scholarly journals Simultaneous Determination of C18 Fatty Acids in Milk by GC-MS

Separations ◽  
2021 ◽  
Vol 8 (8) ◽  
pp. 118
Author(s):  
Meiqing Chen ◽  
Yangdong Zhang ◽  
Fengen Wang ◽  
Nan Zheng ◽  
Jiaqi Wang
Keyword(s):  
Fatty Acids ◽  
High Sensitivity ◽  
Raw Milk ◽  
Uht Milk ◽  
Milk Samples ◽  
Accuracy And Precision ◽  
Different Temperatures ◽  
Chromatographic Resolution ◽  
Commercial Milk

The determination of C18 fatty acids (FAs) is a key and difficult aspect in FA profiling, and a qualified method with good chromatographic separation and high sensitivity, as well as easy methylation, is required. A GC-MS method was established to simultaneously determine C18 FAs in milk. To simplify the methylation protocol for milk samples, besides a base-catalyzation methylation (50 °C for 20 min), the necessity of an additional acid-catalyzation was also studied using different temperatures (60 °C, 70 °C, 80 °C, and 90 °C) and durations (90 min and 150 min). The results showed that the chromatographic resolution was improved, although three co-eluted peaks existed. The base-catalyzation was sufficient, and an additional acid-catalyzation was not necessary. The proposed method was validated with good sensitivity, linearity, accuracy, and precision, and then applied in determining C18 FAs in 20 raw milk and 30 commercial milk samples. UHT milk presented a different profile of C18 FAs from raw milk and PAS milk samples, which indicated that excessive heating could change the profile. Overall, the proposed method is a high-throughput and competent approach for the determination of C18 FAs in milk, and which presents an improvement in chromatographic resolution and sensitivity, as well as a simplification of methylation.

Application of a microbial sensor for determination of short-chain fatty acids in raw milk samples

1992 ◽  
Vol 195 (1) ◽  
pp. 1-2 ◽  
Author(s):  
Hiroyuki Ukeda ◽  
Gotthold Wagner ◽  
G�nther Weis ◽  
Manfred Miller ◽  
Henning Klostermeyer ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Raw Milk ◽  
Short Chain Fatty Acids ◽  
Short Chain ◽  
Milk Samples ◽  
Microbial Sensor ◽  
Chain Fatty Acids

scholarly journals Evaluation of development in indirect determination of milk fat free fatty acids in Czech Republic

2013 ◽  
Vol 61 (6) ◽  
pp. 1669-1679 ◽  
Author(s):  
Oto Hanuš ◽  
Eva Samková ◽  
Jan Říha ◽  
Marcela Vyletělová Klimešová ◽  
Petr Roubal
Keyword(s):  
Fatty Acids ◽  
Free Fatty Acids ◽  
Milk Fat ◽  
Raw Milk ◽  
Important Indicator ◽  
Indirect Determination ◽  
Milk Samples ◽  
Bulk Milk ◽  
Instrumental Values

Free fatty acids (FFAs) in fat are important indicator of raw milk quality. Result reliability of FFAs is important. Aim was to verify MIR–FT (mid infrared spectroscopy with Fourier’s transformations) method for its calibration to determine FFAs, time stability of MIR–FT FFA calibration and calibration levelling in laboratory networks. Reference (RE) milk samples (1 set = 8) were prepared according to CSN 57 0533 (FFAs in mmol.100g−1 of fat). MIR–FT instruments were: 1 LactoScope FTIR (DE); 2 Bentley FTS (BE); 2 MilkoScan FT 6000 (FO). 3 calibrations of MIR–FT (5) in 3 laboratories were performed. Bulk milk samples came from 4 herds and 2 breeds. These 4 samples were used for calibration in native and modified form. Modification increased FFAs by cca 100%. Calibration set had 8 samples. 1 between calibration interval was checked monthly by proficiency testing (PT). PT set had 10 samples. 5 samples were with native milk and 5 had modified fat content, lower and higher. Maximal value of difference variability for calibration quality validation is x (sd of difference MIR–FT and RE) plus 1.64 multiple of sd (on 95% level), 1.0613 mmol.100g−1. Mean validation correlation coefficient (r) between MIR–FT and RE results was 0.802 ± 0.082 (P < 0.001), from 0.666 to 0.945. Minimal value at calibration is x minus 1.64 multiple of sd (0.668). Correlations between MIR–FT results were higher by 8.4% (0.869 (P < 0.001) > 0.802). Example PT with 10 and 5 milk samples had similar results of r 0.887 and 0.953 (P < 0.001 and P < 0.05). There is possibility to construct a levelling programme for calibrated instruments. Some equation between PT reference and instrumental values could correct MIR–FT results for their better comparability.

