Oxime-trimethylsilyl Derivatives Research Articles

Characteristic fragmentation patterns of trimethylsilyl and trimethylsilyl-oxime derivatives of plant disaccharides as obtained by gas chromatography coupled to ion-trap mass spectrometry

The characteristic fragmentation pattern of six reducing and two non reducing type disaccharides – (neohesperidose, acuminose, sambubiose, rutinose, vicianose, primverose, and two arabinosyl-inositols) has been described. These saccharides have not been previously identified by on-line chromatographic techniques. Unambiguous specific characteristics of the TMS (oxime)s such as mass distribution, syn/anti oximes ratios and elution order proved to be associated with their reducing or non reducing character, with their aldosyl property and with the position of their O-glycosidic linkages. The practical utility of the mass fragmentation study of these rare disaccharides was demonstrated, at the first time, by the simultaneous, on-line identification and quantification of the acuminose, vicianose, primverose and arabinosyl-inositol contents of tea leaves, from green and black tea blends of Indian and Chinese origin.

Cyclic Polyalcohols: Fingerprints To Identify the Botanical Origin of Natural Woods Used in Wine Aging

Cyclic polyalcohol composition of 80 natural wood samples from different botanical species, with the majority of them used in the oenology industry for aging purposes, has been studied by gas chromatography-mass spectrometry (GC-MS) after its conversion into their trimethylsilyloxime derivatives. Each botanical species showed a different and specific cyclic polyalcohol profile. Oak wood samples were characterized by the richness in deoxyinositols, especially proto-quercitol. Meanwhile, other botanical species showed a very low content of cyclic polyalcohols. The qualitative and quantitative study of cyclic polyalcohols was a useful tool to characterize and differentiate woods of different botanical origin to guarantee the authenticity of chips used in the wine-aging process. Monosaccharide composition was also analyzed, showing some quantitative differences among species, but cyclic polyalcohols were the compounds that revealed the main differentiation power.

Gas chromatographic–mass spectrometric characterisation of tri- and tetrasaccharides in honey

A GC–MS method has been used to characterize tri- and tetrasaccharides in honey after their derivatization into trimethylsilyloxime derivatives. Based on retention data and mass spectra, a total of 25 trisaccharides were characterized; 12 being unequivocally identified using standards and two of them detected for the first time in honey. Erlose and panose were the major trisaccharides in the 12 honeys under analysis, their concentrations ranging 30–1214 mg 100 g −1 of honey and 17–863 mg 100 g −1 of honey, respectively. The GC–MS method also allowed the analysis of tetrasaccharides. Besides nystose, another nine tetrasaccharides were characterized; six of them were sucrose derivatives. Tetrasaccharides were present in concentrations lower than 230 mg 100 g −1 of honey.

Characteristic fragmentation patterns of the trimethylsilyl and trimethylsilyl–oxime derivatives of various saccharides as obtained by gas chromatography coupled to ion-trap mass spectrometry

The fragmentation patterns of selected glycosidic linkage containing non-reducing (methylmannoside, methylgalactoside, lactitol, sucrose, trehalose, raffinose, erlose, melezitose) and reducing saccharides (maltose, cellobiose, lactose, melibiose, palatinose, primeverose, rutinose) have been compared as their trimethylsilyl and as their trimethylsilyl–oxime derivatives. Fragmentation characteristics of the glycosidic linkage containing trimethylsilyl–oxime derivatives have been investigated at the first time: these spectra are not available in the official libraries (NIST, Wiley). Applying gas chromatography-ion trap mass spectrometry, informative fragments of high masses with high intensities have been obtained. Results confirmed characteristic differences between the simple trimethylsilyl derivative providing non-reducing glycosides and the trimethylsilyl, syn and antioxime species. Fragmentation starts at the glycosidic linkage resulting in the case of the non-reducing di- and trisaccharides in two, identical fragments of ring structure, with the abundant selective fragment ion at m/ z = 361. In the case of reducing disaccharides fragmentation provides two different moieties: one moiety of ring structure at m/ z = 361, and one of the open chain trimethylsilyl–oxime moiety with two special fragment ions at m/ z = 361 and at m/ z = 538. These fragmentation patterns proved to be independent on the position of the glycosidic linkage. Distribution of the selective fragment ions, obtained from their total ion current elutions, was evaluated on a quantitative basis, expressed in percentages of the total of ions formed. Reproducibility in the formation of these selective fragment ions, depending on their amount to be fragmented, proved to be proper for identification and quantitation purposes, equally. On this basis, in addition to the authentic ones, also two reducing disaccharides (primeverose and rutinose), as authentic compounds not available on the market, were identified and quantified in natural matrices.

