Simultaneous determination of nine intense sweeteners in foodstuffs by high performance liquid chromatography and evaporative light scattering detection--development and single-laboratory validation

Preparation of CoFe@C composite modified electrode for neohesperidin dihydrochalcone sensing and its application in Chinese medicine

CoFe@C was first prepared by calcining the precursor of CoFe-metal-organic framework-74 (CoFe-MOF-74), then an electrochemical sensor for the determination of neohesperidin dihydrochalcone (NHDC) was constructed, which was stemmed from the novel CoFe@C/Nafion composite film modified glassy carbon electrode (GCE). The CoFe@C/Nafion composite was verified by field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM). Electrochemical impedance spectroscopy (EIS) was used to evaluate its electrical properties as a modified material for an electrochemical sensor. Compared with CoFe-MOF-74 precursor modified electrode, CoFe@C/Nafion electrode exhibited a great synergic catalytic effect and extremely increased the oxidation peak signal of NHDC. The effects of various experimental conditions on the oxidation of NHDC were investigated and the calibration plot was tested. The results bespoken that CoFe@C/Nafion GCE has good reproducibility and anti-interference under the optimal experimental conditions. In addition, the differential pulse current response of NHDC was linear with its concentration within the range 0.08 ~ 20 µmol/L, and the linear regression coefficient was 0.9957. The detection limit was as low as 14.2 nmol/L (S/N = 3). In order to further verify the feasibility of the method, it was successfully used to determine the content of NHDC in Chinese medicine, with a satisfactory result, good in accordance with that of high performance liquid chromatography (HPLC).

Simultaneous analysis of natural and artificial sweeteners in sugar-free drinks and urine samples by column-switching UHPLC-charged aerosol detection method

Sweeteners are considered an alternative to high-calorie foods or drinks and have been widely used globally. However, the simultaneous separation and detection of high-polarity natural and artificial sweeteners are challenging owing to their broad-spectrum physical and chemical properties. Herein, we developed a column-switching UHPLCCAD method and used it for detecting and quantitating 12 sweeteners, including natural sweeteners (erythritol, mannitol, xylitol, sorbitol and stevioside) and artificial sweeteners (acesulfame potassium, saccharin sodium salt, sodium cyclamate, sucralose, aspartame, alitame and neotame). The LOD and LOQ were 0.932-6.25 μg/mL and 3.10-20.83 μg/mL, respectively, and the method demonstrated excellent linearity (R² ≥ 0.9990), good precision (intraday and interday precision was 0.59-6.88 %), and high recovery (average recoveries were 85.16-108.64 %). This method was applied to determine the sweeteners in 15 sugar-free drinks purchased from the local Chinese supermarkets. What's more, natural sweetener erythritol and artificial sweetener acesulfame potassium were suspected over addition in sugar-free drinks. Meanwhile the method was applied to the sweeteners in various sugar-free drinks and the dynamic monitoring of transit and excretion in vivo after drinking. Those prove that the method can be used to the detection of sugar free drinks and quality control of the sweeteners. The study highlights the potential of UHPLC-charged aerosol detection technology in detection of multiple components in food industry.

Determination of neotame in various foods by high-performance liquid chromatography coupled with ultraviolet and mass spectrometric detection

A new analytical technique involving protein precipitation, heating, lipid degreasing, and SPE procedures combined with HPLC-UV and HPLC-MS/MS has been developed for the determination of neotame in a variety of food samples. This method is applicable for high-protein, high-lipid, or gum-based solid samples. The limit of detection of the HPLC-UV method was 0.5 μg/mL, while that of the HPLC-MS/MS method was 3.3 ng/mL. The spiked recoveries of neotame in 73 kinds of foods were in the range of 81.1-107.2 % with UV detection. The spiked recoveries obtained by HPLC-MS/MS in 14 kinds of foods ranged from 81.6 % to 105.8 %. This technique was successfully used to determine the contents of neotame in two positive samples, indicating its applicability in food analysis.

