Amine Switchable Hydrophilic Solvent Vortex-Assisted Homogeneous Liquid-Liquid Microextraction and GC-MS for the Enrichment and Determination of 2, 6-DIPA Additive in Biodegradable Film.

2, 6-diisopropylaniline (2, 6-DIPA) is a crucial non-intentionally organic additive that allows the assessment of the production processes, formulation qualities, and performance variations in biodegradable mulching film. Moreover, its release into the environment may have certain effects on human health. Hence, this study developed simultaneous heating hydrolysis-extraction and amine switchable hydrophilic solvent vortex-assisted homogeneous liquid-liquid microextraction for the gas chromatography-mass spectrometry analysis of the 2, 6-DIPA additive and its corresponding isocyanates in poly(butylene adipate-co-terephthalate) (PBAT) biodegradable agricultural mulching films. The heating hydrolysis-extraction conditions and factors influencing the efficiency of homogeneous liquid-liquid microextraction, such as the type and volume of amine, homogeneous-phase and phase separation transition pH, and extraction time were investigated and optimized. The optimum heating hydrolysis-extraction conditions were found to be a H2SO4 concentration of 2.5 M, heating temperature of 87.8 °C, and hydrolysis-extraction time of 3.0 h. As a switchable hydrophilic solvent, dipropylamine does not require a dispersant. Vortex assistance is helpful to speed up the extraction. Under the optimum experimental conditions, this method exhibits a better linearity (0.0144~7.200 µg mL-1 with R = 0.9986), low limit of detection and quantification (0.0033 µg g-1 and 0.0103 µg g-1), high extraction recovery (92.5~105.4%), desirable intra- and inter-day precision (relative standard deviation less than 4.1% and 4.7%), and high enrichment factor (90.9). Finally, this method was successfully applied to detect the content of the additive 2, 6-DIPA in PBAT biodegradable agricultural mulching films, thus facilitating production process monitoring or safety assessments.

The magnetic layered double hydroxide/zeolitic imidazolate framework-8 nanocomposite coupled with HPLC-MS/MS for the detection of heterocyclic aromatic amines in thermally processed meat.

In this research, a novel magnetic nanocomposite (Fe3O4@Zn/Al-LABSA-LDH/ZIF-8) was synthesized using Fe3O4 as the magnetic core, layered double hydroxide (LDH) with linear alkylbenzene sulfonic acid (LABSA) intercalation and zeolitic imidazolate framework-8 (ZIF-8) as the shell. Benefiting from the intercalation of LABSA into LDH combined with ZIF-8, the multiple interactions, including π-π stacking, hydrogen bonding, and electrostatic interactions, conferred high selectivity and good extraction capability to the material towards heterocyclic aromatic amines (HAAs). Fe3O4@Zn/Al-LABSA-LDH@ZIF-8 was used as an adsorbent for magnetic solid-phase extraction (MSPE) to enrich HAAs in thermally processed meat samples, followed by high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) detection. The method exhibited a low detection limit (0.021-0.221 ng/g), good linearity (R2 ≥ 0.9999), high precision (RSD < 7.2 %), and satisfactory sample recovery (89.7 % -107.5 %). This research provides a promising approach for developing novel adsorbents in sample preparation and improving analytical performance.

Systematic evaluation of benzoylation for liquid chromatography-mass spectrometry analysis of different analyte classes.

LC-MS is an indispensable tool for small molecule analysis in many fields; however, many small molecules require chemical derivatization to improve retention on commonly used reversed-phase columns and increase ionization. Benzoyl chloride (BzCl) derivatization is commonly used for derivatization of primary and secondary amines and phenolic alcohols, though evidence exists that with proper reaction conditions (i.e., specific bases), other hydroxyl groups may be derivatized too. Previous studies have examined BzCl concentration, reaction times, and reaction temperatures for derivatization of amines and phenols for LC-MS analysis; however, use of different bases, base concentration, and extending to conditions to hydroxyl groups for LC-MS analysis has not been well-studied. To address this understudied area and identify reaction conditions for both amino and hydroxyl groups, we performed a systematic study of reaction conditions on multiple classes of potential targets. For selected derivatization methods, detection limits and performance in a variety of biological matrices were assessed. Results highlight the importance of tailoring derivatization methods for a given application as they varied by molecule and/or molecule class. Compared to the standard BzCl method commonly used, alternative methods were identified to better derivatize challenging analytes (glucosamine, choline, cortisol, uridine, cytidine) with detection limits reaching 1100, 9, 38, 170, and 67 nM compared to undetectable, 170, 86, 1000, and 86 nM respectively. Sub-nanomolar detection limits were achieved for norepinephrine with alternative derivatization approaches. Improved derivatization methods for several classes and molecules including nucleosides, steroids, and molecules containing hydroxyl groups were also identified.

