A simple method for the simultaneous derivatization of carbohydrates, polyols, amines and amino acids using hexamethyldisilazane and N,O‐bis(trimethylsilyl)trifluoroacetamide was developed. This method allows the direct derivatization of urine samples without sample pretreatment before derivatization. The method was successfully used for analysis of the selected metabolites in urine samples of healthy individuals and neonates suffering from galactosemia. The limits of detection by positive chemical ionization gas chromatography with tandem mass spectrometry analysis were in the range of 1.0 mgL‐1 for mannitol to 4.7 mg/L for glucose. 相似文献
Several extraction and derivatization procedures were evaluated for the quantification of (2-methoxyethoxy)acetic acid (MEAA)
in urine. MEAA is a metabolite and a biomarker for exposure to 2-(2-methoxyethoxy)ethanol, a glycol ether with widespread
use in various industrial applications and the specific use as an anti-icing additive in the military jet fuel formulation
JP-8. Quantification of glycol ether biomarkers is an active area of analytical research. Various sample preparation procedures
were evaluated: liquid–liquid extraction (LLE) using ethyl acetate yielded the highest recovery, and solid-phase extraction
(SPE) gave low recovery of MEAA. Two derivatization procedures were thoroughly investigated and validated, namely, silylation
of MEAA with N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA), and esterification of MEAA using ethanol. Quantification was performed by
gas chromatography (GC) with a mass spectrometer as detector and using a polydimethylsiloxane (HP-1) capillary column. Deuterated
2-butoxyacetic acid (d-BAA) was used as an internal standard. Recovery studies of spiked human urine demonstrated the accuracy
and precision of both procedures. The limit of detection (LOD) and other figures of merit for both derivatization procedures
will be discussed in detail. Applications of these analysis procedures are also discussed.
Disclaimers Mention of company names and/or products does not constitute endorsement by the Centers for Disease Control and Prevention
(CDC). The findings and conclusions in this report are those of the authors and do not necessarily represent the views of
the National Institute for Occupational Safety and Health. 相似文献
The trimethylsilyl (TMS) derivatives of a mixture of nine bile acids (six free and three conjugated), namely lithocholic, deoxycholic, chenocholic, cholic, hyodeoxycholic, ursodeoxycholic, glycodeoxycholic, glycocholic and glycochenodeoxycholic acids, have been prepared by a new, simple, efficient derivatization procedure, based on the use of a mixture of N -methyl- N -trimethylsilyl-1,1,1- trifluoroacetamide and 1-(trimethylsilyl)imidazole, as the silylating agent. The above-mentioned bile acids were completely trimethylsilylated on all hydroxyl and carboxyl groups whereas carbonyl and amino groups remained untouched. 相似文献
Summary: Carboxylic acids were efficiently activated with N,N′‐carbonyldiimidazole (CDI) and applied for the acylation of cellulose under homogeneous conditions using dimethyl sulfoxide (DMSO)/tetrabutylammonium fluoride trihydrate (TBAF) as solvent. The simple and elegant method is a very mild and easily applicable tool for the synthesis of pure aliphatic, alicyclic, bulky, and unsaturated cellulose esters with degrees of substitution of up to 1.9. Products are soluble in organic solvents, e.g., DMSO or N,N‐dimethylformamide (DMF). The cellulose esters were characterized by elemental analysis, FT‐IR, 1H and 13C NMR spectroscopy and show no impurities or substructures resulting from side reactions.
