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Portable Raman is used to quantify trigonelline, an alkaloid that contributes to the health benefits of some foods. A simple method to quantify the presence of diluted trigonelline in solutions using surface enhanced Raman spectroscopy is described. Portable Raman is a tool that could be used in quality control of food items such as coffee and quinoa.

Psychoactive gamma-hydroxybutyrate (GHB) and its prodrug gamma-butyrolactone (GBL) are substances that are increasingly abused as date-rape and recreational (party) drugs. Since the non-controlled GBL converts into the illicit GHB both in-vivo and in-vitro, their legal distinction is of crucial importance.For the forensic determination of illegally added GHB and GBL in commonly consumed beverages, this work presents a simple and sensitive method that employs direct-injection ion chromatography combined with spectrophotometric detection. The method allows to trace GHB-GLB interconversion, whether in vivo or in vitro lactone cleavage or intramolecular GHB esterification, and thus complies with pertinent requirements of law enforcement agencies.

The photometric determination of nitrate is limited by the fact that the respective methods (salicylic acid, brucine, 2,6-dimethyl phenol, Nesslers reagent after reduction of nitrate to ammonium) are subject to interferences. The direct potentiometric determination using an ion-selective nitrate electrode causes problems in the presence of fairly large amounts of chloride or organic compounds with carboxyl groups. The polarographic method, on the other hand, is not only more rapid, but also practically insensitive to chemical interference, thus ensuring more accurate results. The limit of quantification depends on the matrix of the sample and is approximately 1 mg/L.

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.

This Bulletin describes analysis methods for determining the following parameters: pH value, total titratable acid, ash alkalinity, formol number, total sulfurous acid, chloride, sulfate, calcium, and magnesium. These methods are suitable for the analysis of jams, fruit and vegetable juices, and their concentrates.

In addition to its natural occurrence in fruit and vegetables, ascorbic acid (Vitamin C) is used as an antioxidant in foods and drinks. Ascorbic acid is furthermore also to be found in numerous drugs.Ascorbic acid and its salts and esters can be determined with titration or by using polarography, for which ascorbic acid is oxidized to form dehydroascorbic acid.Bi-voltammetric or photometric equivalence point indication can be used for titrimetric determination. It must be taken into account here that only bi-voltammetric indication is independent of the inherent color of the sample. Polarography is the most selective of the methods described, as other reducing or oxidizing substances are not recorded.

Cadmium, lead, and copper can be determined simultaneously in oxalate buffer by anodic stripping voltammetry (ASV) after digestion with sulfuric acid and hydrogen peroxide. Tin present in the sample does not interfere with the determination of lead.For the voltammetric determination of tin please refer to Application Bulletin no. 176.

It has been known for years that consuming too much nitrates from foodstuffs can result in cyanosis, particularly for small children and susceptible adults. According to the WHO standard, the hazard level lies at a mass concentration c(NO3-) ≥ 50 mg/L. However, more recent studies have shown that when nitrate concentrations in the human body are too high, they can (via nitrite) result in the formation of carcinogenic and even more hazardous nitrosamines.Known photometric methods for the determination of the nitrate anion are time-consuming and prone to a wide range of interferences. With nitrate analysis continually increasing in importance, the demand for a selective, rapid, and relatively accurate method has also increased. Such a method is described in this Application Bulletin. The Appendix contains a cselection of application examples where nitrate concentrations have been determined in water samples, soil extracts, fertilizers, vegetables, and beverages.

This bulletin describes the determination of calcium, magnesium, and alkalinity in water by complexometric titration with EDTA as titrant. It is grouped into two parts, the potentiometric determination and the photometric determination.There are multiple definitions of the different types of water hardness. In this Application Bulletin, the following definitions are used: alkalinity, calcium hardness, magnesium hardness, total hardness, and permanent hardness. Explanations of these definitions and other expressions are provided in the Appendix.Determination of alkalinity during the photometric part is carried out in a separate acid-base titration before the complexometric titration of calcium and magnesium in water. Permanent hardness can be calculated from these values. The determination of calcium and magnesium in beverages (fruit and vegetable juices, wine) is also described.The photometric part includes the determinations of total and calcium hardness and thereby indirectly magnesium hardness using Eriochrome Black T and calconcarboxylic acid as indicators (in accordance with DIN 38406-3).

This Bulletin describes a simple polarographic method for the determination of quinine in drinks and tablets. Whereas in drinks quinine can be determined directly, in the case of tablets it must first be extracted. The limit of quantification is 0.2 mg/L or 4 μg/tablet.

