Derivatization Method Research Articles

Research Progress of Derivatization Method in MALDI Mass Spectrometry Imaging

Research Progress of Derivatization Method in MALDI Mass Spectrometry Imaging

Development of a Method for Quantitation of Glyceraldehyde in Various Body Compartments of Rodents and Humans.

There is limited information available about the physiological content of glyceraldehyde, a precursor of toxic advanced glycation end products. The conventional derivatization method for aldoses using 1-phenyl-3-methyl-5-pyrazolone did not allow reproducible quantification of glyceraldehyde due to the instability of glyceraldehyde compared to other aldoses. We optimized the derivatization condition to achieve high and reproducible recovery of derivatives for liquid chromatography tandem mass spectrometry quantification. Based on the stability of glyceraldehyde during sample preparation and high recovery of spiked standard, the present method provides reproducible quantification of glyceraldehyde in the body. The glyceraldehyde contents in fasting conditions in the rodent liver (mice: 50.0 ± 3.9 nmol/g; rats: 35.5 ± 4.9 nmol/g) were higher than those in plasma (9.4 ± 1.7 and 7.2 ± 1.2 nmol/mL). The liver glyceraldehyde levels significantly increased after food consumption (p < 0.05) but remained constant in the plasma. High fat diet feeding significantly increased plasma glyceraldehyde levels in mice (p < 0.005). In healthy human volunteers, the plasma glyceraldehyde levels remained unchanged after the consumption of steamed rice. In patients with type 2 diabetes, the plasma glyceraldehyde level was positively correlated with the plasma glucose level (r = 0.84; p < 0.0001).

Automated Trimethyl Sulfonium Hydroxide Derivatization Method for High-Throughput Fatty Acid Profiling by Gas Chromatography-Mass Spectrometry.

Fatty acid profiling on gas chromatography–mass spectrometry (GC–MS) platforms is typically performed offline by manually derivatizing and analyzing small batches of samples. A GC–MS system with a fully integrated robotic autosampler can significantly improve sample handling, standardize data collection, and reduce the total hands-on time required for sample analysis. In this study, we report an optimized high-throughput GC–MS-based methodology that utilizes trimethyl sulfonium hydroxide (TMSH) as a derivatization reagent to convert fatty acids into fatty acid methyl esters. An automated online derivatization method was developed, in which the robotic autosampler derivatizes each sample individually and injects it into the GC–MS system in a high-throughput manner. This study investigated the robustness of automated TMSH derivatization by comparing fatty acid standards and lipid extracts, derivatized manually in batches and online automatically from four biological matrices. Automated derivatization improved reproducibility in 19 of 33 fatty acid standards, with nearly half of the 33 confirmed fatty acids in biological samples demonstrating improved reproducibility when compared to manually derivatized samples. In summary, we show that the online TMSH-based derivatization methodology is ideal for high-throughput fatty acid analysis, allowing rapid and efficient fatty acid profiling, with reduced sample handling, faster data acquisition, and, ultimately, improved data reproducibility.

De Novo Sequencing of Heparin /Heparan Sulfate Oligosaccharides by Chemical Derivatization and LC-MS /MS.

The biological function of glycosaminoglycan (GAG) oligosaccharides is dictated in part by the pattern of modifications (sulfation, acetylation/deacetylation, and epimerization of uronic acids) occurring in oligosaccharide regions of the polysaccharide. The sequencing of the pattern of modifications of glycosaminoglycan (GAG) oligosaccharides is highly challenging due to the heterogeneity of most naturally occurring GAGs. While liquid chromatography coupled with mass spectrometry (LC-MS) is widely used to determine GAG oligosaccharide composition, the high lability of sulfates in the gas phase makes structural interrogation by tandem mass spectrometry (MS/MS) unlikely to yield useful sequence information. Here we describe a method for the chemical derivatization of GAG oligosaccharides that replaces sulfate groups in a site-specific manner. The resulting derivatized GAG oligosaccharides can be chromatographically separated with high efficiency using C18 reversed-phase chromatography and sequenced using standard LC-MS/MS methods.

Simple and Reproducible Derivatization with Benzoyl Chloride: Improvement of Sensitivity for Multiple Lipid Classes in RP-UHPLC/MS.