Bioelectronic Tongues Mimicking Insect Taste Systems for Real-Time Discrimination between Natural and Artificial Sweeteners

A bioelectronic tongue (B-ET) mimicking insect taste systems is developed for the real-time detection and discrimination of natural and artificial sweeteners. Here, a carbon nanotube field-effect transistor (CNT-FET) was hybridized with nanovesicles including the honeybee sugar taste receptor, gustatory receptor 1 of Apis mellifera (AmGr1). This strategy allowed us to detect glucose, a major component of nectar, down to 100 fM in real time and identify sweet tastants from other tastants. It could also be utilized for the detection of glucose in dextrose tablet solutions. Importantly, we demonstrated the discrimination between natural and artificial sweeteners down to 10 pM even in real beverages such as decaffeinated coffee using our hybrid platform. In this respect, our B-ET mimicking insect taste systems can be a powerful tool for various applications such as food screening and basic studies on insect taste systems.

Enhancement of Antioxidant Activities in Black Soy Milk through Isoflavone Aglycone Production during Indigenous Lactic Acid Bacteria Fermentation

Black soybeans contain high antioxidant compounds such as isoflavone but mainly in glucoside form, with low antioxidant activities. Fermentation by lactic acid bacteria (LAB) can enhance the antioxidant properties, but its ability is strain-dependent. This study aims to study the ability of Indonesian indigenous LAB, Lactiplantibacillus plantarum WGK 4, Streptococcus thermophilus Dad 11, and Lactiplantibacillus plantarum Dad 13, to enhance the antioxidant properties during black soy milk fermentation. Fermentation was carried out at 37 °C for 24 h. Viable cell, acid production, Folin–Ciocalteu assay, antioxidant activity (DPPH), isoflavone aglycone daidzein and genistein, and β-glucosidase activity were measured every six hours. All LAB strains could grow well during the fermentation of black soy milk. Lactiplantibacillus plantarum WGK 4 produced the highest acid (1.50%). All three LAB strains could enhance antioxidant activity (DPPH) from 24.90% to 31.22–38.20%, followed by increased isoflavone aglycone. All strains could increase daidzein and genistein content, ranging from 61% to 107% and 81% to 132%, respectively. All three Indonesian indigenous LAB enhanced antioxidant properties of black soy milk relatively at the same level and potentially could be used as a starter culture of black soy milk fermentation.

Reagent sequence for planar chromatographic analysis of eight sweeteners in food products approved in the European Union

Sweeteners, which are regulated as food additives in the European Union, are used as tabletop sweeteners or added to foods for sweetening with the aim of reducing the calorie content. For their simple analysis, a quantitative high-performance thin-layer chromatography multi-imaging (HPTLC−UV/Vis/FLD) method was developed, which used a reagent sequence to detect eight important sweeteners in eight different food products. The samples were dissolved or diluted and separated on HPTLC plates silica gel 60 F254 with a mixture of ethyl acetate, methanol, and acetic acid 5:1:1, V/V. Due to the different structures and detectabilities of the sweeteners, different post-chromatographic derivatization reagents were compared for multi-detection of the sweeteners on the same plate. First, the UV absorbance was detected, and then the derivatization reagent sequence was performed with the primuline reagent, then ninhydrin glacial acetic acid reagent, and finally 2-naphthol sulfuric acid reagent. It was important to arrange and use the reagents according to their increasing acidity. Zones of interest can be confirmed by mass spectrometry. Compared to the status quo analysis of sweeteners, the whole method is simple, robust, and rapid considering the minimalist sample preparation and reagent sequence applied on the same plate. In addition, the influence of food sample matrix on the results is easily understood due to the image-giving nature and multi-detection.