Potassium is one of the most common elements and can be found in many different minerals and other potassium compounds. It is of importance for humans, animals and plants as it is an essential mineral nutrient and involved in many cellular functions like cell metabolism and cell growth. For these reasons, it is important to be able to declare the potassium content of food or soil to reduce problems that may arise by a potassium deficiency or extensive consumption.This bulletin describes an alternative to flame photometric method using an ion selective electrode and direct measurement or standard addition technique. Several potassium determinations in different matrices using the combined potassium ion-selective electrode (ISE) are presented here. Additionally, general hints, tips and tricks for best measurement practice are given.

The formol number represents a further parameter for the characterization of fruit and vegetable juices. As this is merely an index (the formalin number does not deal with the molecular size, nor with the quantity of amino acids), the conditions of the titration can be adapted to meet practical needs. This concerns mainly the pH value of the endpoint of the SET titration (pH = 8.5, pH = 9.0, pH = 9.2, etc.).

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 Bulletin describes two methods for the determination of iron at the Multi Mode Electrode.Method 1, the polarographic determination at the DME, is recommended for concentrations of β(Fe) > 200 μg/L. For this method the linear range is up to β(Fe) = 800 μg/L.For concentrations < 200 μg/LMethod 2, the voltammetric determination at the HMDE, is to be preferred. The detection limit for this method is β(Fe) = 2 μg/L, the limit of quantification is β(Fe) = 6 μg/L. The sensitivity of the method cannot be increased by deposition.Iron(II) and iron(III) have the same sensitivity for both methods.These methods have been elaborated for the determination of iron in water samples. For water samples with high calcium and magnesium concentrations such as, for example, seawater, a slightly modified electrolyte is used in order to prevent precipitation of the corresponding metal hydroxides. The methods can also be used for samples with organic loading (wastewater, beverages, biological fluids, pharmaceutical or crude oil products) after appropriate digestion.

Determination of sodium, ammonium, potassium, calcium, and magnesium in a grapefruit soft drink using cation chromatography with direct conductivity detection after advanced dialysis for inline sample preparation.

Determination of sodium, ammonium, potassium, calcium, and magnesium in a functional fruit juice using cation chromatography with direct conductivity detection after advanced dialysis for inline sample preparation.

Determination of sodium, potassium, magnesium, and calcium in orange juice using cation chromatography with direct conductivity detection applying automated dilution and subsequent Metrohm Inline Ultrafiltration.

This application focuses on the simultaneous analysis of cations and suppressed anions with a dual channel Metrohm IC operated by OpenLab CDS.

Nitrate is present in all common agricultural products and due to an extensive use of fertilizers, the nitrate content can be disconcertingly high in vegetables and their fabricated products, like juices. The nitrate content is regulated in many countries because it can form nitrosamines within the human body. Nitrosamines can potentially cause cancer and therefore, the World Health Organization (WHO) has defined an accepted daily intake (ADI) for nitrate of 3.7 mg/kg. To control the nitrate content e.g., in juices, a quick and inexpensive assessment of its concentration is performed via standard addition with a nitrate ion selective electrode . The method can be automated and is faster and less expensive compared to competing chromatographic or spectroscopic methods.

One of the major sources of fluoride intake for humans comes from foodstuff, such as tea. Tea actually has one of the highest potentials to increase the daily fluoride intake. Excessive fluoride intake may lead to dental or skeletal fluorosis. The World Health Organization does not recommend consuming water with a fluoride content higher than 1.5 mg/L. In the presented method according to DIN 10807, the fluoride content can be assessed quickly with an ion selective electrode.

Dissolved oxygen (DO), incorporated into juices during processing, affects quality parameters of the beverage during storage such as Vitamin C concentration, color, and aroma. Various oxygen removal methods are used during juice production, such as vacuum-deaeration or gas sparging to increase product quality and extend shelf life. However, these methods have the drawback that the aroma might be affected since the volatile compounds are also removed. By assessing the DO content in fruit juices, manufacturers can improve the overall product quality. This application note describes a fast and accurate determination of dissolved oxygen in juices by using an optical sensor.

Determination of chloride, nitrate, and sulphate in sugar-containing solutions without matrix elimination using anion chromatography with direct conductometric detection.

Near-infrared spectroscopy (NIRS) is a fast, chemical-free analytical method for the simultaneous analysis of density, water activity, and moisture of green coffee beans.

Near-infrared spectroscopy (NIRS) is a fast, chemical-free alternative analytical technology for caffeine and moisture analysis in roasted coffee beans and grounds.

NIRS enables rapid, chemical-free analysis of glucose, fructose, sucrose, and Brix in fruit juices without sample prep, offering a fast alternative to traditional methods.

Determination of citrate and acetate in isotonic solutions using ion-exclusion chromatography with direct conductivity detection.

Determination of acetic, propionic, isobutyric, butyric, isovaleric, valeric, and caproic acid in potato juice using ion-exclusion chromatography with suppressed conductivity detection.