Microwave-Assisted Derivatization of Glucose and Galactose for Gas Chromatographic Determination in Human Plasma

Monosaccharides are usually analyzed by use of automatic monitors or enzymatic immunoassays. However, gas chromatography (GC) is an accurate and precise technique for galactose quantification (1), and it is regarded as a reference method for glucose (2). GC procedures require a long derivatization time in 2 consecutive reactions of 60–90 min to generate the aldonitrile pentaacetate derivative. Fast derivatization techniques are often requested today because the bottleneck for sample throughput has moved from analysis to sample preparation. Recently, we dramatically decreased the derivatization time for sugars (mono- and disaccharides) in GC analysis (3) by using trimethylsilyl-oxime derivatives. This derivative, however, gives …

Determination of Oligofructose, a Soluble Dietary Fiber, by High-Temperature Capillary Gas Chromatography

A high-temperature capillary gas chromatographic method was developed for the quantitative determination of oligofructose in foods and food products. Sample preparation involves oxymation and silylation of the extracted sugars. The oximetrimethylsilyl derivatives are analyzed on an apolar capillary column, with detection by flame ionization. The method is accurate, with recovery of spiked samples at >96%. Repeatability was excellent; RSD values of 1.1% were obtained. Other common oligosaccharides, such as malto-, isomalto-, and galactooligosaccharides, and levan do not interfere, making the method specific and reliable.

Sugar profiles of Spanish unifloral honeys

The levels of various sugars (fructose, glucose, sucrose, maltose, maltulose, kojibiose, isomaltose, raffinose, erlöse and melezitose) as well as the glucose/fructose and glucose/water ratios were determined in different Spanish unifloral honey types (rosemary, orange blossom, lavender, sunflower, eucalyptus, heather, honeydew). Sugars were determined by gas chromatography of the trimethylsilyloxime derivatives. There were significant differences among the honey types in relation to sugar composition. Fructose, glucose, sucrose, maltose and the glucose/water ratio were selected by discriminant analysis as the better parameters for the correct classification of the honey samples into their parent types. These sugars appear to be very valuable as characterization parameters for honeydew honey, followed by sunflower, heather and eucalyptus honeys, with 100%, 92.9%, 83.3% and 75.0% correct classifications, respectively. For the remaining honey types the percentages of successful classifications ranged from 53.8% to 69.2%.

Influence of the storage conditions on some physicochemical and mycological parameters of honey

AbstractThe authors studied the changes in yeast and mould counts, pH, free and lactone acidity, colour and sugar composition undergone by honeys with water contents of 169, 188 and 220 g kg‐1 on storage at refrigeration temperature (4–7°C), room temperature and 28°C for two years. Of the solid culture media assayed, honey agar and osmophilic medium fostered yeast growth while malt‐extract agar and yeast‐extract‐malt‐extract agar allowed for better development of filamentous fungi. The yeasts isolated belonged to the genera Saccharomyces, Schizosaccharomyces and Zygosaccharomyces, while filamentous moulds were of the genera Aspergillus, Penicillium, Fusarium and Alternaria. The honeys studied underwent no visible microbial alternations under any of the conditions tested, although yeast population increased significantly with time. Free and lactone acidity increased slightly but the pH was practically constant. The honeys darkened gradually with time, the effect increasing with the storage temperature. The analysis of various sugars carried out by capillary column gas chromatography of their trimethylsilyloxime derivatives indicated that all of them changed significantly after 2 years. Levels of fructose, glucose, sucrose, maltose, kojibiose, isomaltose and trisaccharides decreased with time whereas those of maltulose and turanose increased over the same period.

Biosynthesis and characterization of 3-hydroxyalkan-2-ones and 2,3-alkanediols: potential products of aldehyde metabolism.

A mass spectrometric study of an enzymatic synthesis of 3-hydroxyalkan-2-ones (acyloins) is presented. Incubation of pyruvate or (13C3)pyruvate and various alkanals in the presence of pig heart pyruvate dehydrogenase or yeast pyruvate decarboxylase resulted in the formation of acyloins with chains two carbons longer than the alkanals. Product formation was rapid for all saturated aldehydes with chain lengths from 2 to 12 carbons. Incubation with 2,3-unsaturated aldehydes did not produce condensation products. Reduction of acyloins with sodium borohydride produced the corresponding 2,3-alkanediols. Analysis by gas chromatography/mass spectrometry was used to characterize the 3-hydroxyalkan-2-ones as the oxime-trimethylsilyl derivatives and the 2,3-alkanediols as the bistrimethylsilyl derivatives.