Aromatic amine antioxidants (AAs) and p-phenylenediamines-quinones (PPD-Qs) in e-waste recycling industry park: Occupational exposure and liver X receptors (LXRs) disruption potential.

Recently, evidence of aromatic amine antioxidants (AAs) existence in the dust of the electronic waste (e-waste) dismantling area has been exposed. However, there are limited studies investigating occupational exposure and toxicity associated with AAs and their transformation products (p-phenylenediamines-quinones, i.e., PPD-Qs). In this study, 115 dust and 42 hand wipe samples collected from an e-waste recycling industrial park in central China were analyzed for 19 AAs and 6 PPD-Qs. Notably, the median concentration of ∑6PPD-Qs (1,110 ng/g and 1,970 ng/m2) was significantly higher (p < 0.05, Mann-Whitney U test) than that of ∑6PPDs (147 ng/g and 34.0 ng/m2) in dust and hand wipes. Among the detected analytes, 4-phenylaminodiphenylamine quinone (DPPD-Q) (median: 781 ng/g) and 1,4-Bis(2-naphthylamino) benzene quinone (DNPD-Q) (median: 156 ng/g), were particularly prominent, which were first detected in the e-waste dismantling area. Occupational exposure assessments and nuclear receptor interference ability, conducted through estimated daily intake (EDI) and molecular docking analysis, respectively, indicated significant occupational exposure to PPD-Qs and suggested prioritized Liver X receptors (LXRs) disruption potential of PPDs and PPD-Qs. The study provides the first evidence of considerable levels of AAs and PPD-Qs in the e-waste-related hand wipe samples and underscores the importance of assessing occupational exposure and associated toxicity effects.

Amine response smartphone-based portable and intelligent polyvinyl alcohol films for real-time detection of shrimp freshness.

Food freshness monitoring is an important component in ensuring food safety for consumers and the food industry. Therefore, there is an urgent need for a portable, low-cost, and efficient detection method to determine the freshness. In this study, polyvinyl alcohol (PVA) was used as polymer carrier to prepare electrospinning film containing curcumin (Cur) and gardenia blue (GB) as intelligent indicator label on food packaging for real-time nondestructive detection of freshness of shrimp. The detection limit of ammonia response is less than or equal to 20 ppm, and the detection time is about 1 min, indicating that it has a sensitive response effect. At the same time, a smartphone application that can identify amines in response to color changes has been developed, and consumers can understand freshness by scanning the label. This study demonstrates the huge potential of smart indicator labels for food freshness monitoring.

Development of a UPLC-MS/MS-based method for simultaneous determination of advanced glycation end products and heterocyclic amines in stewed meat products.

A novel analytical strategy was proposed to simultaneously quantify two advanced glycation end products (AGEs) including Nε-(Carboxymethyl)lysine (CML), Nε-(Carboxyethyl)lysine (CEL) and eight heterocyclic amines (HAs) including IQ, MeIQ, MeIQx, 4,8-DiMeIQx, 7,8-DiMeIQx, PhIP, Harman, and Norharman. The procedure was based on a two-step extraction, solid phase extraction (SPE) purification followed by ultra performance liquid chromatography tandem mass spectrometry. The established method showed a good linearity (R2 ≥ 0.9950), rapid processing time (8 min per sample), satisfactory recoveries (matrix spiked recoveries range from 72.2% to 119.6%) and precision (intra-day and inter-day RSDs were <19.3%). The limit of quantification (LOQ) and limit of detection (LOD) resulted to be between 0.05-15 ng/g and 0.2-50 ng/g, respectively. The validated technique was further applied to determine HAs and AGEs in eight stewed meat product samples consumed in Shanghai, with the amount of HAs and AGEs ranging from 2.851 to 18.289 ng/g and 118.158-543.493 ng/g, respectively.

