Determination of sodium cromoglycate in human plasma by liquid chromatography with tandem mass

A sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the determination of sodium cromoglycate (SCG) in human plasma after a nasal dose of 10.4 mg sodium cromoglycate nasal spray, using pravastatin sodium as the internal standard. The method was validated over a linear range of 0.300-20.0 ng/mL. SCG and I.S. were extracted from 1.0 mL of heparinized plasma by C(18) solid-phase extraction cartridges using methanol as eluting solvent. The dried residue was reconstituted with 100 microL of mobile phase, and 10 microL was injected onto the LC-MS/MS system. Chromatographic separation was achieved on a C(18) column (250 x 4.6 mm i.d., 5 microm particle size) with a mobile phase of methanol-acetonitrile-water (containing 2 mmol/L ammonium acetate; 42.5:42.5:15, v/v/v) at a flow rate of 0.4 mL/min. The analytes were detected with a triple quad LC-MS/MS using ESI with positive ionization. Ions monitored in the multiple reaction monitoring mode were m/z 469.0 (precursor ion) to m/z 245.0 (product ion) for SCG and m/z 447.2 (precursor ion) to m/z327.1 (product ion) for pravastatin sodium (internal standard) The average recovery of SCG from human plasma was 94.88% and the lower limit of quantitation was 0.3 ng/mL. Results from a 3-day validation study demonstrated excellent precision and accuracy across the calibration range of 0.3-20 ng/mL. The method was successfully applied to the pharmacokinetic study of SCG in healthy Chinese volunteers. Copyright (c) 2008 John Wiley & Sons, Ltd.     

Liquid chromatography/quadrupole time-of-flight mass spectrometry for determination of saxitoxin and decarbamoylsaxitoxin in shellfish

Saxitoxin (STX) and decarbamoylsaxitoxin (dcSTX) were determined by liquid chromatography with quadrupole time-of-flight mass spectrometry (Q-TOF MS). A shellfish tissue was extracted with 0.1 mol/l HCl under ultrasonication, and cleanup of extract was accomplished by solid-phase extraction with a C18 cartridge. Chromatographic separation was carried out on a C18 column (150 mm x 2.1 mm, 3.5 microm) with gradient elution of MeOH-H2O (20:80) containing 0.05% heptafluorobutyric acid and MeOH-H2O (15:85) containing 0.05% acetic acid. The protonated molecule [M + H]+ ions at m/z 257 for dcSTX and 300 for STX were selected in precursor ion scanning for Q-TOF MS in the positive electrospray ionizaion mode. Average recoveries and relative standard deviations, by analyzing samples spiked at a level of 0.1, 0.8 or 1.6 microg/g, were 84-92 and 8-14%, respectively. Identification of the presence of the toxins in shellfish tissues was based on the structural information offered by Q-TOF MS.     

A packaging contaminant: isopropylthioxanthone (ITX) in dairy products

A fast, simple and very selective liquid chromatography-mass spectrometry (LC-MS) method for the detection of isopropylthioxanthone (ITX) in dairy products has been developed and validated. After addition of an ITX-d(3) as internal standard and a simple extraction from the sample with acetonitrile, the extract was centrifuged and directly injected into the LC-MS system. Chromatographic separation was achieved by means of a Gemini C18 column (100 mm x 2.0 mm i.d. 5 microm) using a gradient of aqueous 20 mM ammonium formiate at pH 4.5 and methanol as the mobile phase, at a flow rate of 0.25 mL min(-1). The method was validated according to the guidelines laid down by the Commission Decision 2002/657/EC using the parent ion [M+H](+) (m/z 255) as quantification ion, and the fragment ion (m/z 213) obtained by in-source collision-induced dissociation (IS-CID) as confirmation ion. Absolute and relative recoveries rates were verified at 5, 10, 15 microg kg(-1) in yoghurt samples and at 5 microg kg(-1) in milk and pudding: mean absolute recoveries were 77% in yoghurt, 50% in pudding and 67% in milk; relative recoveries (after internal standard correction) were always >97% in each matrix. The detection limit (CCalpha) and the detection capability (CCbeta) of method were 6.2 and 7.2 microg kg(-1), respectively.     

