Ứng dụng

Today’s Raman instrumentation is faster, more rugged, and less expensive than previous instrumentation.The design of high performance, portable and handheld devices has introduced the technology to new application areas that were previously not possible with older, more cumbersome instruments. Handheld Raman instruments such as the NanoRam® from B&W Tek are well-suited for pharmaceutical applications such as the testing of raw materials, verification of final products and the identification of counterfeit drugs due to the technique’s extremely high molecular selectivity.

Ternary mixtures of aqueous sugar solutions are measured and multivariate models of the concentration of analytes developed using BWIQ software.

Cellulose is a common naturally-derived raw excipient found in the majority of pharmaceutical products. Raw material testing is required to ensure that consumers are receiving quality cellulose and its derivatives. The NanoRam®-1064 is an asset for pharmaceutical identity testing, minimizing fluorescence generated by typical handheld Raman systems with 785 nm lasers. As such, the NanoRam®-1064 is used here to identify cellulose derivatives that would normally fluoresce with a 785 nm laser.

Fructose (fruit sugar) is the only ketose that occurs naturally. It is found free in a mixture with dextrose (honey, sweet fruits, tomatoes) or bound as a component of cane sugar and various starch-like carbohydrates. As fructose tastes sweeter than dextrose, it finds great use as a sweetening agent. In 1932, the polarographic reducibility of sugar was described for the first time by Heyrovsky and Smoler. The following method can be used to determine the fructose content of fruit, fruit juice and honey quantitatively.

This Application Bulletin gives an overview of the volumetric water content determination according to Karl Fischer. Amongst others, it describes the handling of electrodes, samples, and water standards. The described procedures and parameters comply with the ASTM E203.

This Bulletin describes fluoride determination in various matrices with the help of the ion-selective fluoride electrode (F-ISE). The F-ISE is comprised of a lanthanum fluoride crystal and exhibits a response in accordance with the Nernst equation across a wide range of fluoride concentrations.The first part of this Bulletin contains notes regarding the handling and care of the electrode and the actual fluoride determination itself. The second part demonstrates the direct determination of fluoride with the standard addition technique in table salt, toothpaste and mouthwash.

Bromide is removed from the sample as BrCN by distillation. The BrCN is absorbed in sodium hydroxide solution and decomposed with concentrated sulfuric acid, then the released bromide ions are determined by potentiometric titration with silver nitrate solution. Iodide does not interfere with the determination. Iodide is oxidized to iodate by hypobromite. After destruction of the excess hypobromite, the potentiometric titration (of the iodine released from iodate) is carried out with sodium thiosulfate solution. Bromide does not interfere, even in great excess. The described methods allow the determination of bromide and iodide in the presence of a large excess of chloride (e.g., in brine, seawater, sodium chloride, etc.).

After acid digestion, the sample solution is neutralized with sodium hydroxide to form sodium dihydrogen phosphate. An excess of lanthanum nitrate is added and the released nitric acid is then titrated with sodium hydroxide solution. NaH2PO4 + La(NO3)3 → LaPO4 + 2 HNO3 + NaNO3 This determination method is suitable for higher phosphate concentrations.

Maleic and fumaric acid can be reduced electrochemically to succinic acid. In acidic solutions a differentiation of the two acids is not possible since both are reduced at the same potential. On the other hand, separation at pH 7.8...8.0 is easily possible since fumaric acid is now more difficult to reduce at the lower proton concentration (as a result of cis-trans isomerism) than maleic acid.

This Application Bulletins describes the determination of nicotinamide (vitamin PP), a vitamin of the B series. Instructions for the determination in solutions (e.g. fruit juice), vitamin capsules and multivitamin tablets are given. The linearity range of the determination is also specified. The limit of detection is approximately 50 μg/L nicotinamide.

This Application Bulletin describes the polarographic determination of folic acid, a vitamin of the B series, also known as vitamin B9 or vitamin BC. Instructions for the determination in solutions (e.g. fruit juice), vitamin capsules and multivitamin tablets are given. The linear range of the determination is also specified. The limit of detection is approx. 75 µg/L folic acid.

