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Surface Enhanced Raman Scattering or SERS is an anomalous enhancement of Raman scattering when molecules are adsorbed to gold or silver nanoparticles – this enhancement can be as large as 107. The advantage of SERS for the analytical chemist lies in its ability to detect analyte concentrations of parts per million and even parts per billion levels, while classical Raman is limited to parts per thousand. Metrohm Raman produces P-SERS assays in the form of nanoparticles printed onto substrates using inkjet technology. This method produces inexpensive test strips that exhibit exceptional stability and sensitivity. There are two markets that can be easily addressed with P-SERS: forensic analysisand food safety. This white paper explains the mechanism of SERS and how it can be applied to handheld Raman analysis with Metrohm Raman Mira systems.

OMNIS Client/Server boosts business performance with scalable server management, cutting costs by reducing hardware, energy use, and maintenance across locations.

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.

Conventional Raman typically has a very small sampling area with a high power density (PD) at the laser focal point on the sample, which means that only a limited portion of a sample is measured, and the result tends to be irreproducible for heterogeneous sample. The high power density may also cause samples to heat up or burn. The large spot adaptor (LSA) for B&W Tek’s handheld Raman products, featuring a much larger sampling area of 4.5 mm in diameter, is designed to overcome these issues.

Patented STRaman technology is a new Raman technique that can identify chemical species nondestructively beneath diffusely scattering packaging material such as plastics or tablet coatings.

B&W Tek’s TacticID®-1064 is a field-ready handheld Raman system utilizing 1064-nm wavelength laser excitation. Designed for forensic analysis by safety personnel, first responders, and law enforcement personnel, the TacticID-1064 significantly reduces fluorescence, allowing users to identify tough street samples such as ecstasy tablets in a variety of colors and mixture forms.

As much as the many types of cement may differ from one another, the characteristic that all of them have in common is the presence of the elements calcium, magnesium, iron, aluminum and silicon.Calcium, magnesium, iron and aluminum can be determined using various indicators following digestion of the cement sample using photometric titration with the Optrode at 610 nm. The determination of silicon, on the other hand, is gravimetric.

This Bulletin, using practical examples, indicates how the user can achieve optimum pH measurements. As this Bulletin is intended for actual practice, the fundamentals - which can be found in numerous books and publications - are treated only briefly.

This Bulletin describes the fully automated determination of uranium according to the method of Davies and Gray: Uranium(VI) is reduced in concentrated phosphoric acid solution with iron(II) to form Uranium(IV). With molybdenum as a catalyst, the excess iron(II) is oxidized with nitric acid. The nitrous acid that is formed is destroyed with sulfamic acid before uranium(IV) is titrated with a potassium dichromate solution in the presence of a vanadium catalyst.

Determination of chlorine in household bleaches.

Dissolution of oil in toluene, and titration with standard 0.1 mol/L trifluoromethanesulfonic acid in acetic acid using isobutyl vinyl ether as a thermometric endpoint indicator.

With MISA and MIRA, easy-to-use test kits and flexible sampling allow rapid and accurate interrogation of suspect materials with minimal time, training, and expense.

The water content of explosive pellets is determined according to Karl Fischer after extraction with methanol.

Moisture in petroleum products causes several issues: corrosion and wear in pipelines and storage tanks, an increase in debris load resulting in diminished lubrication, blocked filters, or even harmful bacterial growth. As a result, increased water content can lead to infrastructure damage, higher maintenance costs, or even unwanted downtimes.Coulometric Karl Fischer titration is the method of choice for low water content in petroleum products. Using a Karl Fischer oven to vaporize the water present in the sample prior to titration not only greatly reduces matrix interferences, it can also be fully automated. This allows a reliable and cost-efficient analysis of the water content according to ASTM D6304 (Procedure B) in products such as diesel, hydraulic oil, lubricant, additive, turbine oil, and base oil.

Sustainable biodiesel can be blended with petroleum diesel. The 893 Professional Biodiesel Rancimat measures the oxidation stability of biodiesel and its blends.

