Saccharinic acids analysis

The saccharinic acids formed from some of the pentoses and hexoses have been the objects of study by Nef and his students. Glattfeld and Hanke reported in 1918 that, during the oxidation of maltose in alkaline solution, an acid had been produced whose phenylhydrazide had an analysis agreeing perfectly with that calculated for a four-carbon saccharinic acid. Furthermore, the properties of the free aeid were those which would be expected of one of these acids. Its configuration could not, however, be reported at that time because of the absence of data as to the properties and constants of the four-carbon saccharinic acids. Nef had also referred to the handicap which this lack of information had imposed on the work with sugars in alkaline solution. Consequently, with this in mind, Glattfeld began in 1920 the systematic synthesis of the four-carbon saccharinic acids. 

There is a recent trend towards simultaneous CE separations of several classes of food additives. This has so far been applied to soft drinks and preserved fruits, but could also be used for other food products. An MEKC method was published (Lin et al., 2000) for simultaneous separation of intense sweeteners (dulcin, aspartame, saccharin and acesulfame K) and some preservatives (sorbic and benzoic acids, sodium dehydroacetate, methyl-, ethyl-, propyl- and isopropyl- p-hydroxybenzoates) in preserved fruits. Ion pair extraction and SPE cleanup were used prior to CE analysis. The average recovery of these various additives was 90% with good within-laboratory reproducibility of results. Another procedure was described by Frazier et al. (2000b) for separation of intense sweeteners, preservatives and colours as well as caffeine and caramel in soft drinks. Using the MEKC mode, separation was obtained in 15 min. The aqueous phase was 20 mM carbonate buffer at pH 9.5 and the micellar phase was 62 mM sodium dodecyl sulphate. A diode array detector was used for quantification in the range 190-600 nm, and limits of quantification of 0.01 mg/1 per analyte were reported. The authors observed that their procedure requires further validation for quantitative analysis. 

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. 

For the analysis and separation of benzoic acid, caffeine, aspartame, and saccharin in dietetic soft drinks, a HPLC system consisting of a Varian MCH-5N-CAP 150 x 4.6 mm column and a variable wave length UV/VIS detector was recommended [32]. The mobile phase is a gradient, beginning with 90% 0.01 M KH2PO4 (pH = 2) and methanol, and ending in 25 minutes with 60 % buffer / 40 % methanol. 

Sample preparation for saccharin analysis by HPLC can be performed as indicated in Section I.C. Methods for extraction have also been described for desserts and sweets containing food thickeners (38) soy sauce, orange juice, and yogurt (60) chewing gum (17,39), and different food samples (42). Aminobenzoic acid, theophyllin, sodium fumarate, and adenine sulfate have been used as internal standards (17,31,39,44). 

Veerabhadrarao et al. (76) used reverse-phase HPLC for the determination of some food additives (acesulfame, saccharine, BA, p-hydroxybenzoic acid). The samples (beverages, tomato sauce) were diluted and then separated on a /rBondapak CJg column with methanol/acetic acid/water (20 5 75) or (35 5 60) as mobile phases. The determination was done at 254 nm. Recoveries varied from 98 to 106% for direct analysis and from 91.6 to 101.8% for extraction of samples (76). 

A paired-ion, reversed-phase high-performance liquid chromatographic method was developed for the simultaneous determination of sweeteners (dulcin, saccharin-Na, and acesulfame-K), preservatives (sodium dehydroacetate, SA, salicyclic acid, BA, succinic acid, methyl-para-hydroxybenzoic acid, ethyl-para-hydroxybenzoic acid, n-propyl-para-hydroxybenzoic acid, n-butyl-para-hydroxybenzoic acid, and isobutyl-para-hydroxybenzoic acid), and antioxidants (3-tertiary-butyl-4-hydroxyanisole and tertiary-butyl-hydroquinone). A mobile phase of acetonitrile-50 ml aqueous tr-hydroxyisobutyric acid solution (pH 4.5) (2.2 3.4 or 2.4 3.6, v/v) containing 2.5 mM hexadecyltrimethylammonium bromide and a Clg column with a flow rate of 1.0 ml/min and detection at 233 nm were used. This method was found to be very reproducible detection limits ranged from 0.15 to 3.00 p,g. The retention factor (k) of each additive could be affected by the concentrations of hexadecyltrimethylammonium bromide and a-hydroxyisobu-tyric acid and the pH and ratio of mobile phase. The presence of additives in dried roast beef and sugared fruit was determined. The method is suitable for routine analysis of additives in food samples (81). 

