Development of derivatization reagents bearing chiral 4-imidazolidinone for distinguishing primary amines from other amino acids and application to the liquid chromatography-tandem mass spectrometric analysis of miso.

We designed and synthesized three novel derivatization reagents bearing chiral 4-imidazolidinone, namely succinimidyl 2-(3-((benzyloxy)carbonyl)-1-methyl, ethyl, and -phenyl-5-oxoimidazolidin-4-yl)acetates (CIMs), for use in liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. The CIMs were able to discriminate primary amines from other compounds such as secondary amines and phenols, based on their unique m/z reduction of precursor ion to form product ion in MS/MS. As amino acid derivatization reagents, the CIMs were compared in terms of enantioseparation of amino acid and detection sensitivity. CIMa-OSu with 1-methyl-5-oxoimidazolidinone moiety gave the best optical resolution and detection sensitivity among the CIM reagents. Next, we applied (R)-CIMa-OSu to determine amino acids in miso by LC-triple-quadrupole MS. The proposed method achieved simultaneous determination of 20 l-amino acids and two d-amino acids (d-alanine and d-serine) in the sample with a high sensitivity (limits of detection 5-238 fmol, signal-to-noise ratio 3.3). After derivatization with CIMa-OSu, it was possible to determine whether each peak in the chromatogram was a component of primary amine or not, by using a high-resolution orbitrap MS instrument.

Oxygenated carbon nanotubes cages coated solid-phase microextraction fiber for selective extraction of migrated aromatic amines from food contact materials.

In this study, an oxygenated carbon nanotubes cages (OCNTCs) material was prepared by calcinating zeolitic imidazole framework-67 (ZIF-67) and then oxidizing the resulting material. The OCNTCs was used as a high efficient solid-phase microextraction (SPME) coating to extract aromatic amines (AAs). The obtained fiber exhibited high selectivity for AAs over other organic compounds in food contact materials (FCMs) due to matched pore size and abundant oxygen-containing groups. Subsequently, coupled with gas chromatography-tandem mass spectrometry (GC-MS/MS), a sensitive method with low limits of detection (0.1-2.0 ng L-1), wide linear ranges (0.5-500 ng L -1) and good precision (RSDs ≤ 8.6%) was developed for analysis of AAs. The specific migrated AAs from food simulants that prepared by standardized migration and thermal migration test were successfully analysed by this developed method with satisfactory recoveries (81.6% - 118.1%) and precision (RSDs, 2.1-9.5%). The results demonstrated that the prepared OCNTCs-coated fibers displayed excellent extraction performance, suggesting a promising application to investigate the migration behaviors of AAs.

Dual 2-Hydroxypropyl-ß-Cyclodextrin and 5,10,15,20-Tetrakis (4-Hydroxyphenyl) Porphyrin System as a Novel Chiral-Achiral Selector Complex for Enantioseparation of Aminoalkanol Derivatives with Anticancer Activity in Capillary Electrophoresis.

In this study, a complex consisting of 2-hydroxypropyl-ß-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin, (named dual chiral-achiral selector complex) was used for the determination of two novel potential anticancer agents of (I) and (II) aminoalkanol derivatives. This work aimed at developing an effective method that can be utilized for the determination of I (S), I (R), and II (S) and II (R) enantiomers of (I) and (II) compounds through the use of a dual chiral-achiral selector complex consisting of hydroxypropyl-ß-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin system by applying capillary electrophoresis. This combination proved to be beneficial in achieving high separation selectivity due to the combined effects of different modes of chiral discrimination. The enantiomers of (I) and (II) compounds were separated within a very short time of 3.6-7.2 min, in pH 2.5 phosphate buffer containing 2-hydroxypropyl-ß-cyclodextrin and 5,10,15,20-tetrakis (4-hydroxyphenyl) porphyrin system at a concentration of 5 and 10 mM, respectively, at 25 °C and +10 kV. The detection wavelength of the detector was set at 200 nm. The LOD for I (S), I (R), II (S), and II (R) was 65.2, 65.6, 65.1, and 65.7 ng/mL, respectively. LOQ for I (S), I (R), II (S), and II (R) was 216.5, 217.8, 217.1, and 218.1 ng/mL, respectively. Recovery was 94.9-99.9%. The repeatability and reproducibility of the method based on the values of the migration time, and the area under the peak was 0.3-2.9% RSD. The stability of the method was determined at 0.1-4.9% RSD. The developed method was used in the pilot studies for determining the enantiomers I (S), I (R), II (S), and II (R) in the blood serum.

