Powder X-ray diffraction can differentiate between enantiomeric variants of calcium lactate pentahydrate crystal in cheese.

Powder X-ray diffraction has been used for decades to identify crystals of calcium lactate pentahydrate in Cheddar cheese. According to this method, diffraction patterns are generated from a powdered sample of the crystals and compared with reference cards within a database that contains the diffraction patterns of known crystals. During a preliminary study of crystals harvested from various Cheddar cheese samples, we observed 2 slightly different but distinct diffraction patterns that suggested that calcium lactate pentahydrate may be present in 2 different crystalline forms. We hypothesized that the 2 diffraction patterns corresponded to 2 enantiomeric forms of calcium lactate pentahydrate (L- and DL-) that are believed to occur in Cheddar cheese, based on previous studies involving enzymatic analyses of the lactate enantiomers in crystals obtained from Cheddar cheeses. However, the powder X-ray diffraction database currently contains only one reference diffraction card under the title "calcium lactate pentahydrate." To resolve this apparent gap in the powder X-ray diffraction database, we generated diffraction patterns from reagent-grade calcium l-lactate pentahydrate and laboratory-synthesized calcium dl-lactate pentahydrate. From the resulting diffraction patterns we determined that the existing reference diffraction card corresponds to calcium dl-lactate pentahydrate and that the other form of calcium lactate pentahydrate observed in cheese crystals corresponds to calcium l-lactate pentahydrate. Therefore, this report presents detailed data from the 2 diffraction patterns, which may be used to prepare 2 reference diffraction cards that differentiate calcium l-lactate pentahydrate from calcium dl-lactate pentahydrate. Furthermore, we collected crystals from the exteriors and interiors of Cheddar cheeses to demonstrate the ability of powder X-ray diffraction to differentiate between the 2 forms of calcium lactate pentahydrate crystals in Cheddar cheeses. Powder X-ray diffraction results were validated using enzymatic assays for lactate enantiomers. These results demonstrated that powder X-ray diffraction can be used as a diagnostic tool to quickly identify different forms of calcium lactate pentahydrate that may occur in Cheddar cheese.

Orthopedic devices; classification for the resorbable calcium salt bone void filler device. Final rule.

The Food and Drug Administration (FDA) is classifying the resorbable calcium salt bone void filler device intended to fill bony voids or gaps of the extremities, spine, and pelvis that are caused by trauma or surgery and are not intrinsic to the stability of the bony structure into class II (special controls). Elsewhere in this issue of the Federal Register, FDA is announcing the availability of a class II special controls guidance entitled "Class II Special Controls Guidance Document: Resorbable Calcium Salt Bone Void Filler Device; Guidance for Industry and FDA." This action is being undertaken based on new information submitted in a classification proposal from Wright Medical Technology under the Federal Food, Drug, and Cosmetic Act as amended by the Medical Device Amendments of 1976, the Safe Medical Devices Act of 1990, and the Food and Drug Administration Modernization Act of 1997.

Calcium chloride and calcium bromide aqueous solutions of technical and analytical grade in Lemna bioassay.

Saturated water solutions of calcium chloride, calcium bromide and their 1:1 mixture are commonly used as "high density brines" for pressure control in oil wells. To compare the effect of these chemicals of technical grade with the effect of the chemicals of analytical grade the Lemna test was used. The multiplication rate, fresh weight, dry to fresh weight ratio, area covered by plants and chlorophyll content were measured as toxicity parameters. The concentrations of tested chemicals were 0.025, 0.05. 0.075 and 0.1 mol dm(-3). Generally, the chemicals of both technical and analytical grade in concentrations of 0.025 mol dm(-3) stimulated the Lemna minor growth, while tested chemicals in concentrations of 0.05 mol dm(-3) did not affect the growth significantly. The exceptions were results obtained by measuring fresh weight. Most of tested chemicals in concentrations of 0.075 mol dm(-3) and all chemicals in concentrations of 0.1 mol dm(-3) reduced the growth. No major differences between effects of tested chemicals of technical and analytical grade on plant growth were observed, except that tested chemicals of analytical grade in concentrations of 0.1 mol dm(-3) increased dry to fresh weight ratio much stronger than chemicals of technical grade. All tested chemicals in all concentrations increased chlorophyll content. After treatment with chemicals of analytical grade much higher increase of chlorophyll a concentration in comparison to increase of chlorophyll b was noticed, while chemicals of technical grade caused more prominent increase of chlorophyll b.