Applications

Botanicals are derived from plant materials and used for their medicinal and therapeutic properties in the nutraceuticals market. They are not as heavily regulated by the U.S. Food and Drug Administration (FDA) like the pharmaceuticals drug market, but they are required to follow Good Manufacturing Practice (GMP Requirements).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 botanicals that would normally fluoresce with a 785 nm laser.

Compared to the classical Epton titration, potentiometrically indicated two-phase titrations using organic-solvent-resistant Surfactrodes can be easily automated and require no toxic and environmentally hazardous chloroform. Even challenging matrices such as fats and oils in bath oils and hair conditioners or strong oxidizing agents in washing powder and industrial cleaners do not interfere with the titration of the ionic surfactants. Results obtained show excellent agreement to those of the Epton titration. Irrespective of the matrix, relative standard deviations of threefold determinations are all below 2.1%. While the Surfactrode Resistant is mainly used for oil-containing formulations, the Surfactrode Refill is ideal for washing powders and soaps. Both electrodes excel by their ruggedness and allow the rapid and precise determination of anionic and cationic surfactants.

Fluoride is commonly used in dental products to help prevent tooth decay. When fluoride is present in high concentrations, these products are regulated by 21 CFR 355. Three fluoride compounds used in over the counter (OTC) anti‐cavity dental products are sodium fluoride, stannous fluoride and sodium monofluorophosphate (MFP). The assay of fluoride in these active ingredients and finished formulations are determined by manual titration, or by ion‐selective electrodes. As a part of USP’s global monograph modernization initiative, an alternative selective and sensitive method has been developed and validated – ion chromatography (IC). The proposed IC method can also be used for the identification test as an alternative to the wet chemistry method.

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.

Anionic surfactants can be titrated with cationic surfactants and vice-versa. The Bulletin describes a multitude of substances that can be determined in this fashion and specifies the respective working conditions and parameters. In contrast to the classic two-phase titration in accordance with Epton, the titration with the anionic and cationic surfactants electrodes can be performed without chloroform. Furthermore, the equivalence point of the titration is difficult to determine in some cases with the Epton method and the titration cannot be automated.In many cases, a surfactant ISE is a remedy that is both environmentally friendly and suitable here. It was developed specially for application with potentiometrically indicated surfactant determinations.

The present Bulletin offers an overview of the multitude of surfactants and pharmaceuticals that can be determined with potentiometric titration. Metrohm provides five different surfactant electrodes for indicating the titration endpoint: the Ionic Surfactant, the High Sense, the Surfactrode Resistant, the Surfactrode Refill and the NIO Surfactant electrode. The manufacture of the respective titrants and their titer determination are described in detail. In addition to this, the Bulletin contains a tabular overview of more than 170 proven applications from the area of surfactant and pharmaceutical analysis. This guideline leads you reliably to your destination: At a glance you can see from the table which surfactant electrode and which titrant are optimally suitable for your product.

On the basis of a multitude of practical examples, this Bulletin describes the potentiometric two-phase titration of ionic surfactants in raw materials and many other formulations.Two surfactant electrodes – the Surfactrode Resistant and the Surfactrode Refill – make it possible to perform this type of surfactant titration, analogous to the classic "Epton titration", with a high degree of automation. The achieved results correlate very well with those of Epton titration. The toxic, carcinogenic and environmentally hazardous chloroform can be replaced by other solvents such as methyl iosbutyl ketone or n-hexane.

This Application Bulletin describes the determination of Sn(II) in presence of Sn(IV) by anodic stripping voltammetry (ASV). Using an electrolyte containing fluoride, Sn(IV) gives no signal, so that a speciation is possible. The limit of detection is 2.5 µg/L.

Pyrithione complexes, such as zinc pyrithione (ZnPT), copper pyrithione (CuPT), and sodium pyrithione (NaPT), are used as fungicides and bactericides. ZnPT is used in the treatment of skin conditions such as seborrheic dermatitis or dandruff. Furthermore, ZnPT is sometimes used as an antibacterial agent in paints to prevent algae and mildew growth. CuPT is primarily in use as a biocide to prevent biofouling of surfaces submerged in water. Meanwhile, NaPT is used as antifungal agent for treatment of mycosis, such as athlete’s foot. The different pyrithione complexes are determined by iodometric titration using a maintenance-free Pt Titrode for the indication.

