been developed. Commercially available deuterated analogues were used as internal standards. Steroids were extracted from serum or testicular fluid with hexane/ethyl acetate, evaporated to dryness, and treated with hydroxylamine to form their oxime derivatives. Upon chromatographic separation, the compounds were quantified using selected reaction monitoring (SRM). For T, the [M+H](+) ion at m/z 304 and the fragment ion at m/z 124 were used as the precursor and product ions. For DHT the ion cluster [M+H+ACN](+) at m/z 347 and the dissociated ion [M+H](+) at m/z 306 were used as the precursor and product ions, respectively. The limits of detectability on-column were in the sub-femtomole range for both compounds and the intra-day coefficient of variation (CV) for analysis from serum was less than 7% for both compounds. Given its high reproducibility, sensitivity, and relative simplicity, this assay should be of use in determining androgen levels in biospecimens, particularly in settings where sample quantity or steroid concentration are low.     

Rapid screening and identification of cytochalasins by electrospray tandem mass spectrometry

The cytochalasin class of fungal metabolites was analyzed by electrospray ionization tandem mass spectrometry (ESI-MS/MS) with the aim of developing a methodology for their rapid identification in microbial extracts. ESI-MS analyses of reference cytochalasins were performed and several product ions were produced in MS/MS experiments on parent ions that are structurally characteristic. A precursor ion search was performed to detect cytochalasins in an ethyl acetate extract of fungal strain RK97-F21. Three cytochalasins were detected and one of the components was identified as epoxycytochalasin H by comparing the tandem mass spectra of the product ions with those of reference compounds. This finding was further validated by LC/MS and LC/MS/MS experiments.     

Determination of ethyl glucuronide in hair samples by liquid chromatography/electrospray tandem mass spectrometry

A method for the determination of ethyl glucuronide (EtG) in hair samples, using liquid chromatography/electrospray tandem mass spectrometry (LC/ESI-MS/MS), was developed and validated. The treatment of hair samples was as follows: to 100 mg of washed (dichloromethane followed by methanol, 1 ml each) and cut (1-2 mm) material, 700 microl of water, 20 microl of internal standard solution (pentadeuterated EtG, D(5)-EtG, 500 microg/l) and 20 microl of methanol were added. Samples were incubated at 25 degrees C overnight and then ultrasonicated for 2 h. Finally, 8 microl of the centrifuged solution (13,000 rpm) were analyzed by LC/ESI-MS/MS in negative ion mode. The surviving ions of EtG and D(5)-EtG were monitored together with the following MRM transitions: m/z 221 --> 75, m/z 221 --> 85 (EtG) and m/z 226 --> 75, m/z 226 --> 85 (D(5)-EtG). The method exhibited a mean correlation coefficient better than 0.9998 over the dynamic range (3-2000 pg/mg). The lower limit of quantification (LLOQ) and the limit of detection (LOD) were 3 and 2 pg/mg respectively. The intra- and interday precision and accuracy were studied at four different concentration levels (3, 5, 56 and 160 pg/mg) and were always better than 7% (n = 5). Matrix effects did not exceed 20%. The method was applied to several hair samples taken from autopsies of known alcoholics, from patients in withdrawal treatment, from social drinkers, from adult teetotalers and from children not exposed to ethanol, with EtG concentrations globally ranging from < or =2 to 4180 pg/mg.     

高效液相色谱法同时测定血清和尿中厚朴酚与和厚朴酚

 建立了大鼠服用厚朴提取物后的血清中及尿中厚朴酚与和厚朴酚的高效液相色谱测定法。色谱柱填料为SpherisorbC18,流动相为甲醇-水-冰醋酸(体积比为70∶30∶1),UV检测波长为294nm,灵敏度0.005AUFS。样品用甲醇沉淀蛋白,上清液酸化后用乙酸乙酯-乙醚萃取,然后测定其中的药物浓度。血清和尿中的药物浓度与峰面积的线性关系良好,线性范围分别为0.05～2mg/L(厚朴酚)、0.025～1mg/L(和厚朴酚);精密度和重现性良好。血清中厚朴酚与和厚朴酚的平均加样回收率分别为95.6%(RSD=3.85%)和93.8%(RSD=3.95%),尿中分别为96.0%(RSD=3.83%)和94.9%(RSD=3.54%)。     

High-performance liquid chromatographic method for simultaneous determination of honokiol and magnolol in rat plasma

