超高效液相色谱-串联四极杆质谱法对N-甲基氧化吗啉及其降解产物的检测

建立了N-甲基氧化吗啉(NMMO) 及其降解产物吗啉、N-甲基吗啉、N-亚硝基吗啉的超高效液相色谱-串联四极杆质谱联用的分析方法.以Waters Acquity BEH C18超高效液相色谱柱为分析柱,乙腈-氨水为梯度洗脱液,4种分析物在3 min内即可达到良好分离;经串联四极杆质谱多反应监测模式检测,4种物质的线性范围为10 ～500 μg/L,检出限为1 ～10 μg/L.考察了酸性、碱性两种流动相体系对样品的分离效果,发现碱性流动相体系的分离效果优于酸性流动相体系,同时发现质谱响应信号随着流动相pH值的增大而减小.在优化条件下,对实际样品以及加标后样品进行测定,结果满意,该方法适合大批量Lyocell纤维纺丝凝固浴等样品的测定以及NMMO的出口检测.     

反相离子对液相色谱法同时测定11种氟喹诺酮类药物的研究

建立了高效液相色谱-荧光法同时测定11种氟喹诺酮类药物的分析方法.主要研究了流动相、流动相配比及流动相的pH对氟喹诺酮分离的影响.确定了液相色谱分析最佳条件.分离条件为:Xbridge Shield RP C18柱,以V(0.10%三氟乙酸)∶V(乙腈)∶V(甲醇)=89∶4∶7为流动相;检测波长为λex=280 nm和λem＝450 nm.方法检出限为:诺氟沙星、环丙沙星、培氟沙星和恩诺沙星0.007μg/mL,单诺沙星0.002 μg/mL,沙拉沙星和氧氟沙星为0.04 μg/mL,二氟沙星和奥比沙星为0.02 μg/mL,依诺沙星、麻保沙星为0.4 μg/mL,各组分回收率在97%～100.2%,相对标准偏差为0.2%～2.9%.     

某些酚类的高温液相色谱行为

建立了高温液相色谱系统,在高温条件下,采用甲醇-水作为流动相,在Polymerx RP-1聚合物(PSDVB)色谱柱上考察了6种酚类样品的色谱行为.实验条件:温度40～160 ℃,流速0.2～5.5 mL/min,流动相中甲醇浓度范围40%～80%.考察了温度、流速和流动相组成对酚类样品的保留、分辨、柱效和系统压力的影响,探讨了酚类样品在聚合物柱上的热力学行为.温度升高2.35℃大约相当于流动相中甲醇浓度增加1%,可以通过改变色谱柱温度调节样品保留和改变选择性.柱温升高,降低了流动相的粘度,允许在高温条件下使用较高的流速实现快速分离.在160℃、V(甲醇):V(水)=40:60,为流动相和3 mL/min流速条件下,可于2.5 min内实现6种酚类的完全分离.     

超高效液相色谱-电喷雾串联质谱法对饲料中匹莫林的测定

建立了超高效液相色谱-串联质谱测定饲料中匹莫林的方法.饲料样品经甲醇-乙腈溶液提取,取部分上清液氮气吹干,用甲醇和水分步溶解后用正己烷除脂,Waters Oasis HLB固相萃取小柱净化,然后用Waters Acquity UPLC BEH C18色谱柱(2.1 mm×50 mm i.d.,1.7 μm)分离,以甲醇和0.1%甲酸-水溶液为流动相进行梯度洗脱,外标法定量.对前处理及液相色谱和质谱条件进行优化.结果表明,匹莫林质量浓度在1 ～500 μg/L范围内线性良好,相关系数大于0.999;在5.0 ～200 μg/kg的添加水平下,匹莫林的平均加标回收率为77% ～86%;相对标准偏差为4.4% ～7.9%;方法的检出限低至2.0 μg/kg,定量下限低至5.0 μg/kg.该方法灵敏度高、稳定性好,可满足饲料中匹莫林残留的检测与确证的要求.     

