Cyclamates analysis

Sweeteners can be roughly divided into two groups bulk and intense sweeteners. Prodolliet (1996) and Gloria (2000) reviewed thoroughly the analysis and properties of intense sweeteners acesulfame-K, alitame, cyclamate, aspartame, glycyrrhizin, neohesperidin DC, saccharin, stevioside, sucralose and thaumatin. They are generally used in low calorie products such as diet... 

This technique has been established for many years particularly for water, soil and feeding-stuff analysis, where a large number of analyses are required for quality control or monitoring purposes. A number of applications have been published for food additives including aspartame (Fatibello et al., 1999), citric acid (Prodromidis et al., 1997), chloride, nitrite and nitrate (Ferreira et al., 1996), cyclamates (Cabero et al., 1999), sulphites (Huang et al., 1999 AOAC Int, 2000), and carbonate, sulphite and acetate (Shi et al., 1996). Yebra-Biumm (2000) reviewed the determination of artificial sweeteners (saccharin, aspartame and cyclamate) by flow injection. 

The effect of sodium cyclamate (Cyc-Na) was also investigated. It was seen that there is no effect of Cyc-Na for the determination of Apt, Ace-K and Sac and Vit C to 40 ppm concentration level. So 5 ppm Cyc-Na was added to Standard sample solutions. The spectral region between 190 and 300 nm which implies woiking with 22 experimental points per spectrum was selected for analysis. In Table 33.2 the compositions of the quatemaiy mixtures employed are summarized. PLS calibrations were performed on 27 calibration spectra and, with the use of the calibration, the concentration of the samples left out during calibration was predicted. 

Polyaza macrocycle derivatives have been employed in a number of analytical applications." " For example, polymer-immobilized cyclam has been employed for the preconcentration of manganese in seawater prior to analysis." ... 

Herrmann et al. (24) used ion-pair chromatography for the determination of cyclamate. The efficiency of LiChrosorb RP-18 and Hypersil MOS 3 with a mobile phase of 5 mM tetrabutylammonium p-toluenesulfonate, pH 3.5, mixed with 12% methanol for the separation of cyclamate from other sweeteners was investigated. With the first column, cyclamate separated from saccharin, but the second was the recommended column for the analysis of cyclamate, saccharin, aspartame, and dulcin in a single run. 

Since cyclamate has poor UV absorbing characteristics, HPLC methods for the analysis of this sweetener require specific detection systems, such as indirect photometry or conductivity. Herrmann et al. (24) used indirect photometry for the detection of cyclamate at 267 nm against a UV-absorbing mobile-phase component, p-toluenesulphonate. Biemer (17) and Wu et al. (47) used a conductivity detector for the determination of cyclamate. According to Biemer (17) the use of this detector offers distinct advantages, since compounds coeluting with cyclamate may not exhibit an electrochemical response and, hence, not appear in the chromatogram. 

Another approach would be to derivatize cyclamate prior to analysis. Cyclamate can be determined by HPLC and UV detection at 314 nm after conversion to A/,/V-dichlorocyclohexyl-amine. Derivatization can be carried out directly in the sample or after extraction and cleanup. /V,/V-Dichlorocyclohexylamine is separated on a reverse-phase column (Nucleosil Cl8 or Fine-pak SIL Cl8 T-5) with a mobile phase of methanol water, 8 2 v/v (43,46). Cyclamate can also be determined at 585 nm after postcolumn derivatization with methyl violet 2B as described by Lawrence and Charbonneau (16). 

TA Biemer. Analysis of saccharin, acesulfame-K and sodium cyclamate by high performance ion chromatography. J Chromatogr 463(2) 463-468, 1989. 

Cyclamate is stable under conditions likely to be encountered in soft drinks, that is, pH range 2-7, pasteurisation and UHT treatments. Analysis is usually using HPLC. Owing to differences in chemistry between cyclamate and other intense sweeteners, cyclamate requires derivatisation before analysis by HPLC (MacArthur et al., 2002). 

As cyclamate was banned in a number of countries before HPLC techniques were fully developed, there have not been many methods published for its analysis using modem procedures. The substance offers a challenge to the analyst as it does not have a useful chromophore in the ultraviolet region and its detection by a change in refractive index would be difficult at the levels used in soft drinks (a maximum of 400 ppm). 