Fermentation and Storage Characteristics of “Fuji” Apple Juice Using Lactobacillus acidophilus, Lactobacillus casei and Lactobacillus plantarum: Microbial Growth, Metabolism of Bioactives and in vitro Bioactivities

Fruit juices have been widely used as the substrates for probiotic delivery in non-dairy products. In this study, three lactic acid bacteria (LAB) strains, including Lactobacillus acidophilus, Lactobacillus casei and Lactobacillus plantarum, were selected to ferment apple juice. During 72-h of fermentation, these LAB strains grew well in the apple juice with significant increases in viable cell counts (from 7.5 log CFU/mL to 8.3 log CFU/mL) and lactic acid content (from 0 to 4.2 g/L), and a reduction of pH value (from 5.5 to around 3.8). In addition, the antioxidant and antibacterial capacities of fermented apple juice in vitro were significantly improved through the phenolic and organic acid metabolisms. After storage at 4°C for 30 days, the total amino acid content of fermented apple juice was significantly increased, although the viable cell counts and total phenolic content were decreased (p < 0.05). Furthermore, the stored fermented apple juices still possessed antibacterial and in vitro antioxidant activities. Overall, all the selected LAB strains could be suitable for apple juice fermentation and can effectively improve their biological activities.

Fullerenol as a water-soluble MALDI-MS matrix for rapid analysis of small molecules and efficient quantification of saccharin sodium in foods

Due to the strong background interferences in the low-mass region and poor reproducibility of conventional organic matrices, it is of great importance to develop a novel matrix for matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) to qualitatively and quantitatively analyze small molecules. In this work, water-soluble fullerenol C₆₀(OH)_24-26 was selected as a MALDI matrix for the analysis of low-molecular-weight compounds in consideration of optical absorption property, water solubility and stability. Compared with the traditional matrices, fullerenol demonstrated lower background interference and stronger peak intensity. In addition, the hydrophilic fullerenol could avoid the heterogeneous crystallization in sample preparation, increase the reproducibility and sensitivity of MALDI-MS, and ameliorate quantitative analysis of small molecules. With saccharin as model analyte, quantitative analysis was carried out using fullerenol as matrix. The results demonstrated satisfying reproducibility and good tolerance to salt. The limit-of-detection of the quantitative analysis was as low as 4 pmol, and the linear range is 1-100 μg mL^-1 with R² greater than 0.99. The analytical results also showed excellent precision and accuracy, low matrix effect and good recovery rate. Fullerenol as a potential matrix was further validated in the quantification of saccharin sodium in different real food samples, such as nuts and drinks. This work not only confirms the potential of fullerenol for the quantitative analysis in food field, but also provides a new technique for rapid analysis of small molecules.

Pretreatment methods for analyzing steviol glycosides in diverse food samples

Steviol glycosides are well-known food sweeteners; their consumption has steadily increased over time. A pretreatment method was developed and validated to better separate rebaudioside A and stevioside from various protein-rich and fatty foods for quantification. This method was applied to soy sauce in liquid type and fish cake and coffee in solid type. Parameters such as linearity, limit of detection (LOD), limit of quantification (LOQ), accuracy, and precision were calculated. Calibration curves were linear in the working range of 5-100 mg/l, with coefficients of determination ≥0.99. The LOD and LOQ were in the ranges of 0.16-0.39 and 0.52-1.28 mg/kg, respectively. The percentage recoveries of the fortified samples were in the 88.01%-103.09% range, and the relative standard deviation was <10%. Method validation predicted a desirable accuracy, linearity, and precision. Therefore, the developed method can be practically applied for the quantitation of steviol glycosides in various foods, including soy sauce in liquid type and fish cake and coffee in solid type.

