Carrots chromatogram

Calcium hydroxide is an excellent adsorbent for resolving carotenoid cis-trans isomers compared with alumina, it is less retentive and less sensitive to temperature and moisture content of the mobile phase. However, calcium hydroxide columns are not commercially available, and separations using them can be difficult to reproduce, owing to extreme sensitivities to mobile-phase composition and temperature. Nine cis-/3-carotenes were characterized from a chromatogram of 18 peaks after isocratic elution of a mixture obtained by thermal isomerization and photoisomerization of /3-carotene (162). Chandler and Schwartz (10), using a calcium hydroxide column and a mobile phase of hexane containing 0.3% acetone, separated six carotene isomers from canned carrots. These were, in order of elution, two cw-a-carotenes, all-tram-a-carotcnc, 13-m-/3-carotcnc, all- ram-/3-carotene, and 9-cw-/3-carotene. A mobile phase of hexane modified with 2% p-methylanisole separated all-rram-/3-carotcnc and its 9-, 13-, and 15-cis isomers in an iodine isomerized mixture (163). 

A gradient HPLC procedure with UV detection, for determination of pesticide residues in fruit and vegetables such as apples, potatoes, and carrots, was used by Beil et al. (57). Figure 3 shows a clean chromatogram of many compounds that was obtained by HPLC and UV detection in apple. 

Figure 1. Shortened chromatogram of amino acids in air-dried carrots. Peak C represents Amadori compounds formed by reaction between glucose and the amino acids threonine, serine, asparagine, glutamic acid, and glutamine.

The determination of carbonyl compounds in carrots is an example of a preliminary reaction which simplifies identification [56]. Carbonyl compounds were determined in an aromatic distillate of carrots after conversion into the corresponding 2,4-dinitro-phenylhydrazones [57]. The derivatives obtained were analysed on a capillary colunm (20 m X 0.3 mm I.D.) with OV-1 as the stationary phase. The chromatogram contained mainly the derivatives of carbonyl compounds even when a non-selective flame-ionization detector was used. The preliminary reactions simplify considerably the interpretation of the results. In some instances, for example in determining impurities in air, it is better to perform preliminary reactions while concentrating a solution containing a specific reagent. This procedure (1) increases the degree of the concentration as the derivatives... 

Gas chromatogram with electron-impact ionization selected ion monitoring for BPA, BPS, and BP extracted from liquid in a can of peas and carrots. [From P. Vihas, N. Campillo,... 

The chromatogram shows BPA, BPS, and BP isolated from the liquid in a can of peas and carrots from a grocery store. Observed levels of these substances in the liquid are 254, 175, and 176 ppb (ng/g), respectively. Observed concentrations in the solid peas and carrots from the same can are 78, 36, and 21 ppb. Health effects, if any, of traces of these substances in our food are unknown. 

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