Determination of primary amines by means of fluorescent schiff base derivatives

The formation of Schiff bases from the reaction of primary amines and several aromatic aldehydes has been studied. In many cases the Schiff bases were too unstable or feebly-fluorescent to be of analytical value. 1-Pyrenealdehyde and 2-fluorenealdehyde, however, were found to be suitable fluorigenic reagents for primary aliphatic amines, forming Schiff bases that were very stable and intensely fluorescent in acidic ethanol. The derivatives of 1-pyrenealdehyde could be detected at concentrations less than 1 ng ml^-1 in pure solution. Derivatives of 1-pyrenealdehyde could be readily produced by reactions at the surface of a t.l.c. plate. Combination of this approach with a simple deproteinizing procedure permitted analysis for nanograna quantities of primary amines in blood serum.     

New technique using solid-phase extraction for the analysis of aromatic amines in mainstream cigarette smoke

A new procedure has been developed for the quantitation of aromatic amines in mainstream cigarette smoke. Two solid-phase extraction (SPE) cleanup steps using different retention mechanisms are required to process the samples. The first step uses a cation-exchange cartridge, followed by a second step that uses a cartridge with a hydrophobic retention character. The aromatic amines eluted from the second SPE cartridge are derivatized with heptafluorobutyric anhydride and analyzed with GC-MS selected ion monitoring in the negative chemical ionization mode. This new method has several advantages over other reported techniques, being sensitive, robust, and easily automated. The detection limits ranged from 0.02 ng/cigarette for tolidine to 1.41 ng/cigarette for aniline and the recoveries were from 79 to 109%.     

固相萃取-气相色谱／质谱同时测定卷烟滤嘴中的四种芳香胺

采用固相萃取-气相色谱/质谱(SPE-GC/MS)法同时测定了卷烟抽吸后滤嘴中截留的1-氨基萘、2-氨基萘、3-氨基联苯和4-氨基联苯四种芳香胺.该法采用5%的盐酸超声振荡提取滤嘴中的芳香胺,提取液经液液萃取后进行衍生化和固相萃取,浓缩后进行GC/MS分析.1-氨基萘、2-氨基萘、3-氨基联苯和4-氨基联苯的检出限分别为0.51、0.42、0.18、0.18 ng/mL,相对标准偏差在0.94%～3.02%之间,回收率在92.67%～97.20%之间.该方法用于卷烟滤嘴中四种芳香胺的测定,结果发现不同材料的滤嘴对四种芳香胺有不同的截留作用.     

Integrated sample-pretreatment strategy for separation and enrichment of microplastics and primary aromatic amines in the migration of teabag

In this work, an integrated sample-pretreatment strategy for the separation and enrichment of microplastics and primary aromatic amines from the migration of teabag was developed. The migration solution of teabag was passed through a homemade device. The microplastics were firstly captured by a silver membrane, and then the primary aromatic amines were enriched by a solid-phase extraction column. The microplastics migrated from teabag were detected by attenuated total reflection-Fourier transform infrared spectrometer and Raman spectroscopy. The data showed the character, the number of particles, area ratio, and morphology of microplastics migrated from the teabag. Subsequently, after the enrichment procedure, a sensitive analytical method for primary aromatic amines was established followed by ultra-high performance liquid chromatography-tandem mass spectrometry. The method showed wide linear ranges with R² greater than 0.9915, low limits of detection (2–18 ng/L), and low limits of quantification (8–50 ng/L). The developed method was adopted to analyze microplastics and primary aromatic amines migrated from nylon and polyethylene terephthalate teabag under different temperatures and times. The integrated sample-pretreatment strategy displayed promising potentials in the one-step preparation of the microplastics and hazardous molecules in the sample of environment and food security.     

Gas Chromatographic Analysis of Cyclophosphamide in Plasma and Tissues Using Nitrogen-Phosphorus Detection

Abstract

A gas chromatographic method for the analysis of cyclophosphamide in plasma, blood, and organ tissues is described. This method involves extraction of aliquots of plasma or tissue homo-genate in alkaline condition with ether. The extracted drug is derivatized with heptafluorobutyric anhydride followed by gas chromatographic separation via a glass column of 183 cm × 2 mm i. d. packed with 3% SE-30 on chromosorb W-HP. The derivatized cyclophosphamide and isophosphamide, an added internal standard, are detected by a nitrogen-phosphorus detector. The sensitivity limit of this method is 10 ng per gm or ml of sample and gives linearity over 100-fold of concentration range.     

