A novel and sensitive method for simultaneous determination of 6 low-calorie bulk sweeteners by HPLC-ELSD.

A novel and sensitive method for the simultaneous analysis of six low-calorie bulk sweeteners (D-allulose, D-tagatose, D-mannitol, mycose, palatinose, and erythritol) without derivatisation was developed using high-performance liquid chromatography-evaporative light scattering detector (HPLC-ELSD). Chromatographic separations were carried out on a Zorbax Original NH2 (5 µm particle size, 250 mm×4.60 mm id, 70 Å) column with flow rate gradient elution with acetonitrile: water (80:20, v/v). Drift tube temperature was set at 50 ℃, the nebuliser carrier gas flow rate was 1.0 mL·min-1, and nitrogen pressure was regulated to 276 kPa with gain:3. The regression equation showed good linearity (R2 = 0.9985-0.9998) for all six low-calorie bulk sweeteners in the tested range (0.060-0.60 mg·mL-1). The limits of detection (LOD) for the six low-calorie bulk sweeteners ranged from 0.02 to 0.06 mg·mL-1. The proposed HPLC-ELSD method was validated for the quantification of the low-calorie bulk sweeteners in 14 types of foods, and the results were satisfactory. In addition, the results showed that the number of sweeteners in each food product varied. The presence of multiple low-calorie bulk sweeteners in certain foods is interesting. This method is successful in monitoring low-calorie bulk sweeteners in food.

[Simultaneous determination of six rare sugars in solid foods by high performance liquid chromatography-evaporative light-scattering detection].

Excessive sugar consumption is associated with metabolic health problems. Rare sugars are gradually being used as substitutes for sugar, and their consumption is increasing daily, raising food-safety issues such as false advertising, adulteration, and overdosing. The determination of rare-sugar compounds has attracted considerable attention in recent years. However, no standard method for the simultaneous determination of six rare sugars (allulose, tagatose, trehalose, isomaltulose, erythritol, and mannitol) in solid foods is available. Therefore, establishing a suitable analytical method for these sugars is necessary. In this study, high performance liquid chromatography coupled with evaporative light-scattering detection was used to determine rare sugars in solid foods. The optimum chromatographic and detector conditions were determined by evaluating the instrument parameters. Analysis was carried out on a Zorbax Original NH2 column (250 mm×4.6 mm, 5 µm) via flow-rate gradient elution (0-15 min, 1.0 mL/min; 15-18 min, 1.0-2.0 mL/min; 18-25 min, 2.0 mL/min) with acetonitrile-water (80∶20, v/v) as the mobile phase. Sharp and symmetric chromatographic peaks were obtained under these conditions. The resolutions for all the six rare sugars were greater than 1.5. Optimization of the evaporative light-scattering detector was extremely important to the responses of the rare-sugar compounds. The two most significant parameters were the nebulizer carrier gas flow rate and drift tube temperature. The detection system was operated under the following conditions: the drift tube temperature was set to 50 ℃, the nebulizer carrier gas was high-purity nitrogen, the carrier gas flow rate was 1.0 mL/min, the nitrogen pressure was regulated to 275.79 kPa, and the gain factor was set to 3. The sample was extracted with 25 mL of water, shaken and vortexed for 10 min, purified with 200 µL of zinc acetate solution and 200 µL of potassium ferricyanide solution, and centrifuged at 4500 r/min for 10 min. Next, 1 mL of the supernatant was passed through a 0.22 µm aqueous-phase filter membrane, and the filtrate obtained was analyzed using the evaporative light-scattering detector. The six rare sugars were quantitatively analyzed using the external standard method and showed good linearity with coefficients of determination (R2) greater than 0.9985. The limits of detection and quantification were 0.020-0.60 and 0.60-1.8 g/100 g, respectively. In addition, when blank solid food samples were spiked with the analytes at three levels, the average recoveries of the six rare sugars were 92.6%-103.2%, with relative standard deviations (RSDs) of 0.7%-4.4%. An RSD of <5% indicated that the method had good precision. Interference experiments were performed to determine whether the sugars and artificial sweeteners commonly found in solid foods affected the targets. The method established in this study was used to analyze the contents of the six rare sugars in actual solid food samples. The experimental results showed various levels of rare glycoconjugates in different solid foods. Moreover, the actual compositions and labeled of rare glycoconjugates in the solid foods were generally consistent. The proposed method features simple operation, rapid results, high sensitivity, and good reproducibility; thus, it meets the requirements for the detection of the six rare sugars in solid foods. It also provides technical support for the development of methodological standards and detection limits for rare sugars in Chinese foods. The results of this study are of great relevance for the daily monitoring of the levels of the six rare sugars in solid foods.

