an efficient and environmentally friendly procedure for one-pot synthesis of 13-acetyl-9-methyl-11-ox-8-oxa-10,12-diazatricyclo [7.3.1. ] trideca-2,4,6-triene from salicylaldehyde, acetylaceton and urea via biginelli condensation and intramolecular michael-addition by using magnesium bromide as an expensive and easily available catalyst under solvent-free condition is desired. the structural el...

A nontargeted, comprehensive 2-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) method was developed for the analysis of fermented cucumber volatiles before and after anaerobic spoilage. Volatile compounds extracted by solid-phase microextraction were separated on a polyethylene glycol 1st-dimension column and 14% cyanopropylphenyl 2nd-dimension column. Among 314 co...

the veterinary drugs residues are also important pollutants found in milk, since veterinary drugs are commonly used in cattle management. considering the role of milk in human nutrition and its wide consumption throughout the world, it is very important to ensure the milk quality. a quantitative structure–retention relationship (qsrr) was developed using the partial least square (pls), kernel p...

Abstract This study aimed to comprehensively analyze primary and secondary metabolites of three different-colored (white, pale green, green) pak choi cultivars ( Brassica rapa subsp. chinensis ) using gas chromatography attached with time-of-flight mass spectrometry (GC-TOFMS) high-performance liquid (HPLC). In total, 53 were identified subjected partial least-squares discriminant analysis. The...

Illegal logging and associated trade have increased worldwide. Such environmental crimes represent a major threat to forest ecosystems society, causing distortions in market prices, economic instability, ecological deterioration, poverty. To prevent illegal imports of products, there is need develop wood identification methods for identifying tree species regulated by the Convention on Internati...

Salvia miltiorrhiza Bunge (Danshen) is an important traditional Chinese medicine herb. This study aimed to investigate the drought-responsive metabolic profiling in S. using gas chromatography time-of-flight mass spectrometry (GC-TOFMS) analysis. Fifty day-old seedlings were treated with two (moderate drought, MD) and four weeks (high HD) of withholding water. The leaf root samples prepared for...

Three new 2-pyranone derivatives, namely Norcardiatones A (1), B (2) and C (3), were isolated from the agar cultures of the strain Nocardiopsis sp. A00203, a mangrove endophytic actinomycete. Their structures were elucidated by spectroscopic and mass-spectrometric analyses, including 1D-, 2D-NMR and HR Q-TOFMS. Compound 1 showed week cytotoxicity against HeLa cells in MTT assay.

3. Experimental Conditions 4. Results and Discussion Comprehensive two dimensional gas chromatography in combination with time-of-flight mass spectrometry detection (GCxGC-TOFMS) was used for drugs of abuse analysis in urine without time consuming sample derivatization. Methamphetamine, cocaine, diacetylmorphine, codeine, oxycodone, ecstasy, acetylcodeine, monoacetylmorphine, hydrocodone, and L...

RATIONALE It is important for the enforcement of the CITES treaty to determine whether agarwood (a resinous wood produced in Aquilaria and Gyrinops species) seen in trade is from a plantation that was cultivated for sustainable production or was harvested from natural forests which is usually done illegally. METHODS We analyzed wood directly using Direct Analysis in Real Time (DART™) ionizati...