Optimization of hydrolysis conditions of alginate based on high performance liquid chromatography.

Alginate is the most abundant polysaccharide compound in brown algae, which is widely used in various fields. At present, the determination of the content of alginate is mostly carried out using sulfuric acid and trifluoroacetic acid hydrolysis followed by the determination of the content, but the results are not satisfactory, and there are problems such as low hydrolysis degree and low recovery rate. Therefore, in this study, based on the optimization of high performance liquid chromatographic conditions for pre-column derivatization of 1-phenyl-3-methyl-5-pyrazolone (PMP), the hydrolysis effects of sulfuric acid, trifluoroacetic acid (TFA), oxalic acid, and formic acid were compared and the hydrolysis conditions were optimized. The results showed that formic acid was the best hydrolyzing acid. The optimal hydrolysis conditions were 95 % formic acid at 110 °C for 10 h. The hydrolysis effect was stable, with high recovery and low destruction of monosaccharides, which made it possible to introduce formic acid into the subsequent polysaccharide hydrolysis. The pre-column derivatization high performance liquid chromatography method established in this study was accurate and reliable, and the hydrolysis acid with better effect was screened, which provided a theoretical basis for the subsequent determination of alginate content.

[Evaluation of nutritional value of Bambusae Concretio Silicea based on content of 15 amino acids].

The content of 15 total amino acids(TAAs) in Bambusae Concretio Silicea was determined by HPLC with phenyl-isothiocyanate(PITC) for pre-column derivatization. The results showed that the content of TAA was 0.61-12.25 mg·g~(-1), and aspartic acid(Asp), glutamic acid(Glu), proline(Pro), glycine(Gly), and valine(Val) were the top five amino acids in terms of the average content. The content of essential amino acids(EAAs), conditionally essential amino acids(CEAAs), non-essential amino acids(NEAAs), and medicinal amino acids(MAAs) was 0.24-4.75, 0.30-4.73, 0.40-7.50, and 0.36-6.51 mg·g~(-1), respectively. Among the delicious amino acids, sweet amino acids(SAA), bitter amino acids(BAA), fresh-taste amino acids(FAAs), and odourless amino acids(OAAs) had the content of 0.22-4.70, 0.19-4.03, 0.13-2.26, and 0.06-1.26 mg·g~(-1), respectively. The 21 batches of Bambusae Concretio Silicea samples presented the same composition but significant differences in the content of amino acids. Among the three producing areas, Guangdong was the area where the samples had the highest content of TAAs, EAAs, CEAAs, NEAAs, MAAs, and delicious amino acids. Furthermore, the ratio of amino acid(RAA), ratio coefficient of amino acid(RCAA), and score of ratio coefficient of amino acid(SRCAA) were calculated to evaluate the nutritional value of Bambusae Concretio Silicea. The results showed that the Bambusae Concretio Silicea samples from Guangdong had better nutritional value. The nutritional value evaluation based on the content of 15 amino acids was proposed to provide data support for the quality grading of Bambusae Concretio Silicea and lay a foundation for the development and utilization of the medicinal material resources.

Detection and quantification of biogenic amines in cephalopod using dansyl chloride pre-column derivatization-HPLC and their production.

The accurate detection of biogenic amines (BAs) is an important means of ensuring the quality and safety of cephalopod seafood products. In this study, the pre-column derivatization of high-performance liquid chromatography (HPLC) was optimized using dansyl chloride (Dns-Cl) to detect BAs in octopus, cuttlefish, and squid. The reasons for the formation of BAs were investigated by assessing their decarboxylase activity and the rates of decomposition. The findings demonstrated that using Dns-Cl to optimize pre-column derivatization enabled the separation of nine different BAs. The detection limits ranged from 0.07 to 0.25 mg/L, and the results exhibited a high level of linearity (R2 ≥ 0.997). The decarboxylase activity and biodegradation rate positively correlated with the formation of BAs at temperatures below 0°C. Notably, the decarboxylase activity of octopus, cuttlefish, and squid exhibited a significant increase with prolonged storage time, and formyltransferase and carbamate kinase may be the key decarboxylase in cephalopod products. These findings serve as a valuable reference for further investigations into the mechanisms behind BAs production and the development of control technologies for BAs in cephalopod products. This study has successfully demonstrated the effectiveness of the Dns-Cl pre-column derivatization-HPLC method in accurately and efficiently detecting BAs in octopus, cuttlefish, and squid. Moreover, it highlights the influence of decarboxylase content and biodegradation rate on the formation of BAs. Importantly, this method can serve as a reference for detecting BAs in various seafood products.