The chemical derivatization of multiple lipid classes was developed using benzoyl chloride as a nonhazardous derivatization agent at ambient conditions. The derivatization procedure was optimized with standards for 4 nonpolar and 8 polar lipid classes and measured by reversed-phase ultrahigh-performance liquid chromatography-tandem mass spectrometry. The derivatization and nonderivatization approaches were compared on the basis of the calibration curves of 22 internal standards from 12 lipid classes. The new method decreased the limit of detection 9-fold for monoacylglycerols (0.9-1.0 nmol/mL), 6.5-fold for sphingoid base (0.2 nmol/mL), and 3-fold for diacylglycerols (0.9 nmol/mL). The sensitivity expressed by the ratio of calibration slopes was increased 2- to 10-fold for almost all investigated lipid classes and even more than 100-fold for monoacylglycerols. Moreover, the benzoylation reaction produces a more stable derivative of cholesterol in comparison to the easily in-source fragmented nonderivatized form and enabled the detection of fatty acids in a positive ion mode, which does not require polarity switching as for the nonderivatized form. The intralaboratory comparison with an additional operator without previous derivatization experiences shows the simplicity, robustness, and reproducibility. The stability of the derivatives was determined by periodical measurements during a one month period and five freeze/thaw cycles. The fully optimized derivatization method was applied to human plasma, which allows the detection of 169 lipid species from 11 lipid classes using the high confidence level of identification in reversed-phase (RP)-ultra high performance liquid chromatography (UHPLC)/mass spectrometry (MS). Generally, we detected more lipid species for monoacylglycerols, diacylglycerols, and sphingoid bases in comparison with previously reported papers without the derivatization.

Method for derivatization and isotopic analysis of the insensitive munition compound 3-nitro-1,2,4-triazol-5-one (NTO)

This paper describes an offline low-temperature derivatization method combined with gas chromatography-isotope ratio mass spectrometry (GC-IRMS) to enable compound-specific isotope analysis (CSIA) of C and N in the explosive compound 3-nitro-1,2,4-triazole-5-one (NTO). NTO is being used widely as a component of insensitive munition (IM) composites such as IMX-101, a formulation that is being used to replace the more shock sensitive TNT in artillery shells. The alkylation of NTO with methyl iodide (MeI) as the derivatization reagent was performed in acetone solution at room temperature using triethylamine (Et3N) as a base catalyst. The methylated product of NTO derivatization was identified as 4-methyl-3-nitro-1,2,4-triazol-5-one (MNTO). Accurate and reproducible results were achieved by systematic optimization of MeI and Et3N concentrations and reaction time. Isotopic values of MNTO obtained by GC-IRMS were normalized against those of two 2,4-dinitroanisole (DNAN) in-house reference materials that had been calibrated with isotopic standard reference materials, USGS40 and USGS41a. The resulting method detection limit for derivatization/GC-IRMS of NTO was 788ng of NTO, yielding a precision of ±0.3‰ for both δ13C and δ15N values in good agreement with δ13C and δ15N values for NTO determined by elemental analyzer-IRMS.

Microscopic Reaction Mechanisms of Formic Acid Generated During Pyrolysis of Cellulosic Insulating Paper

Cellulosic insulating paper is the essential component of the insulation in power transformers. Under the thermal stress inside the transformer, the cellulosic insulating paper degrades and generates formic acid. Meanwhile, the presence of formic acid further accelerates the aging process of cellulosic insulating paper. This study takes the cellulose molecule composed of D-glucose as the research object. The ReaxFF reactive force field is applied to simulate the high-temperature thermal aging process of cellulosic insulating paper. During pyrolysis process, the number of formic acid molecules presents short-term fluctuations and continuous increases. Though simulation, the main reaction pathways of cellulose pyrolysis to generate formic acid are obtained. In addition, an accelerated thermal aging experiment of oil-paper insulation is designed. The formic acid in the experimental samples is detected by the silanization derivatization method. Through the combination of simulation and experimental results, the feasibility of formic acid as an aging indicator for cellulosic insulating paper is further demonstrated.

