Defining a metrologically traceable and sustainable calibration hierarchy of international normalized ratio for monitoring of vitamin K antagonist treatment in accordance with International Organization for Standardization (ISO) 17511:2020 standard: communication from the International Federation of Clinical Chemistry and Laboratory Medicine-SSC/ISTH working group on prothrombin time/international normalized ratio standardization.

Calibration of prothrombin time (PT) in terms of international normalized ratio (INR) has been outlined in "Guidelines for thromboplastins and plasmas used to control oral anticoagulant therapy" (World Health Organization, 2013). The international standard ISO 17511:2020 presents requirements for manufacturers of in vitro diagnostic (IVD) medical devices (MDs) for documenting the calibration hierarchy for a measured quantity in human samples using a specified IVD MD. The objective of this article is to define an unequivocal, metrologically traceable calibration hierarchy for the INR measured in plasma as well as in whole blood samples. Calibration of PT and INR for IVD MDs according to World Health Organization guidelines is similar to that in cases where there is a reference measurement procedure that defines the measurand for value assignment as described in ISO 17511:2020. We conclude that, for PT/INR standardization, the optimal calibration hierarchy includes a primary process to prepare an international reference reagent and measurement procedure that defines the measurand by a value assignment protocol conforming to clause 5.3 of ISO 17511:2020. A panel of freshly prepared human plasma samples from healthy adult individuals and patients on vitamin K antagonists is used as a commutable secondary calibrator as described in ISO 17511:2020. A sustainable metrologically traceable calibration hierarchy for INR should be based on an international protocol for value assignment with a single primary reference thromboplastin and the harmonized manual tilt tube technique for clotting time determination. The primary international reference thromboplastin reagent should be used only for calibration of successive batches of the secondary reference thromboplastin reagent.

New planar substrates for the in situ synthesis of peptide arrays.

The performance of new cellulose membranes, aminofunctionalized via a PEG spacer, as a solid support in the synthesis of peptide arrays is described. The new membranes are stable to trifluoroacetic acid (TFA) and strong aqueous base for days. These properties extend the scope of synthesis considerably, e.g., more efficient side chain cleavage protocols can be applied which yielded peptides of improved purity. For the first time, cellulose membranes with a loading as high as 5 micromol/cm2 were accessible. Additionally, newly developed polypropylene membranes with hydroxy- or amino functionalities were successfully employed for the SPOT synthesis of peptides and phosphopeptides. The membranes are compatible with antibody binding as well as enzymatic phosphorylation assays.

A new compact disc format of high density array synthesis applied to peptide nucleic acids and in situ MALDI analysis.

A fully automated synthesizer was constructed and designed to perform high speed miniaturized syntheses of compound libraries using the SPOT technique. Utilizing magnetically controlled drop-on-demand ink jet nozzles, an r/phi array format of 2500 spots can be simultaneously dispensed from up to 24 separate reagent valves onto a rotating disc as the solid phase in less than three minutes. In addition, a complete wash station is on board allowing for fully programmable combinatorial syntheses without manual attention. A new carbon black/polypropylene composite solid phase disc was developed and tested for its functionalisation/loading, spot detection, durability and MALDI-TOF target capabilities. The carbon black/polypropylene composite was then successfully employed jointly as the solid phase in the syntheses of short peptide and PNA oligomers and as the target probe holder for MALDI-TOF measurement without transfer of the material. Several protocols for PNA syntheses were also investigated and an optimised PNA methodology for the carbon black/polypropylene composite is reported.