Determination of cyclamate in foods by high performance liquid chromatography–electrospray ionization mass spectrometry

Rapid and sensitive quantification of cyclamate in beverages by miniature microplasma optical emission spectrometry

Most of the available methods for the quantification of cyclamate depend on laboratory instruments and their application in the field was limited. Herein, a simple and sensitive method was developed for the determination of cyclamate in beverage samples based on chemical vapor generation and miniature point discharge optical emission spectrometry (μPD-OES). The combination of headspace sampling and μPD-OES not only simplifies the separation process of cyclamate, improves sensitivity, and alleviates matrix interference but also eliminates the use of a bulky and expensive instrument. Under the optimal conditions, this method provided a limit of detection of 0.1 mg L^-1 comparable to or better than most reported methods. The method eventually was applied to 14 different beverages and cyclamate was found below the threshold set by Chinese Standards for Food Additives. The proposed method provides great potential for the field analysis of cyclamate in the supervision of food safety.

Determination of 19 anthelmintics in environmental water and sediment using an optimized PLE and SPE method coupled with UHPLC-MS/MS

A sensitive quantification method using pressurized liquid extraction (PLE) and solid phase extraction (SPE) coupled with ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for determination of 19 anthelmintic drugs (ADs) belonging to seven structural groups (Benzimidazoles, Diphenylsulfides, Imidazothiazoles, Hexahydropyrazines, Macrocylic lactones, Salicylanilides, Tetrahydropyrimidines) in environmental water and sediment samples. Eleven SPE cartridges, sample pH, elution solvents were tested to determine the optimal conditions for extraction. Among these investigated SPE types, the best recoveries for 19 target ADs were obtained from Oasis HLB cartridge with 37-102%, 45-103%, 37-88%, 28-82% and 31-90% for spiked river water, tap water, rainwater, wastewater, and sediment respectively (with RSD < 15%), except for closantel. The 19 ADs were separated within 10 min by a BEH C18 column and monitored in both positive and negative ions modes with switching electrospray ionization source. The cross-talk interferences were solved by identification of secondary mass spectrum of substances through MRM-IDA-EPI scanning using Qtrap. These interference peaks could be efficiently eliminated by setting MRM segments or using Qtrap to obtain tertiary fragmented information. The developed methods were satisfactory in terms of linearity, accuracy, and precision, and used eight isotopically labeled compounds as internal standards to correct matrix effects. Method quantification limit (MQL) for 19 ADs was below 1.1 ng/L, 0.4 ng/L, 5.4 ng/L and 2.3 ng/g for river water, tap water, wastewater, and sediment, respectively. The validated method was successfully used to investigate the occurrence of anthelmintics in water and sediment samples from Chengdu, China. All ADs were detected in environment with the concentrations at ng/L level.

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.

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%.

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.

A novel solid-phase extraction for the concentration of sweeteners in water and analysis by ion-pair liquid chromatography-triple quadrupole mass spectrometry

A highly sensitive method for the simultaneous trace (ng/L) quantification of seven commonly used artificial sweeteners in a variety of water samples using solid-phase extraction and ion-pair high-performance liquid chromatography (HPLC) triple quadrupole mass spectrometer with an electrospray ionization source (ESI-MS) in negative ion multiple reaction monitoring mode was developed. Ten solid phase extraction (SPE) cartridges were tested to evaluate their applicability for the pre-concentration of the analytes, and their loading and eluting parameters were optimized. Satisfactory recoveries (77-99%) of all of the studied sweeteners were obtained using a Poly-Sery PWAX cartridge with 25 mM sodium acetate solution (pH 4) as wash buffer and methanol containing 1mM tris (hydroxymethyl) amino methane (TRIS) as eluent. The method is sound and does not require pH adjustment or buffering of water samples. The HPLC separation was performed on an Athena C18-WP column with water and acetonitrile, both containing 5mM ammonium acetate and 1mM TRIS as mobile phases, in gradient elution mode. The linearity, precision, and accuracy of the method were evaluated, and good reproducibility was obtained. Method quantification limits varied between 0.4 and 7.5 ng/L for different water samples. The post-extraction spike method was applied to assess matrix effects, and quantification was achieved using internal standard calibration to overcome the unavoidable matrix effects during ESI-MS analysis. The method was applied to the analysis of thirteen water samples from Tianjin, China, including wastewater, tap water, surface water, and groundwater. The method described here is time-saving, accurate and precise, and is suitable for monitoring artificial sweeteners in different water matrices.