Rapid and highly sensitive liquid chromatography/electrospray ionization tandem mass spectrometry method for the quantitation of buspirone in human plasma: application to a pharmacokinetic study

A rapid and sensitive method for the quantitation of buspirone in human plasma by liquid chromatography/electrospray ionization tandem mass spectrometry (LC/ESI-MS/MS) was developed. Plasma samples were treated by liquid-liquid extraction with methyl tert-butyl ether (MTBE). The chromatographic separation was performed isocratically on a reversed-phase Shiseido C18 column (50 mm x 2.0 mm, 3 microm) with a mobile phase of acetonitrile/0.1% acetic acid (1:1, v/v). The acquisition was performed in multiple reaction monitoring (MRM) mode, monitoring the transitions m/z 386 --> 122 for buspirone and m/z 409 --> 238 for amlodipine (the internal standard). The method was validated to determine its specificity, recovery, limit of quantitation, accuracy and precision. The lower limit of quantitation was 0.02 ng/mL with a relative standard deviation of less than 10%. The present method provides an accurate, precise and sensitive tool for buspirone and was successfully applied to a pharmacokinetic study in eight subjects.     

Quantification of D-amino acids in the central nervous system of Aplysia californica by liquid chromatography/tandem mass spectrometry

A sensitive, specific and reliable liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed for simultaneous determination of D-amino acids in the central nervous system (CNS) of Aplysia californica. In order to correct for any potential matrix effects on measured signals, deuterium-labeled L-Asp-d3 was used as an internal standard. Pre-column derivatization of the sample with 7-fluoro-4-nitrobenzoxadiazole (NBD-F) allowed both effective in-line pre-concentration and sensitive MS/MS detection of the analytes. An extraction column (50x0.25 mm, 5 microm C18 silica particles) was used to pre-concentrate/stack samples. Enantiomeric separation of amino acid enantiomers was achieved on a chiral column packed with teicoplanin aglycone bonded silica particles (170x0.25 mm, 5 microm) with an MS-friendly mobile phase. The characteristic precursor to product ion transitions, m/z 297-->279 (for NBD-Asp), m/z 269-->223 (For NBD-Ser), m/z 311-->293 (for NBD-Glu) and m/z 300-->282 (for NBD-L-Asp-d3) were monitored for the quantification. Samples from the CNS of A. californica and heart tissues were analyzed. D-Asp was detected at high levels in all the ganglia and nerve tissues, but not in the heart tissue. Further, neither D-Ser nor D-Glu was detected in Aplysia, a widely used neuronal model.     

液相色谱-质谱法同时鉴别中药制剂中的15种糖皮质激素

为了打击药物的非法滥用,建立起鉴别中药制剂中可能添加的糖皮质激素的液相色谱-质谱分析方法。针对不同的中药剂型,采用不同的试样处理方式。提取后的样品溶液采用Diamond C18柱(5 μm,250 mm×4.6 mm)分离,以流动相A（水-四氢呋喃,体积比为100∶1）和B（乙腈-水-四氢呋喃,体积比为80∶20∶1）进行梯度洗脱。通过与对照品保留时间、一级质谱及二级质谱图的对比进行定性。应用该法鉴定了中药制剂中的糖皮质激素,在供试品溶液中检出了醋酸泼尼松。     

Semi-permeable surface analytical reversed-phase column for the improved trace analysis of acidic pesticides in water with coupled-column reversed-phase liquid chromatography with UV detection. Determination of bromoxynil and bentazone in surface water.

The coupled-column (LC-LC) configuration consisting of a 3 microm C18 column (50 x 4.6 mm I.D.) as the first column and a 5 microm C18 semi-permeable-surface (SPS) column (150 x 4.6 mm I.D.) as the second column appeared to be successful for the screening of acidic pesticides in surface water samples. In comparison to LC-LC employing two C18 columns, the combination of C18/SPS-C18 significantly decreased the baseline deviation caused by the hump of the co-extracted humic substances when using UV detection (217 nm). The developed LC-LC procedure allowed the simultaneous determination of the target analytes bentazone and bromoxynil in uncleaned extracts of surface water samples to a level of 0.05 microg/l in less than 15 min. In combination with a simple solid-phase extraction step (200 ml of water on a 500 mg C18-bonded silica) the analytical procedure provides a high sample throughput. During a period of about five months more than 200 ditch-water samples originating from agricultural locations were analyzed with the developed procedure. Validation of the method was performed by randomly analyzing recoveries of water samples spiked at levels of 0.1 microg/l (n=10), 0.5 microg/l (n=7) and 2.5 microg/l (n=4). Weighted regression of the recovery data showed that the method provides overall recoveries of 95 and 100% for bentazone and bromoxynil, respectively, with corresponding intra-laboratory reproducibilities of 10 and 11%, respectively. Confirmation of the analytes in part of the samples extracts was carried out with GC-negative ion chemical ionization MS involving a derivatization step with bis(trifluoromethyl)benzyl bromide. No false negatives or positives were observed.     