Response Surface Methodology of Quantitative of Heterocyclic Aromatic Amines in Fried Fish Using Efficient Microextraction Method Coupled with High-Performance Liquid Chromatography: Central Composite Design.

Meat and meat products are indispensable part of our diet. Heat processing of these tasty foods such as fried fish causes to form heterocyclic aromatic amines (HAAs). The sources of heating have directly affected on the level and type of HAAs. In this research, 2-amino-1-methyl-6-phenylimidazo [4'5-b] pyridine (PhIP), 2-amino-3-methylimidazo [4,5-f]quinolone (IQ), 2-amino-3,4-dimethylimidazo [4,5-f] quinoline (MeIQ) and 2-amino-3,4-dimethylimidazo [4,5-f] quinoxaline (MeIQx) were determined using an efficient analytical methodology coupled with high-performance liquid chromatography. The effective parameters were optimized by central composite design. The results of this survey demonstrated that rang of relative standard deviation were between 4.5 and 8.2, extraction recoveries were obtained 86-97% and limits of detection were between 0.40 and 0.63 for 4 HAAs. The amounts of HAAs found in 20 different fried fish samples were between 0 and 4.8 ng g-1. PhIP with 1.57 ng g-1 and MeIQ with 2.08 ng g-1 have the lowest and highest average level of HAAs, respectively.

A novel magnetic solid-phase extraction method for detection of 14 heterocyclic aromatic amines by UPLC-MS/MS in meat products.

The current study developed a cheap and effective method for the simultaneous extraction of 14 heterocyclic aromatic amines (HAAs) in food matrix. Core-shell Fe3O4@PDA nanoparticles were constructed and acted as the magnetic solid-phase extraction adsorbent to separate and purify HAAs from meat products for the first time. Then, UPLC-MS/MS technique was employed to identify and quantify the HAAs easily. Fe3O4@PDA nanoparticles were synthesized and characterized successfully. Totally 14 HAAs were completely separated in 19.99 min with good regression coefficients. LODs and LOQs were in the range of 0.013-0.247 ng/g and 0.056-0.803 ng/g, respectively. The intra-day precisions and inter-day precisions were below 9%. Except for IQ[4,5-b], Phe-p-1, PhIP, other 11 types of HAAs (DMIP, 1,5,6-TMIP, IQ, IQx, MeIQ, MeIQx, 7,8-DiMeIQx, AαC, MeAαC, Harman, Norharman) could acquire relatively high recoveries (71.06%-108.49%). The proposed method was successfully devoted to the evaluation of HAAs levels in 8 commercial meat products to verify the adaptability.

Comparison of Stir Bar Sorptive Extraction and Solid Phase Microextraction of Volatile and Semi-Volatile Metabolite Profile of Staphylococcus Aureus.

