Combination of Standard Addition and Isotope Dilution Mass Spectrometry for the Accurate Determination of Melamine and Cyanuric Acid in Infant Formula.

In the melamine scandals of the early 2000s, different companies of the dairy industry cheated their products by applying chemical substances to feign a higher content of nitrogen. However, this had a severe toxic impact on the kidney health of consumers. As a result, tremendous effort was put into the prevention of further harm to the public.

Direct extraction with acetonitrile of hemp seed oil for the analysis of pesticides by using comprehensive two-dimensional gas chromatography-triple quadrupole mass spectrometry.

The method herein described involves a rapid and limited-volume (0.5 mL of acetonitrile) solvent-extraction sample preparation process, for pesticide determination in hemp seed oil. The extraction method was characterized by the absence of both clean-up or pre-concentration steps.

Development of a novel certified reference material for the determination of polycyclic aromatic hydrocarbons (PAHs) in whey protein powder.

Matrix-based certified reference materials (CRMs) play a central role in the analysis of food contaminants for ensuring measurement accuracy and comparability, as they exhibit the same matrix effects during sample preparation and measurement as the food sample under investigation. However, the availability of such CRMs is still limited. This is also true for matrix CRMs containing polycyclic aromatic hydrocarbons (PAHs), for which maximum levels in food are set in the EU by the Commission Regulation (EU) 2023/915 and in Switzerland by the regulation SR 817.

The qNMR Summit 5.0: Proceedings and Status of qNMR Technology.

The goal of the qNMR Summit is to take stock of the status quo and the recent developments in qNMR research and applications in a timely and accurate manner. It provides a platform for both advanced and novice qNMR practitioners to receive a well-rounded update and discuss potential qNMR-related applications and collaborations. For over a decade, scientists from academia, industry, nonprofit institutions, and governmental bodies have focused on the standardization of qNMR methodology, as well as its metrological and pharmacopeial utility.

Development of the first universal mixture for use in system suitability tests for High-Performance Thin Layer Chromatography.

The use of chromatographic methods in routine analysis includes System Suitability Tests (SST). This paper presents a novel approach to SST in HPTLC, which allows qualification of the entire R range of an HPTLC plate independently of the samples. It is based on the Universal HPTLC mix (UHM), a pre-defined mixture of eight reference substances: guanosine, sulisobenzone, thymidine, paracetamol, phthalimide, 9-hydroxyfluorene, thioxanthen-9-one, and 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl)phenol, selected to cover a broad range of polarities and functional groups.

Corrigendum: Enzymatic Synthesis of 2-Keto-3-Deoxy-6-Phosphogluconate by the 6-Phosphogluconate-Dehydratase From .

[This corrects the article DOI: 10.3389/fbioe.2020.

Enzymatic Synthesis of 2-Keto-3-Deoxy-6-Phosphogluconate by the 6-Phosphogluconate-Dehydratase From .

The availability of metabolic intermediates is a prerequisite in many fields ranging from basic research, to biotechnological and biomedical applications as well as diagnostics. 2-keto-3-deoxy-6-phosphogluconate (KDPG) is the key intermediate of the Entner-Doudoroff (ED) pathway for sugar degradation and of sugar acid and sugar polymer breakdown in many organisms including human and plant pathogens. However, so far KDPG is hardly available due to missing efficient synthesis routes.

Recombinant AroL-Catalyzed Phosphorylation for the Efficient Synthesis of Shikimic Acid 3-Phosphate.

Shikimic acid 3-phosphate, as a central metabolite of the shikimate pathway, is of high interest as enzyme substrate for 5-enolpyruvoyl-shikimate 3-phosphate synthase, a drug target in infectious diseases and a prime enzyme target for the herbicide glyphosate. As the important substrate shikimic acid 3-phosphate is only accessible via a chemical multi-step route, a new straightforward preparative one-step enzymatic phosphorylation of shikimate using a stable recombinant shikimate kinase has been developed for the selective phosphorylation of shikimate in the 3-position. Highly active shikimate kinase is produced by straightforward expression of a synthetic aroL gene in Escherichia coli.

Certified Reference Material for Use in H, P, and F Quantitative NMR, Ensuring Traceability to the International System of Units.

In recent years, quantitative NMR (qNMR) spectroscopy has become one of the most important tools for content determination of organic substances and quantitative evaluation of impurities. Using Certified Reference Materials (CRMs) as internal or external standards, the extensively used qNMR method can be applied for purity determination, including unbroken traceability to the International System of Units (SI). The implementation of qNMR toward new application fields, e.

Biocatalytic Asymmetric Phosphorylation Catalyzed by Recombinant Glycerate-2-Kinase.

The efficient synthesis of pure d-glycerate-2-phosphate is of great interest due to its importance as an enzyme substrate and metabolite. Therefore, we investigated a straightforward one-step biocatalytic phosphorylation of glyceric acid. Glycerate-2-kinase from Thermotoga maritima was expressed in Escherichia coli, allowing easy purification.

Method development in quantitative NMR towards metrologically traceable organic certified reference materials used as (31)P qNMR standards.

Quantitative nuclear magnetic resonance (qNMR) spectroscopy is employed by an increasing number of analytical and industrial laboratories for the assignment of content and quantitative determination of impurities. Within the last few years, it was demonstrated that (1)H qNMR can be performed with high accuracy leading to measurement uncertainties below 1 % relative. It was even demonstrated that the combination of (1)H qNMR with metrological weighing can lead to measurement uncertainties below 0.

Quantitative assessment of preloaded 4-alkoxybenzyl alcohol resins for solid-phase peptide syntheses by 1D and 2D HR-MAS NMR.

The quality of preloaded Wang resins is very important for the success of solid-phase peptide syntheses (SPPS). A critical factor is the capping of remaining hydroxyl groups after loading with the first amino acid, since these free alcohols lead to truncated sequences during the following SPPS steps. Because the detection of hydroxyl groups by color tests is difficult and unreliable, the capping efficiency is often controlled by time-consuming peptide test syntheses.

Formation of Fmoc-beta-alanine during Fmoc-protections with Fmoc-OSu.

During the Fmoc-protection of H-alpha-Me-Val-OH, an unknown side product was found and isolated. The characterization using various analytical methods led unambiguously to the result that Fmoc-beta-Ala-OH was formed during the reaction. The reagent Fmoc-OSu was proven to be the source of Fmoc-beta-Ala-OH, following a mechanism that involved many deprotonation and elimination steps and a Lossen-type rearrangement as key sequence.