Analytical Methods for Determination of Non-Nutritive Sweeteners in Foodstuffs

Sweeteners have been used in food for centuries to increase both taste and appearance. However, the consumption of sweeteners, mainly sugars, has an adverse effect on human health when consumed in excessive doses for a certain period, including alteration in gut microbiota, obesity, and diabetes. Therefore, the application of non-nutritive sweeteners in foodstuffs has risen dramatically in the last decade to substitute sugars. These sweeteners are commonly recognized as high-intensity sweeteners because, in a lower amount, they could achieve the same sweetness of sugar. Regulatory authorities and supervisory agencies around the globe have established the maximum amount of these high-intensity sweeteners used in food products. While the regulation is getting tighter on the market to ensure food safety, reliable analytical methods are required to assist the surveillance in monitoring the use of high-intensity sweeteners. Hence, it is also necessary to comprehend the most appropriate method for rapid and effective analyses applied for quality control in food industries, surveillance and monitoring on the market, etc. Apart from various analytical methods discussed here, extraction techniques, as an essential step of sample preparation, are also highlighted. The proper procedure, efficiency, and the use of solvents are discussed in this review to assist in selecting a suitable extraction method for a food matrix. Single- and multianalyte analyses of sweeteners are also described, employing various regular techniques, such as HPLC, and advanced techniques. Furthermore, to support on-site surveillance of sweeteners’ usage in food products on the market, non-destructive analytical methods that provide practical, fast, and relatively low-cost analysis are widely implemented.

Simultaneous determination of sweeteners and preservatives in beverages by HPLC-DAD-ELSD

People suffering from diabetes or being overweight must severely reduce their sugar use, often seeking food with sweeteners. Often, sugar is replaced by non-nutritious sweeteners in beverages, which also contain several other substances like vitamins, caffeine, amino acids, phenolic compounds and thus increasing the shelf life of the beverages is additionally treated with the addition of preservatives. As the concentration of additives in food (including beverages) is determined by the legislation in force, it is necessary to have an appropriate analytical method for food control. Since artificial sweeteners and preservatives are very different substances, they are determined separately using different HPLC methods. In this work HPLC method combining the advantages of specific (diode array detector, DAD) and universal (evaporative light scattering detector, ELSD) detector was validated and used for simultaneous determination of benzoic acid, sorbic acid, aspartame, acesulfame K, saccharin, sucralose and steviol glycosides in sugar-free beverages. The proposed analytical method showed good linearity, precision, and accuracy. Measured limits of detection (0.6 – 11.8 mg.dm-3 depending on the analyte) were sufficient to analyze 5-times diluted beverage samples. The validated method has been successfully used for the simultaneous analysis of artificial sweeteners and preservatives in beverage samples (energy drinks, ice teas, carbonated drinks). Except for steviol glycosides, the concentration of monitored substances in beverages did not exceed the maximum permitted concentrations given in the valid legislation.

Quantification of artificial sweeteners in alcoholic drinks using direct analysis in real-time QTRAP mass spectrometry

Artificial sweeteners have been widely used as replacements for sugars in foods. Rapid determination of artificial sweeteners contained in various foods are highly desirable for the routine analysis. Here, we report a robust approach based on direct analysis in real time coupled with QTRAP mass spectrometry to screen and quantitate simultaneously seven artificial sweeteners, including aspartame, saccharin, acesulfame-K, neotame, sucralose, cyclamate and alitame in alcoholic drinks. The detection method merely involved a simple sample pretreatment process, with a good linearity, low limit of quantification, satisfied recovery and relative standard deviation for each target compound. More importantly, the approach is highly sensitive and accurate in monitoring the seven artificial sweeteners in whisky, Chinese liquors, beer and wines obtained from the supermarket. The results demonstrated that the approach described here could be suitable for large-scale application in routine quality control analysis of artificial sweeteners.

