Development of a liquid chromatography-electrospray mass spectrometric method for the simultaneous analysis of benzoxazolinones and their degradation products

A new method for the simultaneous analysis of some benzoxazolinones, aminophenoxazinones and malonamic acids was developed based on liquid chromatography (LC) coupled to mass spectrometry (MS), using electrospray ionization (ESI) and operating in positive mode. Different ESI-MS parameters, such as fragmentor voltage, capillary voltage, drying gas flow, nebulizer gas pressure and drying gas temperature, were optimized in order to obtain structural information and to achieve maximum sensitivity. Chromatographic separation was performed by a reversed-phase LC column using a linear gradient of water and methanol. Quality assurance of the developed method was assessed by measuring parameters as linearity, sensitivity, repeatability and reproducibility. Quantification method based on the use of internal standard was developed, selecting synthetic 2-methoxy-2H-1,4-benzoxazin-3(4H)-one as internal standard. Good correlations were obtained for all analytes relative to this compound in the range of 0.05-1.5 ng/microL. Instrumental detection limits were between 0.02 and 0.2 ng/microL. Repeatability and reproducibility studies showed acceptable coefficient of variation values.     

Determination of aromatic amine mutagens,PBTA-1 and PBTA-2, in river water by solid-phase extraction followed by liquid chromatography-tandem mass spectrometry

We describe a novel method for the determination of two kinds of aromatic amine mutagens, 2-[2-(acetylamino)-4-[bis(2-methoxyethyl)-amino]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-1) and 2-[2-(acetylamino)-4-[bis(2-cyanoethyl)-ethylamino]-5-amino-7-bromo-4-chloro-2H-benzotriazole (PBTA-2), in river water based on liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS-MS). A solid-phase extraction procedure was used for the extraction of PBTA-1 and PBTA-2 from river water. The procedure was rapid and the relative standard deviations were below 4%. The detection limits of PBTA-1 and PBTA-2 in river water using the proposed method were found to be 1 and 2 ng/l, respectively. The compounds were detected by this method in river water taken from two sites in the Yodo River system at the ng/l level.     

Utilisation of electrospray time-of-flight mass spectrometry for solving complex fragmentation patterns: application to benzoxazinone derivatives

In this paper we describe the application of electrospray time-of-flight mass spectrometry (ESI-TOFMS) to structural elucidation of the fragment ions formed from a range of natural and synthetic allelochemical derivatives. The extensive mass spectrometric characterisation of ten non-glucosylated benzoxazinone derivatives using this method is described here for the first time. The analytes include six naturally occurring 1,4-benzoxazin-3(4H)-one derivatives, including the hydroxamic acids DIMBOA [2,4-dihydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one] and DIBOA [2,4-dihydroxy-2H-1,4-benzoxazin-3(4H)-one], lactams HBOA [2-hydroxy-2H-1,4-benzoxazin-3(4H)-one] and HMBOA [2-hydroxy-7-methoxy-2H-1,4-benzoxazin-3(4H)-one], benzoxazolinones BOA [benzoxazolin-2(3H)-one] and MBOA [6-methoxy-benzoxazolin-2(3H)-one] and four synthetic variations, 2'H-DIBOA [4-hydroxy-2H-1,4-benzoxazin-3(4H)-one], 2'OMe-DIBOA [2-methoxy-4-hydroxy-2H-1,4-benzoxazin-3(4H)-one], 2'H-HBOA [2H-1,4-benzoxazin-3(4H)-one] and 2'OMe-HBOA [2-methoxy-2H-1,4-benzoxazin-3(4H)-one]. Assignments of the mass spectral fragments were aided by elemental composition calculation results, comparison of structural analogues and background literature, and acquired knowledge regarding feasible structures for the compounds. The influence of substituents on the chemical reactivity of the compounds with respect to the observed MS behaviour over varying nozzle potentials is addressed and, through comparison of the structural analogues, generic fragmentation patterns have also been identified.     