For the analysis of volatile bacterial compounds, solid phase microextraction (SPME) is currently the most widely used metabolite concentration technique. Recently, the potential of stir bar sorptive extraction (SBSE) for this use has been demonstrated. These two approaches were therefore used in combination with gas-chromatography coupled with mass-spectrometry (GC-MS) for the analysis of volatile and semi-volatile bacterial compounds produced by Staphylococcus aureus. In both cases, SPME and SBSE/headspace sorptive extraction (HSSE) enrichment was carried out in two coating phases. A whole analytical and statistical process was developed to differentiate the metabolites produced from the metabolites consumed. The results obtained with SBSE/HSSE and SPME were compared and showed the recovery of 90% of the compounds by SBSE/HSSE. In addition, we were able to detect the production of 12 volatile/semi-volatile compounds by S. aureus, six of which had never been reported before. The extraction by SBSE/HSSE showed higher concentration capacities and greater sensitivity than SPME concerning bacterial compounds, suggesting that this technique may therefore become the new preferred option for bacterial volatile and semi-volatile compound analysis.

Cinnamil- and Quinoxaline-Derivative Indicator Dyes for Detecting Volatile Amines in Fish Spoilage.

Colorimetric indicators are versatile for applications such as intelligent packaging. By interacting with food, package headspace, and/or the ambient environment, color change in these indicators can be useful for reflecting the actual quality and/or monitoring distribution history (e.g., time and temperature) of food products. In this study, indicator dyes based on cinnamil and quinoxaline derivatives were synthesized using aroma compounds commonly present in food: diacetyl, benzaldehyde, p-tolualdehyde and p-anisaldehyde. The identities of cinnamil and quinoxaline derivatives were confirmed by Fourier transform infrared (FT-IR) spectroscopy, mass spectrometry (MS), 1H nuclear magnetic resonance (NMR) and 13C NMR analyses. Photophysical evaluation showed that the orange-colored cinnamil derivatives in dimethylsulfoxide (DMSO) turned to dark brownish coloration when exposed to strong alkalis. The cinnamil and acid-doped quinoxaline derivatives were sensitive to volatile amines commonly present during the spoilage in seafood. Quinoxaline derivatives doped by strong organic acid were effective as pH indicators for volatile amine detection, with lower detection limits than cinnamil. However, cinnamil exhibited more diverse color profiles than the quinoxaline indicators when exposed to ammonia, trimethylamine, triethylamine, dimethylamine, piperidine and hydrazine. Preliminary tests of acid-doped quinoxaline derivatives on fresh fish demonstrated their potential as freshness indicators in intelligent packaging applications.

Emergence of mutagenic/carcinogenic heterocyclic amines in traditional Saudi chicken dishes prepared from local restaurants.

In the current investigation, five most potential HAs (MeIQx, 4,8-DiMeIQx, IQ, MeIQ and PhIP) were analyzed in traditional Saudi chicken dishes (shawaya, Ala Al-Faham, kebab, saleeg, mandi, kabsa and madhbi) prepared from local restaurants. The aims of the present study were to identify the presence of HAs in cooked chicken dishes, and to conclude how the levels and types of HAs could be affected by cooking methods and food ingredients. In control samples, HAs were found at higher levels ranged from not quantified to 33.72 ng/g. Nonetheless, in chicken dishes, the HAs (MeIQx, 4,8-DiMeIQx and PhIP) amounts are varied at higher range and relatively detected at lower levels from not quantified to 16.35 ng/g, IQ and MeIQ were not identified in any of the studied chicken dishes except shawaya where found to be not quantified. The HAs reduction rates were obtained at higher values in all of the studied samples, among them mandi sample demonstrates the reduction rates higher than 70%, whereas saleeg sample shows the reduction rates almost 100% except PhIP (~95%). The obtained outcomes have markedly showed that HAs occurrence in thermally processed chicken dishes is extremely affected from both cooking methods and addition of food ingredients.

Determination of Heterocyclic Amines in Meat Matrices Using Enhanced Matrix Removal-Lipid Extraction and Liquid Chromatography-Tandem Mass Spectrometry.