Simultaneous analysis of polyethylene glycol in dietary supplement tablets using high-performance liquid chromatography and verification with liquid chromatography-electrospray ionization mass spectrometry

Polyethylene glycol (PEG) are widely applied in detergents, cosmetics, and food additives. A simultaneous analytical method was developed to detection the polyethylene glycol (100-10000 Da). High-performance liquid chromatography (HPLC) with evaporative light scattering detector (ELSD) could analyze successively PEG products. The method was verified with liquid chromatography-electrospray ionization mass spectrometry (LC-ESI-MS/MS). The retention times of PEG 200-8000 ranged from 1.97 to 12.33 min. Method validation was performed to the International Conference on Harmonization (ICH) guidelines and the Korea Ministry of Food and Drug Safety (MFDS); linearity: R² > 0.997, LOD: 7.47-16.24 µg/mL, LOQ: 22.40-75 µg/mL, repeatability (%RSD): 0.2-2.5, recovery (%): 90.4-104.9% for film-coated tablet, 80.1-95.9% for sugar-coated tablet. A total of 115 PEG could be identified by extracted ion chromatography in mass analysis, based on the charge state represented as [M+Na⁺+H₃O⁺_n-1]. This method can be applied for successive identification of PEGs in PEG-containing products.

PCN-222 metal-organic framework: a selective and highly efficient sorbent for the extraction of aspartame from gum, juice, and diet soft drink before its spectrophotometric determination

In this paper, we describe synthesis and application of an iron porphyrinc metal-organic framework PCN-222(Fe) for solid phase extraction of aspartame, an artificial non-saccharine sweetener, from gum, juice and diet soft drink samples prior to its determination by spectrophotometry. The mesoporous MOF was synthesized solvo-thermally and characterized by Fourier transform-infrared spectroscopy, powder X-ray diffraction, scanning electron microscopy, and Brunauer-Emmett-Teller techniques. To obtain the best extraction efficiency of aspartame, significant affecting parameters such as pH of sample solution, amount of the sorbent, type and volume of eluting solvent, and adsorption and desorption times were investigated and optimized. Under optimum conditions, the calibration graph for aspartame was linear in the range of 0.1 to 100.0 mg.L^-1 and relative standard deviation of aspartame was 1.7% (n = 7). Limit of detection of method calculated as 0.019 mg.L^-1 and the enrichment factor of 350 folds was obtained. Adsorption capacity of synthesized sorbent was found to be 356 mg.g^-1. Hierarchical porosity, the eight terminal-OH groups of the Zr₆ node, and hydrogen bonding possibly play vital role for selective adsorption of aspartame. The optimized method was successfully applied to the determination of aspartame in real samples with reasonable recoveries (> 98%).

Determining High-Intensity Sweeteners in White Spirits Using an Ultrahigh Performance Liquid Chromatograph with a Photo-Diode Array Detector and Charged Aerosol Detector

In China, white spirit is not only an alcoholic drink but also a cultural symbol. A novel and accurate method for simultaneously determining nine sweeteners (most authorized for use in China) in white spirits by ultrahigh performance liquid chromatography (UHPLC) with a photo-diode array detector (PDA) and charged aerosol detector (CAD) was developed. The sweeteners were acesulfame, alitame, aspartame, dulcin, neotame, neohesperidine dihydrochalcone, saccharin, sodium cyclamate, and sucralose. The sweeteners were separated within 16 min using a BEH C18 column and linear gradient-elution program. The optimized method allowed low concentrations (micrograms per gram) of sweeteners to be simultaneously detected. The CAD gave good linearities (correlation coefficients > 0.9936) for all analytes at concentrations of 0.5 to 50.0 μg/g. The limits of detection were 0.16 to 0.77 μg/g. Acesulfame, dulcin, neohesperidine dihydrochalcone, and saccharin were determined using the PDA detector, which gave correlation coefficients > 0.9994 and limits of detection of 0.16 to 0.22 μg/g. The recoveries were 95.1% to 104.9% and the relative standard deviations were 1.6% to 3.8%. The UHPLC-PDA-CAD method is more convenient and cheaper than LC-MS/MS methods. The method was successfully used in a major project called “Special Action against Counterfeit and Shoddy white spirits” and to monitor risks posed by white spirits in China.