Synthesis and cytotoxic activity of benzo[a]pyrano[3,2-h] and [2,3-i]xanthone analogues of psorospermine, acronycine, and benzo[a]acronycine

Condensation of 2-hydroxy-1-naphthalenecarboxylic acid with phloroglucinol afforded 9,11-dihydroxy-12H-benzo[a]xanthen-12-one (6). Construction of an additional dimethylpyran ring onto this skeleton, by alkylation with 3-chloro-3-methyl-1-butyne followed by Claisen rearrangement, gave access to 6-hydroxy-3,3-dimethyl-3H,7H-benzo[a]pyrano[3,2-h]xanthen-7-one (12) and 5-hydroxy-2,2-dimethyl-2H,6H-benzo[a]pyrano[2,3-i]xanthen-6-one (13), which were methylated into 6-methoxy-3,3-dimethyl-3H,7H-benzo[a]pyrano[3,2-h]xanthen-7-one (14) and 5-methoxy-2,2-dimethyl-2H,6H-benzo[a]pyrano[2,3-i]xanthen-6-one (15), respectively. Osmium tetroxide oxidation of 14 and 15 gave the corresponding (+/-)-cis-diols 16 and 17, which afforded the corresponding esters 18-21 upon acylation. Similarly, condensation of 2-hydroxy-1-naphthalenecarboxylic acid with 3,5-dimethoxyaniline gave 11-amino-9-methoxy-12H-benzo[a]xanthen-12-one (23) which was converted into 11-amino-9-hydroxy-12H-benzo[a]xanthen-12-one (24) upon treatment with hydrogen bromide in acetic acid. Alkylation with 3-chloro-3-methyl-1-butyne followed by Claisen rearrangement afforded 6-amino-3,3-dimethyl-3H,7H-benzo[a]pyrano[3,2-h]xanthen-7-one (25) and 5-amino-2,2-dimethyl-2H,6H-benzo[a]pyrano[2,3-i]xanthen-6-one (26). The new benzopyranoxanthone derivatives only displayed marginal antiproliferative activity when tested against L1210 and KB-3-1 cell lines. The only compounds found significantly active against L1210 cell line, 16 and 20, belong to the benzo[a]pyrano[3,2-h]xanthen-7-one series, which possess a pyran ring fused angularly onto the xanthone basic core.     

Dibenzodiazepines in reactions of 2-acetyl-dimedone with 3,4-diaminobenzophenone

The reactions of 2-acetyldimedone and 2-acetyl-3-methoxy-5,5-dimethylcyclohex-2-en-1-one with 3,4-diaminobenzophenoneproduce2-[1-(2-amino-5-benzoylphenyl)amino]ethylidene-5,5-dimethyl-1,3-cyclohexanedioneand 2-acetyl-3-(2-amino-5-benzoylphenyl)amino-5,5-dimethylcyclohex-2-en-1-one, which are cyclized by the action of hydrochloric acid, yielding the respective hydrochlorides of 8-benzoyl- and 7-benzoyl-3,3,11-trimethyl-2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepin-2-ones. Hydrolytic cleavage of the 8-benzoyl derivative leads to 2-acetyl-3-(2-amino-4-benzoylphenyl)amino-5,5-dimethylcyclohex-2-en-1-one. A similar cleavage to form 2-acetyl-3-(2-aminophenyl)amino-5,5-dimethylcyclohex-2-en-1-one is observed for the known hydrochloride of 3,3,11-trimethyl-2,3,4,5-tetrahydro-1H-dibenzo[b,e][1,4]diazepin-2-one. The structures of the products were confirmed by PMR spectra and x-ray diffraction data.Riga Technical University, Riga LV-1658. Latvian Institute of Organic Chemistry, Riga LV-1006. University of Cincinnati, Ohio, USA. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 3, pp. 379–391, March, 1997.     

Suitability of hollow fibre liquid-phase microextraction for the determination of acidic pharmaceuticals in wastewater by liquid chromatography-electrospray tandem mass spectrometry without matrix effects

The applicability of hollow fibre liquid-phase microextraction (LPME), as an alternative to solid-phase extraction (SPE), for the extraction/enrichment of acidic drugs (e.g. ibuprofen, clofibric acid, bezafibrate, etc.) from water samples prior to the determination by LC-ESI-MS-MS has been evaluated. After LPME method optimisation, it was found that this technique can provide very clean extracts, which do not lead to signal suppression during LC-ESI-MS-MS analysis of the analytes. The limits of quantification (0.5-42 ng/L) are suitable for the analysis of these drugs in wastewater. However repeatability needs to been improved (intra-day R.S.D. = 3.4-32%), which may be expected by automation and the development of commercially available devices and fibres specially prepared for analytical purposes. The method was finally applied to wastewater samples (treated and untreated) and results comparable to SPE were obtained.     

