Polyhydroxyalkanoates (PHA) are polyesters of various hydroxyalkanoates accumulated in numerous bacteria. All of the monomeric units of PHA are enantiomerically pure and in R-configuration. R-Hydroxyalkanoic acids can be widely used as chiral starting materials in fine chemical, pharmaceutical and medical industries. In this study, we established an efficient method for the production of chiral hydroxyalkanoic acid monomers from PHA. Pseudomonas putida cells containing PHA were resuspended in phosphate buffer at different pH. We observed that the optimal initial pH for intracellular PHA degradation and monomer release was at pH 8-11 with pH 11 as the best. At initial pH 11, PHA containing 3-hydroxyoctanoic acid and 3-hydroxyhexanoic acid was degraded with an efficiency of over 90% (w/w) in 9 h, and the yield of the corresponding monomers was also over 90%. Under the same conditions, unsaturated monomers were also effectively produced from PHA containing 3-hydroxy-6-heptenoic acid, 3-hydroxy-8-nonenoic acid, and 3-hydroxy-10-undecenoic acid. The monomers (e.g., 3-hydroxyoctanoic acid) were further isolated using solid phase extraction and purified on reversed phase semipreparative liquid chromatography. We confirmed that the purified 3-hydroxyoctanoic acid monomer has exclusively the R-configuration.

Triglycerides, together with nine synthetic phenolic antioxidants most commonly used to prevent oxidation of edible oils and fats, as well as the natural antioxidants tocopherols and a-tocopherol acetate, were separated by high performance liquid chromatography by means of a reversed phase Cls-column and gradient elution with water/acetonitrile/methanol/isopropanol. Besides dilution of the oil with isopropanol/hexane, no further example preparation was required. UV detection was applied. The synthetic antioxidants propyldodecylgallate, octyldodecylgallate, dodecylgallate, 3-tert-butyl-4-hydroxyanisol, tert-butylhydroquinone, 3,5-di.tert.butyl-4-hydroxytoluene, 2,6.di-tert-butyl-4.hydroxymethylphenol, 2,4,5-trihydroxybutyrophenone and nordihydroquaiaretic acid, as well as a-and 6-tocopherol and atocopherol acetate were base-line separated; f~ and ytocopherol, however, eluted together. The triglycerides, detected at ~ --215 nm, were separated according to their partition number. The absorption at ~ --215 nm revealed saturated and unsaturated triglycerides. The absorption at ~ --280 nm indicated triglycerides with conjugated unsaturation, relating information about refining and heat treatment of the oil. Oxidized unsaturated triglycerides showed absorption at k = 230 nm. Triglycerides of ricinoleic acid, a hydroxymonounsaturated acid, gave identical UV spectra. The simultaneous detection of antioxidants and triglycerides may be used to study inhibition effects by antioxidants in oils.

In the 1990s the CCQM (Comité consultatif pour la quantité de la matière) defined the term 'primary method'. It also identified some methods that are considered to be primary. One of these methods is titrimetry. In this paper, the principle of titrimetry and two practical examples performed at the highest metrological level in the frame of key comparison CCQM-K8 are discussed. It is evident that titrimetry is a very powerful method leading to highly accurate results when performed correctly, and does not depend on whether the classical metrological approach or a new experimental design using modern laboratory technology is applied.

This report describes a key comparison of monoelemental calibration solutions, organized under the auspices of the Consultative Committee for Amount of Substance (CCQM) in 1999-2000 and piloted by the Federal Laboratories for Materials Testing and Research (EMPA, Switzerland) and the Laboratoire National d'Essais (BNM-LNE, France). Solutions of aluminium, copper, magnesium and iron were measured. Although different methods of measurement were applied, most of the thirteen participating national metrology institutes achieved results within the required target range for a combined standard uncertainty of 0.5 % relative for each element. The methods used were titrimetry, coulometry, gravimetry, isotope dilution mass spectrometry and inductive coupled plasma/emission spectrometry.