Effects of seasoning addition and cooking conditions on the formation of free and protein-bound heterocyclic amines and advanced glycation end products in braised lamb.

The accumulation of heterocyclic amines (HAs) and advanced glycation end products (AGEs) in thermally processed meats has been arising safety concerns. The effects of cooking conditions and seasoning addition on the formation of HAs and AGEs in Chinese traditional braised lamb were investigated by UPLC-MS/MS analysis. Soy sauce significantly increased the formation of HAs and AGEs, among which light soy sauce had the greatest promoting effect (69.45-15300.62 %). Conversely, spices inhibited HAs and AGEs formation, the inhibition rate of free HAs and AGEs reached 22.06-34.72 % when using 70 % ethanol extract. Hot blanching treatment and adding soy sauce and spices at a later stage could significantly suppress HAs and AGEs production. Flavonoids, including galangin, hesperidin, narirutin, etc., were identified as key effectors in spices. These findings help to promote awareness of the formation of HAs and AGEs in braised lamb and provide valuable insights for optimizing processing techniques to minimize their production.

Structural elucidation of derivatives of polyfunctional metabolites after methyl chloroformate derivatization by high-resolution mass spectrometry gas chromatography. Application to microbiota metabolites.

Metabolomics has become an essential discipline in the study of microbiome, emerging gas chromatography coupled to mass spectrometry as the most mature, robust, and reproducible analytical technique. Silylation is the most widely used chemical derivatization strategy, although it has some limitations. In this regard, alkylation by alkyl chloroformate offers some advantages, such as a rapid reaction, milder conditions, better reproducibility, and the generation of more stable derivatives. However, commercial spectral libraries do not include many of the alkyl derivatives, mainly for polyfunctional metabolites, which can form multiple derivatives. That introduces a huge bias in untargeted metabolomics leading to common errors such as duplicates, unknowns, misidentifications, wrong assignations, and incomplete results from which non-reliable findings and conclusions will be retrieved. For this reason, the purpose of this study is to overcome these shortcomings and to expand the knowledge of metabolites in general and especially those closely related to the gut microbiota through the thorough study of the reactivity of the different functional groups in real matrix derivatized by methyl chloroformate, a common representative alkylation reagent. To this end, a systematic workflow has been developed based on exhaustive structural elucidation, along with computational simulation, and taking advantage of the high sensitivity and high-resolution gas chromatography-mass spectrometry. Several empirical rules have been established according to chemically different entities (free fatty acids, amino acids, polyols, sugars, amines, and polyfunctional groups, etc.) to predict the number of derivatives formed from a single metabolite, as well as their elution order and structure. In this work, some methyl chloroformate derivatives not previously reported as well as the mechanisms to explain them are given. Extremely important is the interconversion of E- and Z- geometric isomers of unsaturated dicarboxylic acids (case of fumaric-maleic and case of citraconic-mesaconic acids), or the formation of cycled derivatives for amino acids, as well as common metabolites, as in the case of serine and cysteine, and many others.

Mechanism of aroma enhancement methods in accelerating Congou black tea acidification subjected to room temperature storage.

Acidification of aroma-enhanced black tea during storage was studied. UPLC-Q-TOF/MS (Ultra Performance Liquid Chromatography and Quadrupole-Time of Flight Mass Spectrometer) and HPLC (High-Performance Liquid Chromatography) analysis of non-volatile substances and organic acids revealed a decrease of soluble sugars and amino acids in aroma-enhanced black tea, while an increase in organic acids such as oxalic acid, malic acid and quinic acid. Further in vitro experiments indicated that the acidification of aroma-enhanced tea during storage can be attributed to decomposition of sugars and amino acids by heating, oxidation of aromatic aldehydes. Meanwhile, the amino acids, catechins, soluble sugars and flavonoids that constitute the taste of black tea are further reduced, changing the taste composition of tea infusion and further increasing its acidity. This study revealed the reasons for black tea acidification during aroma enhancement and storage and provided a theoretical basis for improving black tea quality.

GC-MS Analysis of Primary Aromatic Amines Originated From Azo Dyes in Commercial Textile or Leather Products Using Helium Alternative Carrier Gases.