Rapid profiling strategy for oligosaccharides and polysaccharides by MALDI TOF mass spectrometry

The application of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI TOF MS) in glycan was limited due to their poor ionization efficiency, compared with biomolecules such as proteins and peptides. Aiming to improve the ionization efficiency and simplify preparation procedure simultaneously during MALDI MS analysis, an on-target derivatization method using 3-aminoquinoline (3-AQ)/α-cyano-4-hydroxycinnamic acid (CHCA) as matrix was employed and it was conducted both in the positive and negative ion MALDI TOF MS. Results indicated that after on-target derivatization, the ions generated had substantially improved S/N ratios and sensitivity in the tandem mass spectra. The B/Y− type ions of 3-AQ-labeled glycans could be easily recognized, and cross-ring A− type ions provided additional information to reveal the linkage patterns. Specifically, positive ion mass spectra with protonated adduct as precursor ion produced a simple fragmentation pattern benefited for sequencing and observation of branches. Furthermore, this method was successfully applied in polysaccharides analysis, including arabinoxylan, xylan, arabinogalactan and dextran after enzymatic or acid degradation. This study demonstrated that it was feasible to analyze higher molecular weight polysaccharides by MALDI TOF MS using 3-AQ/CHCA matrix through appropriate hydrolysis, and it allowed much efficient structural interpretation with increased sensitivity and characteristic fragment ions.

Marker Compounds Adsorbed on Dust Particles (PM10) Sampled According to Standard EN 12341 in the Outdoor Air Near the Cement Plant

Compounds adsorbed onto PM10 in the air near the cement plant were determined. Several side reactions that occur in the hot flue gas stream at the same time as the actual main reactions are also possible. This leads to the formation of traces of organic nitrogen compounds. For the GC/MS determination of polar organic compounds silylation as a derivatization method was used. Organic compounds detected are derivatives of sugars, sugar alcohols, and mono-, di- and tri-carboxylic acids. The composition is characteristic for pollution of the urbane atmosphere. Nitrogen organic compounds formed during the urea thermolytic process in hot cement kiln gases represent parabanic acid, 5-hydroxyhydantoin, 4,5-dihydroxyhydantoin, 5-oxoproline, and cyanuric acid. The inorganic part of aerosols detected includes oxyanions of sulfamic acid, sulfate, sulfite, phosphate, and vanadate(V) with ammonium as a cation. Chemical compositions of particles are crucial to assess the health impacts since the biological responses to aerosols are not always linked with major constituents but rather with toxicologically potent minor components.

Determination of Formaldehyde Yields in E-Cigarette Aerosols: An Evaluation of the Efficiency of the DNPH Derivatization Method

Recent reports have suggested that (1) formaldehyde levels (measured as a hydrazone derivative using the DNPH derivatization method) in Electronic Nicotine Delivery Systems (ENDS) products were underreported because formaldehyde may react with propylene glycol (PG) and glycerin (Gly) in the aerosol to form hemiacetals; (2) the equilibrium would shift from the hemiacetals to the acetals in the acidic DNPH trapping solution. In both cases, neither the hemiacetal nor the acetal would react with DNPH to form the target formaldehyde hydrazone, due to the lack of the carbonyl functional group, thus underreporting formaldehyde. These reports were studied in our laboratory. Our results showed that the aerosol generated from formaldehyde-fortified e-liquids provided a near-quantitative recovery of formaldehyde in the aerosol, suggesting that if any hemiacetal was formed in the aerosol, it would readily hydrolyze to free formaldehyde and, consequently, form formaldehyde hydrazone in the acidic DNPH trapping solution. We demonstrated that custom-synthesized Gly and PG hemiacetal adducts added to the DNPH trapping solution would readily hydrolyze to form the formaldehyde hydrazone. We demonstrated that acetals of PG and Gly present in e-liquid are almost completely transferred to the aerosol during aerosolization. The study results demonstrate that the DNPH derivatization method allows for an accurate measurement of formaldehyde in vapor products.

Synthesis, spectroscopic and computational evaluation of a xanthene-based fluorogenic derivatization reagent for the determination of primary amines

To detect an analyte, typically at the sub-nanomolar scale, extremely sensitive analytical tools are required. Fluorescence is the spectroscopy of choice to achieve such a level due to its non-invasive nature and efficiency in accurately probing the sub-nanomolar concentration range. Here, we report the design, synthesis and photophysical characterization of a fluorogenic derivatization reagent with exclusive selectivity for primary amines. This xanthene-based dye owns an exacerbated fluorogenic character making the derivatized amine absorbing in yellow and emitting in the vermilion edge. In addition to being fluorogenic, this derivatization method also has the crucial advantage of being chromogenic (colorless => fuchsia). Chemical quantum calculations give an insight into the dye's molecular properties, while the development of an LC analytical method provides proof of concept regarding its application for the analysis of primary amines in a complex matrix.

