TP-Technical Posters

Available sample size, mass sensitivity, efficiency and the detector type are important criteria in the selection of separation column dimensions. Compared to conventional 4 mm i.d. columns, microbore columns excel, above all, by their low eluent consumption. Once an eluent is prepared, it can be used for a long time. Additionally, the lower flow rates of microbore columns facilitate the hyphenation to mass spectrometers due to the improved ionization efficiency in the ion source.

With the same injected sample amount, a halved column diameter involves a lower eluent flow and results in an approximate four-fold sensitivity increase. In a converse conclusion, this means that with less sample amount, microbore columns achieve the same chromatographic sensitivity and resolution than normal bore columns. This makes them ideally suited for samples of limited availability.

Modern laboratories involved in routine process and quality control of fats and oils demand high analytical productivity with minimum operator involvement. Automated thermometric titrimetry is well suited to the task. No electrical contact with titrating solutions is required, so samples can be titrated in a totally nonaqueous environment. The endpoint is determined automatically, not prone to operator bias and can be detected in highly colored or turbid solutions, or even in media containing suspended solids. The thermometric sensing probe requires no maintenance, special preparation, regeneration or calibration and can be stored dry between titrations.

Two determinations common in the analysis of fats and oils illustrate the versatility of the technique, namely the free fatty acid (FFA) content and the iodine value (IV). In both analyses, excellent agreement has been demonstrated with results obtained by official methods of analysis. The titrations are very fast, typically less than a minute in duration, and can be conducted using an automatic sample changer.

In this study, we developed a straightforward and sensitive method for the trace determination of iodide in brine used for chlor-alkali electrolysis. The method involves the oxidation of iodide to iodate and the subsequent determination of the iodate by differential pulse voltammetry. The quantitative iodide conversion to iodate is achieved by treatment with sodium hypochlorite. After 20 minutes reaction time, excess hypochlorite is removed by adding sodium sulfite. Interfering metal traces are complexed by EDTA addition.

The described differential pulse voltammetric method for the determination of iodide in brine has significant advantages over other commonly employed methods. Besides the excellent price-performance ratio, the voltammetric iodide determination excels by its sensitivity, selectivity and high degree of matrix independence.

The Restriction of Hazardous Substances (RoHS) Directive 2002/95/EC stipulates maximum limits for the hazardous metals cadmium, lead and mercury as well as the hexavalent chromium and the brominated flame retardants in electrical and electronic products. To ensure compliance, reliable analysis methods are required.

This poster deals with the wet-chemical determination of trace concentrations of the six RoHS-restricted substances in a wide variety of materials including metals, electrotechnical components, plastics and wires. After sample preparation according to IEC 62321, the metals lead, cadmium and mercury are best determined by anodic stripping voltammetry (ASV) and the flame retardants PBB and PBDE are quantified by direct-injection ion chromatography (IC) using spectrophotometric detection. Chromium(VI) can be determined either by adsorptive stripping voltammetry (AdSV) or IC. Both methods are very sensitive and meet prescribed RoHS limits.

This study compares air sampling data obtained by a filter-based method including off-line manual filter extraction followed by ion chromatographic analysis with those gained by an automated Particle-Into-Liquid-Sampler coupled to an ion chromatograph (PILS-IC).

PILS-IC is a straightforward instrument for aerosol sampling that provides near real-time measurements for long-term unattended operation and is thus an indispensable tool to monitor rapid changes in aerosol particle ionic composition.

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.

Levoglucosan is a combustion product of cellulose and hemicellulose and, as such, widely used as a tracer for biomass burning sources in atmospheric aerosols. Glass fiber filters containing winter and summer aerosol fractions were extracted with water and analyzed for levoglucosan, mannosan, galactosan and sugar alcohols. The analytical method couples ion chromatography (IC) with a highly sensitive pulsed amperometric detector (IC-PAD) providing a simple alternative to GC/MS, which requires intensive and expensive sample extraction as well as derivatization.

A Metrosep A Supp 15 – 150 was coupled to a Metrosep Carb 1 – 150. The calibration for the anhydrosugars and sugar alcohols is linear over a wide concentration range. Less than 17 minutes were needed to achieve separation with a limit of detection for levoglucosan of approximately 5 ng/m³.