Determination of sorbate and benzoate in a functional drink using ion-exclusion chromatography with suppressed conductivity detection.

Determination of carbonate in sparkling water using ion-exclusion chromatography with suppressed conductivity detection.

Determination of malate and ascorbate in orange juice using ion-exclusion chromatography with suppressed conductivity detection and inline dialysis for sample preparation.

Determination of citric, malic, quinic, succinic, lactic, formic, and acetic acid in roasted coffee using anion chromatography with conductivity detection after suppression.

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.

The separation of sugar and sugar alcohols in beverages is performed on a Metrosep Carb 2 - 150/4.0 type column using sensitive pulsed amperometric detection as the detection method. The method is explained exemplarily on an apple beverage.

Sucralose is an artificial, non-nutritive sweetener that is approximately 600 times sweeter than saccharose. Sucralose is used in low-calorie refreshments such as soft drinks. Sucralose lends itself readily to determination there using ion-exclusion chromatography. A post-column addition of NaOH is required prior to pulsed amperometric detection.Keywords: E 965

EU Regulation 1169/2011 defines rules for nutrition declaration on foodstuffs. The objective is to provide food information to the general public and to label food ingredients that are hazardous to health when consumed in larger quantities. This Application Note describes the determination of three sugars in apple juice with the aid of the Metrosep Carb 2 - 150/2.0 column.

Besides the typical sugar components, orange juice contains inositol. This sugar alcohol serves as an important signaling and messenger molecule. This Application Note shows the determination of inositol besides glucose, fructose, and sucrose in orange juice on a Metrosep Carb 2 - 150/4.0 column with pulsed amperometric detection (PAD).

The Metrohm IC Driver for OpenLab CDS opens ion chromatography to the world of HPLC, running under OpenLab CDS. In this application, a soft drink is analyzed for sugars and sugar alcohol content applying pulsed amperometric detection.

Application: Free and total carbohydrate determination in instant coffee with IC-PAD according to AOAC 996.04 and ISO 11292.

Precise online monitoring of peracetic acid (PPA) for beverage bottling requires a reliable stainless steel process analyzer.

Oxidation stability is an important parameter defining the quality of tea. It also provides information about the long-term stability of the naturally included antioxidants and thus the stability of the product. However, tea cannot be measured directly with the Rancimat method, as no evaluable induction time is obtained. The reason for this is that no measurable oxidation product is formed. However, using polyethylene glycol (PEG) as carrier material, many of these samples can be directly and reproducibly measured without any sample preparation. This is due to the antioxidants that are naturally present in the sample matrix, which stabilize the induction time of the PEG. The induction time can therefore be directly related to the oxidation stability of the sample.A reproducible and accurate determination of the oxidation stability is feasible using the 892 Professional Rancimat. In this Application Notes the oxidation stability of different teas is determined in this way. More information on the Rancimat method can be found on the Metrohm website.

The freshness as well as the smell and taste of coffee depend, among other things, on the content of antioxidants. The antioxidant content is critical to set a retail price and therefore it is of great interest for manufacturers and distributors to determine it. Classically, this parameter is determined via long-term storage tests. Oxidation stability offers a fast, alternative method, which can define the quality of coffee.Using the modified Rancimat method, the oxidation stability of coffee can be determined quickly and reliably. The sample is analyzed together with polyethylene glycol (PEG). The antioxidants present in the sample matrix stabilize the induction time of the PEG. The induction time can therefore be related directly to the oxidation stability and antioxidant content of the sample.This Application Note demonstrates the feasibility of the modified Rancimat method. Using the 892 Professional Rancimat, reproducible and accurate determination of the oxidation stability of different coffees is possible.

Some studies suggest that consumption of the artificial sweetener, aspartame, is correlated with increased risk for brain and hematopoietic cancers, however, others find it to be a safe food additive. Consequently, the US and EU approve aspartame as a multi-purpose sweetener with an acceptable daily intake of 40 mg/kg body weight/day. However, the clear health hazard to individuals suffering from phenlyketonuria and ongoing criticism by health food advocates continues to fuel the challenge against aspartame’s widespread use in the food industry.Using Misa (Metrohm Instant SERS Analyzer), beverage products are screened for aspartame levels with no sample preparation beyond simple dilution of a consumer product.

Paraquat is a highly effective, yet exceptionally toxic herbicide used to manage weeds in agricultural operations. In recognition of paraquat’s danger, the EU and several other countries have banned its use for any application, though the US EPA permits its limited use by licensed applicators. Despite tight regulation, paraquat continues to be produced and is liberally used as an herbicide in over 100 countries without regulatory oversight.Testing for paraquat typically requires involved sample processing and analysis by trained chemists using expensive laboratory instruments such as HPLC, CE, and LC/MS. Misa achieves trace level detection of paraquat residue in tea leaves in a fully integrated, portable, smart system for easy on-site testing by non-technicians.

