The different quantities of A-type and B-type carbonated apatites determined by vibrational microspectroscopy in calcified deposits were well correlated with those of the four shapes of morphologic classification, with the three phases in the progressive calcification process and with the clinical symptoms of calcific tendonitis.

Acetaminophen is still worldwide used for analgesic and antipyretic therapy by millions of tablets and other dosage forms. Two polymorphs of acetaminophen have been published: form I is a monoclinic crystal and form II is an orthorhombic crystal. Form I (the usual form) is more stable at room temperature than form II.1-4) Form I has poor binding and densification properties, 5,6) and is not suitable for direct compression into tablet. The preparation for monoclinic acetaminophen tablets therefore needs a series of time-and material consuming processes and excipients, and the size of the tablets cannot but be enlarged. On the other hand, the orthorhombic acetaminophen not only has a sliding plane for good compression but also shows a faster dissolution rate than the monoclinic form. [6][7][8] Therefore, many studies have focused on how to prepare the orthorhombic form of acetaminophen. [8][9][10] An unstable third modification of acetaminophen (form III) has been found after different crystallization methods and the cooling rates, but the ambiguous explanations due to various differential scanning calorimetry (DSC) curves obtained have caused argument. [8][9][10][11] In the present study, a simple, quick and timesaving tool of Fourier transform infrared (FT-IR) microspectroscopy equipped with a micro hot stage (thermal FT-IR microscopic system) was used to readily and exactly explain the phase transition of metastable forms of acetaminophen by one-step process, as compared with different DSC thermograms of acetaminophen polymorphs prepared by different methods. ExperimentalMaterials Acetaminophen was of pharmaceutical grade, purchased from Seven Star Pharm. Co., Ltd. Taiwan, ROC. It was first recrystallized from aqueous solution, and then stored at 25°C, 75% relative humidity (RH) for further use. KBr crystal was of analytical IR grade, purchased from Jasco Co., Tokyo, Japan.Thermal FT-IR Microspectroscopic Study The acetaminophen powder was sandwiched between two KBr pieces by a hydraulic press to form a disc. This sample disc was directly put on a micro hot stage (DSC microscopy cell, FP 84, Mettler, Switzerland). The cell was then set on the stage of the microscope installed in the FT-IR microscopic spectrophotometer (Micro FTIR-200, Jasco, Tokyo, Japan) with an MCT detector. The system was operated in the transmission mode. The desired sample size for determination was selected and defined by means of an Aperture Through Optical System (ATOS) using microscope. The temperature of DSC microscopy cell was monitored with a central processor (FT80HT, Mettler, Switzerland). The heating rate of DSC assembly was controlled at 3°C/min in ambient conditions. The sample disc was previously equilibrated at the starting temperature (25°C) for about 3 min and then heated to 200°C. The thermal-responsive IR spectra were recorded with respect to the temperature. After the first heating process, the sample disc was cooled to 25°C and then re-heated from 25 to 200°C in the same conditions. Preparation and Determination of Diff...

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