Automated free fatty acid determination using flow injection analysis solvent extractions

Canham, John S.; Pacey, G.E.

doi:10.1007/bf02542438

Cited by 25 publications

(12 citation statements)

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“…The method proposed by Ekstrom [13] was based on copper soap colorimetry, using one extraction to achieve a reaction of the FFA with copper ions and another to recover copper ions that are subsequently monitored. This method was also modified by others [14,15] using a phase or membrane separator, and channels and oil samples were injected after being pre-diluted and homogenized with toluene. Nouros et al [16] suggested an automated FI titrimetric method for the determination of olive oil acidity.…”

Section: Introductionmentioning

confidence: 99%

A Novel Approach for Determination of Free Fatty Acids in Vegetable Oils by a Flow Injection System with Manual Injection

Ayyıldız¹,

Kara²,

Sherazi³

2011

Lipids

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A non-aqueous flow injection method for determining free fatty acid (FFA) content in corn and sunflower oil samples was developed. A single-line manifold system was built by modification of an HPLC for flow injection analysis (FIA). Without pre-treatment, oil samples were injected into a n-propanol solution containing KOH and phenolphthalein (PHP). The main parameters, such as flow rate of carrier phase, length, geometry, inner diameters of the coils and reagent concentration were all optimized. The proposed FIA method was validated for precision, accuracy, linear region, limit of detection (LOD) and limit of quantification (LOQ). The intra- and inter-day measurements of the precision of the method were found to be within the limits of acceptance criteria (RSD < 1%), and were rugged when the method was performed by a different analyst. The linear concentration range was calculated as 0.09-1.50 and 0.07-1.40 FFA% for corn and sunflower oils, correspondingly. The LOD and LOQ were found to be 7.53 × 10(-4)-2.28 × 10(-3) oleic acid % and 7.11 × 10(-4)-2.23 × 10(-3) oleic acid % for corn and sunflower oils, respectively. The results were compared with those obtained by the AOCS (Ca-5a-40) method using statistical t and F tests, and a significant difference was not observed between the methods at a 95% confidence level. The proposed method is suitable for quality control of routine applications due to its simplicity, high sample throughput, and economy of solvents and sample, offering considerable promise as a low cost analytical system that needs minimum human intervention over long periods of time.

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Section: Introductionmentioning

confidence: 99%

A Novel Approach for Determination of Free Fatty Acids in Vegetable Oils by a Flow Injection System with Manual Injection

Ayyıldız¹,

Kara²,

Sherazi³

2011

Lipids

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“…Hypothesis testing was therefore made for the slope of the line (β 1 ) with a null hypothesis, H o : β 1 = 1. The t-statistic is calculated from the expression: [4] The "estimate" equals the slope from the regression analysis, the "hypothesized value" equals 1, and "standard error of estimate" is obtained from SAS output. Table 5 summarizes results of the regression analysis.…”

Section: Resultsmentioning

confidence: 99%

A modified method for determining free fatty acids from small soybean oil sample sizes

Rukunudin

White

Bern

et al. 1998

J Americ Oil Chem Soc

122

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A modification of the AOCS Official Method Ca 5a-40 for determination of free fatty acids (FFA) in 0.3 to 6.0-g samples of refined and crude soybean oil is described. The modified method uses only about 10% of the weight of oil sample, alcohol volume, and alkali strength recommended in the Official Method. Standard solutions of refined and crude soybean oil with FFA concentrations between 0.01 and 75% were prepared by adding known weights of oleic acid. The FFA concentrations, determined from small sample sizes with the modified method, were compared with FFA percentages determined from larger sample sizes with the Official Method. Relationships among determinations obtained by the modified and official methods, for both refined and crude oils, were described by linear functions. The relationship for refined soybean oil had an R 2 value of 0.997 and a slope of 0.99 ± 0.031. The values for crude soybean oil are defined by a line with R 2 = 0.9996 and a slope of 1.01 ± 0.013. JAOCS 75, 563-568 (1998). KEY WORDS:Crude soybean oil, free fatty acid, Official Method, refined soybean oil, titration.In the soybean industry, the presence and development of any amount of free fatty acid (FFA) in soybean oil is undesirable. The FFA content of oil in soybeans indicates how well the beans have been treated during the period between harvest and processing. The eventual consequence of high FFA content is monetary loss because processing soybeans with high FFA content results in more refining loss. Specifically, refining loss is the sum of oil weight lost during removal of FFA and other impurities plus the weight of entrained neutral oil in soapstock during the normal alkali-refining process. The percentage of oil lost during refining can be estimated as a multiple of the FFA percentage. Norris (1) estimates the potential loss at about three times the FFA content. Because of the economic impact of high FFA, it is important to determine the initial level of FFA in soybean oil and also to monitor its concentration during processing.The standard method for FFA determination in extracted crude and refined soybean oil samples is based on an acidbase titration technique in a nonaqueous system. The method commonly used is AOCS Official Method Ca 5a-40 (2). The procedure prescribes an oil sample of maximum 56.4 g and minimum 3.53 g for the titration, depending on the level of FFA in the oil sample. When oil quantities are limited, as in some storage studies or when experimental use of oilseed crops is evaluated, sample sizes of this magnitude are not possible. A simple and inexpensive method is needed that accurately quantifies FFA content from a smaller sample size.The use of smaller amounts of chemicals will have an impact, especially in developing countries, where chemicals are scarce and expensive. Also, it is prudent to limit the use of resources, particularly those hazardous to the environment. For example, hexane, a solvent used in the titration, is a hazardous, highly flammable compound, and its disposal can be harmful to the en...

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“…For example, a pH-stat method has been recently proposed to measure glucose oxidase in a non-buffered medium (Iturbe et al 1989) or to calculate the rate of the esterolysis reaction of N-acetyltyrosine ethyl ester by a-chymotrypsin (Shimizu et al 1989). These techniques do not need any complex apparatus, as for continuous monitoring of reactions by means of Solvent Extraction Flow Injection Analysis (SEFIA) procedures that is often used in fatty acid production (Ekstr6m 1981; Canham and Pacey 1987).…”

Section: Discussionmentioning

confidence: 99%

A fed-batch technique for 2-heptanone production by spores of Penicillium roquefortii

Creuly

Larroche

Gros

1990

Appl Microbiol Biotechnol

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A fed-batch technique for the production of 2-heptanone from octanoic acid by Ca-alginate/Eudragit RL-entrapped spores of Penicillium roquefortii is presented. It involves the use of a pH-stat apparatus, the increase in pH arising due to the reaction being overcome by direct substrate addition. When the reaction is performed at pH 5.5, no true constant rate period can be achieved due to a gradual buffering of the medium connected with a decrease in the catalytic activity of the spores. At pH 6.5 the system exhibits high stability and the reaction rate remains constant for at least 300 h with a value of 0.975 m M / h and a substrate concentration close to 4 mM. The process used may be very useful in the study of long-term behaviour of biocatalysts when the medium is not renewed and when the reaction involves an ionic compound and a neutral one.

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Automated free fatty acid determination using flow injection analysis solvent extractions

Cited by 25 publications

References 10 publications

A Novel Approach for Determination of Free Fatty Acids in Vegetable Oils by a Flow Injection System with Manual Injection

A Novel Approach for Determination of Free Fatty Acids in Vegetable Oils by a Flow Injection System with Manual Injection

A modified method for determining free fatty acids from small soybean oil sample sizes

A fed-batch technique for 2-heptanone production by spores of Penicillium roquefortii

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