超高效液相色谱-串联质谱法同时检测口腔卫生用品中的硝基咪唑类药物

建立了采用超高效液相色谱-串联质谱同时检测口腔卫生用品(牙膏及漱口水)中甲硝唑、替硝唑、奥硝唑、二甲硝咪唑和洛硝唑的方法。试样以0.1%(体积分数)的甲酸水溶液/乙腈(95:5, v/v)稀释,经高速离心后过滤膜净化,采用Cloversil C18色谱柱(100 mm×2.1 mm, 3.5 μm)分离,以0.1%甲酸水溶液和乙腈为流动相梯度洗脱,质谱检测,外标法定量。5种硝基咪唑类化合物在1.0～60.0 μg/L质量浓度范围内线性关系良好,相关系数r均不小于0.9992;在10.0、20.0和100 mg/kg加标水平的平均回收率为91.5%～108%,相对标准偏差为1.14%～5.22%;方法的定量限(LOQ,以信噪比为10计)为2.0 mg/kg。该方法可靠、稳定,可满足口腔卫生用品中硝基咪唑类药物含量检测与确证的需要。     

Development and validation of a liquid chromatography with tandem mass spectrometry method for the determination of nitroimidazole residues in beeswax

In this study, a new method for the determination of 12 nitroimidazoles and their hydroxymetabolites (metronidazole, hydroxymetronidazole, dimetridazole, ronidazole, hydroxydimetridazole, ipronidazole, hydroxyipronidazole, carnidazole, ornidazole, secnidazole, ternidazole, tinidazole) in beeswax has been developed and validated. The optimized sample preparation procedure included melting and dilution of beeswax in a mixture of n‐hexane and isopropanol followed by extraction with 2% acetic acid. The extracts were purified on strong cation exchange based solid‐phase extraction cartridges and evaporated in a vacuum system with vortex motion. The separation and detection of the nitroimidazoles in the beeswax extracts were achieved within 12 min by liquid chromatography tandem mass spectrometry using a pentafluorophenyl analytical column and applying a gradient elution with acetonitrile and 0.01% acetic acid as mobile phases. The method performance characteristics were evaluated at three concentration levels (1, 2, and 5 μg/kg) and the method was found to be suitable for determination of all tested nitroimidazoles. The limits of detection and quantification were 0.2–0.5 and 0.5–1 μg/kg, respectively. The recoveries varied from 71.2 to 104.9% while the relative standard deviations were less than 13.8% under the intermediate precision conditions.     

气相色谱-质谱法测定祛痘化妆品中4种硝基咪唑类化合物

建立了同时测定祛痘化妆品中4种硝基咪唑类化合物(甲硝唑、奥硝唑、洛硝唑和塞克硝唑)的气相色谱-质谱联用(GC-MS)分析方法。样品用碳酸钠溶液溶解后以乙酸乙酯提取,经浓缩和(或)正己烷除脂后,用N,O-双(三甲基硅烷基)乙酰胺衍生,样液经DB-5 MS(30 m×0.25 mm×0.25μm)毛细管色谱柱分离,GC-MS的选择离子监测(SIM)模式检测,以保留时间和特征离子比值定性,同位素内标法定量。结果表明,4种硝基咪唑类化合物在0.10~5.0 mg/L范围内线性关系良好,相关系数均不小于0.998;方法检出限(S/N=3)为0.05~0.10 mg/kg;在祛痘水和祛痘膏样品中进行3个水平的加标实验,平均回收率为85.6%~104%,相对标准偏差(RSD,n=6)为2.9%~6.5%。实际样品检测表明本方法准确可靠,适用于祛痘化妆品中硝基咪唑类化合物的同时测定。     

基于QuEChERS提取的高效液相色谱-串联质谱法同时测定4种不同基质类型化妆品中15种硝基咪唑类禁用药物

建立了同时测定4种不同基质类型化妆品中15种硝基咪唑类(NMZs)禁用药物的高效液相色谱-串联质谱法(HPLC-MS/MS)。样品经溶剂超声提取,改良的QuEChERS方法净化后,过0.22μm滤膜上机检测。采用XSelect CSH C_(18)色谱柱(2.1 mm×150 mm,3.5μm)进行分离,以0.1%甲酸乙腈-0.1%甲酸水溶液作为流动相梯度洗脱,流速为0.25 mL/min。采用正离子模式电喷雾电离(ESI~+),多反应监测(MRM)模式检测,基质匹配标准曲线外标法定量。结果表明,15种硝基咪唑类药物在5～500μg/L范围内线性良好,相关系数(r~2)0.99,检出限(LOD)和定量下限(LOQ)分别为0.8～200μg/kg和4～400μg/kg。3个不同浓度加标水平下,平均加标回收率为86.8%～115%,相对标准偏差(RSD)为0.3%～8.4%。该方法前处理简单、分离效果好、回收率高,适用于化妆品中硝基咪唑类禁用药物的测定。     

Formation of Radical Anions by Electrochemical Reduction of Nitroimidazoles in Aprotic Solvents and Mixed Solvent

The EPR spectra of radicals obtained by electrolytical reduction of 2-nitroimidazole and 4-nitroimidazole were measured in mixed solvents. The behavior of the nitrogen coupling constants with the solvent composition is discussed in terms of equilibria between radicals in different solvents. The equilibrium constants of the DMSO/water system were determinated. Molecular orbital calculations in the frame of LCAO-HMO method account correctly for the spin distribution of both compounds investigated.     

