Simultaneous Determination of Pesticide Residues and Mycotoxins in Storage Pu-erh Tea Using Ultra-High-Performance Liquid Chromatography Coupled with Tandem Mass Spectrometry.

Mycotoxins and pesticides are the most concerning chemical contaminants that can affect the quality of Pu-erh tea during its production and storage. This study presents a method that can simultaneously determine 31 pesticide residues and six mycotoxins in Pu-erh tea within 11 min using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS) after QuEChERS extraction. The lower limit of quantification (LOQ) for all analytes ranged between 0.06 and 50 ppb. Recoveries for each pesticide and mycotoxin ranged between 62.0 and 130.3%, with intra- and inter-day precisions lower than 15%. Good linear relationships were obtained, with correlation coefficients of r2 > 0.991 for all analytes. The established method was applied to 31 Pu-erh tea samples, including raw and ripened Pu-erh tea with different storage times. As a result, pesticide residues were not detected in any of the collected samples, and the mycotoxins detected in the samples were well below the official maximum residue limits (MRLs). Notably, the levels of aflatoxin B1 (AFB1), aflatoxin G1 (AFG1) and aflatoxin G2 (AFG2) were lower than 1 ppb in the samples stored for more than 30 years.

Plasmonic gold nanoparticles as multifaceted probe for tissue imaging.

The localized surface plasmon resonance property of gold nanoparticles enables their application as a versatile and sensitive imaging probe, with intense colour, enhanced fluorescence and strong MS ion intensity for biological tissue imaging.

Chemical Printing of Biological Tissue by Gold Nanoparticle-Assisted Laser Ablation.

A chemical printing method based on gold nanoparticle (AuNP)-assisted laser ablation has been developed. By rastering a thin layer of AuNPs coated on a rat kidney tissue section with a UV laser, biomolecules are extracted and immediately transferred/printed onto a supporting glass substrate. The integrity of the printed sample is preserved, as revealed by imaging mass spectrometric analysis. By studying the mechanism of the extraction/printing process, transiently molten AuNPs were found to be involved in the process, as supported by the color and morphological changes of the AuNP thin film. The success of this molecular printing method was based on the efficient laser-nanomaterial interaction, that is, the strong photoabsorption, laser-induced heating, and phase-transition properties of the AuNPs. It is anticipated that the molecular printing method can be applied to perform site-specific printing, which extracts and transfers biochemicals from different regions of biological tissue sections to different types of supporting materials for subsequent biochemical analysis with the preservation of the original tissue samples.

Enhancement of Image Contrast, Stability, and SALDI-MS Detection Sensitivity for Latent Fingerprint Analysis by Tuning the Composition of Silver-Gold Nanoalloys.

Metal alloy nanoparticles (NPs) offer a new combination of unique physicochemical properties based on their pure counterparts, which can facilitate the development of novel analytical methods. Here, we demonstrated that Ag-Au alloy NPs could be utilized for optical and mass spectrometric imaging of latent fingerprints (LFPs) with improved image contrast, stability, and detection sensitivity. Upon deposition of Ag-Au alloy NPs (Ag:Au = 60:40 wt %), ridge regions of the LFP became amber colored, while the groove regions appeared purple-blue. The presence of Au in the Ag-Au alloy NPs suppressed aggregation behavior compared to pure AgNPs, thus improving the stability of the developed LFP images. In addition, the Ag component in the Ag-Au alloy NPs enhanced optical absorption efficiency compared to pure AuNPs, resulting in higher contrast LFP images. Moreover, varying the Ag-Au ratio could enable the tuning of the resulting surface plasmonic resonance absorption and hence affect image contrast. Furthermore, the Ag-Au alloy NPs assisted the surface-assisted laser desorption/ionization MS analysis of chemical and biochemical compounds in LFPs, with better detection sensitivity than either pure AgNPs or AuNPs.

Comprehensive Quantitative Analysis of SQ Injection Using Multiple Chromatographic Technologies.

Quality control of Chinese medicine injections remains a challenge due to our poor knowledge of their complex chemical profile. This study aims to investigate the chemical composition of one of the best-selling injections, Shenqi Fuzheng (SQ) injection (SQI), via a full component quantitative analysis. A total of 15 representative small molecular components of SQI were simultaneously determined using ultra-high performance liquid chromatography (UHPLC) coupled with quadrupole tandem time-of-flight mass spectrometry (Q-TOF-MS); saccharide composition of SQI was also quantitatively determined by high performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) on an amino column before and after acid hydrolysis. The existence of polysaccharides was also examined on a gel permeation chromatography column. The method was well validated in terms of linearity, sensitivity, precision, accuracy and stability, and was successfully applied to analyze 13 SQI samples. The results demonstrate that up to 94.69% (w/w) of this injection product are quantitatively determined, in which small molecules and monosaccharide/sucrose account for 0.18%-0.21%, and 53.49%-58.2%, respectively. The quantitative information contributes to accumulating scientific evidence to better understand the therapy efficacy and safety of complex Chinese medicine injections.