Simultaneous determination of six α-dicarbonyl compounds in traditional Chinese medicines using high-performance liquid chromatography-fluorescence detector with pre-column derivatization.

A reliable method for determination of six α-dicarbonyl compounds in traditional Chinese medicines was first developed and validated by high-performance liquid chromatography-fluorescence detector with pre-column derivatization. α-Dicarbonyl compounds in traditional Chinese medicines were extracted and derivatized with 2,3-diaminaphthalene. The derivatization procedure of six α-dicarbonyl compounds was confirmed by high-resolution mass spectrometry. The limits of quantitation for six α-dicarbonyl compounds ranged from 3.70 × 10-3 to 2.21 × 10-2  µM. The established method showed good linearity (regression coefficient > 0.9990), precision (relative standard deviation < 3.37%), and high recovery (97.8%∼113.1%). The developed method was successfully applied to detect the six α-dicarbonyl compounds in traditional Chinese medicines. The result exhibited six α-dicarbonyl compounds was found in the 15 kinds of traditional Chinese medicines, which suggested us that the determination of α-dicarbonyl compounds should be paid more attention in the quality control of traditional Chinese medicines.

[Assay of amino acids in leaves of Eucommia ulmoides under arbor forest mode and leaf-oriented cultivation mode by pre-column derivatization HPLC].

This study aims to develop the pre-column derivatization high performance liquid chromatography(HPLC) method for the determination of 16 kinds of amino acids in Eucommia ulmoides leaves, and compare the content of amino acids in the leaves harvested at different time and under leaf-oriented cultivation mode(LCM) and arbor forest mode(AFM). The HPLC conditions are as below: phenyl isothiocyanate(PITC) as pre-column derivatization agent, Agilent ZORBAX C_(18 )column(4.6 mm×250 mm, 5 µm), mobile phase A of acetonitrile-water(80∶20), mobile phase B of 0.1 mol·L~(-1) sodium acetate solution-acetonitrile(94∶6), gradient elution, flow rate of 1.0 mL·min~(-1), injection volume of 5 µL, column temperature of 40 ℃, and detection wavelength of 254 nm. The HPLC profile indicated well separation of 16 kinds of amino acids and the amino acid content in E. ulmoides leaves was up to 16.26%. In addition, the amino acid content in leaves of E. ulmoides under LCM was higher than under AFM. The amino acid content varied with the harvesting time. Through orthogonal partial least squares discriminant analysis, the amino acids of E. ulmoides under LCM and AFM were compared, which can distinguish the leaves under LCM from those under AFM. Principal component analysis was applied to comprehensively score the amino acids of E. ulmoides leaves. The results showed that the score of leaves under LCM was higher than that under AFM. Nutritional evaluation results indicated that the proteins in E. ulmoides leaves belonged to high-quality vegetable proteins. The established method for the determination of amino acid content is reliable. With the amino acid content as index, the leaf quality of E. ulmoides under LCM is better than that under AFM. This study lays a theoretical basis for the promotion of LCM for E. ulmoides and the development of medicinal and edible products from E. ulmoides leaves.

Fluorogenic substrates and pre-column derivatization for monitoring the activity of bile salt hydrolase from Clostridium perfringens.

The bile acid pool has a profound impact on human health and disease. The intestinal microbiota initiates the metabolism of conjugated bile acids through a critical first step catalyzed by bacterial bile salt hydrolase (BSH) and provides unique contributions to the diversity of bile acids. There has been great interest in surveying BSH activity. We compared two substrates with either 2-(7-amino-4-methyl-coumarinyl)acetic acid or 7-amino-4-methyl-coumarin as fluorescent reporters of BSH activity. The BSH-catalyzed conversion of the natural substrate taurocholic acid was followed through an HPLC-based assay by applying 7-nitrobenzo[c][1,2,5]oxadiazole as scavenger for taurine, released in the enzymatic reaction. Hence, a new opportunity to monitor the activity of bile salt hydrolases was introduced.