The esterification of cellulose using carboxylic acids activated in situ with N,N′‐carbonyldiimidazole. 相似文献
Simplified method for simultaneous identification of proteins, drying oils, waxes, and resins in the works‐of‐art samples was developed. Liquid chromatography with mass spectrometry and gas chromatography with mass spectrometry were used to identify natural materials most frequently encountered in historical paintings. Protein binders were extracted with ammonia and purified using miniaturized solid‐phase microextraction (Omix tips) to efficiently suppress matrix interferences. Zwitterionic stationary phase was used for separation of 16 underivatized amino acids analysis with hydrophilic interaction liquid chromatography that was subsequently quantified with liquid chromatography with mass spectrometry. Gas chromatography with mass spectrometry was used to analyze drying oils, waxes, and resins after one‐step saponification/transmethylation with (m‐trifluoromethylphenyl)trimethylammonium hydroxide (Meth‐Prep II). While the drawback of this reagent is low reactivity towards hydroxyl groups, sample pretreatment was much simpler as compared to the other methods. Fatty acids derivatization with the Meth‐Prep II reagent was compared with their silylation using N,O‐bis(trimethylsilyl) trifluoroacetamide/trimethylchlorosilane mixture. It was concluded that fatty acids analysis as their methyl esters instead of trimethylsilyl esters had a minor impact on the method sensitivity. The developed method was used to analyze samples from 16th and 17th century historical paintings. 相似文献
Summary Fragmentation patterns of the essential amino acids (AAs) as their silyl derivatives have been obtained with the aid of ion
trap detection (ITD). Three derivatizing reagents, hexamethyldisilazane+trifluoroacetic acid (HMDS+TFAA),bis-(trimethylsilyl)trifluoroacetamide (BSTFA) andN-methyl-N-(t-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) were used. Simple and multiple derivatives obtained with each reagent have
been investigated, with regard to their sensitivity and selectivity.
Our study performed in the concentration range of 5-2000 ng amino acids has shown that, contrary to literature data, thirteen
of the twenty-two AAs investigated including the TBDMS derivatives give rise to more than one peak when eluted. As a result
of ion/molecule interaction the very informative ions of high masses, ([M]+, [M+TMS/(TBDMS)]+, [M+1]+) are formed with considerable intensities. The fragments [M-CH3]+, [M-C4H9]+, [M-(CH3)2Si]+, [M-TMS/(TBDMS)COO]+, [M-TBDMSOH]+, [M-TBDMSO]+, [M-TBDMSNH]+ and numerous others could be utilized for identification purposes.
Presented at Balaton Symposium on High Performance Separation Methods, Siófok, Hungary, September 1–3, 1999 相似文献
Direct analysis in real‐time mass spectrometry (DART‐MS) with in situ silylation was used for the rapid analysis of the flavonoids silybin ((2R,3R)‐3,5,7‐trihydroxy‐2‐[3‐(4‐hydroxy‐3‐methoxyphenyl)‐2‐hydroxymethyl‐2,3‐dihydrobenzo[1,4]dioxin‐6‐yl]chroman‐4‐one) and rutin (quercetin‐3‐O‐rutinoside). Three different derivatization reagents, hexamethyldisilazane/trimethylchlorosilane/pyridine (HMDS/TMCS/pyridine), N,O‐bis(trimethylsilyl)acetamide/trimethylchlorosilane/N‐trimethylsilyimidazole (BSA/TMCS/TMSI), and N,O‐bis(trimethylsilyl)trifluoroacetamide/trimethylchlorosilane (BSTFA/TMCS), were applied. Silybin and rutin were detected with various degrees of silylation, and the formation of dimers with pyridine and imidazole was also observed. HMDS/TMCS/pyridine was the best choice for the DART‐MS analysis of silybin, and BSA/TMCS/TMSI was the most effective for the detection of rutin. The effects of the DART source temperature on desorption, ionization, in‐source fragmentation, dimer formation, and hydrolysis of the trimethylsilyl groups were also studied. In addition, the collision‐induced dissociation properties of the derivatized silybin and rutin were explored. With our in situ silylation method, the derivatized bioactive compounds in intact medical pills could also be detected by DART‐MS. 相似文献
Most previously described derivatization procedures with N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) or N-methyl-N-(trimethylsilyl)trifluoroacetamide (MSTFA) for the GC–MS analysis of steroids, such as estrone (E1), 17β-estradiol (E2), estriol (E3) and 17α-ethynylestradoil (EE2), used a heating process of 45–80 °C (typically 70 °C) for 25–60 min, usually in combination with a catalyst. However, we found that it is not necessary to heat and add catalyst for the derivatization with BSTFA. Best reaction conditions for MSTFA are heating at 70 °C for 10 min. Derivatization of EE2 using MSTFA without heating results in three products: TMS-E1, mono-TMS-EE2 and di-TMS-EE2.