超高效液相色谱法测定虾青素

建立超高效液相色谱法快速检测虾青素的方法。采用UPLC BEH C_8色谱柱(50 mm×2.1 mm,1.7μm),考察了流动相、流量及柱温对虾青素样品分离的影响,确定了最佳色谱条件:等度洗脱,流动相为甲醇–水(体积比为75∶25),流量为0.5 mL/min,柱温为40℃,检测波长为475 nm。虾青素的质量浓度在0.2~10.0μg/mL范围内与其色谱峰面积呈良好的线性关系,线性相关系数r=0.998 8,检出限(S/N=3)为0.1μg/mL,定量限(S/N=10)为0.2μg/mL。测定结果的相对标准偏差为0.41%(n=6),加标回收率为105.8%~110.3%。该方法快速、简单、可靠、灵敏、重复性好,可用于虾青素有关样品的快速检测。     

超高效液相色谱-串联质谱法测定食品包装材料中全氟辛烷磺酸盐

建立了超高效液相色谱-串联质谱(UPLC- MS/MS)测定食品包装材料中全氟辛烷磺酸盐(PFOS)的方法.采用乙腈作为溶剂,加速溶剂提取法提取食品包装材料中的PFOS.色谱条件:ACQUITY UPLC BEH C₁₈色谱柱（1.7 μm,2.1 mm×50 mm）;柱温:30 ℃;流动相:乙腈/水,梯度洗脱;流速:0.2 mL/min;经UPLC分离后用多级反应监测(MRM)方式测定.用2个子离子的相对丰度定性, 外标法定量.PFOS在0.005～0.500 μg/mL范围内线性良好(R2=0.999),PFOS的回收率为90.0%～101.6%,相对标准偏差RSD为1.5%～3.5%.方法检出限为0.1 μg/m2(S/N≥3).     

液相色谱-串联质谱法同时测定大黄鱼中20种磺胺类药物残留

建立了一种液相色谱-电喷雾串联质谱同时测定大黄鱼中20种磺胺类药物残留的方法.均质样品先后用乙腈、二氯甲烷提取,合并提取液,取部分提取液经氮吹浓缩.残渣用1 mL流动相溶解,饱和正己烷脱脂净化.采用ZORBAX Eclipse XDB-C8色谱柱,以含0.2%乙酸的水溶液和甲醇(7: 3)为流动相,梯度洗脱,在电喷雾-多反应监测离子模式下,进行定量定性分析.方法的定量限为5 μg/kg;以标准加入法计算回收率,在10～40 μg/kg添加范围内,平均回收率为79.6%～109%;相对标准偏差为3.55%～16.5%.     

高效液相色谱法测定腐竹中的三聚氰胺

建立了腐竹中三聚氰胺的高效液相色谱检测方法.样品经0.1 mol/L的盐酸溶液提取,亚铁氰化钾和乙酸锌沉淀蛋白,以0.05 mol/L磷酸二氢钾溶液(pH 3.0)-乙腈为流动相,300-SCX离子交换色谱柱分离,二极管阵列检测器于波长240 nm处进行检测.该方法线性范围为0.1～5 μg/mL,检出限为2.0 mg/kg,测定结果的RSD为1.3%～2.5%(n=6),加标回收率为85.8%～92.1%,方法能够满足检测要求.     

固相萃取/超高效液相色谱－串联质谱法测定香辛调料中的曲托喹酚

采用MCX固相萃取柱净化,以超高效液相色谱－串联质谱（UPLC－MS/MS）法建立了香辛调料中曲托喹酚的测定方法。样品采用0.2%酸性乙醇提取,经MCX柱净化浓缩后,在ACQUITY BEH C18色谱柱上以乙腈和0.1%甲酸水溶液为流动相梯度洗脱,UPLC－MS/MS以MRM方式进行定量分析。结果表明,曲托喹酚在0.1～50 ng/mL范围内线性关系良好,相关系数（r）大于0.998,方法的检出限（LOD）为0.2 μg/kg,定量下限（LOQ）为0.5 μg/kg。化合物在不同基质的4个加标水平（0.5、2、10、100 μg/kg）下的回收率为74.5%～98.8%,相对标准偏差（RSD）为3.1%～9.1%。该方法灵敏、准确、可靠,可用于香辛调料中曲托喹酚的测定。     