Determination of cyclamate in foods by ultraperformance liquid chromatography/tandem mass spectrometry

A highly sensitive and selective method that requires minimal sample preparation was developed for the confirmation and quantitation of cyclamate in a variety of foods by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). Sample preparation consisted of homogenization followed by extraction and dilution of cyclamate with water. HPLC separation was achieved using a bridged ethyl hybrid C18 high-pressure column with a mobile phase consisting of 0.15% acetic acid and methanol. Under electrospray ionization negative conditions, quantitation was achieved by monitoring the fragment m/z = 79.7 while also collecting parent ion m/z = 177.9. Two food matrixes, diet soda and jelly, were subjected to a validation procedure in order to evaluate the applicability of the method. The cyclamate limit of detection for both matrixes was determined to be 0.050 microg/g with a limit of quantitation of 0.150 microg/g. The correlation coefficient of the calibration curves was >0.9998 from 0.0005 to 0.100 microg/mL. The method has been used for the determination of cyclamate in several foods and the results are presented.     

Succinylmonocholine analytics as an example for selectivity problems in high-performance liquid chromatography/tandem mass spectrometry, and resulting implications for analytical toxicology

The determination and quantitation of drugs in biological matrices using high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS) is becoming increasingly popular in analytical toxicology, while at the same time a growing awareness for the limits of this technique can be observed. Our group previously developed a rapid HPLC/ESI-MS/MS method for the detection and quantitation of succinylcholine (SUX) and succinylmonocholine (SMC) using ion-pairing extraction of samples with subsequent separation by gradient chromatography on a Synergi Hydro RP C18 column (4 microm, 150 x 2 mm). Identification of analytes was achieved in the multiple reaction monitoring (MRM) mode, using two characteristic ion transitions each, the respective analytes' retention time as well as co-elution of stable isotopic analogues.In both native serum as well as urine an interference with the main MRM transition of SMC was found to co-elute with this analyte, thus severely compromising the identification and quantitation of this target analyte. The interference was further shown to be eliminated from serum and urine by exposure to alkaline conditions and hence proven to share a key physicochemical property with SMC. The observed absence of the second and third most intense ion transitions of SMC in the unknown substance was the only useful distinction between both compounds.The detailed presentation of selectivity problems encountered during method development is intended to initiate further discussion on this yet underrepresented issue in HPLC/MS/MS. The present work emphasizes the need to monitor more than just one ion transition to confidently rule out signal interferences, ensure correct analyte identification as well as quantitation, and thus avoid false-positive results. In this context, the employment of minor MRM transitions for the quantitation and identification of a given analyte is presented as a satisfactory solution to HPLC/MS/MS selectivity problems, and proposed as a possible alternative to previously published approaches.     

High-throughput LC-MS/MS assay for 6-methoxy-2-naphthylacetic acid, an active metabolite of nabumetone in human plasma and its application to bioequivalence study

A simple, precise and accurate assay for the determination of 6-methoxy-2-naphthylacetic acid (6-MNA), an active metabolite of nabumetone in human plasma, was developed and validated using liquid chromatography-tandem mass spectrometry (LC-MS/MS). The analyte (6-MNA) and propranolol (internal standard, IS) were extracted from 200 microL aliquot of human plasma via solid-phase extraction employing HLB Oasis cartridges and separated on a Discovery HS C18 (50 x 4.6 mm, 5 microm) column. Detection of analyte and IS was done by tandem mass spectrometry with a turbo ion spray interface operating in positive ion and multiple reaction monitoring acquisition mode. The total chromatographic runtime was 3.0 min with retention time for 6-MNA and IS at 1.97 and 1.26 min, respectively. The method was validated over a dynamic linear range of 0.20-60.00 microg/mL for 6-MNA with mean correlation coefficient r > or = 0.9986. The intra-batch and inter-batch precision (%CV) across five validation runs (lower limit of quantiation, low-, medium- and high-quality controls and upper limit of quantitation) was less than 7.5%. The accuracy determined at these levels was within -5.8 to +0.2% in terms of percentage bias. The method was successfully applied for a bioequivalence study of 750 mg nabumetone tablet formulation in 12 healthy Indian male subjects under fasted condition.     