Simultaneous determination of nine phenolic compounds in imitation wild Dendrobium officinale samples using ultrahigh-performance liquid chromatography-tandem mass spectrometry.

Dendrobium officinale Kimura et Migo (D. officinale), one of the nine everlasting types of grass, has gained increasing attention owing to its important roles in alternative medicines and drug discovery. Due to its natural resources being in danger of being extinct, imitation wild planting is becoming increasingly common. To assess the product's quality completely, an efficient ultrahigh performance liquid chromatography-triple quadrupole tandem mass spectrometry (UHPLC-QQQ-MS/MS) method was established to simultaneously quantify nine phenolic compounds in D. officinale samples. The extraction parameters, including solvent, solvent concentration, solid-liquid ratio, and extraction time, were systematically optimized with the single-factor test. The results demonstrated that extraction with a 1:200 solid-to-liquid ratio of 80% methanol for 1.5 h was the most efficient condition for the extraction of flavonoids. Satisfactory retention times and resolution of the nine analytes were acquired on the Thermo Scientific Hypersil GOLD column with multiple reaction monitoring in negative ion scanning mode. The method was validated to demonstrate its selectivity, linearity, precision, accuracy, and robustness. Thus, the verified UHPLC-QQQ-MS/MS method was successfully applied to the quantification of phenolic components present in D. officinale samples. The results indicated that the quantity and composition of phenolic components in D. officinale from various provenances were significantly different. This work provides a theoretical foundation for the cultivation and assessment of wild D. officinale quality.

Simultaneous Rapid Determination of Seven Alternaria Toxins in Tuberous Crops during Storage Using QuEChERS Coupled with Ultrahigh-Performance Liquid Chromatography-Tandem Mass Spectrometry.

Robust and sensitive ultrahigh-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) combined with the quick, easy, cheap, effective, rugged, and safe (QuEChERS) method was applied for the detection of seven Alternaria toxins (ATs) in tuberous crops. The influence of tuber conditions (fresh, germinated, and moldy) during storage on the concentration of the seven ATs is also investigated. ATs were extracted with acetonitrile under acidic conditions and purified with a C18 adsorbent. ATs were scanned with electrospray ionization (positive/negative ion) dynamic switching and detected in MRM mode. Calibration curve analysis results reveal good linear relationships in all toxin concentration ranges (R2 > 0.99). The limit of detection and limit of quantification were 0.25-0.70 and 0.83-2.31 µg/kg, respectively. The average recoveries of the seven ATs were 83.2-104% with intra-/inter-day precision at 3.52-6.55% and 4.02-7.26%, respectively. The developed method provided adequate selectivity, sensitivity, and precision in detecting the seven ATs at trace levels, and dispensed with standard addition or matrix-matched calibration to compensate for matrix effects. ATs in the fresh, germinated, and moldy samples of tuberous crops in storage (taro, potato, sweet potato, yam, cassava) were analyzed with this method, and the concentrations were 2.01-14.51 µg/kg and significantly increased with storage duration. ALS was detected in most samples, whereas no quantities of ALT and ATX-I were detected. AME was often detected in combination with AOH in sweet potatoes. TeA and Ten were mostly detected in taro, potato, and yam. The established method could be used for the simultaneous detection and quantification of multicomponent toxins in elaborate matrices.