Two methods have been published which were designed to analyse a range of sweeteners and preservatives in one run. The fust method, published in German by Hagenauer-Hener et al. (1990), describes the analysis of aspartame, acesulfame K, saccharin, caffeine, sorbic acid and benzoic acid in soft drinks and foods. The method relies on a similar system to that given above but with a less complex solvent system (Figure 10.5). The solvent system has been modified to include a gradient portion to elute the preservatives more quickly. 

Three spectrophotometric procedures are given in the AOAC compendium of methods (960.22, 962.13 and 967.11) for the analysis of caffeine, all of which have an extraction stage followed by a quantification procedure. There is also an HPLC method, discussed earlier, which was designed to measure saccharin, benzoic acid and caffeine at the same time (AOAC, 978.08). Again, the HPLC method, EN 12856 1999 (Anon, 1999a), can be used for the analysis of caffeine, but this analyte was not included in the collaborative study. 

Polarographic methods of analysis have been applied to samples of foods containing saccharin (1+1-1+1+ ). In a procedure (1+1+) saccharin is extracted into organic solvents in an acidic medium. Further purification is achieved by column chromatography. The residue obtained is dissolved in 0.1 N NaOH and an aliquot is polarographed in a supporting electrolyte of 0.1 N HC1, 0.1 N KC1 and 0.1 Bu N Br. 

Weigh accurately 20 mg of each standard (caffeine, saccharin, and benzoic acid). Transfer quantitatively to a 100-mL volumetric flask. Dilute to mark with the mobile phase from Section E. For the analysis involving aspartame, 20 mg of aspartame was transferred to a 100-mL volumetric and was diluted to the mark with the previously prepared standard solution. This procedure results in two standard solutions. One solution contains all four standards and the other contains only three known compounds. 

FIGURE 13-5. Analysis of caffeine, saccharin, and benzoic acid. Sample (1) saccharin, (2) caffeine, and (3) benzoate. Column /rBondapak C]8 (10 gm) 3.9 ID mm x 150 mm. Flow rate 1.0 mL/min. Mobile phase 20% MeOH/80% 1 M acetic acid, pH = 2.4. (Note Actual separation will depend upon the quality of the mobile phase and column packing.)... 

A general CE method using an imidazole-formic acid buffer has been validated [22] for analysis of the potassium counter-ion of an acidic drug. Sodium was used as the internal standard. The method was also applied to calcium, magnesium and lithium salts. The method can also be applied to the characterisation and identification of ionic raw materials and excipients such as sodium saccharin and sodium phosphate buffers. 

The real-time in situ synchrotron PXRD technique found its next application in the mechanistic study of mechanochemically promoted co-crystallization of carbamazepine and nicotinamide as representatives of active pharmaceutical ingredients (API) [62], In the case of carbamazepine saccharin co-crystal, in situ analysis confirmed previous studies by cryomiUing that neat grinding led to amorphization while LAG synthesis rapidly produced the co-crystal. The other investigated system involved two-step neat grinding synthesis of nicotinamide suberic acid 2 1 co-crystal. The ex situ PXRD analysis had revealed a stepwise mechanism with the 1 1 cocrystal as the intermediate. Whereas LAG synthesis was too fast for ex situ approach, in situ monitoring enabled the discovery of an unknown phase that preceded the rapid formation of the 1 1 intermediate (Fig. 1.28). However, the authors were not successful at full characterization of the new phase due to its pronounced instability. 