超高效液相色谱-串联质谱法测定大鼠血浆中的磷酸西他列汀

建立了大鼠血浆中磷酸西他列汀含量检测的超高效液相色谱-串联质谱(UPLC-MS/MS)分析方法。以大鼠空白血浆为基质,通过添加标准品的方法配制含磷酸西他列汀和内标物氟西汀的样品,选用甲醇为沉淀剂,经离心除去血浆中的蛋白质,上清液用于目标物的检测。采用Thermo Hypersil Gold C18柱(50 mm×2.1 mm, 1.9 μm)为分析柱,Phenomenex Security Guard C18(4 mm×3.0 mm)为预柱,以乙腈和0.05%(v/v)甲酸水溶液为流动相进行梯度洗脱,流速为200 μL/min, 5 min内实现了快速分离。采用电喷雾正离子(ESI+)模式电离,选择反应监测(SRM)模式检测,确定了磷酸西他列汀和氟西汀的监测离子对分别为m/z 408.0→235.0和m/z 310.0→148.0,用基质匹配标准溶液法进行定量。结果表明: 大鼠血浆中磷酸西他列汀的质量浓度在1～1000 μg/L范围内时线性关系良好(r=0.9991),检出限(信噪比为3)为0.2 μg/L;其平均回收率为85%～115%;日内及日间的相对标准偏差(RSDs)均小于15%,满足生物样品检测的要求。将该方法初步用于大鼠静脉注射后的血浆样品中磷酸西他列汀的检测。该方法快速、灵敏度高、操作简便、重现性好,能够用于磷酸西他列汀药代动力学等方面的研究。     

液相色谱-串联质谱法同时测定贝类中大田软海绵酸、鳍藻毒素、蛤毒素和虾夷扇贝毒素

建立了同时测定贝类中大田软海绵酸(okadaic acid, OA)及其衍生物鳍藻毒素(dinophysistoxin-1, DTX-1)、蛤毒素(pectenotoxin-2, PTX-2)和虾夷扇贝毒素(yessotoxin, YTX)的液相色谱-串联质谱分析方法。样品经甲醇提取,固相萃取柱净化,C18色谱柱分离,经含甲酸和甲酸铵的乙腈-水溶液为流动相梯度洗脱,选择反应监测(SRM)模式检测,正、负离子切换扫描,基质标准校正,外标法定量。结果表明,OA、DTX-1和YTX的线性范围为2.0～200.0 μg/L,定量限(以信噪比(S/N)≥10计)为1.0 μg/kg; PTX-2的线性范围为1.0～100.0 μg/L,定量限为0.5 μg/kg;几种化合物的添加平均回收率为83.1%～105.7%,相对标准偏差(RSD)为3.16%～9.29%。成功应用本法对黄海灵山湾海域采集的贝类样品进行了分析,发现部分样品中含有大田软海绵酸、鳍藻毒素、蛤毒素和虾夷扇贝毒素。     

High-performance liquid chromatography assays for desmethoxyyangonin, methysticin, kavain and their microsomal metabolites

Three novel, simple and reproducible high-performance liquid chromatography quantitative assays with UV detection were developed and validated for three major kavalactones--desmethoxyyangonin, methysticin and kavain--in rat liver microsomes using diazepam as an internal standard; liquid-liquid extraction was used for sample preparation and analysis was performed on a Shimadzu 10A high-performance liquid chromatography system. The analysis was carried out in reversed-phase mode with a Luna C(18) column (150 x 2.00 mm, 3 microm) at 40 degrees C. The limit of quantitation was 0.1 microg/mL using 0.25 mL of microsomal solution. The assays were linear over the range 0.1-10 microg/mL for desmethoxyyangonin, methysticin and kavain. Quality control samples exhibited good accuracy and precision with relative standard deviations lower than 15% and recoveries between 85 and 105%. The assays exhibited satisfactory performance with high sensitivity for quantifying desmethoxyyangonin, methysticin and kavain in rat liver microsomes and were successfully used to determine the three kavalactones and their microsomal metabolites.     