scholarly journals Routine Determination of Milk Fat Composition for Nutritional and Technological Purposes

2019 ◽  
Vol 67 (6) ◽  
pp. 1485-1491
Author(s):  
Eva Samková ◽  
Oto Hanuš ◽  
Jiří Špička ◽  
Lenka Pecová ◽  
Jan Bedrníček ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Dairy Cow ◽  
Milk Fat ◽  
High Reliability ◽  
Raw Milk ◽  
Routine Method ◽  
Milk Samples ◽  
Fatty Acids Profile ◽  
Holstein Dairy Cow

78 individual milk samples (IS) were taken in the Czech Fleckvieh and Holstein dairy cow herds and 33 bulk milk samples (BS) were taken in 13 Holstein dairy cow herds to compare two methods for the determination of fatty acids (FAs) – routine/indirect (infrared (IR) spectroscopy, MIR-FT) and reference/direct (gas chromatography, GC). The IS results show that the fatty acids C16:0 and C18:1 and the group of saturated (SFA) and unsaturated (UFA) FAs can be determined using routine method with a relatively high reliability (correlations (r) 0.7543, 0.7607, 0.8424 and 0.9492; P < 0.001). In case of polyunsaturated FAs is the r lower (0.2891; P < 0.05). In BS the tightness of relations is stronger in the case of the SFA and UFA (r 0.7094; 0.9389; P < 0.001), while for the group of TFA (trans isomers of unsaturated FAs) and PUFA (polyunsaturated FAs) are lower r (0.5897 and 0.5931; P < 0.001 respectively). Routine method for fatty acids profile determination is efficient for selection of raw milk to guarantee the production of specific dairy products with increased content of healthful fatty acids.

Determination of Selected Phthalates in Some Commercial Cosmetic Products by HPLC-UV

2020 ◽  
Vol 23 (10) ◽  
pp. 1010-1022
Author(s):  
Emrah Dural
Keyword(s):  
High Performance ◽  
Phthalate Esters ◽  
High Sensitivity ◽  
Hplc Method ◽  
Cosmetic Products ◽  
Limit Of Quantification ◽  
Nail Polish ◽  
Accuracy And Precision ◽  
Butyl Phthalate