A novel strategy for high-specificity, high-sensitivity, and high-throughput study for gut microbiome metabolism of aromatic carboxylic acids

Aromatic carboxylic acids (ACAs) may be as transformed key metabolites via gut microbiome for playing better pharmacological effects. However, it's rare to achieve high-specificity, high-sensitivity, and high-throughput detection simultaneously, especially, for tracing trace ACAs in gut microbiome. In this work, firstly, a novel dual-template and double-shelled molecularly imprinted 96-well microplates (DDMIPs) was designed and amplified signal for p-hydroxybenzoic acid (PBA) and 3,4,5-trimethoxycinnamic acid (TMA). Additionally, the DDMIPs and a stable isotope labeling derivatization (SILD) method combined with the ultra-high performance liquid chromatography triple quadrupole tandem mass spectrometry (UHPLC-TQ MS) was firstly stepwise integrated, achieving high-effective, high-sensitive, and high-throughput study of gut microbiome metabolism. The whole strategy showed lower limits of detections (LODs) up to 1000 folds than the traditional method, and revealed a more real metabolism-time profile of PBA and TMA by 3-step signal amplification. The platform also laid the foundation for fast, simple, high-selective, high-effective, and high-throughput metabolism and pharmacological research.

Progress of sample preparation and analytical methods of dried fruit foods

坚果、果脯等干果类食品含有丰富的营养成分,深受国内外广大消费者的喜爱。但这些食品在果实生产、加工、储运时会使用农药或产生霉变等,造成干果中农药、重金属、霉菌毒素或添加剂等有害成分残留,甚至超过国家限量要求,带来严重的食品安全问题。因此,加强干果类食品的质量监督具有重要的经济和社会意义。但干果类食品基质复杂,有害物质种类多,结构和性质差异大,含量低,其分析检测需要快速高效的样品前处理技术和准确灵敏的分析检测方法。该文主要综述了近十年来干果类食品中有害物质的样品前处理及分析检测方法研究进展。其中样品前处理方法主要包括各种场辅助萃取法、相分离法和衍生化萃取方法等。场辅助萃取法主要是借助超声波和微波场等外场(协同)作用加快干果中有害物质的溶出速度,提高其萃取效率。相分离法,包括固相(微)萃取、分散固相萃取和液相(微)萃取法等,具有溶剂消耗少、分离富集效率高的优势,是干果样品分析中较常使用的前处理方法。该文还重点介绍了干果中各类有害成分分析检测技术,主要包括色谱、原子光谱、无机质谱、电化学分析等常规实验室方法,以及一些适用于现场分析的快速检测技术,并以此为基础,展望了干果类食品中有害物质分析检测技术的发展趋势。

합성제올라이트의 폼알데하이드 흡착능 평가

In this study, the adsorption capacity of formaldehyde was analyzed by using Activated Carbon and five types of synthetic zeolite. The experiments were conducted according to 2,4-dinitrophenylhydrazine (DNPH) derivatization and high pressure liquid chromatography (HPLC) methods for analysis of formaldehyde. The adsorption capacity of formaldehyde was discussed by outflow/inflow of concentration, amount of adsorption per gram of adsorbent, averaged removal rate and economic evaluation. Total amount of adsorption per gram of adsorbent decreased steadily for increasing the fill amount of adsorbent. The most amount of adsorption was represented for Beta Zeolite Fe, but the economic evaluation was relatively high for Zeolite A. Activated Carbon showed relatively superior persistence of adsorption in the adsorption experiment for 200 minutes. The stability of adsorption was evaluated to relatively superior for Zeolite X in the repeated experimental results of the 20 minutes adsorption for formaldehyde. This study suggested that the selective use of various synthetic zeolite may be useful for formaldehyde removal considering adsorption capacity and economic feasibility.