Determination of M+4 stable isotope labeled cortisone and cortisol in human plasma by microElution solid-phase extraction and liquid chromatography/tandem mass spectrometry

A sensitive microElution solid-phase extraction (SPE) liquid chromatography/tandem mass spectrometry (LC/MS/MS) method has been developed and validated for the determination of M+4 stable isotope labeled cortisone and cortisol in human plasma. In this method, M+4 cortisone and M+4 cortisol were extracted from 0.3 mL of human plasma samples using a Waters Oasis HLB 96-well microElution SPE plate using 70 microL methanol as the elution solvent, and chromatographed on a Waters Symmetry C18 column (4.6 x 50 mm, 3.5 microm). M+9 cortisone and M+9 cortisol were used as the internal standards. A PE Sciex API 4000 tandem mass spectrometer interfaced with the liquid chromatograph via a turboionspray source was used for mass analysis and detection. The selected reaction monitoring (SRM) of precursor --> product ion transitions were monitored at m/z 365.2 [M+H](+) --> 167.0 and at m/z 367.3 [M+H](+) --> 125.1 for M+4 cortisone and M+4 cortisol, respectively. The lower limit of quantitation was 0.1 ng mL(-1) and the linear calibration range was from 0.1 to 100 ng mL(-1) for both analytes. This method demonstrated to be very reproducible and reliable.     

High-throughput determination of carbocysteine in human plasma by liquid chromatography/tandem mass spectrometry: application to a bioequivalence study of two formulations in healthy volunteers

A rapid and sensitive liquid chromatography/tandem mass spectrometry (LC/MS/MS) method to determine carbocysteine in human plasma was developed and fully validated. After methanol-induced protein precipitation of the plasma samples, carbocysteine was subjected to LC/MS/MS analysis using electrospray ionization (ESI). The MS system was operated in the selected ion monitoring (SRM) mode. Chromatographic separation was performed on a Hypurity C18 column (i.d. 2.1 mm x 50 mm, particle size 5 microm). The method had a chromatographic running time of 2.0 min and linear calibration curves over the concentration ranges of 0.1-20 microg/mL for carbocysteine. The lower limit of quantification (LLOQ) of the method was 0.1 microg/mL for carbocysteine. The intra- and inter-day precision was less than 7% for all quality control samples at concentrations of 0.5, 2.0, and 10.0 microg/mL. These results indicate that the method was efficient with a simple preparation procedure and a very short running time (2.0 min) for carbocysteine compared with methods reported in the literature and had high selectivity, acceptable accuracy, precision and sensitivity. The validated LC/MS/MS method has been successfully used to a bioequivalence study of two tablet formulations of carbocysteine in healthy volunteers.     

高效液相色谱/四极杆-飞行时间质谱测定神经性贝毒

采用高效液相色谱/四极杆 飞行时间质谱(HPLC/Q TOFMS)联用技术对贝类样品中的短裸甲藻毒素 PbTx-2 进行了检测研究。样品经丙酮提取、C18小柱净化后,用Zorbax XDB C18色谱柱(2.1 mm i.d.×150 mm,3.5 μ m)进行分离,流动相为甲醇 水(体积比为85∶15)溶液(含0.5 mmol/L NH4Ac),流速0.20 mL/min 。电喷雾正离子模式,选择质子化PbTx 2分子离子 ［M+H］ +作为前体离子进行TOFMS扫描、测定。结果表明,样品的平均加标     

Determination of piceatannol in rat serum and liver microsomes: pharmacokinetics and phase I and II biotransformation

A method of analysis of piceatannol in biological fluids is necessary to study the kinetics of in vitro and in vivo metabolism and determine its concentration in foodstuffs. A novel and simple high-performance liquid chromatographic method was developed for simultaneous determination of piceatannol and products of its metabolism in rat serum and liver microsomes. Serum, or microsomes (0.1 mL), were precipitated with acetonitrile after addition of the internal standard, 4-methylumbelliferone. Separation was achieved on a phenomenex C(18) column (250 x 4.6 mm i.d., 5 microm) equipped with a phenomenex C(18) (4 x 3.0 mm i.d., 5 microm) guardcolumn with fluorescence excitation at 320 nm and emission at 420 nm. Separation was also possible with UV detection at 310 nm. The fluorescent calibration curves were linear ranging from 0.05 to 100 microg/mL. The mean extraction efficiency was >95%. Precision of the assay was <10% (coefficient of variation), and was within 10% at the limit of quantitation (0.05 ng/mL). Bias of the assay was lower than 7%. The limit of detection was 50 ng/mL for a 0.1 mL sample. The assay was applied successfully to the in vitro kinetic study of metabolism of piceatannol in rat liver microsomes and pharmacokinetics in rats. Three metabolites of piceatannol have been identified. .     