Chrome plating is an important electroplating technique that covers metal or plastic surfaces with a thin layer of chromium for both protection and decoration purposes. The sulfate and sulfuric acid concentrations in the baths are important parameters in the coating process and require continuous monitoring. The anions in the chrome baths are separated on the Metrosep A Supp 5 - 250/4.0 column and are determined using conductivity detection in accordance with sequential suppression.

Determination of trace levels of chloride, nitrate, phosphate, and sulfate in a boiler feed water using anion chromatography with conductivity detection after chemical suppression.

Determination of hypophosphite, phosphite, and phosphate in a nickel bath using anion chromatography with conductivity detection after chemical suppression and inline cation exchange.

Perchlorate in water is mainly due to anthropogenic sources such as fertilizers, fireworks, rocket fuel, etc. Trace analysis of perchlorate in water samples is a critical task. The high content of standard anions leads to large peaks that interfere with the very small perchlorate peak. In the heart-cut technique, the perchlorate fraction – widely freed of interfering anions – is re-injected onto the column thus providing a sharp peak.

Forensic institutes examine terrorist attacks and warfare agents via trace detection analysis of the used explosives and their residuals. Of particular importance is the acquisition of «chemical fingerprints» for criminal investigation departments and governmental security agencies. Institutes for public health and environmental protection analyze such compounds that can contaminate the underlying soil and infiltrate ground water.Forensic investigation with ion chromatography (IC) using suppressed conductivity detection allows a sensitive and robust determination of anionic contaminants such as chlorate, thiosulfate, thiocyanate, and perchlorate next to the common inorganic anions over a broad concentration range.

The guideline value for chromium in the World Health Organization’s (WHO) «Guidelines for Drinking-water Quality» is 50 µg/L. It should be noted here that chromium concentrations are often expressed as total chromium and not as chromium(III) or (VI). Chromium(VI) is responsible for changes in genetic material, and is found in significantly lower concentrations than Cr(III). Therefore an extremely sensitive method is required to monitor Cr(VI) in drinking water.The powerful adsorptive stripping voltammetry (AdSV) technique on the ex-situ mercury film modified glassy carbon electrode using DTPA as complexing agent can be used to determine such low concentrations.

The guideline value for total chromium in the World Health Organization’s (WHO) «Guidelines for Drinking-water Quality» is 50 µg/L. Chromium(VI) is more toxic than its trivalent form (Cr(III)) and is also less abundant. Therefore a robust and sensitive method is required to monitor its concentration in drinking water. The mercury film modified scTRACE Gold can be used to monitor chromium(VI), offering easy handling and a high grade of stability.

The concentration of Sb(III) and Sb(total) in an electroless nickel bath is determined by anodic stripping voltammetry (ASV). In c(HCl) = 0.6 mol/L only Sb(III) shows a signal. In w(HCl) = 10% the Sb(total) content is determined.

Rapid inline monitoring of the major SC1/SC2 bath constituents is possible with reagent-free near-infrared spectroscopy, e.g., the 2060 The NIR-R Analyzer.

The ASTM B825 is used to determine the corrosion and tarnish film on metal surfaces. This is achieved by using the so-called cathodic reduction method. With the help of a Metrohm Autolab PGSTAT302N and a Metrohm Autolab 1 L corrosion cell, a procedure to replicate the ASTM B825 is shown.

A corrosion inhibitor is a substance that reduces the corrosion rate of a metal. A corrosion inhibitor is usually added in a small concentration to the corrosive environment. This application note shows how Metrohm Autolab instruments can be used to check the quality of inhibitors.

The International Standard ISO 17463 describes the determination of the anticorrosive properties of high impedance organic protective coatings on metals. This technique uses cycles composed of electrochemical impedance spectroscopy (EIS) measurements, cathodic polarizations and potential relaxation. This application note shows the compliance of the Metrohm Autolab PGSTAT M204 and flat cell with the standard ISO 17463.

A reference electrode has a stable and well-defined electrochemical potential (at constant temperature), against which the applied or measured potentials in an electrochemical cell are referred. A good reference electrode is therefore stable and non-polarizable. In other words, the potential of such an electrode will remain stable in the used environment and also upon the passage of a small current. This application note lists the most used reference electrodes, together with their range of use.

Determination of trace chloride in cement and clinker by potentiometric titration with silver nitrate using the Ag-Titrode.