Rapid analysis of cyclamate in foods and beverages by gas chromatography-electron capture detector (GC-ECD)

A rapid method for determination of sodium cyclamate in foods and beverages was developed. Sodium cyclamate was converted to N,N-dichloridecyclohexylamine by reaction with sodium hypochlorite under acid condition. N,N-dichloridecyclohexylamine was subsequently extracted by n-hexane and determined by gas chromatography. Conditions such as derivatization time, the concentration of sodium hypochlorite and sulphuric acid were optimised. Amino acids, aliphatic amines, and food additives such as preservatives, dyes and sweeteners showed no interference for quantification of cyclamate. The correlation coefficient of calibration curve was 0.9993 in the range of 5.0-250mg/L. The limits of detection (LOD) and limits of quantification (LOQ) were calculated as three or ten times the signal-to-noise ratio (S/N), respectively. The LOD and LOQ for yellow wine and fruit juice were 0.05 and 0.2mg/L, respectively. The LOD and LOQ for cake and preserved fruit were 0.25 and 0.8mg/kg, respectively. The intra-day and inter-day RSD were 0.28% and 1.1% (n=5), respectively. The method was successfully applied for determination of cyclamate in yellow wine, cake, fruit juice and preserved fruit. This method was simple, fast, and sensitive. It was suitable for the determination of cyclamate in foods and beverages for safety and quality control inspections.

Determination of Artificial Sweeteners in Beverages and Special Nutritional Products Using High Performance Liquid Chromatography

This paper presents two high performance liquid chromatographic (HPLC) methods used for the separation and determination of artificial sweeteners aspartame, acesulphame K, sodium saccharin, and sodium cyclamate in beverages and special nutritional products (special food intended for specific population groups). All four compounds are soluble in aqueous solutions and can easily be separated and determined by HPLC with a diode array detector (DAD). The first method involved separation of aspartame, acesulphame K, and sodium saccharin on a C18 column with an isocratic elution of phosphate buffer and acetonitrile as mobile phase. The second method was used to separate sodium cyclamate on a C18 column with methanol and water as mobile phase. Under optimum conditions, both methods showed good analytical performance, such as linearity, precision, and recovery. The methods were successfully applied for the analysis of real samples of soft drinks and special nutritional products.

China's food safety regulation and mass spectrometry

Food safety is essential to people's health and people's livelihood. To ensure that food safety is an important current strategy of the governments, both regulation and standardization are important support for implementing this strategic initiative effectively. The status and prospects of China's food laws, regulations, and standards system are introduced. China now has established a complete law regime providing a sound foundation and good environment for keeping the health of people, maintaining the order of social economy and promoting the international trade of food. At the same time, it is undoubtedly important to strengthen standardization and improve the food safety standards system. In the administration of food safety, mass spectrometry is becoming more and more important and many analytical methods developed in China are based on its application.

Simultaneous determination of nonnutritive sweeteners in foods by HPLC/ESI-MS

Nonnutritive sweeteners are the low calorie substances used to replace sugar and other caloric ones. Determination of these sweeteners in foods is important to ensure consistency in product quality. In this study, seven artificial (aspartame, saccharin, acesulfame-K, neotame, sucralose, cyclamate, and alitame) and one natural sweetener (stevioside) were simultaneously determined in different foods using high performance liquid chromatography (HPLC) coupled with electrospray ionization mass spectrometric detection (ESI-MS). The target compounds were quantified using a selective ionization recording (SIR) at m/z 178, 397, 377, 293, 641, 312, 162, and 182 to cyclamate, sucralose, neotame, aspartame, stevioside, alitame, acesulfame-K, and saccharin, respectively, with warfarin sodium (SIR m/z 307) being used as an internal standard. The correlation coefficient of the calibration curve was better than 0.998 (n = 6), in the range of 0.05 to 5.00 microg/mL for cyclamate, 0.30 to 30.0 microg/mL for sucralose, 0.10 to 10.0 microg/mL for neotame, 0.20 to 20.0 microg/mL for aspartame, 0.50 to 15.0 microg/mL for stevioside, 0.08 to 8.00 microg/mL for alitame, 0.10 to 15.0 microg/mL for acesulfame-K, and 0.05 to 5.00 microg/mL for saccharin. The limits of detection (LODs) were below 0.10 microg/mL, whereas the limits of quantification (LOQs) were below 0.30 microg/mL. It is concluded that the method has merits such as high sensitivity, specificity, and simplicity versus the those of the other methods reported in the literature.