Egan, H., Kirk, R.S. and Sawyer, R. (1990b) Analysis of cyclamates, in Pearson s Chemical Analysis of Foods, 8th edn, Longman, Harlow, pp. 216-17. 

Neville, G. A. J. C. Ethier, N. F. H. Bright, and R. H. Lake. 1971. Characterization of some lincomycin and cyclamate salts by thermal analysis and infrared spectrosAc soc. Off. Anal. Cheifi4 1200-1210. 

Cyclam has also been used in the mobile phase for HPLC analysis. For example, Colgan et al. [81] added the macrocycle to a reversed phase analysis of the drug tenidap to reduce peak tailing and improve reproducibility. 

Colgan, S., Hammen, P., Knutson, K., and Bordner, J. (1996) Investigation of Cyclam-Containing Mobile Phases for the Liquid Chromatographic Analysis of Tenidap, J. Chromatogr. Sci. 34, 111-114. 

Uncommon IPRs were tested recently. Polymerized acyl monoglydnate surfactant was found to be as effective as sodium dodecylsulfate for the resolution of organic amines [126]. For the analysis of pyridine-based vitamins in infant formnlas, dioc-tylsulfosuccinate produced a unique retention pattern [133], Among bizarre IPRs, tris(hydroxymethyl)aminomethane was used for the determination of cyclamate in foods. It was selected over different ion-pair reagents such as triethylamine and dibu-tylamine, based on sensitivity and time economies [134]. Hexamethonium bromide, a divalent IPR, was used successfully to separate sulfonates and carboxylates [135]. 

In the present study, we synthesized dibromo(l,4,8,ll-tetraazacyclotetradecane)copper(II) ([CuBr2(cyclam)]) and diaqua(l,4,8,ll-tetraazacyclotetradecane)copper(II) difluoride four hydrate ([Cu(cyclam)-(H20)2]F2 4H20) complexes and performed single crystal structure analysis and X-ray absorption near-edge structure (XANES) measurements in crystals and in aqueous solution. Furthermore, DV-Xa molecular orbital calculations have been made for models based on these results, and the structures and electronic states of the [Cu(cyclam)] complexes in crystals and in aqueous solution are discussed, in particular, on the axial coordination to Cu(II). 

Synthesis and Single Crystal Structure Analysis of [CuBr2(cyclam)] complex... 

While RPLC and RPIPC techniques applied with UV detection have already been elaborated for analyzing saccharin and acesulfam-K [67,68], the liquid chromatographic analysis of sodium cyclamate is barely substantiated in the literature because of the non-chromophoric structure of this compound. The only exception is the HPLC method introduced by Hermann et al. with direct photometric detection [69],... 

Fig. 8-79. Analysis of cyclamate in chewing gum. - Separator column IonPac AS4A eluent 0.0017 mol/L NaIlC03 flow rate 2 mL/min detection suppressed conductivity injection 50 pL of a spiked chewing gum sample (taken from [70]).

The analysis of the experimental M-B distances has also allowed the location of some examples of ionic complexes described in the literature as MLn(q1-BH4). The long Cu-B distances preclude BLC- coordination. These examples are the copper complexes [Cu(Cyclam)]+[BH4]", [Cu(TMAC)]+ [BH4] , (TMAC = CyclamMe4) (see Table 3) and the chromium complex [(py Crtq1 -BH4)]+[BH4] . 

Spectrophotometric analysis of cyclohexylsulphamic acid (46) and its salts has been carried out. The procedure involves conversion of the cyclamate to N,N-dichloro-cyclohexylamine (123) using excess hypochlorite. 123 is determined by measuring its UV absorption at 314 nm. Two collaborative studies have been reported using this analytical technique for the determination of cyclamate in soft drinks, desserts and jams162,163. The first study reports the results of nine laboratories assaying 3 soft drinks with cyclamate levels of 0.36-0.37 g kg"1 and 3 jams with cyclamate levels of 1.23-1.50 g kg -1. Average recoveries of cyclamate were 99.7% in the soft drinks and 103.8% in the jams with reproducibility coefficients of variation of 6.7% and 4.4%, respectively. The second study involved determination of cyclamates at much lower concentration levels, namely 90-311 mg 1 1 and 202-526 mg kg-1. The results from 15 collaborators gave cyclamate recoveries of 97.5% in soft drinks with relative standard deviations from 4.7% to 6.5%. The recovery from desserts was 98.6% with relative standard deviations of 6.9% to 8.5%. 

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