Gold nanoparticles bridging infra-red spectroscopy and laser desorption/ionization mass spectrometry for direct analysis of over-the-counter drug and botanical medicines.

With a coating of gold nanoparticles (AuNPs), over-the-counter (OTC) drugs and Chinese herbal medicine granules in KBr pellets could be analyzed by Fourier Transform Infra-red (FT-IR) spectroscopy and Surface-assisted Laser Desorption/Ionization mass spectrometry (SALDI-MS). FT-IR spectroscopy allows fast detection of major active ingredient (e.g., acetaminophen) in OTC drugs in KBr pellets. Upon coating a thin layer of AuNPs on the KBr pellet, minor active ingredients (e.g., noscapine and loratadine) in OTC drugs, which were not revealed by FT-IR, could be detected unambiguously using AuNPs-assisted LDI-MS. Moreover, phytochemical markers of Coptidis Rhizoma (i.e. berberine, palmatine and coptisine) could be quantified in the concentrated Chinese medicine (CCM) granules by the SALDI-MS using standard addition method. The quantitative results matched with those determined by high-performance liquid chromatography with ultraviolet detection. Being strongly absorbing in UV yet transparent to IR, AuNPs successfully bridged FT-IR and SALDI-MS for direct analysis of active ingredients in the same solid sample. FT-IR allowed the fast analysis of major active ingredient in drugs, while SALDI-MS allowed the detection of minor active ingredient in the presence of excipient, and also quantitation of phytochemicals in herbal granules.

Comprehensive quantitative analysis of Shuang-Huang-Lian oral liquid using UHPLC-Q-TOF-MS and HPLC-ELSD.

Shuang-Huang-Lian oral liquid (SHL) is a well-known Chinese patent drug containing three herbal medicines: Radix Scutellariae, Flos Lonicerae Japonicae and Fructus Forsythiae. It is usually used to treat acute upper respiratory tract infection caused by virus or bacteria. Although the licensing of botanical drug Veregen approved by FDA has indicated the importance of quantitative analysis in quality control of herbal medicines, quantitative evaluation of a Chinese patent drug like SHL remains a challenge due to the complex chemical profile. In this study, 15 small molecular components of SHL (four flavonoids, six quinic acid derivatives, three saponins and two phenylethanoid glycosides) were simultaneously determined using ultra-high performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF-MS). The contents of the three major saccharides, namely fructose, glucose and sucrose were quantified using high performance liquid chromatography-evaporative light scattering detector on an amino column (HPLC-ELSD). The macromolecules were quantified by precipitating in 80% ethanol, drying the precipitate, and then weighing. The established methods were validated in terms of linearity, sensitivity, precision, accuracy and stability and then successfully applied to analyze 12 batches of commercial products of SHL produced by four different manufacturers. The results indicated that 57.52-78.11% (w/w) of SHL could be quantitatively determined (non-saccharide small molecules: 1.77-3.75%, monosaccharides: 0.93-20.93%, macromolecules: 2.63-5.76% and sucrose: 49.20-65.94%). This study may provide a useful way to comprehensively evaluate the quality of SHL.

Folding fan mode counter-current chromatography offers fast blind screening for drug discovery. Case study: finding anti-enterovirus 71 agents from Anemarrhena asphodeloides.

A new application of counter-current chromatography (CCC) in drug discovery, called folding fan mode (FFM), is designed to eliminate the extensive and time-consuming calculation of the partition coefficients of some preset compounds in conventional CCC separation. Careful reading of reports in the literature reveals that, when two-phase solvent systems are listed in a polarity-increasing sequence, the isolates also show a similar trend in polarity. The relationship between the two-phase solvent system and the isolates is like that between the folds and the picture of a folding fan. We can directly select a two-phase solvent system to separate fractions having similar polarity, just as opening a fan reveals a picture. The solvent ratio of two-phase solvent systems can be adjusted according to the polarity and weight ratio of active fractions rather than the partition coefficients. Without preset compounds, FFM-CCC not only requires no measurement of partition coefficients, but also achieves true blind screening. This paper reports the method's first success in drug discovery: six anti-EV71 saponins were found from the mixture (9.13 g) of ethanol extract and water extract of Anemarrhena asphodeloides after a total of four CCC separations, using hexan/ethyl acetate/methanol/butanol/water as the model solvent system. Among these saponins, timosaponin B-II displayed a comparable IC50 (4.3 ± 2.1 µM) and a 40-fold higher selective index (SI=92.9) than the positive control (IC50=361.7 ± 104.6 µM, SI=2.4), ribavirin. The structure-activity relationship (SAR) of these compounds was also studied.