This Application Note covers the photometric determination of calcium in cement using the Optrode (610 nm). After digestion of the cement sample, calcium is titrated with EDTA to the murexide endpoint.

Basic additives are added to petroleum products to inhibit corrosion as they have a neutralizing effect on acidic compounds, which are formed as a result of degradation processes. Total base number (TBN) indicates the amount of basic additives present and thus can be used as a measure for the degradation of the petroleum product.Using an automated titration system with a photometric sensor to detect the end point ensures that the titrations are always carried out under the same conditions. This improves the precision and reliability of the results.This Application Notes describes the fully automated photometric determination of TBN in used engine oil using the Metrohm Optrode for the indication of the methyl orange endpoint (at 520 nm).

The pHe value is an indicator for the acid strength and shows the presence of strong acids or bases in ethanol. In Europe, ethanol is used as a blending component in gasoline and needs to have a pHe value between 6.5 and 9.0.This Application Note describes a fast and accurate determination of the pHe value using the EtOH-Trode.

Denatured fuel ethanol may contain additives such as corrosion inhibitors and detergents as well as contaminants from manufacturing that can affect the acidity of produced ethanol fuel. An increased acid content in solvents could lead to a variety of problems like a shorter storage stability or chemical corrosion. Using the Optrode with phenolphthalein as indicator, the acidity is determined as acetic acid by titration with sodium hydroxide as titrant.

The determination of the physical and chemical parameters as electrical conductivity, pH value, alkalinity, the calcium and magnesium hardness as well as the total hardness are necessary for evaluating the water quality. A fast and accurate determination in tap water is realized using an automated OMNIS System working in parallel on different workstations. An 856 Conductivity Module with Dosinos extends the system.

Ethanol, bio-ethanol and biofuel (E85) are increasingly used as substitutes for petroleum-based fuels. During storage, they often come into contact with metallic substrates or surfaces, e.g., in barrels, tanks, or other containers. Excessive concentrations of ions in the stored fuel promotes corrosion. Monitoring the total concentration of the ions present in the fuel matrix should be the first step of an effective anti-corrosion strategy.An easy, fast, and cost-effective method to determine the total amount of ions is by measuring the electrical conductivity according to DIN 15938.

Determination of Cr(VI) and Cr(III) in chromium baths by iodometric potentiometric titration with thiosulfate using the combined Pt electrode.

Printable Surface Enhanced Raman Scattering (P-SERS) silver substrates were used with Metrohm Raman’s Mira DS handheld Raman analyzer to successfully detect heroin in 18 crude street heroin samples. Detection of heroin with P-SERS was accomplished easily and very quickly, with minimal sample clean-up. Solvent studies were also implemented to determine the optimal solvent for crude sample extraction, with results included here.

Many refiners look at discounted opportunity crudes as a means to improve their margin spread. The varieties of these cheap crude oils on the market are growing in number, but they have hidden risks for the purchaser caused by factors such as high naphthenic acid and sulfur content. Sulfur compounds and naphthenic acids are among the substances that contribute to the corrosive nature of crude oils and petroleum products. This is why the risk of corrosion is increased when processing crude oils with high naphthenic acid and sulfur content. The refiner must balance the cost benefit versus the risk and the cost of corrosion control when processing these crudes. A reliable acid number determination is a crucial part of corrosion control. Guest authors Bert Thakkar, Bryce McGarvey, and Colette McGarvey of Imperial Oil and Larry Tucker and Lori Carey of Metrohm USA were involved in the development of the new ASTM Method D8045 for acid number determination. Here, they report on the method and how it came to be.

A person suspected of possessing a narcotic can be charged with a crime only after the identity of the illicit substanceis confirmed. This confirmation is typically provided by analytical chemists in forensic laboratories and requires highly technical separation and detection methods. Unfortunately, such labs often have deep caseloads that lead to delays in testing. Handheld Raman analyzers bring the reliability and accuracy of lab analysis to first responders in the field, allowing for rapid and accurate identification of street drugs with a white powder appearance. With such tools, demand for forensic analysis can be reduced and enforcement agencies can enforce drug policies with greater safety, speed, and precision.