A robust method for simultaneous quantification of eugenol, eugenyl acetate, and β-caryophyllene in clove essential oil by vibrational spectroscopy

Attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy in tandem with chemometrics was used for accurate quantification of total eugenol, eugenyl acetate, and β-caryophyllene compounds of clove oil (CO) using partial least squares (PLS) regression with various spectral derivatization methods. A set of six of the fifty-one CO samples was chosen to build up the calibration sets for the compounds, while the rest were selected as the prediction set. Data for total eugenol, eugenyl acetate, and β-caryophyllene was acquired by gas chromatography-mass spectrometry (GC-MS) and used as reference values for ATR-FTIR calibration. The best calibration results were achieved using raw spectra in the region 1560-1480, 1814-1700, and 2954-2780 cm−1 for total eugenol, eugenyl acetate, and β-caryophyllene with high regression coefficients (R-square) of 0.9999, 0.9966, and 0.9997, respectively and low root mean square error of prediction (RMSEP) values of 0.5054%, 0.2330%, and 0.4593%, respectively. The results of the study indicated that ATR-FTIR with PLS regression could be used for accurate and simultaneous quantification of total eugenol, eugenyl acetate, and β-caryophyllene compounds of COs without using any toxic chemicals or pretreatments.

Amine-Rich Coatings to Potentially Promote Cell Adhesion, Proliferation and Differentiation, and Reduce Microbial Colonization: Strategies for Generation and Characterization

Biomaterial surface modification represents an important approach to obtain a better integration of the material in surrounding tissues. Different techniques are focused on improving cell support as well as avoiding efficiently the development of infections, such as by modifying the biomaterial surface with amine groups (–NH2). Previous studies showed that –NH2 groups could promote cell adhesion and proliferation. Moreover, these chemical functionalities may be used to facilitate the attachment of molecules such as proteins or to endow antimicrobial properties. This mini-review gives an overview of different techniques which have been used to obtain amine-rich coatings such as plasma methods and adsorption of biomolecules. In fact, different plasma treatment methods are commonly used with ammonia gas or by polymerization of precursors such as allylamine, as well as coatings of proteins (for example, collagen) or polymers containing –NH2 groups (for example, polyethyleneimine). Moreover, this mini-review will present the methods used to characterize such coatings and, in particular, quantify the –NH2 groups present on the surface by using dyes or chemical derivatization methods.

Real-time Raman analysis of the hydrolysis of formaldehyde oligomers for enhanced collagen fixation

Formaldehyde (FA) is widely applied as a fixative for proteins such as collagen. Current studies have confirmed that the reversible oligomer-to-monomer equilibrium of FA in aqueous solution and the proportion of FA monomer is a significant factor affecting tissue fixation. Since the hydrolysis of FA oligomers is a dynamic process affected jointly by different factors, its real time monitoring has proved to be challenging. In this work, by utilizing the well-established Raman technique as an analytical platform, we identified the factors affecting the hydrolysis of FA oligomers by rationally examining the νs (OCO) and νas (OCO) modes with varying conditions, such as time, pH, temperature, and FA concentration. The optimized conditions of the highest hydrolysis rate of oligomers into monomers for fixation on collagen and tissues have been found to be relatively low FA concentration (≤5%) in phosphate-buffered saline at pH 9.0 in room temperature. In order to compare the fixation quality of the optimized conditions to that of the conventional conditions used by current medical practices (4% FA concentration in tap water under room temperature), Raman spectroscopy and chemical derivatization methods with o-phthalaldehyde and fluorescent probe FAP-1 have been investigated, and our results revealed that the FA molecules under our optimized conditions have reacted with at least 15% more amino groups within collagen compared to those under the conventional conditions mentioned above. This study provides direct evidence of the FA equilibrium in solution by Raman spectroscopy, which could be applied for the optimal use of FA in medicine, even at an industrial scale.

