• Journal of Marine Bioscience and Biotechnology
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• v.15 no.2
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• pp.96-102
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• 2023

Salicornia herbacea, a noted halophyte, has been widely researched for its diverse physiological activities. The continuous exploration of its compounds is essential. This study employed gas chromatography (GC) coupled with mass spectrometry (MS) for qualitative analysis. This involved pretreatment including trimethylsilyl (TMS) derivatization of the S. herbacea extract, facilitating its GC analysis. Five compounds, including various fatty acids and β-sitosterol, were identified by direct analysis of the methanol extract of S. herbacea without pretreatment by GC-MS. Conversely, the analysis of the TMS-derivatized extract revealed 28 distinct peaks. Quantitative analysis further indicated that the predominant compounds in the S. herbacea extract were sugars and sugar derivatives, notably glucose, fructose, and glucitol. The collective concentration of these sugars and its derivatives amounted to 116.45 mg/g, representing 11.6% of the dry weight of the raw S. herbacea. Following sugars and their derivatives, fatty acids constituted the next most abundant group of compounds. However, the presence of amino acids and organic acids was relatively low.

• Mass Spectrometry Letters
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• v.3 no.1
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• pp.15-17
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• 2012

Eighteen of the PDE-5 inhibitors and their analogues were analyzed using GC-EI-MS. Fourteen of them could be identified by simple GC-MS method without derivatization, but hydroxyhongdenafil, hydroxyvardenafil, xanthoanthrafil and mirodenafil could not be identified without derivatization for the high polarity due to the presence of hydroxyl groups. N,O-bis(trimethylsilyl) trifluoroacetamide (BSTFA) and N-methyl-N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA), widely used trimethylsilyl (TMS) derivatizing reagents, were used to improve the sensitivity of the hydroxylated analogues. And the analytes could be identified by GC-MS after the derivatization.

• Korean Journal of Pharmacognosy
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• v.48 no.1
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• pp.46-50
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• 2017

This study was conducted to investigate the antioxidative activities and tyrosinase inhibition effects of fractions from the distilled water extract of Inonotus obliquus. Moreover, GC-MS based analysis with trimethylsilyl (TMS) derivatization was carried out for active compound in the extract of I. obliquus. In DPPH radical scavenging ability, $SC_{50}$ values of the ethyl acetate fraction was 0.393 mg/ml as a result of the most effective than other fractions. Meanwhile, aqueous fraction showed higher effect in tyrosinase inhibitoty activity. In GC-MS based analysis with TMS derivatization, 7 compounds including syringic acid, vanillic acid and protocatechuic acid were observed in ethyl acetate fraction, and oxalic acid is the main compound in aqueous fraction. As a result, it was confirmed that oxalic acid in aqueous fraction from the distilled water extract of I. obliquus was a compound showing tyrosinase inhibition effect.

• Bulletin of the Korean Chemical Society
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• v.30 no.7
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• pp.1497-1504
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• 2009

GC/MS analysis of catecholamines (CAs) in biological sample may produce poor reproducible quantitaion when chemical derivatization is used as the technique to form a volatile derivative. Significant quantities of the side products can be formed from CAs with primary amine during the derivatization reaction under un-optimized conditions. We have tested various chemical derivatization techniques in an attempt to find an optimum derivatization method that will reduce side product formation, enable to separate several catecholamine derivatives in GC chromatogram, and obtain significant improvement of detection sensitivity in GC/MS analysis. Whereas several derivatization techniques such as trimethylsilylation (TMS), trifluoroacylation (TFA), and two step derivatization methods were active, selective derivatization to form O-TMS, N-heptafluorobutylacyl (HFBA) derivative using N-methyl-N-(trimethylsilyl)-trifluoroacetamide (MSTFA) and N-methyl-bis(heptafluorobutyramide) (MBHFBA) reagents was found to be the most effective method. Moreover, this derivative formed by selective derivatization could provide sufficient sensitivity and peak separation as well as produce higher mass ion as base peak to use selected ion in SIM mode. Calibration curves based on the use of an isotopically labeled internal standard show good linearity over the range assayed, 1 ~ 5000 ng/mL, with correlation coefficients of > 0.996. The detection limits of the method ranged from 0.2 to 5.0 ppb for the different CAs studied. The developed method will be applied to the analysis of various CAs in biological sample, combined with appropriate sample pretreatment.