固相萃取-高效液相色谱法同时测定传统禽肉制品中的9种杂环胺类化合物

建立了固相萃取-高效液相色谱同时测定传统禽肉制品中9种杂环胺类化合物(HAAs)(包括2-氨基-3-甲基咪唑并［4,5-f］喹啉、2-氨基-3,4-二甲基咪唑并［4,5-f］喹啉、2-氨基-3,8-二甲基咪唑并［4,5-f］喹喔啉、2-氨基-3,4,8-三甲基咪唑并［4,5-f］喹喔啉、2-氨基-1-甲基-6-苯基-咪唑并［4,5-b］吡啶、3-氨基-1-甲基-5H-吡啶并［4,3-b］吲哚、3-氨基-1,4-二甲基-5H-吡啶并［4,3-b］吲哚、9H-吡啶并［4,3-b］吲哚、1-甲基-9H-吡啶并［4,3-b］吲哚)含量的分析方法。经过条件优化,肉样选用乙酸乙酯进行提取,提取液经丙基磺酸(PRS)和C18固相萃取小柱净化,采用TSK-gel ODS-80TM色谱柱,以乙腈和0.05 mol/L醋酸-醋酸铵缓冲液(pH 3.4)为流动相进行梯度洗脱分离,紫外-荧光检测器串联方式对目标化合物进行检测。通过波长扫描,确定紫外检测波长为263 nm,荧光激发波长/发射波长随时间切换程序为: 0～21 min, 300 nm/440 nm; 21～23.8 min, 315 nm/410 nm; 23.8～35 min, 265 nm/410 nm。在上述条件下,9种HAAs在35 min内实现基线分离。3个加标水平的平均回收率为60.47%～90.55%(n=6),相对标准偏差(RSD)为0.49%～9.74%(n=6),检出限(以信噪比为3计)为0.1～3.6 μg/kg。该方法简便快速、结果准确、灵敏度高,可作为测定传统禽肉制品中多种杂环胺类化合物的有效方法。     

Synthesis of analogues of the 2,3,6,-triazaphenothiazine ring system

Treatment of 2,3-dichloroquinoxalines with 2-amino-6-picoline-3-thiol gave a mixture of 2,3-bis(2-amino-6-picolinyl-3-thio)quinoxalines ( 16 , R = H, CI) and 2,3-bis (N,N-dimethylamino)quinoxalines ( 15 , R = H, CI) separated by fractional crystallization. A similar reaction of 3-amino-6-methoxypyridine-2(1H)-thione ( 9 ) with 4,5-dichloropyridazin-3(2H)-one ( 21 ) gave 4-chloro-5-(3-amino-6-methoxypyridyl-2-thio)pyridazin-3(2H)-one ( 22 ). Concentrated hydrochloric acid-catalysed cyclization of 22 gave the non-rearranged 7-methoxy-2,3,6-triazaphenothiazin-1(2H)-one. The action of compound 22 in refluxing glacial acetic acid gave, on the other hand, 7-methoxy-2,3,6-triazaphenothiazin-4(3H)-one via a Smiles rearrangement. These cyclized compounds are the first known derivatives of the new 2,3,6-triazaphenothiazine ring system.     

Enzymatic reduction of 9-methoxytariacuripyrone by Saccharomyces cerevisiae and its antimycobacterial activity

Biotransformation processes have been successfully utilized to obtain products of pharmaceutical, chemical, food, and agricultural interest, which are difficult to obtain by classic chemical methods. The compound with antituberculous activity, 9-methoxy-tariacuripyrone (1), isolated from Aristolochia brevipes, was submitted to biotransformation with the yeast Saccharomyces cerevisiae under culture, yielding 5-amino-9-methoxy-3,4-dihydro-2H-benzo[h]chromen-2-one (2). The structure of (2) was elucidated on the basis of spectroscopic analyses. The results mainly show the reduction of the double bond and the nitro group of compound (1). Metabolite (2) demonstrated an increase in anti-tuberculous activity (MIC = 3.12 μg/mL) against the drug-sensitive Mycobacterium tuberculosis (H37Rv) strain, with respect to that shown by (1).     