BACKGROUND: In recent years, due to the global shortage of helium gas, the development of gas chromatography (GC) analytical methods using alternatives to helium carrier gases is necessary. OBJECTIVE: The objective of this study was to examine the applicability of hydrogen and nitrogen as alternative carrier gases using the test method for azo compounds in the Act on Control of Household Products Containing Harmful Substances of Japan. METHOD: The gas chromatograph mass spectrometer (GC-MS) analytical method using hydrogen and nitrogen as alternative carrier gases was compared with a method using helium for 26 primary aromatic amines (PAAs) originated from azo dyes. RESULTS: When hydrogen and nitrogen were used as carrier gases under the same conditions used during analysis using helium (same column, gas flow rate, oven temperature conditions, etc.), sufficient peak separation of 26 PAAs was obtained. The sensitivities of the methods using helium and hydrogen were comparable, whereas the sensitivity was lower when nitrogen was used, with the detection limits ranging from 1/220 to 1/25. However, all carrier gases achieved quantification at concentrations below the standard value (30 µg/g) of the Act on Control of Household Products Containing Harmful Substances, and the results were in agreement with the standard value for the target product. CONCLUSIONS: Our results indicated that hydrogen or nitrogen can be used as alternative carrier gases to helium for GC-MS analysis of azo compounds producing specific aromatic amines. HIGHLIGHTS: Using hydrogen or nitrogen as an alternative carrier gas to helium, azo compounds could be quantified with excellent accuracy.

Selenium content, chemical composition and volatile components of essential oil and hydrosol from flowers of Cardamine violifolia.

Cardamine violifolia is a unique selenium hyperaccumulating vegetable in China, but its flowers are commonly wasted in large-scale cultivation. To better utilize this resource, this study explored the selenium content, chemical composition, and volatile organic compounds (VOCs) of hydro-distilling essential oil (EO) and hydrosol from C. violifolia flowers. ICP-MS results indicated that the EO and hydrosol contained selenium reaching 13.66±2.82 mg/kg and 0.0084±0.0013 mg/kg, respectively. GC-MS analysis revealed that organic acids, hydrocarbons, and amines were the main components of EO. Additionally, benzyl nitrile, benzaldehyde, benzyl isothiocyanate, benzyl alcohol, megastigmatrienone, and 2-methoxy-4-vinylphenol also existed in considerable amounts. The hydrosol extract had fewer components, mainly amines. HS-SPME-GC-MS corresponded to the composition analysis and aromatic compounds were the prevalent VOCs, while HS-GC-IMS primarily identified C2-C10 molecular alcohols, aldehydes, ethers, and sulfur-containing compounds. This study first described the chemical composition and VOC profiles of EO and hydrosol from selenium hyperaccumulating plant.

Integrating Post-Ionization Separation via Differential Mobility Spectrometry into Direct Analysis in Real Time Mass Spectrometry for Toy Safety Screening.

Direct analysis in real time (DART) enables direct desorption and ionization of analytes, bypassing the time-consuming chromatographic separation traditionally required for mass spectrometry (MS) analysis. However, DART-MS suffers from matrix interference of complex samples, resulting in compromised detection sensitivity and quantitation accuracy. In this study, DART-MS was combined with differential mobility spectrometry (DMS) to provide an additional dimension of post-ionization ion mobility separation within a millisecond time scale, compensating for the lack of separation in DART-MS analysis. As proof-of-concept, primary aromatic amines (PAAs), a class of potentially hazardous chemicals, were analyzed in various toy products, including bubble solutions, finger paints, and plush toys. In addition to commercial Dip-it glass rod and metal mesh sampling tools, a customized rapid extractive evaporation device was designed for the accelerated extraction and sensitive analysis of solid toy samples. The incorporation of DMS in DART-MS analysis enabled the rapid separation and differentiation of isomeric analytes, leading to improved accuracy and reliability. The developed protocols were optimized and validated, achieving good linearity with correlation coefficients greater than 0.99 and acceptable repeatability with relative standard deviations less than 10%. Moreover, satisfactory sensitivity was realized with limits of detection and quantitation ranges of 0.2-5 and 1-20 µg/kg (µg/L) for the 11 PAA analytes. The established methodology was applied for the analysis of real toy samples (n = 18), which confirmed its appealing potential for toy safety screening and consumer health protection.