Brilliant Blue (BB) FCF, more commonly known as FD&C Blue #1, is the most commonly used blue dye worldwide for food and beverages. It is generally accepted as safe and non-toxic. Aside from foods labelled as organic or as free from artificial dyes, there is little objection to the use of BB at levels at or exceeding 100 μg/g in foods.This application for Misa (Metrohm Instant SERS Analyzer) is unique. The benefit is twofold — successful detection of a fluorescent dye, and a unique sample cleanup technique that permits detection of a target that does not exhibit a strong SERS signal and is present in a complex matrix. While Misa successfully detects BB in direct sampling, this application describes a simple extraction method that improves detectability of BB with Misa.

Determination of citrate, malate, succinate, lactate, and acetate using ion-exclusion chromatography with conductivity detection after chemical suppression.

Determination of chloride, nitrate, phosphate, sulfate, and citrate in beverages using anion chromatography with a high-pressure gradient and conductivity detection after chemical suppression.

Determination of lactate, formate, chloride, phosphate, and sulfate in orange juice using anion chromatography with conductivity detection after chemical suppression and inline sample preparation by dialysis.

Determination of phosphoric acid in a soft drink using anion chromatography with conductivity detection after chemical suppression.

Determination of citrate and isocitrate in orange juice using anion chromatography with conductivity detection after chemical suppression and inline dialysis for sample preparation.

Determination of fluoride in green tea using anion chromatography with conductivity detection after chemical suppression.

Cola drinks (also known as soft drinks) contain a high amount of phosphoric acid. Quality control of these beverages includes determining the phosphate content. Phosphate analysis also indicates the dilution factor of the phosphate concentrate during cola processing. Achieving proper dilution of the concentrates is in the best interest of soft drink producers and bottling companies to ensure the highest quality beverages are made for consumers.

Strong citrate retention delays chromatographic anion determination in beverages containing citric acid. The use of a step gradient reduces the retention time of the citrate, thus considerably shortening the analysis period.

OpenLab CDS is the newest generation of chromatography data systems from Agilent, combining chromatography and mass spectrometry in a single software platform. The Metrohm IC Driver for OpenLab CDS integrates Metrohm IC instrumentation for full control and data acquisition. The present application describes the simultaneous analysis of anions and cations in a soft drink with a dual channel IC system. Eluent is prepared by applying Inline Eluent Production.

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.This Application Note describes the photometric determination of ascorbic acid according to the standard ISO 6557-2. To increase the objectivity on the determined equivalence point and the reproducibility of the results, an autotitrator equipped with a photometric sensor, the Optrode, is used. The titrant 2,6-Dichlorophenol-indophenol (DCIP or DPIP) simultaneously serves as titrant and indicator.

The present Application Note describes an automated system with which the acidity can be determined in a wide variety of juice samples. The high degree of automation (e.g., automated calibration and titer determination) reduces errors to a minimum and offers outstanding reproducibility.

This Application Note describes the iodometric, bivoltametric determination of ascorbic acid in orange juice using the Double Pt-sheet electrode.

This Application Note describes the bivoltametric titration of ascorbic acid in orange juice. 2,6-dichlorophenol indophenol (DPIP) is used as titrant; endpoint determination takes place using the Double Pt-sheet electrode.

Vitamin C is an important antioxidant and an important component of orange juice. A convenient and precise method for Vitamin C determination in fruit juices is titration, which is also described in numerous standards (ISO 6557/1, ISO 6557/2, AOAC 967.21).OMNIS enables quick and accurate determination of Vitamin C content in orange juice using potentiometric titration with iodine as titrant and a separate double Pt-sheet electrode.

Many of the key factors that influence coffee taste correlate with chemical properties that can be measured. These include pH, titratable acidity, refractive index, and caffeine. Historically, many of these analyses have included long, manual sample preparation processes using the time-consuming, liquid chromatography (LC) technique. This Application Note looks at a faster, simpler, alternative method for analysis of key quality parameters in coffee using a single titration platform: OMNIS.

Direct titration is a simple and precise way to accurately measure the caffeine content in different nonaqueous products. The OMNIS Titrator equipped with a dSolvotrode reliably determines caffeine through flexible analyses combined with high-end software.

The iodometric back titration is a precise method used to accurately measure the caffeine content in various aqueous samples. Reliable determinations are made easy using the OMNIS Titrator equipped with a dPt Titrode.

Determination of caffeine in a cola soft drink using RP chromatography with UV/VIS detection.

Determination of phenylalanine, aspartame, caffeine, and benzoate in a soft drink using RP chromatography with UV detection.

Ascorbic acid (vitamin C) can be determined in fruit and vegetable juices at the DME without sample preparation.

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

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