Synthesis of certain pyrazolo[3,4-d]pyrimidin-3-one nucleosides

Synthesis of the pyrazolo[3,4-d]pyrimidin-3-one congeners of guanosine, adenosine and inosine is described. Glycosylation of 3-methoxy-6-methylthio-1H-pyrazolo[3,4-d]pyrimidin-4(5H)-one ( 13 ) with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose ( 16 ) in the presence of boron trifluoride etherate gave 3-methoxy-6-methylthio-1-(2,3,5-tri-O-benzoyl-β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4(5H)-one ( 17 ) which, after successive treatments with 3-chloroperoxybenzoic acid and methanolic ammonia, afforded 6-amino-3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)one ( 18 ). The guanosine analog, 6-amino-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidine-3,4(2H,5H)-dione ( 21 ), was made by sodium iodide-chlorotrimethylsilane treatment of 6-amino-3-methoxy-1-(2,3,5-tri-O-acetyl-β-D-ribofuranosyl)pyrazolo[3,4-d]pyrimidin-4(5H)one ( 19 ), followed by sugar deprotection. Treatment of the adenine analog, 4-amino-1H-pyrazolo[3,4-d]pyrimidin-3(2H)-one ( 11 ), according to the high temperature glycosylation procedure yielded a mixture of N-1 and N-2 ribosyl-attached isomers. Deprotection of the individual isomers afforded 4-amino-3-hydroxy-1-βribofuranosylpyrazolo-[3,4-d]pyrimidine ( 26 ) and 4-amino-2-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-3(7H)-one ( 27 ). The structures of 26 and 27 were established by single crystal X-ray diffraction analysis. The inosine analog, 1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidine-3,4(2H,5H)-dione ( 28 ), was synthesized enzymatically by direct ribosylation of 1H-pyrazolo[3,4-d]pyrimidine-3,4(2H,5H)-dione ( 8 ) with ribose-1-phosphate in the presence of purine nucleoside phosphorylase, and also by deamination of 26 with adenosine deaminase.     

Cytotoxic metabolites of <Emphasis Type="Italic">Streptimonospora salina</Emphasis>

Streptimonospora salina gen. nov., sp. nov. was found to produce three phenoxazinone antibiotics, 2-amino-3H-phenoxazin-3-one (1), 2-methylamino-3H-phenoxazin-3-one (2), 2-acetylamino-3H-phenoxazin-3-one (3), and one phenazine antibiotic, phenazine-1-carboxylic acid (4). The chemical structures of the compounds were determined using 1D and 2D NMR spectrometry and electrospray mass spectrometry (ESMS). Compounds 1-4 exhibited modest cytotoxicity against a human renal carcinoma cell line ACHN with IC₅₀ values of 35.4, 12.4, 65.4, and 82.9 μM, respectively. Compound 2 was discovered for the first time from a biological origin. Published in Khimiya Prirodnykh Soedinenii, No. 4, pp. 405–406, July–August, 2008     

2-氨基-3-氰基-4-芳基-6-甲氧基-1,4,9,10-四氢萘并[2,1-b]吡喃衍生物的一步合成

以芳醛、丙二腈和7-甲氧基-1,2,3,4-四氢萘-2-酮为原料,在六氢吡啶催化下以乙醇为溶剂,在室温合成了一系列新的2-氨基-3-氰基-4-芳基-6-甲氧基-1,4,9,10-四氢萘并[2,1-b]吡喃衍生物,反应条件温和,产率较高,并通过IR,1H NMR和元素分析表征产物的结构,还通过单晶X射线衍射分析确证产物的构象.     

