Determination of Biogenic Amines in Pu-erh Tea with Precolumn Derivatization by High-Performance Liquid Chromatography

Chromatographic Methods and Sample Pretreatment Techniques for Aldehydes, Biogenic Amine, and Carboxylic Acids in Food Samples

This review paper critically examines the current state of research concerning the analysis and derivatization of aldehyde, aromatic hydrocarbons and carboxylic acids components in foods and drinks samples, with a specific focus on the application of Chromatographic techniques. These diverse components, as vital contributors to the sensory attributes of food, necessitate accurate and sensitive analytical methods for their identification and quantification, which is crucial for ensuring food safety and compliance with regulatory standards. In this paper, High-Performance Liquid Chromatography (HPLC) and Gas Chromatographic (GC) methods for the separation, identification, and quantification of aldehydes in complex food matrices were reviewed. In addition, the review explores derivatization strategies employed to enhance the detectability and stability of aldehydes during chromatographic analysis. Derivatization methods, when applied judiciously, improve separation efficiency and increase detection sensitivity, thereby ensuring a more accurate and reliable quantification of aldehyde aromatic hydrocarbons and carboxylic acids species in food samples. Furthermore, methodological aspects encompassing sample preparation, chromatographic separation, and derivatization techniques are discussed. Validation was carried out in term of limit of detections are highlighted as crucial elements in achieving accurate quantification of compounds content. The discussion presented by emphasizing the significance of the combined HPLC and GC chromatography methods, along with derivatization strategies, in advancing the analytical capabilities within the realm of food science.

Ultrasensitive quantification of trace amines based on N-phosphorylation labeling chip 2D LC-QQQ/MS

Trace amines (TAs) are metabolically related to catecholamine and associated with cancer and neurological disorders. Comprehensive measurement of TAs is essential for understanding pathological processes and providing proper drug intervention. However, the trace amounts and chemical instability of TAs challenge quantification. Here, diisopropyl phosphite coupled with chip two-dimensional (2D) liquid chromatography tandem triple-quadrupole mass spectrometry (LC-QQQ/MS) was developed to simultaneously determine TAs and associated metabolites. The results showed that the sensitivities of TAs increased up to 5520 times compared with those using nonderivatized LC-QQQ/MS. This sensitive method was utilized to investigate their alterations in hepatoma cells after treatment with sorafenib. The significantly altered TAs and associated metabolites suggested that phenylalanine and tyrosine metabolic pathways were related to sorafenib treatment in Hep3B cells. This sensitive method has great potential to elucidate the mechanism and diagnose diseases considering that an increasing number of physiological functions of TAs have been discovered in recent decades.

Ultrahigh-Performance Supercritical Fluid Chromatography and Detection of Multiple Biogenic Amines in Gentamicin Sulfate: Method Development Using Computer-Assisted Modeling

In order to solve the problem of difficult separation of various biogenic amines (BAs), which have similar structures or very different polarities, in gentamicin, by conventional liquid chromatography, a new ultrahigh-performance supercritical fluid chromatography (UHPSFC) method was developed. In this method, 10 BAs were derivatized precolumn using dansyl chloride and separated using a UHPSFC system. By computational simulation, complete separation of 10 BAs was successfully achieved. Detection was performed using a photodiode array (PDA) and single-quadrupole mass spectrometry (MS) together with electrospray ionization (ESI). A wide linear range (10-2500 ng/mL) was achieved, with the limits of detection (LODs) between 1.2 and 10.0 ng/mL and the limits of quantification (LOQs) between 5.0 and 25.0 ng/mL. Apart from high sensitivity, this UHPSFC-PDA/ESI-MS detection method also displayed high accuracy, the matrix effect was reduced by an appreciable extent, and the recovery rates of the 10 BAs were between 84.1 and 117.1%. For comparison, high-performance liquid chromatography-tandem mass spectrometry (MS/MS) was also used for the detection of underivatized BAs in gentamicin, showing good linearity and high sensitivity (LODs from 0.05 to 1.00 ng/mL and LOQs from 1.00 to 12.50 ng/mL) for all BAs except for spermine and spermidine. Although single-quadrupole MS is inferior to MS/MS in terms of sensitivity, the UHPSFC method could detect more BAs. It also achieved the quantification limits required for impurity determination, demonstrating a potential strategy to offer a map overview of possible BA presence in fermentation antibiotics.