Aim and scope: Due to the serious toxicological risks and their widespread use, quantitative determination of phthalates in cosmetic products have importance for public health. The aim of this study was to develop a validated simple, rapid and reliable high-performance liquid chromatography (HPLC) method for the determination of phthalates which are; dimethyl phthalate (DMP), diethyl phthalate (DEP), benzyl butyl phthalate (BBP), di-n-butyl phthalate (DBP), di(2- ethylhexyl) phthalate (DEHP), in cosmetic products and to investigate these phthalate (PHT) levels in 48 cosmetic products marketing in Sivas, Turkey. Materials and Methods: Separation was achieved by a reverse-phase ACE-5 C18 column (4.6 x 250 mm, 5.0 μm). As the mobile phase, 5 mM KH2PO4 and acetonitrile were used gradiently at 1.5 ml min-1. All PHT esters were detected at 230 nm and the run time was taking 21 minutes. Results: This method showed the high sensitivity value the limit of quantification (LOQ) values for which are below 0.64 μg mL-1 of all phthalates. Method linearity was ≥0.999 (r2). Accuracy and precision values of all phthalates were calculated between (-6.5) and 6.6 (RE%) and ≤6.2 (RSD%), respectively. Average recovery was between 94.8% and 99.6%. Forty-eight samples used for both babies and adults were successfully analyzed by the developed method. Results have shown that, DMP (340.7 μg mL-1 ±323.7), DEP (1852.1 μg mL-1 ± 2192.0), and DBP (691.3 μg mL-1 ± 1378.5) were used highly in nail polish, fragrance and cream products, respectively. Conclusion: Phthalate esters, which are mostly detected in the content of fragrance, cream and nail polish products and our research in general, are DEP (1852.1 μg mL-1 ± 2192.0), DBP (691.3 μg mL-1 ± 1378.5) and DMP (340.7 μg mL-1 ±323.7), respectively. Phthalates were found in the content of all 48 cosmetic products examined, and the most detected phthalates in general average were DEP (581.7 μg mL-1 + 1405.2) with a rate of 79.2%. The unexpectedly high phthalate content in the examined cosmetic products revealed a great risk of these products on human health. The developed method is a simple, sensitive, reliable and economical alternative for the determination of phthalates in the content of cosmetic products, it can be used to identify phthalate esters in different products after some modifications.

Determination of Viable Bacterial Populations in Raw Milk within 20 Minutes by Using a Direct Epifluorescent Filter Technique

1997 ◽  
Vol 60 (7) ◽  
pp. 874-876 ◽  
Author(s):  
CLAUDE P. CHAMPAGNE ◽  
NANCY J. GARDNER ◽  
JULIE FONTAINE ◽  
JACQUES RICHARD
Keyword(s):  
Raw Milk ◽  
Plate Count ◽  
Bacterial Populations ◽  
Filter Technique ◽  
Milk Samples ◽  
Standard Plate ◽  
Plate Counts ◽  
Direct Epifluorescent Filter Technique ◽  
Triton X

The results from a shortened procedure for the direct epifluorescent filter technique (DEFT) determination of viable bacterial populations in raw milk were compared to standard plate counts. Shortening the prefiltration trypsin-Triton X-100 incubation period from 10 to 3 min enabled the completion of the analysis within 20 min. The short DEFT method results had a correlation coefficient (r) of 0.81 with plate counts. With respect to precision, the average difference between values of duplicate plate count analyses was 0.16 log units; that of the short DEFT was 0.14 log units. The slopes of the regressions equations were less than 1, indicating that a direct correlation is not achieved. Short DEFT values were 0.17 log units higher than those of plate counts on milk samples containing less than 10,000 CFU/ml. For milk samples containing counts over 10,000 CFU/ml, short DEFT values averaged only 0.05 log units above plate count readings. Daily preparation of the stain appears unnecessary since acridine orange solutions stored for up to 2 days at 4°C did not produce results significantly (P &gt; 0.05) different from those obtained with fresh solutions. The short DEFT method has potential for the assessment of the bacteriological quality of raw milk in tanker deliveries.

scholarly journals Determination of Four Fluoroquinolones in Milk by Liquid Chromatography

1997 ◽  
Vol 80 (5) ◽  
pp. 982-987 ◽  
Author(s):  
José E Roybal ◽  
Allen P Pfenning ◽  
Sherri B Turnipseed ◽  
Calvin C Walker ◽  
Jeffrey A Hurlbut
Keyword(s):  
Fluorescence Detection ◽  
Solid Phase ◽  
Raw Milk ◽  
Extraction Column ◽  
Isocratic Elution ◽  
Standard Curve ◽  
Milk Samples ◽  
Relative Standard ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method with fluorescence detection is presented for the analysis of 4 fluoroquinolones; enrofloxacin (ENRO), ciprofloxacin (CIPRO), sarafloxacin (SARA), and difloxacin (DIFLX) in milk. The procedure consists of extraction of milk with acidified ethanol, isolation and retention on a cation exchange solid-phase extraction column, elution with basic methanol, and LC analysis with fluorescence detection. LC analysis is performed by isocratic elution using an acetonitrile-2% acetic acid (15 + 85) mobile phase and an Inertsil phenyl column with fluorescence detection at excitation and emission wavelengths of 278 and 450 nm, respectively. A target level of 10 ppb for each of the 4 fluoroquinolones has been established for this method. Average recovery from fortified raw milk samples (5-100 ppb each) based on a 5-point standard curve calculation was 70-90%, with relative standard deviations of &lt;15%.