Aerosol concentrations of the isomeric anhydrosugars made up the largest fraction of identified carbohydrates in both winter and summer. Owing to elevated wood burning during the winter season, concentrations of the anhydrosugars were clearly higher in winter, while sugar alcohol and glucose contributions were more prevalent during the summer season. Separation between the levoglucosan and mannosan peaks can be further increased by using a Metrosep Carb 1 – 250.

The presented methodology allows the sensitive and robust determination of routine smoke marker determinations for a deeper understanding of biomass burning aerosols.

In routine chemical analysis, the predominant challenge involves a higher sample throughput, improved reproducibility, liquid handling flexibility and reduced personnel costs. In response to these requirements, the 872 Extension Module Liquid Handling in combination with the MagIC Net™ software and the well-proven Dosino technology expands the possibilities of inline sample preparation and opens up new fields of application. Among others, the module can be used, together with an optional mixing vessel, for pH adjustments, pre-column derivatizations, or the mixing of solutions.

As a representative of an inline sample preparation technique, this poster describes the performance of precise dilutions. By using only one single stable standard solution, multi-point calibration curves can be automatically recorded by diluting a concentrated standard in an external vessel.

The ProcessLab atline analysis system presented here permits the direct determination of the nickel sulfate and hypophosphite concentrations as well as the alkalinity in electroless nickel plating baths. All relevant process parameters are available immediately after sampling and allow an exact replenishment of consumed bath components.

By the use of ProcessLab, electroless nickel plating baths can be operated more economically and ecologically while at the same time operating and disposal costs are considerably reduced. This also makes a positive contribution to husbanding resources and environmental protection.

This poster describes a simple and sensitive method for the determination of perfluorooctanoate (PFOA) and perfluorooctane sulfonate (PFOS) in water samples by suppressed conductivity detection. Separation was achieved by isocratic elution on a reversed-phase column thermostated at 35 °C using an aqueous mobile phase containing boric acid and acetonitrile. The PFOA and PFOS content in the water matrix was quantified by direct injection applying a 1000 μL loop. For the concentration range of 2 to 50 μg/mL and 10 to 250 μg/mL, the linear calibration curve for PFOA and PFOS yielded correlation coefficients (R) of 0.99990 and 0.9991, respectively. The relative standard deviations were smaller than 5.8%.

The presence of high concentrations of mono and divalent anions such as chloride and sulfate has no significant influence on the determination of the perfluorinated alkyl substances (PFAS). In contrast, the presence of divalent cations, such as calcium and magnesium, which are normally present in water matrices, impairs PFOS recovery. This drawback was overcome by applying Metrohm`s Inline Cation Removal. While the interfering divalent cations are exchanged for non-interfering sodium cations, PFOA and PFOS are directly transferred to the sample loop. After inline cation removal, PFAS recovery in water samples containing 350 mg/mL of Ca²⁺ and Mg²⁺ improved from 90…115% to 93…107%.

While PFAS determination of low salt-containing water samples is best performed by straightforward direct-injection IC, water rich in alkaline-earth metals are best analyzed using Metrohm`s Inline Cation Removal.

Hydroxyl is an important functional group and knowledge of its content is required in many intermediate and end-use products such as polyols, resins, lacquer raw materials and fats (petroleum industry). The test method to be described determines primary and secondary hydroxyl groups. The hydroxyl number is defined as the mg of KOH equivalent to the hydroxyl content of 1 g of sample.
The most frequently described method for determining the hydroxyl number is the conversion with acetic anhydride in pyridine with subsequent titration of the acetic acid released:
H₃C-CO-O-CO-CH₃ + R-OH -> R-O-CO-CH₃ + CH₃COOH
However, this method suffers from the following drawbacks:
   - The sample must be boiled under reflux for 1 h (long reaction time and  laborious, expensive sample handling)
   - The method cannot be automated
   - Small hydroxyl numbers cannot be determined exactly
   - Pyridine has to be used, which is both toxic and foul-smelling
Both standards, ASTM E 1899-08 and DIN 53240-2, offer alternative methods that do not require manual sample preparation and therefore can be fully automated:

The method suggested in ASTM E 1899-08 is based on the reaction of the  hydroxyl groups attached to primary and secondary carbon atoms with excess toluene-4-sulfonyl-isocyanate (TSI) to form an acidic carbamate. The latter can  then be titrated in a non-aqueous medium with the strong base tetrabutyl- ammonium hydroxide (TBAOH).
 