The Effects of Different Processing Methods on the Levels of Biogenic Amines in Zijuan Tea

This study aimed to evaluate the effects of processing methods on the content of biogenic amines in Zijuan tea by using derivatization and hot trichloroacetic acid extraction with HPLC-UV. The results showed that the most abundant biogenic amine in the original leaves was butylamine, followed by ethylamine, methylamine, 1,7-diaminoheptane, histamine, tyramine, and 2-phenethylamine. However, during the process of producing green tea, white tea, and black tea, the content of ethylamine increased sharply, which directly led to their total contents of biogenic amines increasing by 184.4%, 169.3%, and 178.7% compared with that of the original leaves, respectively. Unexpectedly, the contents of methylamine, ethylamine, butylamine, and tyramine in dark tea were significantly reduced compared with those of the original leaves. Accordingly, the total content of biogenic amines in dark tea was only 161.19 μg/g, a reduction of 47.2% compared with that of the original leaves, indicating that the pile-fermentation process could significantly degrade the biogenic amines present in dark tea.

Total Content of Piperidine Analysis in Artane by RP-HPLC Using Pre-Column Derivatization with 4-Toluene Sulfonyl Chloride

A simple, sensitive and accurate reversed-phase high-performance liquid chromatography (RP-HPLC) method was established for the determination of piperidine and piperidine hydrochloride in artane, using pre-column derivatization with 4-toluenesulfonyl chloride. The RP-HPLC method was carried out on a Inertsil C18 column (250 × 4.6 mm I.D.) maintained at 30°C. The mobile phase consisted of water with 0.1% phosphoric acid (phase A) and acetonitrile (phase B) (32:68, V:V) at a flow rate of 1.0 mL/min. Linearity of piperidine was found in the range of 0.44-53.33 μg/mL with R2 = 0.9996. The limit of detection was estimated to be 0.15 μg/mL, and the limit of quantitation was 0.44 μg/mL. The average recovery was 101.82% with relative standard deviations of 0.6% at three spiked levels. The developed method using HPLC-ultraviolet system was a rapid tool for routine analysis of piperidine in the bulk form with good accuracy.

Impact of Various Microbial-Fermented Methods on the Chemical Profile of Dark Tea Using a Single Raw Tea Material

In the present study, we produced Pu-erh, Liubao, Qingzhuan, and Fuzhuan teas using a single raw tea material and applied widely targeted metabolomics to study the impact of various microbial-fermented methods on the chemical profile of dark tea. The contents of catechins and free amino acids decreased drastically, whereas the contents of gallic acid and theabrownins increased significantly during microbial fermentation. Pu-erh tea had the highest content of theabrownins (11.82 ± 0.49%). Moreover, MS-based metabolomics analysis revealed that the different types of dark teas were significantly different from their raw material. A total of 85 differential metabolites were screened among 569 metabolites identified referring to self-compiled database. Glycosylated, hydroxylated, methylated, and condensed and oxidated products originating from microbial bioconversion of their corresponding primitive forms were significantly increased in dark teas. These results suggest that various microbial-fermented methods greatly affect the metabolic profile of dark tea, which can provide useful information for dark tea biochemistry research.

Isolation, analysis and in vitro assessment of CYP3A4 inhibition by methylxanthines extracted from Pu-erh and Bancha tea leaves

Methylxanthines, purine alkaloids found in plants, are found in beverages (coffee, tea, cocoa) and foods (chocolate and other cocoa-containing foods) commonly consumed worldwide. Members of this family include caffeine, theophylline and theobromine. Methylxanthines have a variety of pharmacological effects, and caffeine and theophylline are used as pharmaceuticals. Methylxanthines are metabolized in the liver predominantly by the enzyme CYP1A2. Their co-administration with CYP1A2 inhibitors may lead to pharmacokinetic interactions. Little is known about the possible drug interactions between caffeine and substrates of other CYP450 enzymes. In our study, methylxanthine fractions inhibited CYP3A4 in a concentration-dependent manner. Concomitant consumption of green tea with CYP3A4 substrates could increase the possibility of interactions, and this requires further clarification. The inhibition of CYP3A4 is not only due to the presence of catechin derivatives but methylxanthines may also contribute to this effect.

Biogenic Amines Formation Mechanism and Determination Strategies: Future Challenges and Limitations

The evolution in foodstuff-monitoring processes has increased the number of studies on biogenic amines (BAs), in recent years. This trend with future perspective needs to be assembled to address the associated health risks. Thus, this study aims to cover three main aspects of BAs: (i) occurrence, physiology, and toxicological effects, most probable formation mechanisms and factors controlling their growth; (ii) recent advances, strategies for determination, preconcentration steps, model technique, and nature of the matrix; and (iii) milestone, limitations with existing methodologies, future trends, and detailed expected developments for clinical use and on-site ultra-trace determination. The core of the ongoing review will discuss recent trends in pre-concentration toward miniaturization, automation, and possible coupling with electrochemical techniques, surface-enhanced Raman scattering, spectrofluorimetry, and lateral flow protocols to be exploited for the development of rapid, facile, and sensitive on-site determination strategies for BAs.