scholarly journals Physical and microbial qualities of raw milk collected from Bangladesh Agricultural University dairy farm and the surrounding villages

1970 ◽  
Vol 6 (2) ◽  
pp. 217-221 ◽  
Author(s):  
MTG Khan ◽  
MA Zinnah ◽  
MP Siddique ◽  
MHA Rashid ◽  
MA Islam ◽  
...  
Keyword(s):  
Microbiological Quality ◽  
Dairy Farm ◽  
Raw Milk ◽  
Viable Count ◽  
Physical Parameters ◽  
Total Viable Count ◽  
Coliform Count ◽  
Milk Samples

The present study was undertaken with the aim of investigating the physical parameters (e.g. organoleptic and specific gravity of raw milk) and also to study the microbiological quality of raw milk (total viable count, Coliform count and Staphylococcal count) from different villages and Bangladesh Agricultural University (BAU) Dairy Farm of Mymensingh District of Bangladesh, during the period from July to November 2007. A total number of 100 raw milk samples were collected at morning and evening from BAU dairy farm and surrounding four villages of BAU campus. The organoleptic and bacteriological qualities of each sample were analyzed. The organoleptic examination included taste panel score to assess consumer's acceptance and the bacteriological analysis comprised enumeration of total viable count (TVC), total colifrom count (TCC) and total staphylococcal count (TSC) for the determination of sanitary quality. The organoleptic quality of the milk samples is more or less same except the Churkhai milk samples which had flat taste (in 16% milk sample). The average values of TVC/ml were log 5.920, 5.934, 6.007, 6.075 and 6.127 for BAU Dairy Farm, Boira, Shutiakhali, Churkahai and Paglabazar respectively; coliform count were log 2.501, 2.522, 2.550, 2.620 and 2.619 respectively; staphylococcal count were log 2.832, 2.812, 2.866, 2.931 and 2.988 respectively. So, it may be concluded that the raw milk samples of BAU Dairy Farm were superior to others collected from the selected villages which may be due to maintaining better hygienic condition. Key words: Raw milk, physical and microbial quality   doi: 10.3329/bjvm.v6i2.2339 Bangl. J. Vet. Med. (2008). 6 (2): 217-221

Note: A rapid method for the determination of lipids an fatty acids in bread by gas chromatography / Nota: Método rápido para la determinación de lípidos y ácidos grasos en pan mediante cromatografía de gases

1998 ◽  
Vol 4 (3) ◽  
pp. 207-210
Author(s):  
Y.A. Sultanovitch ◽  
O. Philipp ◽  
M. Schmelewa ◽  
H.D. Isengard
Keyword(s):  
Fatty Acids ◽  
Gas Chromatography ◽  
Solvent Extraction ◽  
Analytical Method ◽  
Extraction Method ◽  
Conversion Factor ◽  
High Sensitivity ◽  
Solvent Extraction Method ◽  
Conventional Solvent Extraction

A new simple and fast analytical method was developed to characterize the content of lipids and fatty acids in bread. First, fatty acids were determined by gas chromatography and then the content of lipids was calculated by using a conversion factor. This method gave very accurate results; it was three times faster than the conventional solvent extraction method and its consumption of solvent was much lower. The high sensitivity allowed the distribution of lipids in bread to be determined.

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