Development of a highly sensitive liquid chromatography with tandem mass spectrometry method for the qualitative and quantitative analysis of high-intensity sweeteners in processed foods

A new method for the simultaneous determination of two sweeteners (Advantame and Neotame) in processed foods using liquid chromatography (LC) with tandem mass spectrometry(MS/MS) was developed herein. Chromatographic separations were performed using an ACQUITY UPLC CSH C18 column at 40 °C via a mobile phase comprising 10-mmol/L ammonium formate and methanol. Samples were prepared via rapid dialysis using 30% methanol solution in a thermostatic shaker set at 160 rpm and 50 °C for 1 h. The matrix in the test solution had no effect on the identification and quantification of the compound without a clean-up step using solid-phase extraction (SPE). This method satisfied all validation criteria with a limit of quantification (LOQ) of 0.01 μg/g for all samples. Using this method, the amounts of Advantame and Neotame in 24 processed foods were subsequently investigated, with the results indicating their detection beyond the lower LOQ. Moreover, a multiple reaction monitoring information-dependent acquisition-enhanced product ion (MRM-IDA-EPI) method was developed and described to further enhance product-identification ability.

Improved method for the determination of 12 non-nutritive sweeteners and monitoring in various foods using liquid chromatography-tandem mass spectrometry

An improved and highly sensitive method was developed and validated for the determination of 12 (7 permitted and 5 non-permitted in Korea) non-nutritive sweeteners in various foods using liquid chromatography-electrospray ionisation-tandem mass spectrometry. The chromatographic separation was performed on an Xbridge BEH C18 column (3 mm × 100 mm, 2.5 μm) with gradient elution using 10 mM ammonium acetate in water and 10 mM ammonium acetate in methanol. Sample preparation consisted of simple dilution, homogenisation, centrifugation and purification with a C18 cartridge prior to analysis. The relative matrix effect (%ME) was within ±20% for all sweeteners. The method also showed good linearity (R² > 0.99). The limit of detection and limit of quantification values in sample were in the range of 0.02-2.66 and 0.06-8.05 mg kg^-1, respectively. The recoveries at three concentration levels ranged between 80% and 119%, with relative standard deviation values below 10%. In addition, the expanded uncertainties determined for 12 sweeteners in 5 different food matrices were confirmed to be <14%. Finally, the method was successfully applied to the analysis of sweeteners in 681 food samples purchased in Korea, Australia and Turkey. These results demonstrate that the method is suitable for the simultaneous determination of multiple-sweeteners in a variety of foods.

On-cartridge derivatisation using matrix solid phase dispersion for the determination of cyclamate in foods

A novel method for determination of sodium cyclamate in foods was developed. In this method, a syringe was loaded with the homogeneous mixture of the sample, KMnO₄ powder and silica dispersant and used as a matrix solid phase dispersion (MSPD) reactor. As the reactor was infiltrated with small amounts of concentrated HCl, cyclamate was converted to 2-chlorocyclohexanone quickly and effectively within 5 min and determined by HPLC on a reversed-phase column using UV detection at a wavelength of 310 nm. Comparing with the traditional derivatisation in solution, the better clean-up was provided using on-cartridge derivatisation of MSPD, and much time, labor, and expense were saved. The results showed good linearity (r² = 0.9998) over the concentration range of 1-500 mg/L. The limit of detection (LOD) and limits of quantification (LOQ) of the cyclamate were 0.3 mg/L and 1 mg/L respectively. The recoveries ranged from 91.6% to 101.3% with the relative standard deviations (RSDs) in the range of 2.5%-4.3%.

