[Simultaneous determination of sugar alcohols and sugars in functional foods by precolumn ultraviolet derivatization--high performance liquid chromatography].

OBJECTIVE: To establish a method using precolumn ultraviolet derivatization coupled with high performance liquid chromatography (HPLC) for simultaneous determination of erythritol, xylitol, galactitol, sorbitol, mannitol, maltitol, glucose and sucrose in functional foods. METHODS: Target sugar alcohols and sugars in food samples were extracted in water by ultrasonic method and then reacted with benzoyl chloride to form violet-absorbing products, which were separated on a C18 column with gradient elution using methanol and water as mobile phase. The experiment was performed using a flow rate of 1.00 mL/min, column temperature at 30 degrees C and detected wavelength at 232 nm. RESULTS: The linear correlation coefficients of all the derivatives were more than 0. 999. The detection limits of the method were as low as 2. 2 microg/mL. The average recoveries were 89.6%-117.0%, with intraday relative standard derivations lower than 5%. CONCLUSION: This method is simple, inexpensive and easy to operate and it is suitable for the determination of sugar alcohols and glucose and sucrose in functional foods.

[Determination of sucralose in foods and beverages by ultraviolet derivatization-high performance liquid chromatography].

OBJECTIVE: To establish a method for determination of sucralose in foods and beverages using high performance liquid chromatography. METHODS: Sucralose was extracted with water and centrifuged, and then derivatized with benzoyl chloride in alkaline medium. The ultraviolet absorbing derivatives were separated on a Hydro-RP 80 angstroms C18 column (250 mm x 4.6 mm, 4 microm, Synergi) using methanol-water (95:5,V/V) as mobile phase with UV detection at 232 nm. RESULTS: A good correlation (correlation coefficient=0. 999 8) between detected and actual sucralose was achieved in the range of 0.05 to 1.00 microg. The detection limit of sucralose was 0.00125 microg. The recoveries were in the range from 97.4% to 102.0% with relative standard deviations of less than 5.0%. The intraday and interday relative standard deviations of the method were 1.52% and 4.04%, respectively. CONCLUSION: This method is simple, rapid, and accurate without the need of special detectors, and it can be used for rapid determination of sucralose in foods and beverages.

Rapid and sensitive detection of Cronobacter spp. (previously Enterobacter sakazakii) in food by duplex PCR combined with capillary electrophoresis-laser-induced fluorescence detector.

Cronobacter spp. (Enterobacter sakazakii) is an emerging opportunistic pathogen with a 40-80% mortality rate in infants and immunocompromised crowd resulting from the consumption of contaminated food. A novel method for detecting Cronobacter spp. in food samples by duplex polymerase chain reaction (PCR) in combination with capillary electrophoresis-laser induced fluorescence (CE-LIF) detector has been developed. The specific gene sequences of 16S-23S rDNA internal transcribed spacer (ITS) and the outer membrane protein A (OmpA) of Cronobacter spp. were amplified by duplex PCR. The PCR products were separated and determined sensitively by CE-LIF within 12min. The relative standard deviations of migration time for the detected DNA fragments were 2.01-2.91%. The detection limit was as low as 1.6×10(1)cfu/mL of Cronobacter spp. Besides, the specificity of the method was verified by 24 non-Cronobacter bacterial strains. A total of 120 commercial infant food formula were tested for the presence of Cronobacter spp. by using the proposed method. This current study demonstrates that the combination of CE-LIF method with duplex PCR is rapid, sensitive and environmental friendly, and has the potential to be adapted for the routine detection of Cronobacter spp. in food samples. To the best of our knowledge, this is the first use of CE-LIF for the detection of Cronobacter spp.