A Novel Method for the Pre-Column Derivatization of Saccharides from Polygonatum cyrtonema Hua. by Integrating Lambert-Beer Law and Response Surface Methodology.

Traditional Chinese medicine (TCM) safety and effectiveness can be ensured by establishing a suitable quality assessment system. This work aims to develop a pre-column derivatization HPLC method for Polygonatum cyrtonema Hua. quality control. In this study, 1-(4'-cyanophenyl)-3-methyl-5-pyrazolone (CPMP) was synthesized and reacted with monosaccharides derived from P. cyrtonema polysaccharides (PCPs), followed by HPLC separation. According to the Lambert-Beer law, CPMP has the highest molar extinction coefficient of all synthetic chemosensors. A satisfactory separation effect was obtained under a detection wavelength of 278 nm using a carbon-8 column and gradient elution over 14 min, with a flow rate of 1 mL per minute. Glucose (Glc), galactose (Gal), and mannose (Man) make up the majority of the monosaccharide components in PCPs, and their molar ratios are 1.73:0.58:1. The confirmed HPLC method has outstanding precision and accuracy, establishing a quality control method for PCPs. Additionally, the CPMP showed a visual improvement from colorless to orange after the detection of reducing sugars, allowing for further visual analysis.

An effective universal protocol for the extraction of fructooligosaccharide from the different agricultural byproducts.

Alternative bio-refinery technologies are required to promote the commercial utilization of plant biomass components. The fructooligosaccharide (FOS) obtained after hydrolysis of the hemicellulose fractions was mainly applied in the pharmaceutical and food industries. Agricultural bi-product is a rich constituent in dietary fibres, which have prebiotic effects on the intestinal microbiota and the host. Herein we explored the impact of FOS on microbiota modulation and the gut homeostasis effect. High fructooligosaccharide recovery was obtained using alkaline extraction techniques. The enzymatic method produced fructooligosaccharides with minor contamination from fructan and glucan components, although it had a low yield. But combining the alkaline and enzymatic process provides a higher yield ratio and purity of fructooligosaccharides. The structure of the fructooligosaccharide was confirmed, according to FTIR, 13C NMR, 1H NMR and 2D-NMR data. Our results could be applied to the development of efficient extraction of valuable products from agricultural materials using enzyme-mediated methods, which were found to be a cost-effective way to boost bio-refining value. Fructooligosaccharides with varying yields, purity, and structure can be obtained.

Assay of amino acids in leaves of Eucommia ulmoides under arbor forest mode and leaf-oriented cultivation mode by pre-column derivatization HPLC / 中国中药杂志

This study aims to develop the pre-column derivatization high performance liquid chromatography(HPLC) method for the determination of 16 kinds of amino acids in Eucommia ulmoides leaves, and compare the content of amino acids in the leaves harvested at different time and under leaf-oriented cultivation mode(LCM) and arbor forest mode(AFM). The HPLC conditions are as below: phenyl isothiocyanate(PITC) as pre-column derivatization agent, Agilent ZORBAX C_(18 )column(4.6 mm×250 mm, 5 μm), mobile phase A of acetonitrile-water(80∶20), mobile phase B of 0.1 mol·L~(-1) sodium acetate solution-acetonitrile(94∶6), gradient elution, flow rate of 1.0 mL·min~(-1), injection volume of 5 μL, column temperature of 40 ℃, and detection wavelength of 254 nm. The HPLC profile indicated well separation of 16 kinds of amino acids and the amino acid content in E. ulmoides leaves was up to 16.26%. In addition, the amino acid content in leaves of E. ulmoides under LCM was higher than under AFM. The amino acid content varied with the harvesting time. Through orthogonal partial least squares discriminant analysis, the amino acids of E. ulmoides under LCM and AFM were compared, which can distinguish the leaves under LCM from those under AFM. Principal component analysis was applied to comprehensively score the amino acids of E. ulmoides leaves. The results showed that the score of leaves under LCM was higher than that under AFM. Nutritional evaluation results indicated that the proteins in E. ulmoides leaves belonged to high-quality vegetable proteins. The established method for the determination of amino acid content is reliable. With the amino acid content as index, the leaf quality of E. ulmoides under LCM is better than that under AFM. This study lays a theoretical basis for the promotion of LCM for E. ulmoides and the development of medicinal and edible products from E. ulmoides leaves.