• Bulletin of the Korean Chemical Society
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• v.28 no.3
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• pp.432-438
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• 2007

Environmentally important phthalic esters have been analyzed by GC-MS in terms of individual phthalic esters or total phthalic esters directly or after derivatization. Derivatization improves the chromatographic characteristics of the highly polar phthalic esters. This study focused on the GC-MS determination of the total phthalic esters and the individual phthalic esters simultaneously. The phthalic esters were hydrolyzed to phthalate and corresponding alcohols in 1 M NaOH solution at 90 oC for 30 min followed by extraction with ethyl acetate after acidifcation. The phthalic acid and alcohols were simultaneously silyl derivatized using bis(trimethylsilyl)trifluoroacetamide (BSTFA) to their corresponding silyl ester and ethers in the mixture of 60% acetone and 40% ethyl acetate at room temperature within 30 min. Because of the high reactivity of BSTFA with the phthalic acid and alcohols effective silyl derivatization was possible simultaneously. GC-MS analysis of the silyl derivatives of phthalic acid and alcohols was performed. The total phthalic ester content was estimated from the analytical result of phthalic silyl ester, while the individual phthalic ester was quantified from the analytical results of alcoholic silyl ethers. This technique was applied to spiked tab water and real seawater samples from the Lake Shihwa in Korea. The results were checked against the results from the direct GC-MS analysis of the phthalic esters and reasonable recoveries with high sensitivity were achieved. The recoveries were higher than 75% with low relative standard deviation (below 10%).

• Applied Biological Chemistry
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• v.35 no.2
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• pp.132-138
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• 1992

For effective determination of methylthiohydantoin amino acids(MTHs) by gas liquid chromatography in the protein sequencing, derivatization with N-methyl-N-(tert.-butyl-dimethylsilyl)trifluoroacetamide(MTBSTFA), a new silylating reagents, was attempted instead of trimethylsilyl(TMSi) derivatives by N,O-bis(trimethylsilyl)trifluoroacetamide(BSTFA) used up to the present and N(O)-butyldimethylsilyl MTHs derivatized by MTBSTFA were analysed on HP-1 capillary column. Twenty one protein amino acids except cystine were indentified. Especially arginine that did not detected with TMSi derivative on packed column until now was resolved by derivatization with MTBSTFA. N(O)-butyldimethylsilyl MTHs showed multiple peaks by MTBSTFA were proline, isoleucine, glycine and tyrosine and hydroxyproline especially showed several extraneous peaks more than two. Calibration curves of N(O)-butyldimethysilyl MTHs of amino acids in the range of $2.5\;nmol{\sim}7.5\;nmole$ showed good linearity. however, those of lysine, histidine and arginine showed linearity in the range of $5.0\;nmole{\sim}15.0\;nmole$. Correlation coefficients and regression coefficients of all calibration curves were highly significant(p<0.001).

• Analytical Science and Technology
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• v.34 no.2
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• pp.68-77
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• 2021

Cannabis is one of the most abused drugs in Korea. The main psychoactive component in cannabis, Δ9-tetrahydrocannabinol, is metabolized to 11-nor-9-carboxy-Δ9-tetrahydrocannabinol (THCCOOH) and THCCOOH-glucuronide (THCCOOH-glu) in the human liver, whereby the amount of THCCOOH-glu found in urine is twice as high as that of THCCOOH. The analytical process adapted by the majority of urine drug-testing programs involves a two-step method consisting of an initial immunoassay-based screening test followed by a confirmatory test if the screening test result is positive. In this study, a qualitative gas chromatography-mass spectrometry (GC-MS) method was developed and validated for the detection of THCCOOH in human urine, where THCCOOH-glu was converted into THCCOOH by alkaline hydrolysis. For purification of the urine extract prior to instrumental analysis, high-speed centrifugation was used to minimize interference. In addition, an injection-port derivatization method using ethyl acetate and N,O-bis(trimethylsilyl)-trifluoroacetamide containing 1 % trimethylchlorosilane was employed to reduce the time required for derivatization, and an aliquot of the final solution was injected into the GC-MS. The method was validated by measuring the selectivity, limit of detection (LOD), and repeatability. The sensitivity, specificity, precision, accuracy, Kappa, F-measure, false positive, and false negative rate were determined by comparing the GC-MS results with those obtained using the immunoassay. The LOD was determined to be 0.32 ng/mL, while the repeatability was within 9.1 % for THCCOOH. Furthermore, a comparison study was carried out, whereby the screening immunoassay exhibited a sensitivity of 86.4 % and a specificity of 100 % compared to GC-MS. The applicability of the developed method was examined by analyzing spiked urine and forensic urine samples obtained from suspected cannabis abusers (n = 221).