Determination of 3-dimethylamino-1-propylamine in cocoamidopropyl betaine using cation chromatography with direct conductometric detection.

Determination of sodium and potassium in toothpaste using cation chromatography with direct conductivity detection.

Determination of sodium lauryl ether sulfate surfactants.

Fluoride protects dental enamel and is an important trace element in toothpaste. A rapid and precise determination is made via standard addition with the help of an ion-selective fluoride electrode (F-ISE).

This Application Note describes the automated determination of the water content in toothpaste using volumetric Karl Fischer titration (MATi 10).

Near-infrared spectroscopy (NIRS) was used in a preliminary study as a fast and accurate method for the quantification of different preservatives and active ingredients in liquid shampoo. This Application Note shows how this analytical method allows the simultaneous determination of several constituents in shampoo in a single measurement.

Near-infrared spectroscopy (NIRS) was used as an analysis method for quality control of aqueous xanthan gum solutions. Quantitative models for the determination of optical density, glucose, and xanthan gum were developed, enabling fast and reliable quality control.

Determination of sodium laureth sulfate (SLES), cocamidopropyl betaine (CABP), cocamidopropylamine oxide (CAW), cocamide diethanolamine (DEA), and carbopol in shampoo is a cost- and time-intensive process due to the use of large volumes of chemicals per analysis. This application note demonstrates that the DS2500 Solid Analyzer operating in the visible and near-infrared spectral region (Vis-NIR) provides a cost-efficient and fast solution for a simultaneous determination these parameters in shampoo. With no sample preparation or chemicals needed, Vis-NIR spectroscopy allows for the complete analysis in less than a minute.

This Application Note shows that visible near-infrared spectroscopy (Vis-NIRS) can determine the sun protection factor (SPF) of sunscreen products. Thanks to measurement durations of less than 30 seconds, NIR spectroscopy is ideally suited for rapid and reliable quality control.

Rapid quality control for toothpaste is achieved by Metrohm`s Vis-NIR analyzers. Vis-NIR technology offers significant advantages compared to standard reference analysis. It is a cost effective and safe method because no hazardous chemicals are used.

This Application Note shows how NIRS is used for the multiparameter analysis of dry matter, pH value, viscosity, and surfactant content in liquid laundry detergent.

Safe and fast ethanol determination in hand sanitizers is possible with reagent-free near-infrared spectroscopy (NIRS). NIRS provides reliable results in a few seconds, quickly indicating when adjustments in formulation are necessary.

This application note presents near-infrared spectroscopy (NIRS) for the rapid and reliable simultaneous quantification of ethanol, glycerol, hydrogen peroxide, and water content in hand sanitizer formulations.

This Application Note shows how near-infrared spectroscopy is used for fast, chemical-free multiparameter quality control of fabric softeners and laundry perfumes.

Near-infrared spectroscopy (NIRS) can simultaneously determine different quality parameters in deodorants like viscosity, pH, density, and aluminum content.

Using the Rancimat method, the oxidation stability of suntan oil can be determined reproducibly and reliably.

This Application Note shows the rapid, non-destructive identification of isopropyl alcohol from two manufacturers using Raman spectroscopy following the creation of a suitable library. The measurements with the hand-held Raman spectrometer Mira M-1 require no sample preparation and provide immediate results that identify the samples unambiguously.

Determination of fluoride, chloride, phosphate, monofluorophosphate, and sulfate in toothpaste using anion chromatography with conductivity detection after chemical suppression.

Whitening toothpaste often contains polyphosphates to remove stains. The analysis of these polyphosphates requires a high-pH hydroxide eluent. The high eluent concentration is suppressed by the high-capacity suppressor MSM-HC.

Monofluorophosphate is used in toothpaste to prevent dental caries. USFDA allows up to 1.5 g/kg fluoride corresponding to 11.5 g/kg sodium monofluorophosphate on over the counter (OTC) dentifices for adults and children above 6 years. Here, a toothpaste is analyzed for monofluorophosphate by ion chromatography applying conductivity detection after chemical suppression.

Dental care products often contain sodium fluoride as an active ingredient. Manufacturers use the United States Pharmacopeia and National Formulary (USP-NF) Monograph «Sodium Fluoride» to quantify sodium fluoride and its anionic contaminants chloride and acetate in these products. The validated USP method proposes ion chromatography (IC) with suppressed conductivity detection to carry out the fluoride assay as well as the impurity determination in a single chromatogram.