高效液相色谱-串联质谱快速测定饲料中硝基咪唑类药物及其代谢物残留

建立了高效液相色谱-串联质谱快速测定饲料中甲硝唑(MNZ)、甲硝唑代谢物(MNZOH)、二甲硝咪唑(DMZ)、二甲硝咪唑代谢物(HMMNI)、洛硝哒唑(RNZ)、异丙硝唑(IPZ)、异丙硝唑代谢物(IPZOH)残留的分析方法。样品经0.1 mol/L pH 8.0磷酸盐缓冲液和乙酸乙酯-丙酮(70∶30)提取,提取液经分散型固相萃取填料N-丙基乙二胺(PSA)净化后,再经正己烷脱脂,液-液分配净化,采用电喷雾电离源(ESI)正离子多反应监测(MRM)模式检测,氘代同位素内标法定量。该方法省去耗时的固相萃取过程,快速、简单、高效,7种目标分析物在2.0~100.0μg/L范围内线性关系良好,相关系数大于0.99,在5.0~25.0μg/kg范围内,3个加标水平的回收率为72.4%~95.6%,相对标准偏差(RSD)均小于12.5%;检出限为2.5μg/kg,定量下限为5.0μg/kg。     

基质分散固相萃取-液相色谱-串联质谱法检测动物源性食品中硝基咪唑药物及其代谢物

建立了基质分散固相萃取-液相色谱-串联质谱(dSPE-LC-MS/MS)定量检测4种动物源性食品基质中硝基咪唑类药物及其代谢物的方法。样品(2.0 g)用乙酸乙酯提取后浓缩,经正己烷脱脂、50 mg乙二胺-N-丙基硅烷(PSA)吸附剂吸附净化后,过0.22μm亲水聚四氟乙烯(PTFE)滤膜。采用C18柱分离,在电喷雾电离(ESI)源和选择反应监测(SRM)模式下检测,基质匹配内标法定量。在0.5~20.0μg/L范围内,硝基咪唑类药物及其代谢物呈现良好的线性关系,相关系数(r~2)0.99;方法的检出限为0.1~0.5μg/kg;在1.0、3.0和10.0μg/kg的加标水平下,硝基咪唑类药物及其代谢物的回收率为84.2%~120.8%,相对标准偏差为2.0%~16.2%(n=6)。该法准确、快速,成本低,易操作,能够满足动物源性食品中硝基咪唑类药物及其代谢物残留的监测要求。     

Crystal structure of 4,5-dinitroimidazole (45DNI)

A single-crystal X-ray diffraction study verified that the target oxidizer molecule, 4,5-dinitroimidazole (45DNI), had been synthesized. Some structural features of 45DNI are discussed and compared with those of 1,4-dinitroimidazole and 2,4 dinitroimidazole. 45DNI crystallizes with two crystallographically unique molecules in the monoclinic space group P2₁/n (#14) with unit-cell parameters a = 11.5360(8) Å, b = 9.071(1) Å, c = 11.822(1) Å, = 107.640(6)°, Z = 8, and has a density of 1.781 g/cm³. The molecular packing consists of infinite one-dimensional chains of 45DNI molecules approximately oriented in the ac direction which are linked by two different hydrogen bonds, and . In the lateral directions the chains are held together by molecular forces.     

Biochar/sodium alginate mixed matrix membrane as adsorbent for in-syringe solid-phase extraction towards trace nitroimidazoles in water samples prior to ultra-high-performance liquid chromatography-tandem mass spectrometry analysis

In the present work, the herb (Poria cocos (Schw.) Wolf) residue, as an environmentally friendly and renewable biomass source, was converted into novel biochar. Biochar/sodium alginate mixed matrix membrane was fabricated. On this basis, a biochar/sodium alginate mixed matrix membrane-based in-syringe solid-phase extraction was developed combined with ultra-high performance liquid chromatography-tandem mass spectrometry to determine nitroimidazoles in water samples. The factors including times of exaction, type, and volume of elution solvent, and sample solution pH were thoroughly optimized. Then the correlation coefficient was 0.9995–0.9997. The limit of detection of four analytes was between 0.006 and 0.014 ng/mL, and the recovery was between 79.02% and 99.1%. Consequently, the established method would provide a new perspective on monitoring nitroimidazoles in water samples.     

Crystal structure of 2,4-dinitroimidazole (24DNI)

A single-crystal X-ray diffraction study verified that the target oxidizer molecule 2,4-dinitroimidazole (24DNI) had been synthesized by thermal rearrangement of 1,4-dinitroimidazole. 24DNI crystallizes in the orthorhombic space group Pbca with unit-cell dimensionsa=10.127(2),b=18.497(2),c=6.333(2) Å, andZ=8 and has a density of 1.770 g/cm³. The molecular packing consists of hydrogen-bonded chains of 24DNI molecules [N(1)–H(1)...N(3)] in thea direction which are held together in the lateral direction by molecular forces. Some structural features of 24DNI·are compared with those of 1,4-dinitroimidazole.