A simple, fast, and efficient method, "enhanced matrix removal of lipids" (EMR-lipid), was proposed, optimized, and validated for identifying five polar heterocyclic amines (HCAs) in meat samples that ranged from high-protein (beef and chicken) to high-fat (pork bacon) matrices. The protocol involves an initial solid-liquid phase extraction followed by a rapid dispersive solid-phase extraction using EMR-lipid sorbents and salting-out partitioning. Acetonitrile containing formic acid at two levels (1% and 2%) efficiently extracted HCAs from different meat matrices. Liquid chromatography-tandem mass spectrometry (MS/MS) with selective reaction monitoring mode was developed for qualitative and quantitative analysis. The highest MS/MS responses and better peak separation of analytes were achieved by adjusting mobile phases to pH 3.0 with instrumental detection limits between 0.01 and 0.05 ng/mL. Good linearity of standard curves was obtained in both pure solvents and postspiked meat extracts between 0.5 and 50.0 ng/mL. The validation results showed good precision, accuracy, and sensitivity for detecting HCAs in spiked meat samples. Satisfactory recoveries of four HCAs were achieved: 65% to 111% in beef, 71% to 106% in bacon, and 42% to 77% in chicken. Matrix effects were also assessed and showed less than -20% of ion suppression in bacon extract, while a medium to high signal suppression was observed in beef (-37% to -55%) and chicken (-28% to -52%). This optimized EMR-lipid method provides acceptable results and advantages for determining trace level HCAs in complex meat matrices.

Fast super/subcritical fluid chromatographic enantioseparations on superficially porous particles bonded with broad selectivity chiral selectors relative to fully porous particles.

Superficially porous particles (SPPs) have shown advantages in enantiomeric separations in HPLC by conserving selectivity while providing higher efficiency separations with significantly reduced analysis times. The question arises as to whether the same advantages can be found to the same extent in super/subcritical fluid chromatography. In this work, the low viscosity advantage of carbon dioxide/MeOH mixtures is coupled with high-efficiency 2.7 µm superficially porous particles for enantiomeric separations. Given the fact that the viscosity of the mobile phase is typically ten times lower than liquid mobile phases it is possible to use flow rates as high as 14 mL/min on 5 cm packed columns. Superficially porous particles (SPPs) were grafted with teicoplanin (TeicoShell), a chemically modified macrocyclic glycopeptide (NicoShell), vancomycin (VancoShell), and isopropyl derivatized cyclofructan-6 (LarihcShell-P). One hundred chiral analytes were separated in a very short time frame, as little as 0.2 min (13 s). Even shorter separations can be obtained with advances in SFC instrumentation. The LarihcShell-P is the only chiral crown ether-based selector which showed high selectivity for primary amines. The Teicoshell column offered unique separations for acidic and neutral analytes. The NicoShell and the VancoShell were useful in separating amine (secondary and tertiary) containing pharmaceutical drugs and controlled substances. By chemically modifying a macrocyclic glycopeptide (NicoShell) we report the first enantiomeric separation of nicotine under SFC conditions within 3 min with a resolution of >3. Additionally, van Deemter plots are constructed comparing the fully porous particles and superficially porous particles bonded with the same chiral selectors. In toto the SPP advantages also were found for SFC. However instrumental shortcomings involving extra column effects and pressure limitations need to be addressed by instrument manufacturers to realize the full advantages of SPPs and other smaller particle supports.

Detoxification of Heterocyclic Aromatic Amines by Probiotic to Inhibit Medical Hazards.

Cancer is the second leading factor of human death in the world. Long-term consumption of cooked red meat brings about various types of cancers like colorectal cancer due to the formation of Heterocyclic Aromatic Amines (HAAs) during the heating process of meat. There are various solutions for the reduction of these toxicants. The aim of this article is to describe probiotic as one of the possible strategies for bioremoval of these carcinogenic and mutagenic substances and change food to functional one as well. The mechanism of biodetoxification is binding by probiotics, which depends on some variables including the probiotic characteristics, kind and content of the mutagens, as well as some properties of media. In this article, after introducing detoxification ability of probiotics and listing of all reported probiotics in this field, the influencing variables are surveyed and finally, opportunities and problems of HAA bioremoval by probiotics are described.