反相高效液相色谱法测定生物转化体系中的甘草酸

采用高效液相色谱法在Hypersil C18色谱柱(4.6 mm i.d.×250 mm,5 μm)上以甲醇-水-冰醋酸(70∶30∶1, 体积比)为流动相分离测定了甘草酸单铵盐生物(酶)转化体系中的甘草酸,流动相流速为1.0 mL/min,紫外检测波长254 nm。实验结果表明,该方法在进样量为0.2~20 μg时具有良好的线性;样品的加标回收率为98%～103％,相应的相对标准偏差为0.16％～1.58％。方法简便、快速、可靠。     

Simultaneous quantification of buprenorphine,norbuprenorphine, buprenorphine glucuronide,and norbuprenorphine glucuronide in human placenta by liquid chromatography mass spectrometry

A LCMS method was developed and validated for the determination of buprenorphine (BUP), norbuprenorphine (NBUP), buprenorphine glucuronide (BUP-Gluc), and norbuprenorphine glucuronide (NBUP-Gluc) in placenta. Quantification was achieved by selected ion monitoring of m/z 468.4 (BUP), 414.3 (NBUP), 644.4 (BUP-Gluc), and 590 (NBUP-Gluc). BUP and NBUP were identified monitoring MS² fragments m/z 396, 414 and 426 for BUP, and 340, 364 and 382 for NBUP, and glucuronide conjugates monitoring MS³ fragments m/z 396 and 414 for BUP-Gluc, and 340 and 382 for NBUP-Gluc. Linearity was 1–50 ng/g. Intra-day, inter-day and total assay imprecision (% RSD) were <13.4%, and analytical recoveries were 96.2–113.1%. Extraction efficiencies ranged from 40.7–68%, process efficiencies 38.8–70.5%, and matrix effect 1.3–15.4%. Limits of detection were 0.8 ng/g for all compounds. An authentic placenta from an opioid-dependent pregnant woman receiving BUP pharmacotherapy was analyzed. BUP was not detected but metabolite concentrations were NBUP-Gluc 46.6, NBUP 15.7 and BUP-Gluc 3.2 ng/g.     

Energy-dependent collision-induced dissociation study of buprenorphine and its synthetic precursors

The collision-induced dissociation (CID) of protonated buprenorphine ([M+H](+) ) and four related compounds was studied by electrospray quadrupole/time-of-flight mass spectrometry (ESI-QTOF MS). The fragmentation pathways were investigated by using energy-dependent CID and pseudo-MS(3) (in-source CID combined with tandem mass spectrometry (MS/MS)) methods. The first steps of the fragmentation are the parallel losses of the substituents from the non-aromatic ring moieties. Depending on the applied collision energies, a large number of further fragment ions arising from the cross-ring cleavages of the core-ring structure were observed. Based on the experimental results, a generalized fragmentation scheme was developed for the five buprenorphine derivatives highlighting the differences for the alternatively substituted compounds. The collision-energy-dependent fragmentation profile of buprenorphine is visualized in a two-dimensional plot to aid its fingerprint identification.     

Synthesis of buprenorphine from oripavine via N-demethylation of oripavine quaternary salts

Buprenorphine was synthesized from oripavine by a sequence involving the conversion of oripavine into its cyclopropylmethyl quaternary salt, N-demethylation with thiolate to N-cyclopropylmethyl nororipavine, and conversion of this material to the title compound by previously available methods. The new synthesis avoids toxic reagents used previously, is shorter, and proceeds in comparable yields. Experimental and spectral data are provided for all new compounds.     

Analysis of buprenorphine and its N-dealkylated metabolite in plasma and urine by selected-ion monitoring

A selected-ion monitoring method was developed for determination of buprenorphine and its N-dealkylated metabolite (norbuprenorphine) in human plasma and urine. N-Propylnorbuprenorphine was added as internal standard to 2-3 ml of sample and the alkaloids were extracted with toluene-2 butanol at pH 9.4. After back-extraction in dilute sulphuric acid, the compounds were heated at 110 degrees C. This procedure led to quantitative loss of methanol followed by ring formation between the 6-methoxy group and the branched side-chain of all compounds. The derivatives were extracted into dichloromethane-2-butanol and treated with pentafluoropropionic anhydride. The resulting derivatives were suitable for selected-ion monitoring analysis. The coefficient of variation was found to be 4.5% at 5 ng/ml and 8.9% at 50 ng/ml in urine. The corresponding values for plasma were 6.2% and 5.3%, respectively. The lower limit of detection in plasma was 150 pg/ml, permitting analysis of plasma levels of buprenorphine for 24 h and urine levels of buprenorphine and norbuprenorphine for more than seven days after a therapeutic dose of buprenorphine. This method is the first with sufficient specificity and sensitivity for characterization of the clinical pharmacokinetics of buprenorphine.     

