Re: Serial Number For Acid Pro 7.0 Free
Денис Окунев
In chemistry, acid value (AV, acid number, neutralization number or acidity) is a number used to quantify the acidity of a given chemical substance. It is the quantity of base (usually potassium hydroxide (KOH)), expressed as milligrams of KOH required to neutralize the acidic constituents in 1 gram of a sample.[1][2][3][4]
A liquid fat sample combined with neutralized 95% ethanol is titrated with standardized sodium hydroxide of 0.1 eq/L normality to a phenolphthalein endpoint. The volume and normality of the sodium hydroxide are used, along with the weight of the sample, to calculate the free fatty acid value.[3]
For determining the acid value of mineral oils and biodiesel, there are standard methods such as ASTM D 974 and DIN 51558, and especially for biodiesel the European Standard EN 14104 and ASTM D664 are both widely used worldwide.[2] Acid value of biodiesel should be lower than 0.50 mg KOH/g in both EN 14214 and ASTM D6751 standard fuels. This is because the FFAs produced can corrode automotive parts, hence these limits protect vehicle engines and fuel tanks.[5]
When oils and fats become rancid, triglycerides are converted into fatty acids and glycerol, causing an increase in acid value.[8] A similar situation is observed during aging of biodiesel through analogous oxidation and when subjected to prolonged high temperatures (ester thermolysis) or through exposure to acids or bases (acid/base ester hydrolysis).[5]
Total acidity, fatty acid profiles, and free fatty acids (FFAs) can be determined for oils such as sunflower and soybean oils obtained by green processes involving supercritical carbon dioxide (scCO2) and pressurized liquid extraction (PLE). The identification and separation of the primary fatty acids responsible for acidity can ensure higher quality of fat and oil products.[12]
In 2020, Dallas Group of America (DGA)[13] and American Oil Chemists' Society (AOCS) devised a standard method (5a-40) for testing free fatty acid in cooking oils.[14][15] The DGA FFAs hand-held test kit was produced from the AOCS test method, but without the burets, flasks, and laboratory hardware. Its portable nature is convenient for both small and large frying operations. Testing next to the fryer or in the comfort of a laboratory setting is simple with the DGA FFAs test kit. It gives accurate results for cooking oil used in potato chips, corn dogs, meat browning, bread products, roasted peanuts, and more.[15]
Objective: The omega-3 polyunsaturated fatty acid eicosapentaenoic acid (EPA) has anticolorectal cancer activity in vitro and in preclinical models. The present study tested whether a novel, enteric-coated formulation of EPA, as the free fatty acid (EPA-FFA), has chemopreventative efficacy in patients with familial adenomatous polyposis (FAP), in a randomised, double-blind, placebo-controlled trial.
Methods: Patients undergoing endoscopic surveillance of their retained rectum postcolectomy were randomised to EPA-FFA (SLA Pharma) 2 g daily or placebo for 6 months. The number and size of polyps in an area of mucosa defined by a tattoo were determined before and after intervention. Global rectal polyp burden was scored (-1, 0, +1) by examination of video endoscopy records. Mucosal fatty acid content was measured by gas chromatography-mass spectrometry.
Results: 55 patients with FAP were evaluated by an intention-to-treat analysis (EPA-FFA 28, placebo 27). Treatment with EPA-FFA for 6 months was associated with a mean 22.4% (95% CI 5.1% to 39.6%) reduction in polyp number (p=0.012) and a 29.8% (3.6% to 56.1%) decrease in the sum of polyp diameters (p=0.027). Global polyp burden worsened over 6 months in the placebo group (-0.34) unlike the EPA-FFA group (+0.09, difference 0.42 (0.10-0.75), p=0.011). EPA-FFA treatment led to a mean 2.6-fold increase in mucosal EPA levels (p=0.018 compared with placebo). EPA-FFA was well tolerated with an incidence of adverse events similar to placebo.
Additive depletion, contamination and oxidation are common pathways of lubricant degradation. The acid number (AN) test is one of the methods available in the oil analysis field used to estimate the amount of additive depletion, acidic contamination and oxidation. AN does not directly measure the rate of oxidation, it merely measures the by-product of oxidation. It is also beneficial to trend AN to determine the rate of depletion of certain additives. The purpose of this article is to attempt to answer the following questions:
AN is the measure of acid concentration in a nonaqueous solution. It is determined by the amount of potassium hydroxide (KOH) base required to neutralize the acid in one gram of an oil sample. The standard unit of measure is mg KOH/g. AN does not represent the absolute acid concentration of the oil sample. The AN measurement detects both weak organic acids and strong inorganic acids.