Heterocyclic aromatic amines in cooked food: A review on formation, health risk-toxicology and their analytical techniques.

Heterocyclic aromatic amines (HAAs) are defined as a major class of poisonous compounds formed from proteinaceous foods during heat processing and flavour-forming. These toxicants have detrimental effects on the human body and eventually bring about mutagenicity and carcinogenicity. Owing to the presence of HAAs at a marginal level in the intricate tissue of food and their interactivity, an effective sample preparation should be employed to extract these controversial chemicals from the food matrix. For separation and detection of HAAs, advanced extraction methods and instrumental techniques have been applied. According to the type of sample preparation, sensitivity of the experiment, laboratory conditions and available facilities, the choice of analytical equipment will be different. In this review, various cooked food samples containing HAAs and heat processing of them have been listed. Also, sample pre-treatment and analytical techniques that have been applied to determine HAAs are discussed.

Transfer of primary aromatic amines from coloured paper napkins into four different food matrices and into cold water extracts.

The aim of this study was to compare the transfer of primary aromatic amines (PAAs) from napkins into cold water extract (CWE) with transfer into four different food matrices. An HPLC-MS/MS multi-analyte method for quantification of 26 PAAs in CWE was validated and applied. In addition, the method was validated for seven different PAAs in four different food matrices (cucumber, rice, pickled gherkin and butter cookie) representing wet, dry, acidic and fatty food. The CWEs of 12 coloured napkin samples were analysed, and 3 napkins released more than 0.01 mg kg-1 PAAs into the CWE. These three napkins were chosen for transfer testing with food samples. In total, seven different PAAs were quantified in the food samples. Results show that the transfer of the tested PAAs into the CWE is in most cases comparable to the transfer into the tested food samples. In some cases, the CWE overestimates transfer into food, except for the transfer of aniline into pickled gherkin, where the CWE underestimates transfer. Therefore, the CWE serves as an adequate and certainly not overestimating simulation of reality for the tested transfer of PAAs into the food samples.

Separation of structurally related primary aliphatic amines using hydrophilic interaction chromatography with fluorescence detection after postcolumn derivatization with o-phthaldialdehyde/mercaptoethanol.

The retention behavior of primary aliphatic amines (homologous series of aliphatic alkyl amines and cycloalkyl amines) and positional isomers of alkylamines in the hydrophilic interaction chromatography mode was studied. The study was carried out on a TSKgel Amide-80 column followed by postcolumn derivatization with fluorescence detection to describe the retention mechanism of tested compounds. The effect of chromatographic conditions including column temperature, acetonitrile content in the mobile phase, mobile phase pH (ranging from 3.5 to 6.8), and salt concentration in the mobile phase was investigated. The final mobile phase consisted of acetonitrile and solution of 20 mM potassium formate pH 3.5 in ratio 80:20 v/v. The analyses were carried out at mobile phase flow rate of 1.0 mL/min and the column temperature of 20°C. The developed method was fully validated in terms of linearity, sensitivity (limit of detection and limit of quantification), accuracy, and precision according to International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use guidelines. The proposed new methods were proved to be highly sensitive, simple, and rapid, and were successfully applied to the determinations of isopropylamine, cyclohexylamine, and cyclopropylamine in relevant active pharmaceutical ingredients.

Acetonitrile extraction coupled with UHPLC-MS/MS for the accurate quantification of 17 heterocyclic aromatic amines in meat products.

This study proposed a simple and accurate acetonitrile extraction pretreatment method coupled with ultrahigh-performance liquid chromatography with tandem mass spectrometry for the simultaneous determination of 17 heterocyclic aromatic amines (HAAs) in meat products. With this new method, all 17 HAAs, including 11 polar and 6 nonpolarHAAs, were simultaneously extracted by acetonitrile and purified by one-step Oasis MCX cartridge purification. Compared with two different improved reference methods, the acetonitrile method could obtain higher recoveries (in the range of 42.5% to 99.0%) and better repeatability (lower than 12.2%). The limits of quantification were calculated between 0.028ngg-1and0.648ngg-1 with high correlation coefficients (r>0.9976) in wide linear ranges. The proposed acetonitrile method was successfully applied to the analysis of the HAAs levels in 10 commercial meat products with satisfactory recoveries.