Development and verification of pre-column derivatization reverse phase-high performance liquid chromatography for determination of Glycine and Histidine content in recombinant proteins / 中国生物制品学杂志

@#Objective To develop and verify a pre-column derivatization reverse phase-high performance liquid chromatography(RP-HPLC) method for determination of Glycine and Histidine content in recombinant proteins.Methods AccQ Tag-C 18(3.9 mm × 150 mm,4 μm) column was used as chromatographic column,6-aminoquinolyl-N-hydroxysccinimidyl carbamate(AQC) was used as pre-column derivatization reagent,while α-aminobutyric acid as internal standard.AccQTag Eluent A solution,acetonitrile solution and high-purity water were used as mobile phases.The UV detection wavelength was 248 nm,injection volume was 10 μL,flow rate was 1.0 mL/min,and column temperature was 37 ℃.The contents of Glycine and Histidine in samples were determined by the internal standard method,and the specificity,linearity,detection limit,quantitative limit,precision,accuracy and stability of the method were verified.Results The developed method effectively separated Glycine,Histidine and internal standard α-aminobutyric acid with high specificity.The standard curves of Glycine in the range of 2.25～11.25 μg/mL and Histidine in the range of 72.85～364.24 μg/mL showed good linearity,each correlation coefficient(R~2) 0.99.The detection limits were 2.25 μg/mL for Glycine and 18.21 μg/mL for Histidine.The quantitative limits were 4.69 μg/mL for Glycine and 32.86 μg/mL for Histidine.The relative standard deviation(RSD) of 6 replicates with the same concentration of Glycine and Histidine were 4.6% and 5.0%,and the RSD of recovery rate in intermediate precision test was 6.9% and 2.0%,respectively.The content of Glycine was close to the quantitative limit,and the average recoveries of high,medium and low concentrations of samples were within 75.9%～111.7%;The recoveries of Histidine ranged from 88.9% to 97.3%.The RSD of Glycine content and Histidine content was 7.7% and 3.3% respectively at 0,12,18,24,30 and 48 h in the same sample.Conclusion The pre-column derivatization RP-HPLC method has accurate and reliable results with high precision,which might be used for quality control of Glycine and Histidine content in recombinant proteins.

Development of a High Performance Liquid Chromatography with Diode Array Detector (HPLC-DAD) Method for Determination of Biogenic Amines in Ripened Cheeses.

Biogenic amines (BAs) are organic, basic nitrogenous compounds formed during the decarboxylation of amino acids. A method for the determination of eight biogenic amines (tryptamine, 2-phenyletylamine, putrescine, cadaverine, histamine, tyramine, spermidine, spermine) in ripened cheeses was developed and validated. Cheese samples with the addition of internal standards were extracted with 0.2 M perchloric acid and pre-column derivatized with dansyl chloride at 60 °C for 15 min, purified with toluene and dried under a stream of nitrogen. The samples were analyzed using high performance liquid chromatography with diode array detector (HPLC-DAD). The method was validated with the BAs at three concentration levels: 50, 100, and 200 mg/kg, respectively. The obtained values of correlation coefficient (R2) ranged at 0.9997−0.9998 for all of compounds. The limits of detection (LOD) and quantification (LOQ) were in ranges 1.53−1.88 and 5.13−6.28 mg/kg, respectively. The recovery for all of biogenic amines ranged from 70 to 120% and the precision (RSDr) value were <20%. The validated method was applied to analysis of 35 real ripened cheese samples purchased in Poland.

In-Needle Pre-Column Derivatization for Amino Acid Quantification (iPDAQ) Using HPLC.