Effects of volatile organic compounds of smoke from different woods on the heterocyclic amine formation and quality changes in pork patty.

This study investigated the effects of smoke derived from cypress (CY), mulberry (MU), metasequoia (ME), pine (PI), and camphor (CA) on the heterocyclic aromatic amines (HAs), flavor, and sensory attributes of smoked pork patty. The results showed that the smoke derived from the five kinds of wood and the flavor of the corresponding smoked meat were classified into three types. Moreover, the smoke of CY and PI, and the smoke of MU and ME can be classified into one category respectively, which significantly improved the flavor of the smoked meat. Both free and protein-bound HAs were detected in smoked meat, while the smoking process significantly increased the HAs content, especially free Norharman (3.26 ng/g in control meat, and 82.24 ng/g in meat smoked with CY). Correlation analysis showed that various volatile organic compounds (VOCs) and HAs were closely associated. Future research should pay attention to the VOCs in smoked meat including vanillin, Close attention should be paid to tridecane and crotonic acid, as well as tetradecane and α-Dehydro-ar-himachalene in smoke, which were consistently correlated with various HAs and may participate in HAs formation. These results may reveal how the smoking process influences the formation of HAs and which factors should be targeted to inhibit HAs in smoked meat products.

Solvent-free automated thermal desorption-gas chromatography/mass spectrometry for direct screening of hazardous compounds in consumer textiles.

The global production of textiles utilizes numerous large-volume chemicals that may remain to some extent in the finished garments. Arylamines, quinolines, and halogenated nitrobenzene compounds are possible mutagens, carcinogens and/or skin sensitizers. For prevention, control of clothing and other textiles must be improved, especially those imported from countries without regulations of textile chemicals. An automated analytical methodology with on-line extraction, separation, and detection would largely simplify screening surveys of hazardous chemicals in textiles. Automated thermal desorption-gas chromatography/mass spectrometry (ATD-GC/MS) was developed and evaluated as a solvent-free, direct chemical analysis for screening of textiles. It requires a minimum of sample handling with a total run time of 38 min including sample desorption, chromatographic separation, and mass spectrometric detection. For most of the studied compounds, method quantification limit (MQL) was below 5 µg/g for 5 mg of textile sample, which is sufficiently low for screening and control of quinoline and arylamines regulated by EU. Several chemicals were detected and quantified when the ATD-GC/MS method was applied in a limited pilot screening of synthetic fiber garments. A number of arylamines were detected, where some of the halogenated dinitroanilines were found in concentrations up to 300 µg/g. This is ten times higher than the concentration limit for similar arylamines listed by the EU REACH regulation. Other chemicals detected in the investigated textiles were several quinolines, benzothiazole, naphthalene, and 3,5-dinitrobromobenzene. Based on the present results, we suggest ATD-GC/MS as a screening method for the control of harmful chemicals in clothing garments and other textiles.

Effects of soy protein and its hydrolysates on the formation of heterocyclic aromatic amines in roasted pork.

This study investigated the influence mechanism of soy protein and its hydrolysates (under three different degree of hydrolysis) on formation of heterocyclic aromatic amines (HAAs) formation in roasted pork. The results showed that 7S and its hydrolysates significantly inhibited the formation of quinoxaline HAAs, and the maximum inhibitory rate of MeIQx, 4,8-MeIQx, and IQx was 69%, 79%, and 100%, respectively. However, soy protein and its hydrolysates could promote the formation of pyridine HAAs (PhIP, and DMIP), its content increased significantly with the increase in the degree of hydrolysis of the protein. The content of PhIP increased 41, 54, and 165 times with the addition of SPI, 7S, and 11S at 11% degree of hydrolysis, respectively. In addition, they promoted the formation of ß-carboline HAAs (Norharman and Harman), in a manner similar with that of PhIP, especially the 11S group. The inhibitory effect on quinoxaline HAAs was probably correlated with DPPH radical scavenging capacity. Nevertheless, the promotive effect on other HAAs might be related to the high levels of free amino acids and reactive carbonyls. This research may provide recommendation for the application of soy protein in high-temperature meat products.

Assessment of physicochemical properties of sorbent materials in passive and active sampling systems towards gaseous nitrogen-containing compounds.

