scholarly journals Lactose quantification in UHT milk by high-performance liquid chromatography and cryoscopy (freezing point depression)

2021 ◽  
Vol 10 (15) ◽  
pp. e454101523224
Author(s):  
Cleiver Júnio Martins Costa ◽  
Camila Alves Moreira ◽  
Ricardo Corrêa de Santana ◽  
Amado Jésus Silva ◽  
Juliana Karla de Souza Teixeira Almeida ◽  
...  

Due to the large number of people with lactose maldigestion, the dairy industries have increased production and diversity of low lactose and lactose-free foods. Consequently, the need to control the lactose hydrolysis process has also risen. This study aimed to correlate freezing point depression (cryoscopy) and lactose concentration, quantified by high-performance liquid chromatography (HPLC), in UHT milk. To accomplish this, UHT milk samples were subjected to seven lactose hydrolysis treatments, using lactase enzyme, resulting in different lactose concentrations. All samples were subjected to HPLC analysis and freezing point measurement, using a cryoscope. The results were plotted on a graph and a linear regression was performed. There was a strong correlation between lactose concentration and freezing point (R = 0,9973) and the coefficient of determination (R2) was 0,9946, which means that 99,46% of the variability of the response data is explained by the linear regression model. Therefore, the results point to the feasibility of estimating the lactose concentration in milk during the hydrolysis process for the production of low lactose milk, by cryoscopy, a quick analysis, with lower cost compared to HPLC and that is already among the analyses commonly performed in dairy industries.

Pteridines ◽  
1994 ◽  
Vol 5 (2) ◽  
pp. 49-54 ◽  
Author(s):  
Peter Mayersbach ◽  
Roman Augustin ◽  
Harald Schennach ◽  
Dietmar Fuchs ◽  
Ernst R. Werner ◽  
...  

Summary We have evaluated a new commercially available enzyme-linked immunorsorbant assay for neopterin :or its suitability in the context of screening of voluntary blood donors. The assay was performed on 1040 consecutive blood donors, and compared with radioimmunoassay and. in a fraction of 142 donors . . : Iso with high performance liquid chromatography. On repetitive assays of all donations showing a concentration exceeding 8.0 nmol/L in the initial assay. three of the radioimmunoassay results were identified as gross outliers. No such gross outliers were detected for the enzyme-linked immunosorbant assay. RegarJing the reproducibility of results exceeding a cut-off limit of \0 nmol/L neopterin. the enzyme-linked ;mmunosorbant assay was better than the radioimmunoassay. Moreover. the enzyme-linked immunosorbant assay was slightly superior to radioimmunoassay when both tests were compared with high performance liquid chromatography (based on linear regression analysis. evaluation of frequencies of concentrations bant assay was slightly superior to radioimmunoassay when both tests were compared with high performance liquid chromatography (based on linear regression analysis. evaluation of frequencies of concentrations rations. Its slight superiority compared to the conventional radioimmunoassay likely results from the higher degree of automatization employed.


Author(s):  
Chien Dinh Viet ◽  
Luyen Nguyen Tien ◽  
Hong Ngoc Nguyen Thi ◽  
Hieu Pham Cong ◽  
Thanh Do Tat ◽  
...  

The study researchs on the hydrolysis process of food and feed samples using High Pressure Asher (HPA-S) to determine several amino acids by high-performance liquid chromatography (HPLC). HPA-S equipment is mainly used for samples treatment in analysis of metals by spectroscopy. However, the study also found that HPA-S can be used in hydrolysis of food and feed samples in order to analyze amino acids. The temperature of HPA-S equipment could reach 300oC and maintain continuously at 130 bar pressure, completely digetsing the most complex samples matrix within an hour. The successful study of the application of HPA-S to hydrolyze samples in order to analyze amino acids makes the time of sample preparation significantly shorter but still gave the equivalent stability, even higher than the common samples hydrolyzation.


DICP ◽  
1989 ◽  
Vol 23 (2) ◽  
pp. 132-135 ◽  
Author(s):  
Linda S. Bullock ◽  
Joseph F. Fitzgerald ◽  
Melvin R. Glick

The stability of famotidine 200 μg/ml in dextrose 5% injection (D5W) and in NaCl 0.9% (NS) solutions in polyvinyl chloride (PVC) minibags was studied when these solutions were stored refrigerated at 4°C for 14 days, or frozen at −20°C for 28 days and then refrigerated for 14 days. Famotidine concentration was determined in the refrigerated samples immediately after compounding (time 0) and also on days 2, 4, 8, and 14 by high-performance liquid chromatography (HPLC). Famotidine concentration was determined by HPLC in frozen samples at time 0 and days 7, 14, 21, 28, 35, and 42. Solutions were also observed for visual changes and pH was tested at these time intervals. Results of the HPLC famotidine analysis demonstrated 94–107 percent recovery of famotidine in D5W and NS at 14 days in refrigerated samples and 98–100 percent recovery of famotidine in minibags frozen for 28 days then refrigerated for 14 days. Analysis of variance showed no time effect on the concentration of famotidine in refrigerated samples (p = 0.741). Linear regression of the frozen minibag data indicated no time effect. Famotidine 200 μg/ml is stable in dextrose 5% injection and NaCl 0.9% injection when stored in PVC bags at 4°C for 14 days, or when frozen for 28 days and then subsequently refrigerated for 14 days.


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