The spectrum of organic acids in wine is extremely complex and represents a challenge for 1C analysis due, in part, to large concentration differences. In many cases, a number of organic additives are added to refreshing drinks. These additives include sweeteners such as saccharin or aspartame, preservatives such as benzoic acid, and flavors such as citric acid and caffeine. They can be simultaneously analyzed using a multimode phase... 

When you examine the chart obtained from the analysis, you may find that the peak corresponding to aspartame appears to be rather small. The peak is small because aspartame absorbs ultraviolet radiation most efficiently at 220 nm, whereas the detector is set to measure the absorption of light at 254 nm. Nevertheless, the observed retention time of aspartame will not depend upon the setting of the detector, and therefore the interpretation of the results should not be affected. The expected order of elution is saccharine (first), caffeine, aspartame, and benzoic acid. Another interesting point is that although the caffeine peak appears to be quite large in this analysis, it is nevertheless quite small when compared with the peak that would be obtained if you injected coffee into the HPLC. For a caffeine peak from coffee to fit onto your graph, you would have to dilute the coffee at least 10-fold. Even decaffeinated coffee usually has more caffeine in it than most sodas (decaffeinated coffee is required to be only 95-96% decaffeinated). 

The final resolution to the question of the exact nature of acid produced by the stomach was provided in 1823 by William Prout, a brilliant physidan with diverse interests outside of medidne. Prout was productive in the fields of chemistry, meteorology, physiology, and clinical medicine. In addition, he was one of the first scientists to apply chemical analysis to biologic materials. He was, thus, able to demonstrate circadian rhythms in his own expired carbon dioxide as well as to propose that the destruction of tissues produced excretory materials, such as uric acid, urea, and carbonic acid. In 1827, he developed a classification of foods into subgroups saccharinous (carbohydrates), oleaginous (fats), and albuminous (proteins). 

Some sweeteners (aspartame, cyclamate, saccharin, and acesulfame K) were determined by CE-SIA with contactless conductivity detection (Stojkovic et al., 2013). The analyses were carried out in an aqueous running buffer consisting of 150 mM 2-(cyclo-hexylamino)ethanesulfonic acid and 400 mM tris(hydroxymethyl)aminomethane at pH 9.1 in order to render all analytes in the fully deprotonated anionic form. The four compounds were determined successfully in food samples the experimental set-up and typical analysis results are illustrated in Figure 2.9. Another SIA system combined with solenoid valves was used to automate an enzymatic method for the determination of aspartame in commercial sweetener tablets. The method involves the enzymatic conversion of aspartame to hydrogen peroxide by the chymotrypsin-alcohol oxidase system, followed by the use of 2,2-azinobis(3-ethylbenzthiazoline-6-sulfonic acid) (ARTS) as electron donor for peroxidase. Chymotrypsin and alcohol oxidase enzymes were immobilized on activated porous silica beads (Pena et al., 2004). 

Kritsunankul et al. [76] proposed flow injection online dialysis for sample pretreatment prior to the simultaneous determination of some food additives by HPLC and UV detection (FID-HPLC). For this, a liquid sample or mixed standard solution (900 pL) was injected into a donor stream (5%, w/v, sucrose) of a FID system and was pushed further through a dialysis cell, while an acceptor solution (0.025 mol/L phosphate buffer, pH 3.75) was held on the opposite side of the dialysis membrane. The dialysate was then flowed to an injection loop of the HPLC valve, where it was further injected into the HPLC system and analyzed under isocratic reversed-phase HPLC conditions and UV detection (230 nm) (Figure 24.6). The order of elution of five food additives was acesulfame-K, saccharin, caffeine, benzoic acid, and sorbic acid, with an analysis time of 14 min. This system has advantages of high degrees of automation for sample pretreatment, that is, online sample separation and dilution and low consumption of chemicals and materials. 

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