Pre-column fluorescent derivatization has been used for the fast quantification of amino acids using high-performance liquid chromatography (HPLC) systems. However, it generally requires an offline in-vial derivatization process with multiple derivatization reagents. The offline derivatization requires the same number of reaction vials as the number of sample vials for use as a reaction chamber for the derivatization reaction in an autosampler. Therefore, the number of samples analyzed per batch using the pre-column derivatization method is halved. To benefit from the pre-column derivatization method, we transformed the derivatization process from an offline chamber process to an online in-needle process (in-needle Pre-column Derivatization for Amino acids Quantification; iPDAQ). Fluorescent derivatization in the injection needle obviated the need for vacant vials as reaction chambers. Consequently, the throughput per batch improved up to two times, and the consumption of derivatization reagents was reduced to less than one-tenth of that in the conventional vial method. We demonstrated to separate and quantify the amino acids in various biological samples. Herein, we presented a novel HPLC-based amino acid quantification method that enables the continuous analysis of a large number of samples. The iPDAQ facilitates accurate amino acid quantification due to the automation of derivatization and achieves improvement in the throughput and reduction of analysis labor.

Detection of Balenine in Mouse Plasma after Administration of Opah-Derived Balenine by HPLC with PITC Pre-Column Derivatization.

We examined the absorption of balenine (Bal) in mouse blood after the administration of a high-purity Bal prepared from opah muscle. Using HPLC with phenyl isothiocyanate pre-column derivatization, we successfully isolated imidazole peptides and their constituents. We detected Bal and 3-methylhistidine (3-Me-His) in mouse blood 1 h after the administration of opah-derived Bal. The concentrations of Bal and 3-Me-His significantly increased to 128.27 and 69.09 nmol/mL in plasma, respectively, but were undetectable in control and carnosine (Car)-administrated mice. In contrast, ß-alanine and histidine did not increase in mouse plasma 1 h after the administration of Car and opah-derived Bal. The present study is the first report on the absorption of food-derived Bal in mouse blood and serves as a pilot study for future clinical trials.

Development of An HPLC Method for the Determination of Mesalazine in Human Plasma by Fluorimetric Derivatization and Application to A Prototype Pharmacokinetic Study.

In this study, a new, fast and sensitive HPLC method with fluorometric detection was developed for the determination of mesalazine in human plasma and applied to a pharmacokinetic study. Mesalazine was precolumn derivatized with NBD-Cl and the fluorescent derivative was separated on a C18 (150 × 4.6 mm × 2.6 µm) analytical column at 30 ºC using a mobile phase composed of acetonitrile-0.1% o-phosphoric acid in water (70:30, v/v) by isocratic elution with flow rate of 1.0 mL min-1. The method was based on the measurement of the derivative using fluorescence detection (λex = 280 nm, λem = 325 nm). The retention time of mesalazine is 3.08 ± 0.06 min. Nortriptiline was used as internal standard. This currently developed method was validated according to ICH criteria by evaluating the specificity, linearity, precision, accuracy and robustness. The method was determined to be linear in a concentration range of 0.25-1.5 µg mL-1 with the correlation coefficient of 0.9997. LOD and LOQ were found to be 0.075 and 0.25 µg mL-1, respectively. Intraday and interday RSD values were less than 5.92%. The plasma concentration-time profile and pharmacokinetic parameters such as AUC0-t, AUC0-∞, Cmax, tmax, t1/2, were calculated according to the assays. The presented method can certainly be used for bioequivalence and bioavailability investigations and routine analysis of the drug in plasma.

Separation and determination of D-malic acid enantiomer by reversed-phase liquid chromatography after derivatization with (R)-1-(1-naphthyl) ethylamine