气相色谱-质谱法测定大气颗粒物中的有机胺类物质

建立了大气颗粒物中有机胺类物质的气相色谱-质谱(GC-MS)分析方法.样品用超纯水超声萃取,然后在碱性条件下,用苯磺酰氯(Benzenesulfonyl chloride,BSC)衍生化,衍生物用二氯甲烷萃取,最后用DB-5MS色谱柱分离测定,实现了13种有机胺(包括7种脂肪胺、2种杂环胺和4种芳香胺)的同时测定.本方法的仪器检出限(S/N=3)和定量限(S/N=10)分别为0.00008～0.017 μg/mL和0.00026～0.0565 μg/mL; 标准曲线线性相关系数为0.9903～0.9996,相关性良好;相对标准偏差(RSD)均小于30％, 除低浓度加标水平的甲胺和苯甲胺,其余样品基质加标平均回收率为54.4％～159.7％,大部分胺具有较高的精密度与准确度.将本方法应用于广州城区PM2.5样品的检测, 共检出有机胺9种,其中甲胺、二甲胺和二丁胺约占9种有机胺总和的90％,是PM2.5中主要胺类物质,而丙胺浓度最低,浓度小于1.0 ng/m3.     

Effect of ionic liquid on the determination of aromatic amines as contaminants in hair dyes by liquid chromatography coupled to electrochemical detection

The room temperature ionic liquid (IL) 1-butyl-3-methylimidazolium bis-(trifluorometanesulfonyl)imide BMIm[NTf?] was used as a novel medium for improvement of separation and quantization of 16 aromatic amines typically present as contaminants in consumer products and detected by HPLC coupled to an electrochemical detector. The aromatic amines, namely 4,4'-diaminodiphenylmethane, 4-chloroaniline, 2-methoxy-5-methyl-aniline, 3,3'-dimethylbenzidine, 2,4-diaminotoluidine, 2-chloro-4-nitroaniline, 4,4'-oxydianiline, aniline, 3,3'-ichlorobenzidine, benzidine, 4-aminobiphenyl, o-dianisidine, o-anisidine, o-toluidine, 4,4'-methylene-bis-2-chloroaniline and 2-naphthylamine are oxidized in methanol/BMIm[NTf?] at a potential around +0.68V to +0.93V vs. Ag/AgCl at a glassy carbon electrode, which is the base for their determination by HPLC/ED. Using the optimized conditions of methanol/BMIm[NTf?] 70:30 (v/v) as mobile phase, flow-rate of 0.8 mL·min?1, column CLC-ODS, Eap = +1.0 V and T = 40 °C analytical curves were constructed for each of the tested amines. Good linearity was obtained in the concentration range of 1.09 mg·L?1 to 217 mg·L?1, with excellent correlation coefficients. The limits of detection reached 0.021 mg·L?1 to 0.246 mg·L?1 and good relative standard deviations (RSD, n = 3) were obtained from the measurements. Satisfactory recovery for each aromatic amine was achieved, ranging from 95 to 103%. The developed method was successfully applied to determine six aromatic amines present as contaminants in commercial hair dye samples.     

Determination of environmentally relevant aromatic amines in the ppt levels by cation selective exhaustive injection-sweeping-micellar electrokinetic chromatography

Environmentally important aromatic amines are determined by micellar electrokinetic chromatography (MEKC) with UV detection. Using a combination of field-enhanced sample injection in the capillary zone electrophoresis format (performed for a longer period than usual, e.g., 200 s at high voltages; cation selective exhaustive injection) and sweeping in the MEKC format, from 10(4)- to 10(5)-fold improvements in detector response are achieved for all positively chargeable test analytes. Preliminary results indicate that limits of detection for the positively chargeable aromatic amines are in the parts per trillion (ppt) levels.     

Derivatization of aromatic amines with bromine for improved gas chromatographic determination

Summary For improved determination of aromatic amines by gas chromatography and detection with an electron capture detector (GC-ECD) a derivatization method based on the bromination of the aromatic ring in an acetic acid medium was developed. In general, all free ortho and para-positions relative to the amino group undergo electrophilic substitution. Separation of at least 30 compounds in a single chromatographic run in 30 min is possible. With this method, 56 aromatic amines were studied and only in 6 cases were no derivatives obtained. Quantitation limits determined from calibration data are 1.2–40 μg L⁻¹ for a 100 mL sample and an injection volume of 1 μL. Previous experiments suggest that both sample and injection volume may be increased to lower the quantitation limit.     

Evaluation of stationary phases and gas chromatographic detectors for determination of amines in water

For the first time, a systematic overview deals with the advantages and disadvantages of several stationary phases (polar and non‐polar) and gas chromatographic detectors (flame ionization detector, nitrogen–phosphorus detector and MS) for the determination of 27 amines (aliphatic and aromatic amines and N‐nitrosamines) in water samples. To increase sensitivity (250 mL of sample was eluted with 150 μL of solvent) and matrix elimination, an automatic SPE system was employed prior to GC determination. The best results in terms of resolution and retention times were achieved using a column coated with 5% phenyl‐dimethylpolysiloxane (DB‐5). Capacity factor (k) values for the 27 amines increased with the rise in the polarity of the stationary phase, ranging from 3.0–27.7 and 2.2–14.4 for polar (polyethylene glycol) and non‐polar (DB‐5) columns, respectively. The detection limits of the method were 0.9–9 μg/L for flame ionization detector, 8–95 ng/L for nitrogen–phosphorus detector and 0.2–6.3 ng/L for MS. The precision was similar for the three detectors (RSD, 3.7–6.0%). The GC‐MS method was applied with a high degree of accuracy and precision to determine amines in real samples including tap, river, pond, well, swimming pool and wastewaters.     