Mass spectrometric analysis of metabolite excretion in five Japanese patients with the late-onset form of glutaric aciduria type II

The variability of clinical and biochemical features in five Japanese patients with the late-onset form of glutaric aciduria type II (GAII) was studied using mass spectrometric procedures. The age at onset ranged from 5 months to five years, presenting acute episodes such as lethargy, hypotonia, hyperammonaemia, hypoglycaemia or Reye's syndrome-like illness, while one of the five cases was asymptomatic at 1 year of age. Organic acid analysis as oxime-trimethylsilyl derivatives by gas chromatography/mass spectrometry revealed the presence of several abnormalities characteristic of GAII in clinically asymptomatic conditions of three patients but not of the two others. Quantitative acylglycine analysis using a stable isotope dilution method and qualitative acylcarnitine analysis by fast atom bombardment mass spectrometry provided diagnostic information in all five patients, regardless of their clinical conditions. However, significant differences in the respective metabolite profiles as well as in their clinical pictures were noted. Although an increased excretion of both isovalerylglycine and isovalerylcarnitine was found in four patients, the fifth showed normal isovalerylglycine excretion during both the acute stage and in remission, despite the increased amount of isovalerylcarnitine in urine. From these results, it was suggested that the variations in clinical severity and metabolite excretion among GAII patients may be attributed not only to the residual enzyme activity at the defective site but also to differences in the capability to conjugate accumulated acyl-coenzyme A.

Metabolic Profiling of Urinary Organic Acids by Single and Multicolumn Capillary Gas Chromatography

High-resolution gas chromatography (HRGC) and gas chromatography/mass spectrometry (GC/MS) are the techniques of choice to determine the retention indices of more than 200 organic acids as their trimethylsilyl (TMS) or oxime-trimethylsilyl derivatives. Several types of apolar and semipolar fused-silica capillary columns (OV-1, SE-52, and OV-1701), used to analyze and separate organic acids isolated from urine samples, are evaluated.

Identification of polysaccharides in pharmaceuticals by capillary gas chromatography

A sensitive method for the identification of polysaccharides in pharmaceuticals is described. Polysaccharides are isolated by gel filtration and subsequently hydrolysed. The monomeric carbohydrates obtained are transformed into oxime-trimethylsilyl derivatives and analysed by capillary gas chromatography. Profiles of 13 different natural or semi-synthetic polysaccharides are discussed. The profiles of the hydrolysis products can be used to identify the polysaccharides mentioned above. Possible interferences by other polymers are given. The method can be used to identify most polysaccharides used as pharmaceutical adjuvants.

End products of glucose and glutamine metabolism by L929 cells.

Products of glucose and glutamine metabolism by L929 cells were detected and quantitated by gas chromatography and mass spectrometry of the oxime-trimethylsilyl derivatives. This method allowed detection and identification of all major carboxylic and amino acids produced in the system. Although lactic acid was expected to be the major product, alanine, citric, glutamic, aspartic, and pyruvic acids were also released into the culture medium at significant rates. Incorporation of labeled carbon from D-[U-13C]glucose showed that the alanine, lactic, and pyruvic acids were derived from glucose as was one-third of the citric acid carbon. The rate of glucose utilization for production of these end products was 29-fold greater than the rate of glucose oxidation to CO2, and calculated ATP production from alanine and pyruvate synthesis exceeded that from lactate synthesis by nearly 2-fold. Utilization of glutamine for synthesis of aspartic, glutamic, and citric acids also exceeded the rate of glutamine oxidation, thereby making end-product synthesis from glucose and glutamine the dominant cellular metabolic activity. In the absence of glucose, synthesis and intracellular levels of aspartic and glutamic acids increased, whereas synthesis and cell content of the other acids decreased markedly. This response is consistent with the metabolic pattern proposed by Moreadith and Lehninger (Moreadith, R.W., and Lehninger, A.L. (1984) J. Biol. Chem. 259, 6215-6221) in which much of the glutamine used by these cells is converted to aspartate in the absence of a pyruvate source and to aspartate or citrate in the presence of pyruvate.