Like any defense and security professional, border agents must quickly and accurately identify suspicious substances at the point of contact. When that substance is fentanyl, which is deadly in microdoses, the stakes are even higher. The Mira DS handheld Raman system from Metrohm Raman offers safe, no-contact identification of over 200 fentanyl analogues. Mira DS protects border agents, while they protect citizens from deadly narcotics, drug smugglers, and illegal entry of goods.

It is widely accepted that prolonged exposure to hexavalent chromium compounds can have dire health effects. This has led to increased regulation of chromium-containing products and greater demand for technologies that can positively identify hexavalent chromium in potential matrices. These include paints, dyes, and primers, which can pose a problem for interrogation with Raman, as strongly colored materials often exhibit fluorescence when stimulated at 785 nm. Fluorescence can obscure the Raman signal and prevent positive identification. MIRA XTR DS provides all the functionality of handheld material ID with a new capability that selectively eXTRacts the Raman signal from fluorescent materials. Fluorescence rejection at 785 nm provides higher sensitivity and resolution than 1064 nm systems, as well as a much wider scope of applications amenable to Raman spectroscopy. MIRA XTR DS offers a comprehensive and versatile material ID test solution for field operations.

This Bulletin describes titrimetric methods for the determination of cadmium, free sodium hydroxide, sodium carbonate, and total cyanide. The free cyanide can be calculated from the total cyanide and the Cd content.

The determination of the acid number plays a significant role in the analysis of petroleum products. This is manifested in the numerous standard procedures in use over the world (internal specifications of multinational companies, national and international specifications of ASTM, DIN, IP, ISO, etc.). These procedures differ mainly in the composition of the used solvents and titrants.This bulletin describes the determination of the acid number in petroleum products by applying different types of titration.The potentiometric determination is described according to ASTM D664, the photometric according to ASTM D974 and the thermometric titration according to ASTM D8045.

This Application Bulletin describes the determination of the total acid number in various oil samples by catalytic thermometric titration as per ASTM D8045.

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 Application Bulletin describes a polarographic method for the determination of cyanide that allows to determine free cyanide fast and accurately. The determination also succeeds in solutions containing sulfides, where other methods fail. Cyanide concentrations in the range b(CN–) = 0.01...10 mg/L cause no problems. Interference caused by anions and complexed cyanides has been investigated.

The determination of the physical and chemical parameters as electrical conductivity, pH value, p and m value (alkalinity), chloride content, the calcium and magnesium hardness, the total hardness, as well as fluoride content are necessary for evaluating the water quality. This bulletin describes how to determine the above mentioned parameters in a single analytical run.Further important parameters in water analysis are the permanganate index (PMI) and the chemical oxygen deman (COD). Therefore, this Bulletin additionally describes the fully automated determination of the PMI according to EN ISO 8467 as well as the determination of the COD according to DIN 38409-44.

The determination of cyanide is very important not only in electroplating baths and when decontaminating wastewater but, due to its high toxicity, also in water samples in general. Concentrations of 0.05 mg/L CN- can already be lethal for fish.This Bulletin describes the determination of cyanide in samples of different concentrations by potentiometric titration.Chemical reactions:2 CN- + Ag+ → [Ag(CN)2]-[Ag(CN)2]- + Ag+ → 2 AgCN

Yaba, produced in Southeast Asia, is a popular drug of abuse and is actively targeted by police squads. Two strong and highly addictive stimulants make up Yaba: caffeine, which comprises up to 60% of each tablet, and methamphetamine at approximately 20%. Identifying these two active ingredients in different proportions in a colorful tablet with other excipients could be an analytical nightmare. With handheld Raman, bulk material identification is achieved in seconds onsite with simple point-and-shoot analysis. SERS (surface-enhanced Raman spectroscopy) analysis is used to detect the minor component in mixtures without interference from fillers, dyes, and coatings. MIRA DS is uniquely capable of both analyses—Raman testing positively identifies caffeine in Yaba, while methamphetamine can be detected with SERS sampling. This application describes quick, dual analysis of Yaba tablets with MIRA DS.

Signal-to-noise ratio, spectrograph design, resolution of MIRA handheld Raman analyzers.