Simultaneous determination of sodium saccharin, aspartame, acesulfame-K and sucralose in food consumed in Korea using high-performance liquid chromatography and evaporative light-scattering detection

Four artificial sweeteners, i.e., sodium saccharin, aspartame, acesulfame-K and sucralose, are permitted for use in Korea, and recent regulatory changes have expanded the number of food categories in which they may be used. Four artificial sweeteners were determined simultaneously in more than 900 food items from 30 food categories that are commercially available in Korean markets, including both domestic and imported products, using high-performance liquid chromatography and evaporative light-scattering detection (ELSD). A new procedure using 75% acetone to remove fat was applied for sample preparation. The levels detected in all samples were below the maximum permitted use levels established in Korea. Despite the increased number of categories, the only one in which sodium saccharin was newly found was takju, an alcoholic beverage. Sodium saccharin was not found in other beverages in the food analysis or in the food label survey, even though its use was reported in a previous study, suggesting that consumer preference outweighs regulatory decisions. When the analytical results were combined with food-consumption data obtained from the Korea National Health and Nutrition Examination Survey 2010-14, the estimated daily intakes of all the sweeteners were considered safe.

Detection and identification of sugar alcohol sweeteners by ion mobility spectrometry

The rapid and sensitive detection of sugar alcohol sweeteners was demonstrated using ion mobility spectrometry (IMS). IMS provides a valuable alternative in sensitivity, cost, and analysis speed between the lengthy gold-standard liquid chromatography-mass spectrometry (LC-MS) technique and rapid point-of-measurement disposable colorimetric sensors, for the Food and Nutrition industry's quality control and other "foodomics" area needs. The IMS response, characteristic signatures, and limits of detection for erythritol, pentaerythritol, xylitol, inositol, sorbitol, mannitol, and maltitol were evaluated using precise inkjet printed samples. IMS system parameters including desorption temperature, scan time, and swipe substrate material were examined and optimized, demonstrating a strong dependence on the physicochemical properties of the respective sugar alcohol. The desorption characteristics of each compound were found to dominate the system response and overall sensitivity. Sugar alcohol components of commercial products - chewing gum and a sweetener packet - were detected and identified using IMS. IMS is demonstrated to be an advantageous field deployable instrument, easily operated by non-technical personnel, and enabling sensitive point-of-measurement quality assurance for sugar alcohols.

Simultaneous determination of sucralose and related compounds by high-performance liquid chromatography with evaporative light scattering detection

Sucralose is widely used in food and beverages as sweetener. Current synthesis approaches typically provide sucralose products with varying levels of related chlorinated carbohydrates which can affect the taste and flavor-modifying properties of sucralose. Quantification of related compounds in sucralose is often hampered by the lack of commercially available standards. In this work, nine related compounds were purified (purity>97%) and identified by liquid chromatography-mass spectrometry (LC-MS) and nuclear magnetic resonance (NMR), then a rapid and simple HPLC coupled with evaporative light scattering detection (ELSD) method has been developed for the simultaneous determination of sucralose and related compounds. Under optimized conditions, the method showed good linearity in the range of 2-600μgmL(-1) with determination coefficients R(2)⩾0.9990. Moreover, low limits of detection in the range of 0.5-2.0μgmL(-1) and good repeatability (RSD<3%, n=6) were obtained. Recoveries were from 96.8% to 101.2%. Finally, the method has been successfully applied to sucralose quality control and purification process monitoring.

A New HPLC-ELSD Method for Simultaneous Determination of N-Acetylglucosamine and N-Acetylgalactosamine in Dairy Foods

A rapid high performance liquid chromatographic method with evaporative light scattering detection (HPLC-ELSD), using a carbohydrate column, was developed for simultaneous determination of N-acetylglucosamine (GlcNAc) and N-acetylgalactosamine (GalNAc) in dairy foods. Sample preparation was performed by precipitation using acetonitrile. The limits of detection were 2.097 mg/L for GlcNAc and 3.247 mg/L for GalNAc. The limits of quantification were 6.043 mg/L for GlcNAc and 9.125 mg/L for GalNAc. Accuracy ranged from 96.4 to 105.7% for GlcNAc and from 97.1 to 104.1% for GalNAc. The precision of the method was <1.7% for GlcNAc and <2.2% for GalNAc. The mean recovery of the method was measured by spiking samples with 30.0–120.0 mg/L GlcNAc or 12.5–50.0 mg/L GalNAc and was found to be 95.1–105.5% for GlcNAc and 99.5–105.9% for GalNAc. The stability test results of standard solutions stored at 4, 20, and 40°C were 96.2–104.7% for GlcNAc and 98.0–106.5% for GalNAc. This study determined GlcNAc and GalNAc in dairy foods using HPLC-ELSD method. This rapid, simultaneous quantitation method might be useful as a mean of convenient quality control of dairy foods.