This Application Bulletins describes the polarographic determination of thiamine (vitamin B1). The procedure allows an analysis in monovitamin preparations. The linear range of the determination is also given. The limit of detection is approx. 50 µg/L thiamine.

This Application Bulletin describes the polarographic determination of riboflavin (vitamin B2). The procedure allows an analysis in monovitamin preparations. The limit of determination is approx. 100 μg/L.

This Application Bulletins describes the polarographic determination of pyridoxine (vitamin B6). The method given allows determination in monovitamin and in some multivitamin preparations. The linear range of the analysis is also specified. The limit of detection is approx. 100 µg/L pyridoxine · HCI.

The effectiveness of antioxidants can be expressed as antioxidant activity. It can be readily determined using the Rancimat method. This is accomplished by first determining the induction time of a mixture made up of hog fat and the antioxidant to be investigated and then by determining the corresponding time for hog fat alone. The quotient expresses the efficiency of the respective antioxidant and is referred to as the antioxidant activity index (AAI). This Application describes the determination of the antioxidant activity index of five common antioxidants.

Generally speaking, the gas extraction or oven method can be used for all samples which release their water when they are heated up. The oven method is indispensable in cases in which the direct volumetric or coulometric Karl Fischer titration is not possible, either because the sample contains disruptive components or because the consistency of the sample makes it very difficult or even impossible to transfer it into the titration vessel. The present Application Bulletin describes automatic water content determination with the aid of the oven technique and coulometric KF titration, using samples from the food, plastic, pharmaceutical and petrochemical industry.

This Application Bulletin provides information regarding the MATi 10 (Metrohm Automated Titration) system. MATi 10 is a completely configured system for automatic volumetric Karl Fischer titration with which the water content in liquid and solid samples can be determined. Up to 24 samples can be analyzed directly in 75 mL titration vessels. The samples are weighed into the titration vessels and covered with an aluminum foil. This prevents falsification of the water content.

The Rancimat method determines the oxidation stability (OSI) and antioxidant capacity (SI) of solid foods. OSI measurements are performed directly, with extracted isolated fat, or via the polyethylene glycol method. SI can be determined when the sample is mixed with a reference of antioxidant-free fat.

This method is applicable to all samples containing glycerin in the absence of other triols or other compounds that react with periodate to produce acidic products. Glycerin may be determined in the presence of glycols. A periodate solution reacts slowly with diols and triols in acidic aqueous media at room temperature. A quantitative amount of formic acid is generated from the reaction with glycerin (a triol). The reaction with diols produces neutral aldehydes. The amount of formic acid generated by this reaction is determined by titration against sodium hydroxide.

Determination of Na, P, and [Na]/[P] in precursor solutions and solids in the manufacture of sodium tripolyphosphate.

A measured amount of salt is titrated directly with a solution of 1 mol/L tetrasodium EDTA to thermometrically determined endpoints for Ca and Mg. Acetylacetone is added to alter the Ca and Mg EDTA stability constants for better endpoint sharpness.

Sulfate is precipitated as barium sulfate by reaction with an acidified barium chromate solution. The excess barium chromate is precipitated by basification with ammonia solution. Residual soluble chromate, equivalent to the sulfate content of the sample, is titrated with a solution of standard ferrous ion to a thermometrically determined endpoint.

The determination of the potassium content in foodstuffs plays a major role in the food and dietary supplement industry, as potassium is an essential mineral nutrient for humans. It is an important intracellular cation and also plays a important role in processes within cells, where it is involved in the regulation of numerous body functions like blood pressure, cell growth and muscle control. As a dietary supplement, potassium is present in e.g., electrolyte powder, electrolyte drinks and food supplements. To quantify the potassium content in such products, e.g. flame photometry can be used. In this work, an alternative, ion measurement by standard addition, is described, which is fast, inexpensive and simple to use.

This Application Note describes the determination of the water content in gelatine using the oven technique.

In this application note, Karl Fischer titration is used to determine water content in sodium acetate trihydrate. The MATi 10 allows this determination to be automated, saving users time in the laboratory.