The method suggested in DIN 53240-2 is based on the catalyzed acetylation  of  the hydroxyl group. After hydrolysis of the intermediate, the remaining  acetic acid is titrated in a non-aqueous medium with alcoholic KOH solution.

The present work demonstrates and discusses an easy way to determine the hydroxyl number according to ASTM E 1899-08 or DIN 53240-2 with a fully automated titrimetric system for a great variety of industrial oil samples.

Comparative measurements show that the new Metrosep C 4 cation column has even better separation characteristics than the previous Metrosep C 2 and Metrosep Cation 1-2 column types.

The Metrosep C 4 column has a clearly improved peak shape which leads to a better separation of the individual peaks. Using Metrosep C 4 the number of theoretical plates per meter was noticeably higher than that obtained on the Metrosep C 2 or C 1-2 column. Additionally for standard cations transition metals and amines, the Metrosep C 4 column shows better results with respect to peak shape, peak height, resolution and asymmetry factor. The clearly improved resolution of the C 4 column with its narrow and high peaks achieves baseline separation for six standard and six transition metal cations. Analysis times and peak areas obtained with the C 4 column are in the same range as those obtained with its predecessors.

As a result of the latest production methods and materials, the promising Metrosep C 4 column excels by an outstanding separation performance for complex mixtures comprising standard cations, transition metal cations and amines.

Metrohm has combined the best aspects of laboratory and online systems to create the 875 ProcessLab – a fully customized, automated atline system for process monitoring. While process-integrated online systems are used for high analysis frequencies, atline analysis systems are applied to long analysis cycles or wherever various parameters are to be measured at different measuring points.
ProcessLab has a compact design that allows for close positioning to the actual process and thus yields faster and more reproducible results. The modular design of ProcessLab gives complete flexibility allowing the configuration of application-specific systems. This flexibility also makes it possible to extend or reconfigure a system in view of future analytical testing needs.
With its ability to be configured for a wide scope of applications in various industries, ProcessLab is a perfect system for the production floor, laboratory or anywhere in between. The electronic components are hermetically separated from the wet-part modules and protected against dust and splashing liquids in harsh plant environments. The reliable industrial PC and PLC-driven I/O Controller make for extensive control and communication possibilities using standard communication protocols. Result outputs can be provided as a direct link to the process control center via analog/digital signals or can be delivered via local network to a plant engineer or laboratory manager. Effective monitoring of real-time results can help tighten specifications, detect problems early and avoid wasting money on out-of-spec products.
ProcessLab is easy to use, robust and provides fast, reliable results for safe process control.

For a variety of reasons, the water content of chocolate is of crucial importance and has to be accurately determined. This poster compares an automated version of the Karl Fischer titration (KFT) using the sequential addition of various solvents with the widespread manual titration at elevated temperatures using a chloroform/methanol mixture. The water contents determined by the two procedures show excellent agreement. However, manual titration requires laborintensive sample preparation, the side reactions are difficult to quantify and hazardous halogenated solvents have to be used. In contrast, automated KFT is straightforward, uses non-hazardous solvents, allows to quantify the side reactions and is easily applicable to water determinations in sugar- and fat-containing matrices.

The combination of 850 Professional IC, 858 Professional Sample Processor, Dosino and MagIC Net™ software offers a variety of sophisticated ion chromatographic sample preparation techniques. One of these is the automated inline dilution of samples.
After the first sample injection, MagIC Net™ verifies if the area of the sample peak lies within the calibration range. If the measured peak area is outside these limits, the software calculates the appropriate dilution factor, dilutes and automatically re-injects the sample.
For all investigated ions (Li⁺, Na⁺, K⁺, Ca²⁺, Mg²⁺, F^–, Cl^– , NO₂^–, Br^–, NO₃^–, SO₄^2– ), automated logical dilution yielded coefficients of determination (R²) better than 0.9999. Direct-injection recoveries for cations and anions were within 98.6…99.5% and 93.4…100.4% respectively. In contrast, after logical dilution, recoveries for cations and anions were within 100.1…102.9% and 98.2…102.6% respectively. The relative standard deviations for all determinations involving diluted sample solutions were smaller than 0.91%.