Micellar-enhanced thermochemically induced fluorescence derivatization (ME-TIFD) method for the determination of metolachlor herbicide residues in water

A sensitive micellar-enhanced thermochemically induced fluorescence derivatization (ME-TIFD) method for a rapid determination of metolachlor (MET) residues based on the O-phthalaldehyde (OPA)-thermoproduct complex of MET (OPA-MET) was investigated. Both SDS and Brij-700 have been used as surfactant micelles. This study advocates the TIFD method analytical parameters curation. Fluorescence enhancement and its stabilization were highlighted for the OPA-MET equimolar complex in micellar aqueous solutions. The new analytical features (K: binding constant and ΔG°: Gibbs energy) for controlling thermodynamic interactions were carried out at 25 °C. Under the optimized conditions, the calibration curves were linear with correlation coefficients ranging from 0.9788 to 0.9896 at the concentration level of 10-580 ng mL–1, and the limits of detection were 0.04-0.7 ng mL−1 at a signal-to-noise (S/N) of 3. The SPE/ME-TIFD applications combined with analysis of well and tap water spiked samples with metolachlor yield satisfactory mean recoveries (RSD) 102.2–108.1% (5.1–7.3%) and 103.6–106.0% (6.3–7.6%), respectively.

Validation of phytosterol analysis by alkaline hydrolysis and trimethylsilyl derivatization coupled with gas chromatography for rice products

In this study, the alkaline hydrolysis and trimethylsilyl derivatization method coupled with gas chromatography-flame ionization detection was validated for phytosterol analysis and then applied for determination of major phytosterols (β-sitosterol, campesterol, and stigmasterol) in rice products highly consumed in Asian countries. Recoveries of three phytosterols from brown rice, rice bran oil and standard reference material-3251 were 87.6–104.4%, 87.7–107.6%, and 92.6–99.1%, respectively, showing good accuracy of analysis. Excellent precision of phytosterol analysis was achieved from repeatability (RSD <4%), reproducibility (RSD <8%) and HorRat ratio (0.3 ≤ HorRatr/HorRatR ≤ 1.0). Limit of quantitation of phytosterol analysis was 0.08–0.09 mg/100 g, showing high sensitivity of analysis. The total phytosterol contents (sum of major phytosterols) of rice products ranged from 18.88 to 1375.47 mg/100 g, which was high in the order of rice bran oil, rice germ, brown rice, rice with large germ, white rice and puffed rice. β-Sitosterol was the most predominant phytosterol in all rice products, which composed about 58.4–63.6% of the total phytosterols. White rice showed much lower phytosterol levels than brown rice and rice bran oil. However, it could be a good source of phytosterols because of the quantity daily consumed.

Determination of cyanogen chloride in organic and water matrices by gas chromatography-mass spectrometry based on thiol derivatization

氯化氰(ClCN)是常用的化工中间体,也是《禁止化学武器公约》附表颁布的化学毒剂之一。采用传统的比色法或气相色谱法对ClCN进行分析时,稳定性差且检出限高。研究建立了有机相及水相中ClCN的巯基化衍生过程及气相色谱-质谱(GC-MS)的检测方法。经比较后选择1-丁基硫醇作为衍生试剂,有机相中ClCN的衍生条件为衍生温度40 ℃,体系pH=9,反应时间10 min,反应结束后直接进行GC-MS分析。水相中ClCN的衍生条件与有机相相同,衍生完毕后进行顶空-固相微萃取(HS-SPME)。实验考察了萃取温度对萃取吸附效果的影响,确定最佳萃取温度为55 ℃。通过GC-EI/MS确认ClCN的巯基化衍生产物为硫氰酸丁酯,并对质谱图中主要的离子碎片进行结构确认。采用气相色谱-串联质谱法(GC-MS/MS)对硫氰酸丁酯裂解规律进行了分析。采用GC-MS/SIM对有机相及水相中的ClCN进行分析。方法学考察结果表明,ClCN在有机相(20~2000 μg/L)及水相(20~1200 μg/L)中相应的范围内线性关系良好(相关系数(R 2)>0.99);在3个添加水平下有机相中CICN的回收率为87.3%~98.8%,不同的水相基质中CICN的回收率为97.6%~102.2%, RSD分别为2.1%~4.7%和2.8%~4.2%,衍生过程具有良好的专属性。采用禁止化学武器公约组织(OPCW)的水平考试空白有机样品(样品基质为正己烷)对研究方法进行验证,该方法能够成功检出目标物。该研究建立的巯基化衍生-气相色谱-质谱法灵敏度高,精密度好,能够为环境中ClCN的定性定量分析提供技术支持。