Analysis of Heterocyclic Amines in Meat by the Quick, Easy, Cheap, Effective, Rugged, and Safe Method Coupled with LC-DAD-MS-MS.

The traditional way to analyze heterocyclic amines (HAs) is time-consuming and uses large amounts of solvents. The objective of this study is to develop a quick and simultaneous analysis method for multiple types of HAs contained in meat products. Results showed that 20 HAs and 1 internal standard (4,7,8-TriMeIQx) can be separated within 30 min using an Inspire C18 column and a gradient solvent system containing 10 mM ammonium acetate (pH 2.9) and acetonitrile. This process resulted in a high degree of separation. Using acetonitrile with 1% acetic acid as an extraction solvent, followed by primary and secondary amine, MgSO4, and C18EC as purified reagent, is highly suitable for extracting HAs using the quick, easy, cheap, effective, rugged, and safe method (QuEChERS). Tandem mass spectrometry with selected reaction monitoring mode were used for analysis, which indicated reasonable recovery (58.9-117.4%) for all 20 types of HAs along with limits of detection and quantification in the range of 0.003-0.05 and 0.01-0.05 ng/g, respectively.

Homochiral metal-organic frameworks based on amino acid ligands for HPLC separation of enantiomers.

Natural amino acids are well known to form coordination polymers with transition metal ions. In this study, six homochiral metal-organic frameworks constructed from Zn2+ or Co2+ ions and various enantiopure amino acid (L-tyrosine, L-histidine, L-tryptophan and L-glutamic acid), namely [Zn(L-tyr)]n (L-tyrZn), [Zn4 (btc)2 (Hbtc)(L-His)2 (H2 O)4 ]·1.5H2 O, {[Zn2 (L-trp)2 (bpe)2 (H2 O)2 ]·2H2 O·2NO3 }n , [Co2 (L-Trp)(INT)2 (H2 O)2 (ClO4 )], [Co2 (sdba)((L-Trp)2 ] and [Co(L-Glu)(H2 O)·H2 O]∞ , were synthesized according to the methods previously reported in the literature. The six homochiral MOFs were explored as the chiral stationary phases for high-performance liquid chromatographic separation of enantiomers using hexane/isopropanol or hexane/dichloromethane as mobile phase. Various types of enantiomers such as alcohols, amines, ketones, ethers, organic acids, etc. can be resolved on these homochiral MOF columns. The results revealed that the enantioseletivities of homochiral MOFs based on amino acids as chiral bridging ligands used as stationary phases are practical in HPLC.

Rapid determination of 9 aromatic amines in mainstream cigarette smoke by modified dispersive liquid liquid microextraction and ultraperformance convergence chromatography tandem mass spectrometry.

Aromatic amines in mainstream cigarette smoke have long been monitored due to their carcinogenic toxicity. In this work, a reliable and rapid method was developed for the simultaneous determination of 9 aromatic amines in mainstream cigarette smoke by modified dispersive liquid liquid microextraction (DLLME) and ultraperformance convergence chromatography tandem mass spectrometry (UPC2-MS/MS). Briefly, the particulate phase of the cigarette smoke was captured by a Cambridge filter pad, and diluted hydrogen chloride aqueous solution is employed to extract the aromatic amines under mechanical shaking. After alkalization with sodium hydroxide solution, small amount of toluene was introduced to further extract and enrich aromatic amines by modified DLLME under vortexing. After centrifugation, toluene phase was purified by a universal QuEChERS cleanup kit and was finally analyzed by UPC2-MS/MS. Attributing to the superior performance of UPC2-MS/MS, this novel approach allowed the separation and determination of 9 aromatic amines within 5.0min with satisfactory resolution and sensitivity. The proposed method was finally validated using Kentucky reference cigarette 3R4F, and emission levels of targeted aromatic amines determined were comparable to previously reported methods At three different spiked levels, the recoveries of most analytes were ranged from 74.01% to 120.50% with relative standard deviation (RSD) less than 12%, except that the recovery of p-toluidine at low spiked level and 3-aminobiphenyl at medium spiked level was 62.77% and 69.37% respectively. Thus, this work provides a novel alternative method for the simultaneous analysis of 9 aromatic amines in mainstream cigarette smoke.