High-performance liquid chromatography with electrochemical detection of buprenorphine and its major metabolite in urine

A procedure was developed for the simultaneous determination of buprenorphine and its major metabolite. N-desalkylbuprenorphine, by reversed-phase high-performance liquid chromatography with electrochemical detection. The detection limit is about 100 pg/ml for the major metabolite and 250 pg/ml for buprenorphine.     

Evaluation of various derivatization approaches for gas chromatography-mass spectrometry analysis of buprenorphine and norbuprenorphine

Various chemical derivatization approaches have been adapted for the analysis of buprenorphine and its major metabolite (norbuprenorphine) by GC-MS based methodologies. These approaches included alkylation, acylation, and silylation resulting in the formation of methyl, acetyl, trifluoroacetyl, pentafluoropropionyl, heptafluorobutyryl, and trimethylsilyl derivatives. This study conducted a comprehensive evaluation on the merits of these approaches based on the following criteria: reaction yields and ionization efficiency of the derivatization products; chromatographic characteristics; and cross-contributions to the intensities of ions designating the analytes and the internal standards. Under acidic derivatization conditions, the analytes could form three artifact products. Overall, derivatization by acetyl anhydride resulted in best performance characteristics.     

Formation of the N-methylpyridinium derivative to improve the detection of buprenorphine by liquid chromatography-mass spectrometry

The legally defensible identification of the narcotic, analgesic buprenorphine, in biological specimen requires considerable sensitivity due to its low therapeutic dosages and corresponding target concentrations. Application of liquid chromatography-electrospray ionisation-mass spectrometry, which became the default method for buprenorphine detection, is impeded by the disadvantageous fragmentation of the stable precursor ion producing unspecific product ions of comparatively low abundance. A chemical modification to form the N-methylpyridinium ether derivative of buprenorphine is presented to improve the selectivity and sensitivity of its detection by liquid chromatography-mass spectrometry (LC-MS). The reaction of buprenorphine with 2-fluoro-1-methyl-pyridinium-p-toluene-sulfonate and triethylamine as catalyst was accomplished in acetonitrile at an ambient temperature yielding a chemically stable derivative. Fragmentation of the permanently charged precursor ion (m/z = 559) leads to the formation of diagnostic and abundant fragments (e.g. m/z = 443 and 450) representing all parts of the molecule. The application of the technique to the identification of buprenorphine in hair samples demonstrates a high specificity, availability of sufficient qualifier ions and a significant (approximately 8-fold) improvement of detection limits with respect to comparable experiments based on underivatised buprenorphine.     

63Ni electron-capture gas chromatographic assay for buprenorphine and metabolites in human urine and feces

A 63Ni electron-capture gas chromatographic assay is described for buprenorphine, a potent narcotic agonist--antagonist. In addition, the assay is useful for the measurement of the metabolite norbuprenorphine and demethoxybuprenorphine, a rearrangement product resulting when buprenorphine is exposed to acid and heat. An extraction procedure was developed which optimized recovery of buprenorphine from biological samples and produced minimal background interferences and emulsion problems. Extract residues were derivatized with pentafluoropropionic anhydride and assayed by gas chromatography. Samples were analyzed with and without enzyme hydrolysis, thus providing a selective and sensitive assay for both free and conjugated buprenorphine, norbuprenorphine and demethoxybuprenorphine. The lower limits of detection following extraction of a 1-ml sample were ca. 10 ng/ml for buprenorphine and demethoxybuprenorphine and 5 ng/ml for norbuprenorphine. Application of the assay to human samples following a 40-mg oral dose of buprenorphine produced no evidence for the presence of demethoxybuprenorphine in urine or feces. Norbuprenorphine (free and conjugated) was present in urinary and fecal samples; buprenorphine (free and conjugated) was found in high amounts only in feces and in trace amounts in urine as conjugated buprenorphine. The urinary and fecal excretion pattern observed for a human subject following oral dosing of buprenorphine suggests enterohepatic circulation of buprenorphine.