Acetyl ketene aminals in Nenitzescu reaction

Nenitzescu reaction of acetyl ketene aminals (N,N-acetals) was investigated. The interaction of 2-acetyl-1-amino-1-anilinoethene with benzoquinone gave 3-acetyl-2-amino-7a-hydroxy-1-phenyl-5,7a-dihydro-1H-indol-5-one, which was then transformed into 3-acetyl-2-amino-6-chloro-5-hydroxy-1-phenylindole. The reaction of benzoquinone with 2-acetyl-1-amino-1-benzoylaminoethene led to the corresponding hydroquinone-adduct which was oxidized to 4-acetylamino-5-(2,5-dihydroxyphenyl)-2-phenyloxazole. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 160–165, January, 1999.     

Determination of total nitrofuran metabolites in shrimp muscle using liquid chromatography/tandem mass spectrometry in the atmospheric pressure chemical ionization mode

The method of MacMahon and Lohne for analysis of nitrofuran metabolites in shrimp was optimized to streamline the extraction processes and the LC analysis. This revised method includes 16 h of mild acid hydrolysis/derivatization followed by ethyl acetate extraction and analysis by LC/MS/MS in the atmospheric pressure chemical ionization mode. This revised method was validated in shrimp for concentrations of 0.25 to 2.0 ng/g. The LOQ was 0.25 ng/g for all metabolites. The LOD was 0.052 nglg for 1-aminohydantoin (AHD), 0.206 ng/g for 3-amino-2-oxazolidinone (AOZ), 0.108 ng/g for semicarbazide (SC), and 0.062 ng/g for 3-amino-5-morpholinomethyl-2-oxazolidinone (AMOZ). The spike recoveries with RSD into negative matrix at 1 ng/g were 100.2% (3.2%) for AHD, 102.5% (1.0%) for AOZ, 103.7% (2.3%) for SC, and 104.0% (3.3%) for AMOZ. The spike recoveries at 1 ng/g into unknown samples (n=108) containing varied levels of nitrofuran metabolites were 112.6% (25.7%) for AHD, 108.1% (12.1%) for AOZ, 103.0% (12.0%) for SC, and 100.3% (6.9%) for AMOZ. Interday precision with samples containing incurred AOZ concentrations of 0.92 to 17.8 ppb performed over a year was 10.4% RSD. The method is accurate and precise for determining nitrofuran concentrations in the edible tissue of shrimp.     

Synthesis of certain 3-alkoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidines structurally related to adenosine,inosine and guanosine

Several 3-alkoxysubstituted pyrazolo[3,4-d]pyrimidine ribonucleosides structurally related to adenosine, inosine and guanosine have been prepared by the direct glycosylation of preformed aglycon precursor containing a 3-alkoxy substituent. Ring closure of 5(3)-amino-3(5)-ethoxypyrazole-4-carboxamide ( 6b ) with either formamide or potassium ethyl xanthate gave 3-ethoxyallopurinol ( 7b ) and 3-ethoxy-6-thioxopyrazolo[3,4-d]-pyrimidin-4(5H,7H)-one ( 10 ), respectively. Methylation of 10 gave the corresponding 6-methylthio derivative 15 . Similar ring annulation of 5(3)-methoxypyrazole-4-carboxamide ( 6a ) with formamide afforded 3-methoxyallopurinol ( 7a ). Treatment of 5(3)-amino-3(5)-methoxypyrazole-4-carbonitrile ( 5a ) with formamidine acetate furnished 4-amino-3-methoxypyrazolo[3,4-d]pyrimidine ( 4 ). High-temperature glycosylation of 7b with 1-O-acetyl-2,3,5-tri-O-benzoyl-D-ribofuranose in the presence of boron trifluoride etherate gave a 2:1 mixture of N-1 and N-2 glycosyl blocked nucleosides 11b and 13b . Deprotection of 11b and 13b with sodium methoxide gave 3-ethoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one ( 12b ) and the corresponding N-2 glycosyl isomer 14b , respectively. Similar glycosylation of either 4 or 7a , and subsequent debenzoylation gave exclusively 4-amino-3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidine ( 9 ) and 3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4-(5H)-one ( 12a ), respectively. The structural assignment of 12a was made on the basis of single-crystal X-ray analysis. Application of this general glycosylation procedure to 15 gave the corresponding N-1 glycosyl derivative 16 as the sole product, which on debenzoylation afforded 3-ethoxy-6-(methylthio)-1-(3-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one ( 17 ). Oxidation of 16 and subsequent ammonolysis furnished the guanosine analog 6-arnino-3-ethoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]-pyrimidin-4(5H)-one ( 19 ). Similarly, starting from 3-methoxy-4,6-bis(methylthio)pyrazolo[3,4-d]pyrimidine ( 20 ), 6-amino-3-methoxy-1-β-D-ribofuranosylpyrazolo[3,4-d]pyrimidin-4(5H)-one ( 23 ) was prepared.     