Abstract L-Malic acid is the Active Pharmaceutical Ingredient of the latest generation of compound electrolyte injection (STEROFUNDIN ISO, Germany) and plays a very important role in the rescue of critically ill patients. The optical purity of L-malic acid is a Critical Quality Attributes. A new reversed-phase high performance liquid chromatography (RP-HPLC) method for pre-column derivatization of D-malic acid enantiomer impurity in L-malic acid bulk drug was established. The derivatization reaction was carried out using (R)-1-(1-naphthyl)ethylamine ((R)-NEA) as a chiral derivatization reagent. The Kromasil C18 column was used with a detection wavelength of 225 nm, a flow rate of 1.0 mL·min-1, and a column temperature of 30 °C. The mobile phase was acetonitrile-0.01 mol·L-1 potassium dihydrogen phosphate solution (containing 20 mmol·L-1 sodium heptanesulfonate, adjusted to pH 2.80 with phosphoric acid) (at a ratio of 45:55) and the resolution of D-malic acid and L-malic acid derivatization products reached 1.7. The proposed method possesses the advantages of simple operation, mild conditions, stable derivatization products and low cost. Also it gave better separation and was more accurate than previous methods

Determination of potential genotoxic impurities chloroacetyl chloride and chloroacetic acid in azintamide raw material / 中国药科大学学报

@#In this paper, chemical derivatization-high performance liquid chromatography was used to determine the potential genotoxic impurities chloroacetyl chloride and chloroacetic acid, respectively, in the raw material of azintamide.Derivatization was carried out using 2-nitrophenylhydrazine followed by the determination.Separation was performed on a Thermo Syncronis C18 column (250 mm × 4.6 mm, 5 μm), with mobile phase consisting of 0.1% phosphoric acid in water (A) and acetonitrile(B) by gradient elution, at a flow rate of 1 mL/min.The column temperature was 40 °C and the detection wavelength was 226 nm.The blank solvent, derivatization reagent, and azintamide did not interfere with the peak of the test substance, and the target component was well separated from the others.For impurities chloroacetyl chloride and chloroacetic acid, the limits of detection (LOD) were 7.5 ng/mL and 15 ng/mL respectively. There was a good linear relationship between the integral area and the concentration in the range of 30-300 ng/mL.The sample recovery rate was in the range of 87.37% ~ 109.75%.The two methods established in this study have good specificity, good precision, high sensitivity and simple operation, which can be used for the trace determination of potential genotoxic impurities chloroacetyl chloride and chloroacetic acid in the raw material of azintamide.

[Ultra-performance liquid chromatography for determination of the contents of biogenic amines in the seminal plasma].

OBJECTIVE: To establish an ultra-performance liquid chromatography (UPLC) method for determination of the contents of the three biogenic amines putacine, spermidine and spermine in human seminal plasma. METHODS: Seminal plasma samples were extracted with 5% trichloroacetic acid and processed by pre-column derivatization with dansyl chloride. Chromatographic separation was performed with a C18 (2.1×50 mm,1.7 µm) chromatographic column using water and acetonitrile for mobile-phase gradient elution at a flow rate of 0.3 ml/min, a detection wavelength of 245 nm, a column temperature of 35℃ and an injection volume was 3.0 µl. The contents of putacine, spermidine and spermine in the seminal plasma of 52 healthy sperm donors (the normal group) and 23 azoospermia patients (the AS group) were measured, and their correlation with routine semen parameters were analyzed. RESULTS: The three biogenic amines showed a good linearity (r ≥ 0.999), with a lower detection limit of 0.03－0.08 µg/ml. The relative standard deviation (RSD) of precision was ≤ 0.72% and the average recovery rate was 79.74%－108.87%. The normal group, compared with the AS patients, showed significantly higher contents of putrescine (ï¼»8.19 ± 7.85ï¼½ vs ï¼»2.43 ± 1.38ï¼½ mg/ml, P < 0.05), spermidine (ï¼»77.30 ± 32.58ï¼½ vs ï¼»31.99 ± 16.21ï¼½ mg/ml, P < 0.05) and spermine (ï¼»246.44 ± 83.99ï¼½ vs ï¼»166.15 ± 79.28ï¼½ mg/ml, P < 0.05). However, the contents of the three biogenic amines in the seminal plasma exhibited no significant correlation with the routine semen parameters in the normal group. CONCLUSIONS: The ultra-performance liquid chromatography method we established, with the advantages of high sensitivity and reproducibility and short peak-time, can quickly and accurately determine the contents of biogenic amines in the seminal plasma.

[Comparative analysis of chemical compositions of fruits of Perilla frutescens var. arguta and P. frutescens var. frutescens by pre-column derivatization with GC-MS].