• YAKHAK HOEJI
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• v.20 no.3
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• pp.125-129
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• 1976

The aim of this investigation was to develop a quantitative gas-liquid chromatographic method of analysis forhyosyamine and scopolamine, and to apply this method to the analysis of preparations. The trimethylsily(TMS) derivatives of the alkaloids were found to be far superior to the nonsilylating compounds in charomatagrams. Bis(trimethylsilyl) acetamide(BSA) was evaluated and found to be a good reagent for silyation of the alkaloids. The optimum derivatization conditions were heating the alkaloids in a closed tube at $70^{\circ)$ for 30 min with a 150 molar excess of BSA to the alkaloids were found to be alkaloids. Calibration curves for the two alkaloids were alkaloid. The standard deviations were 1.1% for hyoscyamine and 1.5% for scopolamine. The minimum detectable amount using the hydrogen flame ionization edtector was determined to be 2$\times$10$^{-11}$ moles of each alkaloid injected.

• Analytical Science and Technology
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• v.19 no.1
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• pp.103-106
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• 2006

A 35-year-old Perubian who suffered from grand mal seizures died in the aircraft on his way from the United States to Hongkong via Incheon international airport of Korea. While performing the autopsy, 115 packs made with double layer of transparent film and black plastic bag containing cocaine were found in the ileum and large intestine. Among of them, 3 packs were ruptured. To determine the concentration of cocaine and its metabolites, blood, urine, bile, liver, spleen, heart, kidney, brain and gastric contents were taken and toxicological analysis was performed. Gas chromatography/mass spectrometry (GC/MS) following liquid-phase extraction using chloroform:isopropanol (=9:1) and derivatization with bis(trimethylsilyl)-trifluoroacetamide (contains 1% trimethylchlorosilane) was performed. High levels of cocaine, benzoylecgonine (BE) and ecgonine methylester (EME) were found in the postmortem blood (0.96, 3.09 and $5.59{\mu}g/mL$) and urine (32.85, 145.35 and $53.17{\mu}g/mL$), respectively. Cocaine and its metabolites were also detected in all other biological specimen.

• Analytical Science and Technology
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• v.19 no.1
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• pp.107-114
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• 2006

Early diagnosis and medical intervention are critical for the treatment of patients with metabolic disorders. A rapid analytical method was developed for simultaneous quantification of organic acids and amino acids in urine without labor-intensive pre-extraction procedure showing high sensitivity and specificity. A new method consisted of simple two-step trimethylsilyl (TMS)-trifluoroacetyl (TFA) derivatization using GC/MS-selective ion monitoring (SIM). Filter paper urine specimens were dried under nitrogen after being fortified with internal standard (tropate) in a mixture of distilled water and methanol. Methyl orange was added to the residue as indicator reagent. Silyl derivative of carboxylic functional group was followed by trifluoroacetyl derivative for amino functional group. N-methyl-N-(trimethylsilyl-trifluoroacetamide) and N-methyl-bistrifluoroacetamide were consecutively added and heated for 15-20 min at $65^{\circ}C-70^{\circ}C$, for TMS-TFA derivative, respectively. This reactant was analyzed by GC/MS-SIM. Linear dynamic range showed 0.001-50 mg with the detection limit of (S/N=3) 10-200 ng, and the quantification limit of 80-900 ng in urine. Correlation coefficient of regression line was 0.994-0.998. When the method was applied to the patients 'urine, it clearly differentiated the normal from the patient with metabolic disorder. The study showed that the developed method could be the method of choices in rapid and sensitive screening for organic aciduria and amino acidopathy.