Pure sodium chloride contains much less iodide than e.g., table salt which usually is fortified with it. Trace determination of iodide is easily performed applying ion chromatography with amperometric detection. This detection mode is particularly selective and sensitive. The actual separation is achieved using a Metrosep A Supp 5 - 250/4.0 column. The detection happens at a silver working electrode. LOQ is at approximately 1.0 μg/L (in solution) and 50 μg/kg in the sample. The use of a shorter column might further improve the LOQ.

This Application Note describes the quantification of protein content in dietary supplements using Vis-NIR spectroscopy to reduce the workload of time-consuming and waste-generating primary methods, such as Kjeldahl digestion.

Near-infrared spectroscopy (NIRS) allows the simultaneous determination of sweeteners such as Stevia and sucralose in blends in less than one minute without any chemicals or sample preparation.

Key quality parameters in the food industry include sucrose, glucose, and fructose, and Brix (dissolved sugar content). Near-infrared spectroscopy (NIRS) allows fast simultaneous determination of multiple sugars without chemicals or any sample preparation.

Nghiên cứu này cho thấy cách quang phổ NIR đo đồng thời hàm lượng capsaicin, Scoville Heat Units (SHU), hoạt độ nước, màu ASTA và hàm lượng tro trong các mẫu bột paprika.

Determination of citric acid and tartaric acid in fruit salt using ion-exclusion chromatography with direct conductivity detection.

Determination of citrate, ascorbate, and acetate in a food additive using ion-exclusion chromatography with suppressed conductivity detection.

Evidence of maleic acid in Asian foodstuffs led to the recall of many starchy foods because long-term consumption of maleic acid can cause kidney problems. Cyclic kojic acid is however approved in Asia, both as a bleaching additive in foodstuffs and as a preservative in cosmetics. This Note describes their simultaneous determination in a single analysis.

Sorbic acid and benzoic acid and their salts are used as food preservatives (E200, E201, E201, E203 and E210, E211, E212, E213 respectively). The content of such preservatives in flavored bottled water may easily be analyzed by ion exclusion chromatography. This method determines the concentration of the respective acid and does not allow differentiating between the counter cations. The determination of sorbic acids and benzoic acid is achieved by conductivity detection after inverse suppression.

Separation of polysaccharides with increasing numbers of inulin units using gradient elution and pulsed amperometric detection.

Determination of sucrose, glucose, and sucralose in a low-calorie sweetener using ion-exclusion chromatography with pulsed amperometric detection after post-column addition of sodium hydroxide.

Determination of polysaccharides (n glucose units) in potato starch using pulsed amperometric detection and a high-pressure gradient.

Inulin is a mixture of many fructose molecules. Inulin is increasingly being used in food production in recent times. This Application Note describes the determination of the inulin content in cakes. Correct analysis requires knowing which type of inulin is present, because the total number of fructose units varies. In this task, for example, the F8 peak (eight fructose units) was quantified.

Stevia is a plant of the Compositae family, the leaves of which can be used as a sweetener. In order for it to be used in the food sector, the purity of the steviol glycosides contained in the Stevia must be monitored. Utilization of the flexIPAD potential profile yields a greater sensitivity than standard PAD. The separation is accomplished on an RP column. Post-column addition of sodium hydroxide enables amperometric detection.

This Application Note presents an update to the standard AOAC method for total GOS determination in foodstuffs.

Worldwide, milk and dairy products are vital sources for human nutrition. A major component and energy source in dairy products is lactose. To efficiently metabolize lactose, the enzyme lactase is indispensable. However, globally nearly 70% of the population is lactose intolerant and they have difficulties to digest lactose. Lactose malabsorption leads to numerous gastrointestinal and extra-intestinal symptoms and other complaints with varying extents. Therefore, consumers rely on accurate food labels and for manufacturers appropriate sensitive analytical techniques are a must to comply with these demands. Ion chromatography with pulsed amperometric detection (IC-PAD) enables the determination of very low lactose contents. Validation according to AOAC requirements shows the high sensitivity and reliability of this method as a routine analysis.