The present study compared the appearance and chemical composition of fruits of Perilla frutescens var. arguta(PFA) and P. frutescens var. frutescens(PFF). VHX-6000 3 D depth of field synthesis technology was applied for the appearance observation. The metabolites were qualitatively and quantitatively analyzed by pre-column derivatization combined with gas chromatography-mass spectrometry(GC-MS). Finally, cluster analysis(CA), principal component analysis(PCA), and orthogonal partial least-squares discriminant analysis(OPLS-DA) were applied for exploring the differences in their chemical compositions. The results indicated that the size and color of PFA and PFF fruits were different. PFF fruits were significantly larger than PFA fruits. The surface color of PFA fruits was brown, while PFF fruits were in multiple colors, such as white, grayish-white, and brown. Amino acids, saccharides, organic acids, fatty acids, and phenolic acids were identified in PFA and PFF fruits. The results of CA, PCA, and OPLS-DA indicated significant differences in the content of components between PFA and PFF fruits. Three metabolites, including D-glucose, rosmarinic acid, and D-fructose, which were significantly higher in PFA fruits than in PFF fruits, were screened out as differential metabolites. Considering the regulation on the content of rosmarinic acid in Perillae Fructus in the Chinese Pharmacopoeia(2020 edition), the medicinal value of PFA fruits is higher than that of PFF. In conclusion, there are differences in appearance and chemical composition between PFA fruits and PFF fruits. These results are expected to provide fundamental data for specifying plant source and quality control of Perillae Fructus.

Derivatization-targeted analysis of amino compounds in plant extracts in neutral loss acquisition mode by liquid chromatography-tandem mass spectrometry.

Amino compounds, such as amino acids and biogenic amines, are important metabolites that can be found in diverse natural matrices. The most common method for amino compound analysis nowadays is reversed-phase liquid chromatography tandem mass spectrometry (RPLC-MS/MS). However, due to the polar and the basic nature of amines, their RPLC retention is often insufficient or peaks are tailing. Derivatization is a way to overcome the issue and in the present work amino compounds are derivatized with diethyl ethoxymethylenemalonate (DEEMM) and analyzed by a RPLC triple quadrupole MS system in neutral loss scan (NLS) mode (loss of 46). This allows to target all compounds in the sample that undergo derivatization with DEEMM, so that the amino compound profile of the sample is obtained. To the best of our knowledge, the NLS acquisition mode has never been employed to target amino compounds after DEEMM derivatization. In the first part of the study, eight amino acids (arginine, aspartic acid, threonine, proline, tyrosine, tryptophan, phenylalanine and isoleucine) were employed as model compounds for method optimization, with good results in terms of DEEMM derivatives detection and repeatability. The developed method was successfully applied to a complex extract from the plant species Carduus nutans subsp. macrocephalus (Desf.) Nyman, with 18 amino acids and 3 other amines being identified. The proposed approach could be employed for straightforward identification of known and unknown amino compounds in different types of matrices.

[Determination of Methoxyacetic acid in urine by pre-column derivatization-liquid-liquid microextraction coupled with gas chromatography].

Objective: To establish a method for determining methoxyacetic acid in urine by pre-column derivatization-liquid-liquid microextraction coupled with gas chromatography (GC) . Methods: Phosphate buffer solution, tert-butoxyacetic acid (internal standard) and pentafluorobenzyl bromide (derivative) were added to the urine sample. After derived in a water bath at 90 ℃ for 40 min, the mixture was cooled and filtered, then the dichloromethane was used as an extractant. After being shaken and centrifuged, the lower organic phase was sucked and injected into a gas chromatograph, separated by a DB-5 capillary column, and detected by an ECD detector. Results: The linear range of the method was 0.6~60.0 mg/L with the correlation coefficients (r) above 0.999. The average recovery was76.6%~110.7%, the inter-day precision was 8.00%~8.82%, and the detection limit was 0.13 mg/L. Conclusion: The method was founded to be high sensitivity, low organic reagent usage and green. So it is suitable for the detection of methoxyacetic acid in urine of occupational exposure to ethylene glycol monomethyl ether.