Sensitive simultaneous determination of three sulfanilamide artificial sweeters by capillary electrophoresis with on-line preconcentration and contactless conductivity detection

A sensitive method followed by capillary electrophoresis with on-line perconcentration and capacitively coupled contactless conductivity detection (CE-C(4)D) was evaluated as a novel approach for the determination of three sulfanilamide artificial sweeteners (acesulfame-K, sodium saccharin and sodium cyclamate) in beverages. The on-line preconcentration technique, namely field-amplified sample injection, coupled with CE-C(4)D were successfully developed and optimized. The separation was achieved within 10 min under the following conditions: an uncoated fused-silica capillary (45 cm × 50 μm i.d., Leff=40 cm), 20 mmol L(-1) HAc as running buffer, separation voltage of -12 kV, electrokinetic injection of -11 kV × 8 s. The detection limits of acesulfame-K, sodium saccharin and sodium cyclamate were 4.4, 6.7 and 8.8 μg L(-1), respectively. The relative standard deviation varied in the range of 3.0-5.0%. Results of this study show a great potential method for the fast screening of these artificial sweeteners contents in commercial beverages.

A novel method for the simultaneous determination of 14 sweeteners of regulatory interest using UHPLC-MS/MS

An improved, efficient, sensitive method for the determination of 14 non-nutritive sweeteners in food products was developed using electrospray ionisation (ESI) ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in the negative-ion mode. Fourteen sweeteners and three internal standards were separated on a reversed-phase UHPLC column using a simple gradient programme. Analyte quantitation and confirmation were performed with data collection in multiple reaction monitoring (MRM) mode. Limits of detection (LODs) were determined in a representative drink, candy and yogurt sample and ranged from 0.1 to 1.8 ng ml(-1) (drinks) and from 0.1 to 2.5 ng g(-1) (candy and yogurt). Repeatability at the limit of quantitation (LOQ) ranged from 1% to 13% relative standard deviation (RSD). Twenty-seven commercially available food products were tested using the optimised method showing that the majority of products contained sweetener concentrations below their assigned maximum usable dose. Recovery studies were performed and accuracy data are presented.

Determination of eight artificial sweeteners and common Stevia rebaudiana glycosides in non-alcoholic and alcoholic beverages by reversed-phase liquid chromatography coupled with tandem mass spectrometry

The method for the determination of acesulfame-K, saccharine, cyclamate, aspartame, sucralose, alitame, neohesperidin dihydrochalcone, neotame and five common steviol glycosides (rebaudioside A, rebaudioside C, steviol, steviolbioside and stevioside) in soft and alcoholic beverages was developed using high-performance liquid chromatography and tandem mass spectrometry with electrospray ionisation (HPLC-ESI-MS/MS). To the best of our knowledge, this is the first work that presents an HPLC-ESI-MS/MS method which allows for the simultaneous determination of all EU-authorised high-potency sweeteners (thaumatin being the only exception) in one analytical run. The minimalistic sample preparation procedure consisted of only two operations; dilution and centrifugation. Linearity, limits of detection and quantitation, repeatability, and trueness of the method were evaluated. The obtained recoveries at three tested concentration levels varied from 97.0 to 105.7%, with relative standard deviations lower than 4.1%. The proposed method was successfully applied for the determination of sweeteners in 24 samples of different soft and alcoholic drinks.