A high-performance liquid chromatographic (HPLC) method is described for the simultaneous determination of honokiol and magnolol in rat plasma. The plasma was deproteinized with acetonitrile which contained an internal standard (diphenyl) and was separated from the aqueous layer by adding sodium chloride. Honokiol and magnolol are extracted into the acetonitrile layer with high yield, and determined by reversed-phase HPLC and ultraviolet detection. The limits of quantitation for honokiol and magnolol were 13 and 25 ng ml⁻¹ in plasma, respectively, and recovery of both analytes was greater than 93%. The assay was linear from 20 to 200 ng ml⁻¹ for honokiol and from 40 to 400 ng ml⁻¹ for magnolol. Variation over the range of the standard curve was less than 15%. The method was used to determine the concentration-time profiles of honokiol and magnolol in the plasma following rectal administration of Houpo extract at a dose of 245 mg kg⁻¹, equivalent to 13.5, 24.4 mg kg⁻¹ of honokiol and magnolol, respectively.     

Liquid chromatography with electrospray ion-trap mass spectrometry for the determination of anatoxins in cyanobacteria and drinking water

Anatoxin-a (AN) and homoanatoxin-a (HMAN) are potent neurotoxins produced by a number of cyanobacterial species. A new, sensitive liquid chromatography/multiple tandem mass spectrometry (LC/MS(n)) method has been developed for the determination of these neurotoxins. The LC system was coupled, via an electrospray ionisation (ESI) source, to an ion-trap mass spectrometer in positive ion mode. The [M+H](+) ions at m/z 166 (anatoxin-a) and m/z 180 (homoanatoxin-a) were used as the precursor ions for multiple MS experiments. MS(2)bond;MS(4) spectra displayed major fragment ions at m/z 149 (AN), 163 (HMAN), assigned to [Mbond;NH(3)+H](+); m/z 131 (AN), 145 (HMAN), assigned to [Mbond;NH(3)bond;H(2)O+H](+), and m/z 91 [C(7)H(7)](+). Although the chromatographic separation of these neurotoxins is problematic, reversed-phase LC, using a C(18) Luna column, proved successful. Calibration data for anatoxin-a using spiked water samples (10 mL) in LC/MS(n) modes were: LC/MS (25-1000 microg/L), r(2) = 0.998; LC/MS(2) (5-1000(microg/L), r(2) = 0.9993; LC/MS(3) (2.5-1000 microg/L), r(2) = 0.9997. Reproducibility data (% RSD, N = 3) for each LC/MS(n) mode ranged between 2.0 at 500 microg/L and 7.0 at 10 microg/L. The detection limit (S/N = 3) for AN was better than 0.03 ng (on-column) for LC/MS(3) which corresponded to 0.6 microg/L.     

Determination of fludioxonil and famoxadone in processed fruits and vegetables by liquid chromatography/electrospray tandem mass spectrometry

The feasibility of using liquid chromatography/ electrospray ionization-tandem mass spectrometry (LC/ESI-MS/MS) for determining 2 fungicides (fludioxonil and famoxadone) in tomato pulp, pear purée, and concentrated lemon juice has been evaluated. A miniaturized extraction-partition procedure requiring small amounts of nonchlorinated solvents was used. The extracts (5 microL) were analyzed by LC/ESI-MS/MS without previous cleanup. Chromatographic determination was performed using a C18 column with isocratic elution. Four MS/MS transitions of precursor ions were monitored simultaneously (2 for each pesticide) by means of negative ESI. Mean recoveries from samples at fortification levels of 0.002-0.020 mg/kg (fludioxonil) and 0.010-0.100 mg/kg (famoxadone) ranged from 77.1 to 96.5%, with associated relative standard deviations between 4.2 and 11.5%.     

Evaluation of a method based on liquid chromatography/electrospray tandem mass spectrometry for analyzing eight triazolic and pyrimidine fungicides in extracts of processed fruits and vegetables

The feasibility of using liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) for determining 8 fungicides (triadimenol, penconazole, propiconazole, hexaconazole, cyproconazole, myclobutanil, fenarimol, and bitertanol) in extracts of tomato puree and lemon juice concentrate has been evaluated. A miniaturized extraction-partition procedure requiring small amounts of nonchlorinated solvents has been used. The extracts (5 microL) were analyzed by LC/ESI-MS/MS without any previous cleanup step. Chromatographic determination has been performed using a C18 column and isocratic elution. Seventeen MS/MS transitions of precursor ions were monitored simultaneously (2 or 3 for each pesticide). The excellent selectivity and good linearity of the LC/MS/MS method allowed quantitation and identification at low levels (limits of quantitation <0.010 mg/kg), even in difficult matrixes, with a run time of only 1.5 min.