This Application Note describes the Raman spectroscopy identification of sugars such as D-galactose, D-glucose, D-maltose, D-mannose, D-sorbitol, fructose, sucrose and inositol. Rapid and non-destructive determination takes place after a suitable spectrum database has been created. Measurements with the portable Raman spectrometer Mira M-1 require no sample preparation and provide immediate and unambiguous results.

Determination of the identity and purity of ingredients is essential for the product quality of functional foods (neutraceuticals) and cosmetics. It prevents the utilization of inferior substances in the production process and thus avoids expensive delays and out-of-spec products. This Application Note describes the identification and checking of fatty acids in functional foods and cosmetics using the Metrohm Instant Raman Analyzer MIRA P.

Determination of chloride, bromide, phosphate, and sulfate in an ashed baking additive using anion chromatography with conductivity detection after chemical suppression.

Determination of iodide in common salt using anion chromatography with amperometric detection at the silver electrode.

Determination of bromide in NaCl crystals using anion chromatography with conductivity detection after chemical suppression.

Determination of sulfite in ginger powder using anion chromatography with conductivity detection after chemical suppression and dialysis for sample preparation.

Determination of fluoride in adipic acid using anion chromatography with conductivity detection after chemical suppression.

Determination of chloride and sulfate in succinic acid using anion chromatography with conductivity detection after chemical suppression.

Determination of fluoride, chloride, nitrate, phosphate, sulfate, trimetaphosphate, and tripolyphosphate in tetrasodium pyrophosphate using anion chromatography with a high pressure gradient and conductivity detection after chemical suppression.

Determination of o-phosphate, pyrophosphate, and trimetaphosphate in sodium tripolyphosphate using anion chromatography with conductivity detection and chemical suppression.

Determination of citrate, dipolyphosphate, and tripolyphosphate in a food additive using anion chromatography with conductivity detection after chemical suppression.

Determination of phosphite in the presence of chloride, nitrate, bromide, nitrate, and sulfate in a potato extract using anion chromatography with conductivity detection after chemical suppression and inline sample preparation by dialysis.

Determination of iodide in a table salt using anion chromatography with conductivity detection after chemical suppression.

N,N-dimethylglycine is an amino acid derivative found in plants and animals. The respective sodium salt is available as nutritional supplement. In this context it is expected to have athletic performance enhancer effects and acts against fatigue. It is also accepted as a poultry feed addition. The determination is performed applying a Dose-in Gradient with subsequent conductivity detection after sequential suppression. To enhance the selectivity of the separation, a combination of a Metrosep A Supp 7 - 250/4.0 and a Metrosep A Supp 16 Guard/4.0 was used.

Determination of sulfate in brine by indirect potentiometric titration with EGTA using platinum and tungsten electrodes.

Determination of calcium pantothenate by nonaqueous potentiometric titration with perchloric acid using separate electrodes.

Vitamin C, also known as ascorbic acid or L-ascorbic acid, is an essential nutrient involved in the repair of tissues and the enzymatic production of certain neurotransmitters. It is required for the functioning of several enzymes and immune performance, and is also an important antioxidant. This nutrient is found in many foods and is often used as a dietary supplement. USP general chapter <580> describes a titration technique to determine the assay of Vitamin C as ascorbic acid, sodium ascorbate, and calcium ascorbate dehydrate, or their mixture in finished dosage forms as capsules, tablets, and oral suspensions. This Application Note demonstrates the Vitamin C determination in water-soluble vitamin tablets. The methodology can also be applied for oil-soluble vitamin or mineral tablets, as well as oil- and water-soluble vitamin or mineral capsules.

Sodium lactate is a salt form of lactic acid used in many regulated industries—therefore an accurate determination of the lactate content is required and is already covered in several norms. One such monograph by the US Pharmacopoeia (USP) results in high accuracies and well-defined titration curves but uses titrants and solvents that are more costly than necessary. In comparison, the presented modified method from Metrohm requires a 1:1 mixture of water and acetone and uses aqueous hydrochloric acid as titrant, resulting in an estimated cost reduction of 40% per titration compared to the USP method (USP–NF 2021, Issue 2). Furthermore, the time needed for each analysis is reduced to just 12% of the USP method (excluding blank determination). This Application Note presents both methods to determine lactate content and shows the results obtained on an OMNIS system.