10-Aryl-7,7-dimethyl-5,6,7,8,9,10-hexahydro-11H-pyrido[3,2-b][1,4]benzodiazepin-9-ones

In reactions of 3-(2-amino-3-pyridyl)amino-5,5-dimethylcyclohex-2-en-1-one with aromatic aldehydes (2- and 4-hydroxy-, 2-hydroxy-3-methoxy-, 4-dimethylamino-, 4-methoxy-, 2,4- and 3,4-dimethoxy-, 3,4-methylenedioxy-, 4-bromo-, 4-fluoro-, 4-chloro-, 2-nitro- and 3-nitrobenzaldehydes, furfural, and 2-thiophenecarbaldehyde), we have obtained the corresponding 10-aryl-7,7-dimethyl-5,6,7,8,9,10-hexahydro-11H-pyrido[3,2-b][1,4]benzodiazepin-9-ones.     

Ultra-trace-level determination of polar pesticides and their transformation products in surface and estuarine water samples using column liquid chromatography-electrospray tandem mass spectrometry.

A method is developed for the determination of polar pesticides and their transformation products [atrazine, deethylatrazine, deisopropylatrazine, hydroxyatrazine, diuron, 3,4-dichlorophenylmethylurea, 3,4-dichlorophenylurea (DPU), monuron, bentazone, anthranil-isopropylamide, chloridazon, metolachlor] in surface, estuarine and sea water samples at the low ng/l level. Solid-phase extraction is combined off-line with column liquid chromatography-electrospray ionization tandem mass spectrometric detection (LC-ESI-MS-MS). The applicability of two solid-phase materials, i.e., LiChrolut EN cartridges and graphitized carbon black extraction disks, is evaluated. The influence of the organic solvent used in gradient LC, as well as the amount of co-extracted humic material on the ESI process is studied. The eluotropic strength of the organic solvent was found to have a distinct effect on the sensitivity of ESI-MS if coupled with LC gradient separations. Methanol gave much better results than acetonitrile and phenylurea compounds are more susceptible to solvent changes than triazines. Co-extracted humic material causes signal suppression in ESI-MS-MS detection. The degree of suppression depends upon the sample pH and the nature of the samples, i.e., surface or estuarine water. Detection limits in LC-ESI-MS-MS ranged from 0.2 to 2 ng/l, with the exception of DPU (8 ng/l). The applicability of the procedure was demonstrated by analyzing surface and estuarine water.     

固相萃取-高效液相色谱法同时测定羊肉制品中9种杂环胺

建立了同时测定羊肉制品中9种杂环胺的固相萃取-高效液相色谱(SPE-HPLC)分析方法。样品经2 mol/L NaOH超声提取、80 mL二氯甲烷液-液萃取,利用阳离子交换柱(MCX柱)净化和富集后进行HPLC分析。采用反相C18色谱柱,以乙腈和0.01 mol/L磷酸溶液(用三乙胺调整pH 3.6)为流动相对杂环胺进行梯度洗脱,使用二极管阵列检测器(DAD)分别在228 nm(2-氨基-9H-吡啶并［2,3-b］吲哚(AaC)、2-氨基-3-甲基-9H-吡啶并［2,3-b］吲哚(MeAaC))、253 nm(2-氨基-3-甲基咪唑并［4,5-f］喹啉(IQ)、1-甲基-9H-吡啶并［3,4-b］吲哚(Harman)、2-9H-吡啶并［3,4-b］吲哚(Norharman))、263 nm(2-氨基-3,8-二甲基咪唑并［4,5-f］喹喔啉(MeIQx)、2-氨基-3,4,8-三甲基咪唑并［4,5-f］喹喔啉(4,8-DiMeIQx)、3-氨基-1-甲基-5H-吡啶并［4,3-b］吲哚(Trp-p-2))、321 nm(2-氨基-1-甲基-6-苯基咪唑并［4,5-b］吡啶(PhIP))处进行检测。实验结果表明,9种杂环胺分离效果良好,回收率为50.27%～94.77%(n=6),相对标准偏差为0.08%～4.42%;通过全波长扫描,确定检出限(以信噪比(S/N)=3计)为1.6～41.0 μg/L。该方法操作简单,结果准确,重现性好,可用于同时检测羊肉制品中9种杂环胺的含量。     