A new approach to the selective comparative metabolite profiling of carboxylic acids in rat urine was established using CE‐MS and a method for positively pre‐charged and 2H‐coded derivatization. Novel derivatizing reagents, N‐alkyl‐4‐aminomethyl‐pyridinum iodide (alkyl=butyl, butyl‐d9 or hexyl), containing quaternary amine and stable‐isotope atoms (deuterium), were introduced for the derivatization of carboxylic acids. CE separation in positive polarity showed high reproducibility (0.99–1.32% RSD of migration time) and eliminated problems with capillary coating known in CE‐MS anion analyses. Essentially complete ionization and increased hydrophobicity after the derivatization also enhanced MS detection sensitivity (e.g. formic acid was detected at 0.5 pg). Simultaneous derivatization of one sample using two structurally similar reagents, N‐butyl‐4‐aminomethyl‐pyridinum iodide (BAMP) and N‐hexyl‐4‐aminomethyl‐pyridinum iodide, provided additional information for recognizing a carboxylic acid in an unknown sample. Moreover, characteristic fragmentation acquired by online CE‐MS/MS allowed for identification and categorization of carboxylic acids. Applying this method on rat urine, we found 59 ions matching the characteristic patterns of carboxylic acids. From these 59, 32 ions were positively identified and confirmed with standards. For comparative analysis, 24 standard carboxylic acids were derivatized by chemically identical but isotopically distinct BAMP and N‐butyl‐d9‐4‐aminomethyl‐pyridinium iodide, and their derivatization limits and linearity ranges were determined. Comparative analysis was also performed on two individual urine samples derivatized with BAMP and N‐butyl‐d9‐4‐aminomethyl‐pyridinium iodide. The metabolite profiling variation between these two samples was clearly visualized. 相似文献
Derivatization of amino acids by 2 M HCl/CH3OH (60 min, 80 °C) followed by derivatization of the intermediate methyl esters with pentafluoropropionic anhydride (PFPA) in ethyl acetate (30 min, 65 °C) is a useful two-step derivatization procedure (procedure A) for their quantitative measurement in biological samples by gas chromatography-mass spectrometry (GC-MS) as methyl ester pentafluoropropionic (PFP) derivatives, (Me)m-(PFP)n. This procedure allows in situ preparation of trideutero-methyl esters PFP derivatives, (d3Me)m-(PFP)n, from synthetic amino acids and 2 M HCl/CD3OD for use as internal standards. However, procedure A converts citrulline (Cit) to ornithine (Orn) and homocitrulline (hCit) to lysine (Lys) due to the instability of their carbamide groups under the acidic conditions of the esterification step. In the present study, we investigated whether reversing the order of the two-step derivatization may allow discrimination and simultaneous analysis of these amino acids. Pentafluoropropionylation (30 min, 65 °C) and subsequent methyl esterification (30 min, 80 °C), i.e., procedure B, of Cit resulted in the formation of six open and cyclic reaction products. The most abundant product is likely to be N5-Carboxy-Orn. The second most abundant product was confirmed to be Orn. The most abundant reaction product of hCit was confirmed to be Lys, with the minor reaction product likely being N6-Carboxy-Lys. Mechanisms are proposed for the formation of the reaction products of Cit and hCit via procedure B. It is assumed that at the first derivatization step, amino acids form (N,O)-PFP derivatives including mixed anhydrides. At the second derivatization step, the Cit-(PFP)4 and hCit-(PFP)4 are esterified on their C1-Carboxylic groups and on their activated Nureido groups. Procedure B also allows in situ preparation of (d3Me)m-(PFP)n from synthetic amino acids for use as internal standards. It is demonstrated that the derivatization procedure B enables discrimination between Cit and Orn, and between hCit and Lys. The utility of procedure B to measure simultaneously these amino acids in biological samples such as plasma and urine remains to be demonstrated. Further work is required to optimize the derivatization conditions of procedure B for biological amino acids. 相似文献