Simultaneous determination of eight short-chain aliphatic amines in drug substances by HPLC with diode array detection after derivatization with halonitrobenzenes.

Short-chain aliphatic amines are a class of hazardous impurities in drug substances. A simple method, involving derivatization followed by high-performance liquid chromatography with diode array detection, has been developed for residue determination of eight aliphatic amines simultaneously in drug substances. Different halonitrobenzenes derivatization reagents were systematically compared. As a result, 1-fluoro-2-nitro-4-(trifluoromethyl)benzene was selected since the derivatization effectively shifted the absorption wavelength to the visible region (400-450 nm), where most drug substances, impurities and even the derivatization reagent absorb very weakly. Due to the redshift effect, interference was minimized and adequately low limits of quantitation were reached (0.24-0.80 nmol/mL). Moreover, the derivatization reaction was readily carried out in dimethyl sulfoxide at room temperature for 1 h using N,N-diisopropylethylamine as catalyst to achieve the highest yield. Without any pre-treatment, the derivatives were analyzed by high-performance liquid chromatography with diode array detection. The high stability of the derivatives within 24 h at room temperature (RSD<1.04%) further facilitated the simultaneous preparation and consecutive analysis of quantities of samples. Finally, the proposed method was successfully applied for residue determination of eight aliphatic amines simultaneously in eight drug substance samples. This study could be helpful for the routine analysis and residue control of aliphatic amines in drug substances.

High performance separation of quaternary amines using microchip non-aqueous electrophoresis coupled with contactless conductivity detection.

This study describes the development of an analytical methodology for the separation of quaternary amines using non-aqueous microchip electrophoresis (NAME) coupled with capacitively coupled contactless conductivity detection (C4D). All experiments were performed using a commercial microchip electrophoresis system consisting of a C4D detector, a high-voltage sequencer and a microfluidic platform to assemble a glass microchip with integrated sensing electrodes. The detection parameters were optimized and the best response was reached applying a 700-kHz sinusoidal wave with 14Vpp excitation voltage. The running electrolyte composition was optimized aiming to achieve the best analytical performance. The mixture containing methanol and acetonitrile at the proportion of 90:10 (v:v) as well as sodium deoxycholate provided separations of ten quaternary amines with high efficiency and baseline resolution. The separation efficiencies ranged from 8.7×104 to 3.0×105 plates/m. The proposed methodology provided linear response in the concentration range between 50 and 1000µmol/L and limits of detection between 2 and 27µmol/L. The analytical feasibility of the proposed methodology was tested in the determination of quaternary amines in corrosion inhibitor samples often used for coating oil pipelines. Five quaternary amines (dodecyltrimethylammonium chloride, tetradecyltrimetylammonium bromide, cetyltrimethylammonium bromide, tetraoctylammonium bromide and tetradodecylammonium bromide) were successfully detected at concentration levels from 0.07 to 6.45mol/L. The accuracy of the developed methodology was investigated and the achieved recovery values varied from 85 to 122%. Based on the reported data, NAME-C4D devices exhibited great potential to provide high performance separations of hydrophobic compounds. The developed methodology can be useful for the analysis of species that usually present strong adsorption on the channel inner walls.