About 20% of our sugar comes from sugar beet crops, mostly grown in Europe and the U.S. where the climate is temperate, whereas the other 80% is produced from sugar cane in tropical areas. Lime salts and pH are very important factors which are controlled during the sugar manufacturing process. Complexometric titration is often used to determine the concentration of lime salts in such kinds of samples. This Application Note presents a more robust method for determining calcium compounds in sugar beet juice. Subjectivity of color change determination is eliminated by using an ion selective electrode (ISE).

Mannitol content determination is an important aspect of quality control in the pharmaceutical and food industries. Selective oxidative cleavage can be used to quantify the amount of 1,2-diol groups in the analyte. Determining the 1,2-diol content by iodometric titration can be fully automated for the most accurate results using an automated titrator and the dPt Titrode from Metrohm.

Titration is an accurate and precise method that can be used to determine the pyrophosphate content in aqueous products. The OMNIS Titrator equipped with a dUnitrode delivers reliable determinations.

This study presents the automatic titration of low sulfite levels in beet crystal sugar using an OMNIS Titrator and a Pt Titrode as the potentiometric sensor.

Determination of Zn, Pb, Cu, and Fe in sugar after wet digestion.

Determination of ascorbic acid (vitamin C) in vitamin capsules after sample digestion.

Determination of cysteine and cystine in caseinate after sample preparation with NaOH.

It is crucial to monitor iodide in NaCl brine to prevent membrane fouling during chlor-alkali electrolysis. Stripping voltammetry offers precise iodide analysis.

Efficiently analyze food products with ion chromatography (IC). Discover its robust applications in quality control for beverages, food additives, and dairy.

The coupling of ion chromatography and inductively coupled plasma mass spectrometry (ICP/MS) leads to a high-performance measurement system that masters several particularly challenging analyses. It enables for example reliable determination of element compositions, oxidation states and chemical bonds. This information is used, for example, for assessing the toxicity of medications, environmental and water samples as well as foods and beverages.

Ion measurement can be conducted in several different ways, e.g., ion chromatography (IC), inductively coupled plasma optical emission spectrometry (ICP-OES), or atom absorption spectroscopy (AAS). Each of these are well-established, widely used methods in analytical laboratories. However, the initial costs are relatively high. In contrast, ion measurement by the use of an ion-selective electrode (ISE) is a promising alternative to these costly techniques. This White Paper explains the challenges which may be encountered when applying standard addition or direct measurement, and how to overcome them in order for analysts to gain more confidence with this type of analysis.

Sulfites are well-known additives in foods and beverages used to extend shelf life and preserve colors. Such properties have led to the broad usage of sulfites in a range of foodstuffs like fruits, cereals, vegetables, seafood, juices, alcoholic and non-alcoholic (soft) beverages, and in some meat products. The term «sulfites» describes a group of molecules that include sulfur dioxide (SO2) and chemically related molecules like sodium sulfite (Na2SO3), sodium bisulfite (NaHSO3), or sodium metabisulfite (Na2S2O5). Sulfite intake has been correlated with several adverse reactions, and therefore sulfites are included in the FAO/WHO Codex Alimentarius list. Labelling sulfite content in foods and beverages is necessary when the total concentration exceeds 10 mg/kg. Metrohm ion chromatography allows the reliable measurement of sulfite in different matrices using either conductivity or amperometric detection. The inclusion of automated sample preparation and cleaning steps with Metrohm instrumentation saves additional analyst time and helps increase sample throughput.

Free white paper gives comprehensive overview of how to reliably assess the quality of infant formula with ion chromatography.

OMNIS Client/Server nâng cao hiệu suất kinh doanh nhờ khả năng quản lý máy chủ linh hoạt, giúp cắt giảm chi phí thông qua giảm phần cứng, tiêu thụ năng lượng và bảo trì tại nhiều địa điểm.