The effect of background derivatization on the signal enhancement of pesticide residues extracted from edible oil samples was studied by GC with negative chemical ionization MS. The analytes were extracted by a solvent extraction process, and the extract was subjected to rapid low‐temperature fat precipitation. The residual fatty acids were silylated by derivatization with N,O‐bis(trimethylsilyl)trifluoroacetamide. The chromatograms obtained from the derivatized samples showed higher signal intensity and lower detection levels when compared to the direct analysis without derivatization. The sensitivity levels of the method are either better or comparable to that of previously reported methodologies. The LODs of the analyzed organochlorine, organophosphorus, and synthetic pyrethroid residues in sunflower, rice bran, and ground oil samples were in the range of 0.02–0.5 ng/g, and the LOQs were in the range of 0.1–2 ng/g. The intraday and interday accuracies were in the range of 81–116% with RSDs less than 14%. The recoveries obtained were in the range of 53–89% with the RSD values less than 13% for all the studied pesticide residues. 相似文献
The interactions between calcite crystal and seven kinds of phosphonic acids, nitrilotris(methylphosphonic acid) (NTMP), nitrilo‐methyl‐bis(methylphosphonic acid) (NMBMP), N,N‐glycine‐bis(methylphosphonic acid) (GBMP), 1‐ hydroxy‐1,1‐ethylenebis(phosphonic acid) (HEBP), 1‐amino‐1,1‐ethylenebis(phosphonic acid) (AEBP), 1,2‐ethylenediamine‐N,N,N′,N′‐tetrakis(methylphosphonic acid) (EDATMP), and 1,6‐hexylenediamine‐N,N,N′,N′‐tetrakis‐ (methylphosphonic acid) (HDATMP) have been simulated by a molecular dynamics method. The results showed that the binding energy of each scale inhibitor with the (1l?0) (1l?0) face of calcite crystal was higher than that with (104) face, which has been approved by the analysis of pair correlation functions. The sequence of scale inhibition efficiencies for phosphonic acids against calcite scale is as follows: EDATMP>HDATMP>HEBP>NTMP>GBMP>HEBP>NMBMP, and the growth inhibition on the (1l?0) face of calcite was at the leading status. Phosphonic acids deformed during the binding process, and electrovalent bonds formed between the phosphoryl oxygen atoms in phosphonic acids and the calcium ions on calcite crystal. 相似文献
N-Methyl-N-tert-butyldimethylsilyltrifluoroacetamide (MTBSTFA) is a silylating agent with a range of applicability in clinical and environmental analysis, particularly when substrates possess at least moderate acidity. In this paper, we demonstrate its applicability and limitations as a reagent for environmental analysis by comparing and contrasting two different target analyte problems in a sewage effluent matrix. In one case, electron ionization was used for the determination of three potential endocrine disrupting compounds: 17β-oestradiol, ethynyl oestradiol, and oestrone where the phenolic functionality was silylated with MTBSTFA and compared with results using N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA) as the reagent. In this instance, a large volume of effluent was subjected to either solid-phase extraction followed by cleanup using high-performance gel permeation chromatography (AppI) or liquid/liquid extraction followed by SPE fractionation and HPLC fractionation (AppII). The method using BSTFA rather than MTBSTFA was demonstrated to work down to low and sub-ppt levels where the target compounds were found. In a parallel and contrasting study, sewage effluent was analysed for 3,5,6-trichloropyridinol (TCP) by extracting one liter of water using liquid–liquid extraction and determined by GC/MS operated in the negative ion chemical ionization (electron capture) mode after derivatization with MTBSTFA. TCP is the major metabolite of the commonly used insecticide, chlorpyrifos, and herbicide trichlorpyr. The recoveries using dichloromethane as the extractant were 59%, with a relative standard deviation of 2%. This method was used to investigate levels of TCP in sewage effluent. During this analysis, a tentatively identified additional isomer of TCP (X-TCP) was found. The 3,5,6-TCP, the common chlorpyrifos metabolite and the synthesized isomer, 3,4,5-TCP were compared with X-TCP. All three isomers have significantly different retention times. The average level of 3,5,6-TCP was 3.4?ng?L?1, while the level of X-TCP was 39.8?ng?L?1. The two approaches are compared and contrasted with respect to artefact formation and matrix component effects. The reagent MTBSTFA is found to be suitable for quantitative analysis of environmental samples for relatively acidic substrates (e.g. phenols and carboxylic acids). More powerful silylating agents such as N-methyl-N-trimethylacetamide or BSTFA are required for sterols and similar substrates. The stability of the two silylating reagents appears to be similar and practical for accurate quantitative analysis. Differences in EI spectra with respect to fragmentation may also dictate which reagent is preferred. 相似文献