[Determination of 19 chlorophenols in fish by QuEChERS-gas chromatography-mass spectrometry].

With the increasing use of chlorine-containing pesticides, hypochlorous acid disinfection water as well as aquatic product insecticides and fungicides are widely used in the cultivation of fish. This has led to the contamination of fish by chlorophenol compounds. However, currently, there is no standard method for the simultaneous determination of 19 chlorophenol compounds in fish. In this study, the optimum chromatography and mass spectrometry conditions were determined by investigating the instrument parameters. The 19 chlorophenol compounds were well separated using the DB-5MS capillary chromatographic column (30 m×0.25 mm×0.25 µm) with a carrier gas flow rate of 1 mL/min. Under this condition, the chromatographic peak was sharp and symmetric. An analytical method was developed for the simultaneous determination of the 19 chlorophenol compounds in fish using gas chromatography-mass spectrometry coupled with QuEChERS pretreatment. The improved QuEChERS method was used in sample preparation. The 19 chlorophenol compounds were extracted with organic solvents and purified with purifying agents. During the experiment, the effect of the kinds and volumes of the extraction solvent, as well as the types and dosages of the purifying agent, on the recoveries of the 19 chlorophenol compounds were investigated. Moreover, the temperature and time of derivatization, as well as the dosage of the derivatization agent, were optimized. All aforementioned analyses were conducted with the aim of determining the optimal pretreatment method. Finally, the optimized gas chromatography-mass spectrometry conditions were employed for the quantitative determination of 19 chlorophenol compounds in fish samples. Based on the experimental results, the best extraction method was determined to be the one where the extraction agent (10 mL ethyl acetate) was added to 3 g sodium chloride and 5 g anhydrous magnesium sulfate in the test tube, followed by ultrasonication for 15 min. The sample was centrifuged at 4500 r/min for 5 min, and 500 mg C18 was selected as the purifying agent to purify the supernatant. The purified supernatant was blown with nitrogen to less than 1 mL at 45 ℃, and then redissolved with ethyl acetate to 1 mL. Subsequently, the sample solution was passed through a 0.22 µm organic filter membrane, following which 50 µL bis(trimethylsilyl)trifluoroacetamide was added for derivatization at 45 ℃ for 30 min. Lastly, the 19 chlorophenol compounds were determined by gas chromatography-mass spectrometry with an electrospray ionization source and selecting ion monitoring mode. The 19 chlorophenol compounds were then quantitatively analyzed by the external standard method. The compounds showed good linearity in the concentration range of 0.4-10 µg/L, with correlation coefficients (R2) greater than 0.998. The limits of detection and limits of quantification were 0.01-0.05 µg/kg and 0.04-0.16 µg/kg, respectively. Moreover, the average recoveries of the 19 chlorophenol compounds were in the range of 70.6%-115.0% at three spiked levels, and the relative standard deviations were in the range of 2.6%-10.5%. The established method in this study was applied to detect and analyze chlorophenol compounds in actual samples. The experimental results showed that various levels of chlorophenol compounds could be detected in different fishes. Among them, the total amount of chlorophenol compounds detected in the Corvina was 8.74 µg/kg, followed by the Crucian carp at 7.59 µg/kg, and the minimum detected amount in rice fish (1.59 µg/kg). With its simple operation, high sensitivity, and good repeatability, the established method simplifies the pre-treatment of fish samples. It can also meet the requirements for the high-throughput detection of 19 chlorophenol compounds in fish, thereby significantly improving the detection efficiency of chlorophenols. Moreover, the method provides crucial technical support and a theoretical basis for the establishment of feasible detection standards for chlorophenols in China, as well as for the control of residue levels of chlorophenol compounds in fish. The findings have important practical significance to implement management measures during fish breeding and transportation.