Ternary-column system for high-throughput direct-injection bioanalysis by liquid chromatography/tandem mass spectrometry

As a continuation of our efforts to improve our high-flow on-line bioanalytical approach for high-throughput quantitation of drugs and metabolites in biological matrices by high-performance liquid chromatography (LC) and tandem mass spectrometry (MS/MS), we have developed a ternary-column on-line LC/MS/MS system with dual extraction columns used in parallel for purification and an analytical column for analysis. The advantage of the dual extraction column system is that sample analysis can take place in one of the extraction columns while the other column is being equilibrated. Thus, the equilibration time does not add to the run time, hence shortening the injection cycle time and increasing the sample throughput. Moreover, the use of two extraction columns in parallel increases the number of samples that can be injected before the system fails due to an overused extraction column. Such a system has successfully been used to develop and validate a positive ion electrospray LC/MS/MS bioanalytical method for the quantitative determination of a guanidine-containing drug candidate in rat plasma. The system used for this work utilized two Oasis HLB extraction columns (1 x 50 mm, 30 microm), one C18 analytical column (3.9 x 50 mm, 5 microm), a ten-port switching value and a tandem mass spectrometer. The on-line analysis was accomplished by the direct injection of 10 microL of the sample, obtained by mixing a rat plasma sample 1:1 with an aqueous internal standard solution. Selected reaction monitoring (SRM) was utilized for the detection of the analyte and internal standard. The standard curve range was 1.00-200 ng/mL. The intra- and inter-day precision and accuracy were within 6.6%. The on-line purification step lasted for only 0.3 min and total run time was only 1.6 min.     

Development and validation of a liquid chromatography/tandem mass spectrometry assay for the quantification of methyl protodioscin in rat plasma: application to a pharmacokinetic study

A high performance liquid chromatography/tandem mass spectrometry assay was first developed and validated for the quantification of methyl protodioscin (MPD), a natural furostanol saponin with distinct antitumor activity, in rat plasma with 17alpha-ethinylestradiol as internal standard (IS). Methanol-mediated protein precipitation was employed for plasma sample pretreatment. The separation was achieved on a C(18) column (150 x 4.6 mm, i.d., 5 microm) by isocratic elution with methanol-water (72:28, v/v) as mobile phase at a flow rate of 1.0 mL/min. Ion acquisition was performed in selective reaction monitoring positive mode by monitoring the transition of m/z 1085.7 --> 1053.7 for MPD, and in selective ion monitoring negative mode by monitoring the deprotonated ion m/z 295.5 for IS. The assay was linear over the concentration range of 2.024-270.0 microg/mL with 2.024 microg/mL as the lower limit of quantification. It was specific, accurate, precise and reproducible with intra- and inter-run RSD <8.3% and RE between -11.5 and 12.8%. The assay was successfully applied to a preclinical pharmacokinetic study after an intravenous dose of 40 mg/kg MPD to rats.     

固相萃取-气相色谱-质谱法测定利多卡因代谢物单乙基甘氨酰二甲苯胺的血药浓度

建立了固相萃取-气相色谱-质谱(GC-MS)测定利多卡因代谢物单乙基甘氨酰二甲苯胺(MEGX)血药浓度的方法。血清中的MEGX采用固相萃取小柱萃取、GC-MS测定。色谱条件为：HP-5MS毛细管柱(15 m×0.25 mm×0.1 μm),初始柱温100 ℃,保持1 min后以40 ℃/min速率升温至200 ℃,保持0.5 min;进样口温度250 ℃;分流进样,分流比1∶1,进样量2 μL;载气为氦气,流量为1.0 mL/min。质谱条件为:离子源温度230 ℃,电子轰击电离,电子能量70 eV,选择离子检测（m/z 58(MEGX)、 m/z 86(普鲁卡因,内标)）。结果表明,MEGX在血清中的浓度在1.562～25 ng/mL范围内的线性关系良好,相关系数0.9981,最低检测限为0.5 ng/mL,不同浓度MEGX的萃取回收率在80.1%～85.7%之间。实验证明该方法快速、准确,选择性好,灵敏度高,适合用于血清中微量MEGX的测定。