The adsorption and desorption behavior of volatile nitrogen-containing compounds in vapor phase by solid-phase microextraction Arrow (SPME-Arrow) and in-tube extraction (ITEX) sampling systems, were investigated experimentally using gas chromatography-mass spectrometry. Three different SPME-Arrow coating materials, DVB/PDMS, MCM-41, and MCM-41-TP and two ITEX adsorbents, TENAX-GR and MCM-41-TP were compared to clarify the selectivity of the sorbents towards nitrogen-containing compounds. In addition, saturated vapor pressures for these compounds were estimated, both experimentally and theoretically. In this study, the adsorption of nitrogen-containing compounds on various adsorbents followed the Elovich model well, while a pseudo-first-order kinetics model best described the desorption kinetics. Pore volume and pore sizes of the coating sorbents were essential parameters for the determination of the adsorption performance for the SPME-Arrow sampling system. MCM-41-TP coating with the smallest pore size gave the slowest adsorption rate compared to that of DVB/PDMS and MCM-41 in the SPME-Arrow sampling system. Both adsorbent and adsorbate properties, such as hydrophobicity and basicity, affected the adsorption and desorption kinetics in SPME-Arrow system. The adsorption and desorption rates of studied C6H15N isomers in the MCM-41 and MCM-41-TP sorbent materials of SPME-Arrow system were higher for dipropylamine and triethylamine (branched amines) than for hexylamine (linear chain amines). DVB/PDMS-SPME-Arrow gave fast adsorption rates for the aromatic-ringed pyridine and o-toluidine. All studied nitrogen-containing compounds demonstrated high desorption rates with DVB/PDMS-SPME-Arrow. Chemisorption and physisorption were the sorption mechanisms in MCM-41- and MCM-41-TP- SPME-Arrow, but additional experiments are needed to confirm this. An active sampling technique ITEX gave comparable adsorption and desorption rates on the selective MCM-41-TP and universal TENAX-GR sorbent materials for all the compounds studied. Vapor pressures of nitrogen-containing compounds were experimentally estimated by using retention index approach and these values were compared with the theoretical ones, calculated using the COnductor-like Screening MOdel for Real Solvent (COSMO-RS) model. Both values agreed well with those found in the literature proving that these methods can be successfully used in predicting VOC's vapor pressures, e.g. for the formation of secondary organic aerosols.

The Flexibility of ß-Content, γ-Confidence Tolerance Intervals to Qualimetry a Simultaneous 22 Aromatic Amines Derived from Azo Dyes in Fabric Using a Sensitive GC-MS Technique.

BACKGROUND: Azo dyes are among the most widely used dyes in the textile industry, releasing a series of carcinogenic aromatic amines that can be absorbed through the skin. OBJECTIVE: This work aims to show that 22 azo dye amines in a textile matrix can be quantified using a GC-MS method. METHODS: Based on the notion of total error and ß-content, γ-confidence tolerance intervals (ß,γ-CCTI), a chemometric approach known as the "uncertainty profile" has been used to completely validate a GC-MS method for the simultaneous assay of 22 azo amines in fabrics. According to International Organization for Standardization (ISO) in ISO 17025 guidelines, analytical validation and measurement uncertainty estimates have evolved to be two main principles for ensuring the accuracy of analytical results and controlling the risk associated with their use. RESULTS: The calculated tolerance intervals allowed for the determination of the uncertainty limits at each concentration level. These limits when compared to the acceptable limits show that a significant portion of the expected outcomes is in conformity. Additionally, the relative expanded uncertainty values, calculated with a proportion of 66.7% and a 10% risk, do not exceed 27.7, 12.2, and 10.9% for concentration levels 1, 15, and 30 mg/L, respectively. CONCLUSION: The capability and flexibility of the ß-content, γ-confidence intervals have been established through the use of this innovative approach to carrying out qualimetry of the GC-MS method depending on the behavior, required conformity proportion, and acceptable tolerance limits of each amine. HIGHLIGHTS: An efficient GC-MS technique for the simultaneous determination of 22 azo amines in a textile matrix has been developed. Analytical validation using a new strategy based on the uncertainty concept is reported, uncertainty associated to measurement results is estimated, and the applicability of our approach to the GC-MS method is investigated.