A change in the acid concentration of an oil can originate from multiple sources. Acidic contaminants, wrong oil, alkaline-reserve depletion and oxidation by-products can cause an increase in acid concentration. Table 1 lists common acids that can be detected.
Understanding the extent of additive depletion is key in determining the RUL of an oil. Some additives are weakly acidic and can elevate the oil's initial AN. As the lubricant ages these additives deplete, thereby reducing the acidity created by the additives. The common antiwear additive, zinc dialkyl dithiophosphate (ZDDP), produces certain AN trends during lubricant aging.
Concurrently, the oil is possibly being contaminated with acidic constituents, increasing the acid content in the oil. The combined effects of additive depletion, acidic contamination and other acidic-affecting events create a challenge in determining what the AN represents.
Currently in North America, the term total acid number (TAN) is being replaced with acid number (AN). This change is based on the fact that AN tests do not detect the total acid concentration of the lubricant. The acid concentration of the lubricant contains both strong and weak components. Strong acidic components are referred to as SAN.
The weak components and the strong components are typically combined as AN. Even though AN is comprised of both acidic components, it does not represent all acidic components in the lubricant. For instance, the AN and base number (BN) tests are not affected by extremely weak acids and bases that have a dissociation constant of less than 10-9. This is the reason that TAN is being replaced by AN.
The pH and AN test methods measure different aspects of the oil's acidic or alkaline character. The pH test method measures the apparent pH of the oil. The apparent pH is a representation of how corrosive the oil may be, but it does not indicate the concentration of acidic or alkaline constituents. The pH test method is useful in applications where corrosive oil could cause considerable damage. It is also valuable in lubricant systems with a high potential for the formation or the contamination of strong acids.
The AN and BN test methods respectively measure the concentration of acidic and alkaline constituents. Both acidic and alkaline constituents can exist in oil at the same time. In fact, some additives are amphoteric, meaning they can behave as either a base or an acid. In some oils, it is important to monitor both the AN and BN to determine the reactions in the oil.
AN and BN do not indicate the strength of the acidic or alkaline constituents in the lubricant, which reduces their ability to indicate the oil's corrosiveness. AN has a better ability than pH to detect and monitor weak acids, which do not readily dissociate in water. This prevents the pH test method from obtaining a good indication of how the weak acid concentration is changing in the lubricant.
The potentiometric method uses a potentiometer to detect the acidic constituents and coverts it to an electronic read out. The output is plotted and analyzed to determine the inflection of the test method. The colorimetric method uses paranaphthol-benzene, which responds to a change in the pH indicator that has been added to the solution. Once the acidic constituents have been neutralized by the KOH, the sample will change from orange to blue-green, indicating the end point.
ASTM D664 measures acidic constituents by using a potentiometer to determine an end point. This method can be used to measure both AN and SAN. To prepare the sample a mixture of toluene, isopropyl alcohol and water is dissolved into a sample. Potassium hydroxide is then titrated into the solution using a burette. The potentiometer output is monitored while the KOH is titrated into the solution.
ASTM D974 is the measure of acidic constituents using a color change to indicate the inflection. The sample is dissolved into a solution of toluene, p-naphtholbenzne, and isopropyl alcohol containing water. The solution is titrated with KOH while the color is monitored. This test is used on new oils and oils that are not excessively dark.
AN tests are typically conducted to obtain an accurate indication of additive depletion and possible contamination of ingressed acids. The standard ASTM methods are time consuming, have relatively poor reproducibility and utilize hazardous materials. In an effort to control the source of these issues, many modified versions of the AN test are currently being used. Each test is specific to its application. For example, a lab may automate the test to reduce labor and increase throughput.
Field tests can also report actual results. For example, one such kit uses a volume-sampling syringe to ensure that the oil samples are the same size. A disposable burette is used to titrate the KOH. Because the oil sample is a specific size, the burette has been scaled to indicate the AN. Once the color has changed, the user only can read the acid number from the burette.
The parabolic curves may characterize rust and oxidized (R&O) oils. The AN remains constant during the additive depletion induction phase. Once the R&O additives have depleted, the base oil will begin to oxidize. The switching trend is representative of EP oils, where some of the additives are acidic. As additives deplete and react, the AN varies. These effects make it hard to trend EP oils unless the normal switching pathway is known in advance.
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