灰化法-气相色谱法测定45种食品中的碘含量

以日常食品为研究对象,建立了气相色谱测定不同食品中碘含量的检测方法。样品经碳酸钾-硫酸锌灰化处理后,采用酸水溶解,以丁酮衍生后进行气相色谱分析。经DB-1701色谱柱(30 m×0.32 mm×0.25μm)分离,电子捕获检测器(ECD)测定,以保留时间定性,峰面积外标法进行定量。考察了不同灰化条件对结果的影响,并对方法的灵敏度、准确度和精密度进行验证。碘的检出限为1.0 ng·g-1,平均加标回收率为99.5%,相对标准偏差(RSD)为3.6%。该方法灵敏、准确、可靠,且分析时间短、抗干扰性好,可用于日常食品中碘安全的监测。     

Quantification of phenylurea herbicides and their free and humic acid-associated metabolites in natural waters.

There is increasing interest in and demand for simultaneously monitoring pesticides as well as related degradation products (DPs) in natural waters, as the latter compounds can be even more toxic than the former ones. A method for determining parts per trillion levels of phenylurea herbicides and their DPs, that is their dealkylated forms and aromatic amines, is described. This method is based on solid-phase extraction with a Carbograph 4 cartridge followed by liquid chromatography (LC) with electrospray (ES) mass spectrometric detection. A study aimed at optimizing the response of the ES-MS detector for very weakly basic chloroanilines was conducted. Results showed that ion signal intensities of the above species were dependent on the composition of the LC mobile phase to an astonishing degree. At concentration levels of a few hundred ng/l, laboratory experiments showed that the aromatic amines considered here were mostly associated to dissolved humic acids (HAs) by both reversible and irreversible bindings. The addition of a reducing agent, i.e., NaBH4, succeeded in liberating that fraction of aromatic amines, which being reversibly bound to quinoidal structures of HAs are bioavailable. Analyte recoveries were better than 85% on extraction from 4 l of drinking water (spike level, 25 ng/l), 2 l of ground water (spike level, 50 ng/l) and 0.5 l of river water (spike level, 200 ng/l). Relative standard deviations ranged between 4.6 and 20% for drinking water, 4.3 and 15% for ground water, 5.9 and 13% for river water. Method detection limits calculated for drinking water, groundwater and surface water were between 3 and 11, 6 and 21, 36 and 75 ng/l, respectively.     

Capillary GC Determination of Amines in Aqueous Samples Using Sorptive Preconcentration on Polydimethylsiloxane and Polyacrylate Phases

The use of sorptive extraction/thermal desorption (SE/TD) for the enrichment of amines from aqueous samples was investigated. The amines were derivatized in situ in the water sample by pentafluorobenzoyl chloride and subsequently enriched onto the SE cartridge. Two SE/TD cartridges were used, a commercially available polydimethylsiloxane (PDMS) packed cartridge and a similar cartridge prepared with newly synthesized poly(butyl acrylate) (PBA). Blank profiles of PBA were not as good as those obtained from the PDMS phase. A complex chromatogram was obtained using mass spectrometric detection. Fortunately, the use of a nitrogen-phosphorus detector (NPD) resulted in clean blanks. The PBA phase showed superior performance for the enrichment of the polar amine derivatives from water samples compared to the PDMS material. Using a CGC-NPD set-up and only 1 mL samples, detection limits are in the sub-ppb range.     

高效液相色谱-荧光检测法测定牛奶中氯霉素的残留量

建立了对牛奶中氯霉素的残留量进行检测的高效液相色谱-荧光检测方法。氯霉素还原后在温和条件下与荧光胺发生衍生化反应,采用十八烷基键合硅胶固定相,以乙腈/四氢呋喃/0.02 mol/L醋酸钠-醋酸缓冲液(pH 6.0)(体积比为16∶8∶76)为流动相,流速1.0 mL/min,柱温40 ℃,荧光检测激发波长为410 nm,发射波长为508 nm。在上述实验条件下,氯霉素检测的线性范围为0.4~800 μg/L (r2=0.9999),检出限为0.2　μg/L。当空白样品中氯霉素添加水平为2~40 μg/L时,该方法的回收率为66.6%~92.8%,相对标准偏差为4.5%~9.4%。该方法适用于牛奶中氯霉素痕量残留的监测,具有干扰小、选择性好、灵敏度高等优点。     