Quantification of Serum Metabolites in Early Colorectal Adenomas Using Isobaric Labeling Mass Spectrometry.

A major challenge in reducing the death rate of colorectal cancer is to screen patients using low-invasive testing. A blood test shows a high compliance rate with reduced invasiveness. In this work, a multiplex isobaric tag labeling strategy coupled with mass spectrometry is adopted to relatively quantify primary and secondary amine-containing metabolites in serum for the discovery of metabolite level changes of colorectal cancer. Serum samples from patients at different risk statuses and colorectal cancer growth statuses are studied. Metabolite identification is based on accurate mass matching and/or retention time of labeled metabolite standards. We quantify 40 metabolites across all the serum samples, including 18 metabolites validated with standards. We find significantly decreased levels of threonine and asparagine in the patients with growing adenomas or high-risk adenomas (p < 0.05). Glutamine levels decrease in patients with adenomas of unknown growth status or high-risk adenomas. In contrast, arginine levels are elevated in patients with low-risk adenoma. Receiver operating characteristic analysis shows high sensitivity and specificity of these metabolites for detecting growing adenomas. Based on these results, we conclude that a few metabolites identified here might contribute to distinguishing colorectal patients with growing adenomas from normal individuals and patients with unknown growth status of adenomas.

Quantification of hetero-cyclic amines from different categories of braised beef by optimized UPLC-TQ-XS/ESI method.

This research work has developed and optimized a sensitive analytical method for separation and quantification of heterocyclic amines (HCAs) mainly including PhIP, Harman, Norharman, IQ, MeIQ, AαC, MeAαC and Trp-P-2 by optimizing UPLC-TQ-XS using electrospray ionization source (ESI+) on ACQUITY UPLC® BEH C18 column in <7 min, from braised beef sample matrix. Meanwhile, modified HCAs extraction by modifying QuEChERS (quick, easy, cheap, efficient, rugged and safe) technique and revisited with solid phase extraction (SPE) for HCAs purification, instead using traditional QuEChERS salts. Moreover, optimized pH conditions of HCA extracts before purification, for better extraction recoveries. Furthermore, this method was validated in terms of method validation parameters. Lastly, simulation of real braised beef model provided the minimum formation of HCAs by optimizing cooking parameters and precursors in a cooking system. Therefore, this method could be applied simultaneously on braised beef matrix either marketed or home cooked for HCAs analysis.

Development and evaluation of a novel fluorescent chiral derivatization reagent DBD-S-M-Pro: first observation of four chiral amino acids in human hair.

This study reports a novel fluorescent chiral derivatization reagent, 4-(N,N-dmethylaminosulfonyl)-2,1,3-benzoxadiazole-(2-succinimidoxy)-trans-2-methyl-L-proline (DBD-S-M-Pro), with a benzoxadiazole structure containing an N-hydroxysuccinimide activation group. DBD-S-M-Pro targets chiral amino-functional compounds under alkaline conditions without a condensation agent. Gradient elution was performed on a BEH C18 (100 × 2.1 mm, 1.7 µm) column with a mobile phase of 0.05% formic acid (FA) in 10 mM ammonium acetate (CH3COONH4) and 0.1% FA in acetonitrile or methanol. The efficiency of the chiral resolution was evaluated under excitation and emission wavelengths of 450 nm and 560 nm, respectively. The 19 chiral amino acids were separated in the range of 1.45-14.84. The resolutions of almost all DL-amino acids exceeded 1.5; the exceptions were serine (Ser) and lysine (Lys), with resolutions of 1.45 and 1.46, respectively. In addition, a new approach was devised for the simultaneous analysis of four chiral amino acids (DL-Glu, DL-Ala, DL-Val, and DL-Phe) in human hair. These amino acids were analyzed in the range of 12.5-400 pmol, with R2 ≥ 0.9990, limits of detection (S/N = 3) of 4-10 pmol, and intraday and interday precisions of 0.57-6.23%. The average spikes in the hair recoveries were 89.76-111.54%, and the matrix effects were 92.47-102.40%. Next, the contents of free chiral amino acids in the hair samples of 10 healthy volunteers (five males and five females) were analyzed with this method, and the differences were compared. The developed DBD-S-M-Pro provides a novel strategy for the sensitive determination of free chiral amino acids in living organisms.