Calculation of Flame Ionization Detector Relative Response Factors Using the Effective Carbon Number Concept

Equations are given for relating flame ionization detector relative response factors to the effective carbon number (ECN) of neat and derivatized components. The ECN ap­ proach can be used for calculating relative response fac­ tors in cases where pure materials are not available for detector calibration. Examples of this approach are given for the analysis of polycyclic aromatic hydrocarbons and oxygenated organics in neat form, alcohols and acids as the trimethylsilylated derivatives, and carbohydrates as the trimethylsilyl-oxime derivatives.

GC Analysis of C2-C7 Carbohydrates as the Trimethylsilyl-oxime Derivatives on Packed and Capillary Columns

GC Analysis of C2-C7 Carbohydrates as the Trimethylsilyl-oxime Derivatives on Packed and Capillary Columns

Analysis of oxime-trimethylsilyl derivatives of organic acids on OV-1701 fused silica capillary column

Analysis of oxime-trimethylsilyl derivatives of organic acids on OV-1701 fused silica capillary column

Urinary organic acids quantitated by age groups in a healthy pediatric population.

Urine samples from 92 individuals of a healthy pediatric population ranging in age from less than 24 h to 12 years were analyzed for organic acid content (amino acids excepted). A few samples from adults were included for purposes of comparison. Acids were extracted by using an anion-exchange procedure, converted to trimethylsilyloxime derivatives, and analyzed by gas chromatography with the help of a small computer system. Identifications were confirmed by using a combined gas chromatograph/mass spectrometer/computer system. The data has been tabulated according to five pediatric age groups. Despite large individual variation within age groups, significant differences in amounts of several acids excreted (based on urinary creatinine concentration) have been determined between age groups. Such differences might be due to one or a combination of several factors, including changes with age in creatinine excretion, in physiologic maturity, and in diet. Such data may help to provide a basis for diagnosing metabolic abnormalities in pediatric patients.

Gas-chromatographic analysis of sugars and related hydroxy acids as acyclic oxime and ester trimethylsilyl derivatives

A g.l.c. method which makes possible the simultaneous analysis of the common types of acidic and neutral sugars is described. Particular advantages are achieved with hydroxy acids, ketoses, and uronic acids. Acids and lactones are first converted into their sodium salts. Free or potential aldehydo and keto groups are transformed into oximes or O-methyloximes. Fully substituted acyclic ester and oxime trimethylsilyl derivatives are prepared with bis(trimethylsilyl)trifluoroacetamide and chlorotrimethylsilane. Syn and anti isomers of the oximes are formed, but a stationary phase can often be chosen on which the two peaks coincide. The silicone stationary phases OV-1, OV-17, QF-1, and XE-60 were used. Retention data are given for aldonic and deoxyaldonic acids, aldoses, ketoses, and uronic acids. Relationships between structure and retention are discussed. The derivatives are suited to structural analysis by gas chromatography—mass spectrometry.

Mass spectra of prostaglandins: II. Trimethylsilyl and alkyloxime-trimethylsilyl derivatives of prostaglandins B1 and B2.

The mass spectra of the trimethylsilyl ester trimethylsilyl ether derivatives of prostaglandins B1 and B2, and of theirO-ethyl andO-methyl oximes are reported and discussed. The high resolution spectra of these compounds are also considered. These spectra are compared with those of the correspondingd 9-trimethylsilyl derivatives and of the selectively labeled trimethylsilyl esterd 9-trimethylsilyl ethers. The base peaks of the spectra of the trimethylsilyl derivatives are formed by sequential loss of C5H11 (by cleavage of C-15/6) and of CO (from the ring). The spectra of the oxime-trimethylsilyl derivatives are dominated by ions resulting from loss of the alkoxy group of the oxime moiety.

Gas-liquid chromatography of trimethylsilyl and alkyl oxime-trimethylsilyl derivatives of some prostaglandins

Retention indices for trimethylsilyl (TMS), methyloxime-trimethylsilyl (MO-TMS), and ethyl oxime-trimethylsilyl (EO-TMS) derivatives of prostaglandins A 1, B 1, B 2, E 1, 8-iso-E 1, E 2, and 8-iso-E 2, and for TMS derivatives of prostaglandins F 1α, F 2α, and F 2β are reported and discussed. The MO-TMS and EO-TMS derivatives of prostaglandins of the E series are more stable than the TMS derivatives and exhibit more regular retention increments. Stereochemical differences in prostaglandins are readily discerned by gas chromatography of these derivatives.