Experimental Design Optimization of Solid‐Phase Microextraction Conditions for the Determination of Heterocyclic Aromatic Amines by High‐Performance Liquid Chromatography

Abstract

Solid‐phase microextraction, using Carbowax‐Templated Resin fiber, coupled with high performance liquid chromatography ultra violet/diode array detector (HPLC‐UV/DAD) has been optimized for the determination of the heterocyclic aromatic amines (HAs). Three variables (absorption time, soaking time, and desorption time) were considered as factors in the optimization process. Interactions between analytical factors and their optimal levels were investigated using two level factorial and Doehlert matrix designs. Absorption time and soaking time were significant variables, and 15 min for each one of the variables was chosen for the best response. The optimized procedure allowed the determination of HAs with detection limits that ranged from 1.58 to 16.8 ng/L (except PhIP: 23.8 ng/L). The reproducibility of the method (n=5), expressed as relative standard deviation was between 2.21% and 28.3%. The method was applied to the analysis of a meat extract sample and the range of recoveries for the amines was 64.14%–112.72%.     

Derivatizat Ion of Primary Aromatic Amines with Fluorescamine

Abstract

Fluorescamine forms stable, fluorescent derivatives with sterically-unhindered primary aromatic amines in both aqueous (borate buffer, pH 9/acetonitrile) and nonaqueous (pyridine/-acetonitrile) media. Aromatic amines with a substituent such as a methyl group or an aromatic ring ortho to the amine functionality either derivatized poorly or not at all because of steric hindrance.     

Enantiomeric separation of alcohols and amines on a proline chiral stationary phase by gas chromatography

A new chiral stationary phase for gas chromatography was prepared by covalently attaching a diproline chiral selector that has proven to be effective in liquid chromatography to a methylhydrosiloxane-dimethylsiloxane copolymer. With this new chiral stationary phase for GC, racemic aromatic alcohols could be resolved without derivatization. Racemic aromatic and aliphatic amines could also be resolved after derivatization of the amino groups with trifluoroacetic anhydride or isopropyl isocyanate. On this stationary phase, the isopropyl isocyanate derivatives of amines showed higher enantioselectivity than the trifluoroacetic anhydride derivatives. In both the enantiomeric separations of alcohols and derivatized amines, the aromatic racemic analytes showed higher enantioselectivities than their aliphatic analogs. Some of the alpha-amino and alpha-hydroxy aromatic acids could also be separated after derivatization to N-trifluoroacetyl methyl esters for amino acids or O-trifluoroacetyl methyl esters for hydroxyl acids.     

Determination of apramycin in animal feeds by solid-phase extraction and liquid chromatography with precolumn derivatization and fluorescence detection

A high-performance liquid chromatographic method for determining apramycin in animal feeds was developed. Apramycin in feeds was extracted with 0.1 M HCl solution and cleaned up with an MCX solid-phase extraction column. The purified extract was derivatized with o-phthaldehyde, and components were separated on a C18 column and detected with a fluorescence detector. Mass spectrometric data confirmed that apramycin was derivatized at all the 4 primary amines on the apramycin molecule. Average recoveries at 8 included levels (5, 10, 20, 40, 80, 200, 400, and 2000 mg/kg) ranged from 92.2 to 100.5%, and the coefficients of variation were < 6.5%. Standard curves were linear over the range 0.05 to 10 microg/mL. The detection and quantitation limits were determined to be 0.2 and 1.0 mg/kg, respectively.     

Monitoring of aromatic amines by HPLC with electrochemical detection: comparison of methods for destruction of carcinogenic aromatic amines in laboratory wastes

A new chemical method for destruction of carcinogenic aromatic amines in laboratory wastes has been developed. The method is based on enzymatic oxidation of the amines in solution (with hydrogen peroxide and horseradish peroxidase), followed by oxidation of the solid residues with permanganate in sulphuric acid medium. To monitor the efficiency of destruction, a reversed-phase HPLC system has been developed, with voltammetric detection with a carbon-fibre detector, which is substantially more sensitive (detection limits from a few ng down to a few pg of amine) than the commonly used ultraviolet photometric detection. It has been demonstrated that the proposed method of destruction is highly efficient (99.8% destruction).     

Synthesis and ionization constants of 2-aryliminotetrahydrofurans

The tetrafluoroborates of 2-aryliminotetrahydrofurans were synthesized by the reaction of 0-ethylbutyrolactonium tetrafluoroborate with aromatic amines, and a number of bases of imido esters with various substituents in the aromatic ring were synthesized by the reaction of aromatic amines with 2,2-diethoxytetrahydrofuran. The ionization constants of the products were measured. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 737–740, June, 1980.