Fast pressurized liquid extraction with in-cell purification and analysis by liquid chromatography tandem mass spectrometry for the determination of UV filters and their degradation products in sediments

This paper presents the development of a fast and sensitive analytical method for the simultaneous determination of UV filters and degradation products having quite different polarities (log Kow 2.19–6.88) in sediment, by means of pressurized liquid extraction (PLE) with in-cell purification and analysis by ultra-performance liquid chromatography (UPLC) coupled to tandem mass spectrometry (MS/MS). Analytes were simultaneously concentrated and purified by placing aluminium oxide as clean-up sorbent in the extraction cell for a faster sample pre-treatment. Under optimized conditions, quantitative recoveries (only one compound below 80%) and satisfactory precision (RSD, 5–15%) were obtained. Low limits of detection were achieved of 0.5–15 ng/g dry weight (dw). The use of PLE extraction and purification and UPLC technology enabled all the compounds to be separated chromatographically in less than 9 min, and with a total chromatographic analysis time of 18 min. This method significantly decreased the overall time of analysis as compared to those of previously developed. Finally, the optimized methodology was applied to investigate the occurrence of the target UV filters in sediment samples collected along the Ebro river basin (Spain). UV filters were detected in 95% of the sediment samples analysed. Results revealed a widespread presence of octocrylene (OC), reaching concentrations up to 24 × 10² ng/g dw, the highest reported so far. Ethylhexyl dimethyl PABA (OD-PABA) and benzophenone-3 (BP3) were also frequently detected (60–65%), but at lower concentrations (4.4–27 ng/g dw). 4DHB (an estrogenic degradation product of BP3) was present in three samples at concentrations between 12 and 21 ng/g dw. These results constitute the first data on the occurrence of OD-PABA and 4DHB in sediments.     

Porous boronate affinity monolith for on-line extraction coupled to high-performance liquid chromatography for sensitive analysis of heterocyclic aromatic amines in food samples

A novel on-line solid-phase microextraction–high-performance liquid chromatography(SPME–HPLC)system was developed for the determination of heterocyclic aromatic amines(HAAs) in food samples. A poly(vinylphenylboronic acid-co-ethylene glycol dimethacrylate) polymer monolith was prepared for on-line efficient extraction and large-volume injection was used to increase the sensitivity of detection.The polymermonolith, based on a ternary porogen, was prepared by in situ polymerization of vinylphenylboronic acid(VPBA) and ethylene glycol dimethacrylate(EGDMA) in a fused-silica capillary column. It showed good permeability, high extraction capacity, and high selectivity. The column-tocolumn reproducibility was satisfactory, and the enrichment factors for HAAs were 3746–7414.Conditions influencing the on-line extraction efficiency, including p H of sample solutions, flow rate of extraction and desorption, and desorption volume, were investigated. The proposed method had low limit of detection(0.10–0.15 ng/L) and good linearity. Trace HAAs in roast beef and lamb samples were determined, and the amounts of 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,7,8-tetramethyl-3H-imidazo[4,5-f]quinoxaline in these samples were 0.235–2.08 ng/g. The recoveries for the five HAAs ranged from74.3% to 119%, and the relative standard deviation(RSDs) were less than 8.2%. The results showed that the proposed on-line method was highly sensitive for monitoring HAAs in different food samples.