Sodium fluoride gel for pharmaceutical use needs to comply with USP requirements. The actual monograph (USP 42) uses two different methods for the identification and the assay. Ion chromatography allows the analysis of these two parameters in one single determination. In the course of the USP monograph modernization, this ion chromatographic approach makes this type of analysis even easier.

Anticavity pharmaceuticals like sodium fluoride and acidulated phosphate topical solution products require strict quality control. This Application Note outlines the fluoride IC assay as described in the USP Monograph Sodium Fluoride and Acidulated Phosphate Topical Solution.

Determination of anionic surfactants in shower lotions and shampoos by potentiometric titration with TEGO®trant A100 using the «Ionic Surfactant» electrode.

Determination of cationic surfactants in hair conditioner by potentiometric titration with dioctyl sodium sulfosuccinate using the «Ionic Surfactant electrode.

Determination of chlorhexidine in wash lotion by potentiometric titration with sodium tetraphenylborate using the NIO surfactant electrode.

Determination of anionic surfactants in shower oil by potentiometric two-phase titration with TEGO®trant A100 using the «Surfactrode Resistant» electrode.

Due to its price and wide availability, the anionic surfactant sodium lauryl sulfate (SLS; SDS) can be found in many detergents as an emulsifier or as a fat solvent e.g., in cleaning or cosmetic products. To avoid causing severe dry skin and hair, and thus skin irritation, regulations in many countries have restricted the sodium lauryl sulfate concentration in ready-to-use products to a range between 0.05–2.5% SLS. To control the concentration of SLS in different products, a titration is carried out with TEGO® trant A100 and the Optrode. The evaluation is done automatically by means of a software, leading to reliable and reproducible results.

Inorganic sulfate is determined in secondary alklysulfonate (raw material) in accordance with DIN EN 14880 with the use of the Pb ISE.

Alkyl glycosides, alkyl maltosides and compounds with polyoxyethylene groups (POE) are numbered among the nonionic surfactants. These surfactants can be analyzed by standard titration with TEGO®trant following derivatization – in this case following sulfonation.

Complexing agents such as EDTA are used in soaps and other detergents in order to remove unwanted metal ions and to lower water hardness. The EDTA content in soaps and detergents can be determined using potentiometric titration with copper sulfate as titrant and the Cu-ISE as electrode.

Anionic surfactants represent, by volume, the most important group of surfactants used in cleaning products. The potentiometric two-phase titration is a universal method for the accurate and fast determination of them. Using the Surfactrode Refill, the anionic surfactants are determined by potentiometric titration with hyamine as titrant.

This Application Note presents a complementary method that allows a consecutive determination after the sample preparation (digestion) of both metal ions in one beaker with an optical sensor and xylenol orange as an indicator.

Accurate, reliable determination of ionic surfactants with the Epton two-phase titration method can be achieved using an OMNIS system as shown in this study.

Manufacturers and laboratories must use validated methods to determine the zinc content in skin care products and pharmaceutical supplements to meet strict quality standards set by the United States Pharmacopeia and National Formulary (USP-NF). USP-NF has updated the zinc monograph (General Chapter <591>, Zinc Determination) and replaced the existing identification procedure of titration with ion chromatography (IC). The analysis involves separating Zn using a Metrosep A Supp 10 column followed by post-column reaction using 4-(2-pyridylazo)resorcinol and detection at 530 nm.

Thiomersal (also called thimerosal) is a mercury containing organic molecule that has been widely used as preservative for vaccines and eye drops. It is very effective, even in very low concentrations, against a wide range of microorganisms and viruses. To reduce the risk for consumers the maximum concentration of mercury in the products is limited by the authorities. Polarography or voltammetry can be used to accurately determine the concentration of thiomersal in vaccines or other cosmetic and pharmaceutical solutions (such as eye drops). The method is simple to perform, specific, and free of interferences.

Underestimation of quality control (QC) processes is one of the major factors leading to internal and external product failure, which have been reported to cause a loss of turnover between 10–30%. As a result, many different norms are put in place to support manufacturers with their QC process. However, time to result and the associated costs for chemicals can be quite excessive, leading many companies to implement near-infrared spectroscopy (NIRS) in their QC process. This paper illustrates the potential of NIRS and displays cost saving potentials up to 90%.