Quantitation of meloxicam in the plasma of koalas (Phascolarctos cinereus) by improved high performance liquid chromatography

An improved method to determine meloxicam (MEL) concentrations in koala plasma using reversed phase high performance liquid chromatography equipped with a photo diode array detector was developed and validated. A plasma sample clean-up step was carried out with hydrophilic-lipophilic copolymer solid phase extraction cartridges. MEL was separated from an endogenous interference using an isocratic mobile phase [acetonitrile and 50 mM potassium phosphate buffer (pH 2.15), 45:55 (v:v)] on a Nova-Pak C18 4-microm (300 x 3.9 mm) column. Retention times for MEL and piroxicam were 8.03 and 5.56 min, respectively. Peak area ratios of MEL to the internal standard (IS) were used for regression analysis of the calibration curve, which was linear from 10 to 1,000 ng/mL (r2 > 0.9998). Average absolute recovery rates were 91% and 96% for MEL and the IS, respectively. This method had sufficient sensitivity (lower quantitation limit of 10 ng/mL), precision, accuracy, and selectivity for routine analysis of MEL in koala plasma using 250-microL sample volumes. Our technique clearly resolved the MEL peak from the complex koala plasma matrix and accurately measured MEL concentrations in small plasma volumes.

Quantitation of meloxicam in the plasma of koalas (Phascolarctos cinereus) by improved high performance liquid chromatography

An improved method to determine meloxicam (MEL) concentrations in koala plasma using reversed phase high performance liquid chromatography equipped with a photo diode array detector was developed and validated. A plasma sample clean-up step was carried out with hydrophilic-lipophilic copolymer solid phase extraction cartridges. MEL was separated from an endogenous interference using an isocratic mobile phase [acetonitrile and 50 mM potassium phosphate buffer (pH 2.15), 45:55 (v:v)] on a Nova-Pak C18 4-microm (300 x 3.9 mm) column. Retention times for MEL and piroxicam were 8.03 and 5.56 min, respectively. Peak area ratios of MEL to the internal standard (IS) were used for regression analysis of the calibration curve, which was linear from 10 to 1,000 ng/mL (r2 > 0.9998). Average absolute recovery rates were 91% and 96% for MEL and the IS, respectively. This method had sufficient sensitivity (lower quantitation limit of 10 ng/mL), precision, accuracy, and selectivity for routine analysis of MEL in koala plasma using 250-microL sample volumes. Our technique clearly resolved the MEL peak from the complex koala plasma matrix and accurately measured MEL concentrations in small plasma volumes.

Analysis of the erosive effects of children's beverages using a pH-cycling model / 대한구강보건학회지

OBJECTIVES: The aims of this in vitro study were (1) to assess the erosive potential of several children's beverages in comparison to cola and orange juice, by using an in vitro pH-cycling model, and (2) to investigate the factors related to dental erosion caused by the beverages. METHODS: Eight different children's beverages (Chorongi, Capri-sun, Grateful nature wisdom, I-kicker, Koal-koal koala, My friend pororo, Qoo, and Strong zzanggu), Cola, and an orange juice, which are available in the Korean market, were used. To characterize each test beverage, the pH, titratable acidity to pH 7.0, concentration of calcium and phosphorus, and degree of saturation with respect to hydroxyapatite (DS(HAP)) were analyzed. Erosive potential of the test beverages was assessed by the depth of enamel loss observed in specimens subjected to pH cycling for 8 days. This cycle consisted of exposure to each beverage for 20 min, thrice daily, and to a remineralizing solution every day. The correlation between the depth of the enamel loss and the chemical properties of the beverages was assessed by Spearman's rank correlation coefficients and multiple linear regression tests (P<0.05). RESULTS: The depth of enamel loss caused by the beverages was found to vary from 0.11 to 105.47 microm. Enamel loss with all the children's beverages tested was lesser compared to that with Cola (P<0.05) but was similar or greater than that with orange juice, except in one beverage. The pH, concentration of calcium, and DS(HAP) were significantly correlated with the depth of enamel loss (rho=-0.842, rho=-0.796, and rho=-0.867, respectively; P<0.01). Multiple regression analysis showed that pH and concentration of calcium were impact variables for the erosive potential of test beverages (P<0.05). CONCLUSIONS: The children's beverages tested had lower erosive potential than Coca Cola, but five (I-kiker, Grateful nature wisdom, Qoo, Capri-sun, and Chorongi) of them had higher erosive potential than orange juice. Moreover, among the chemical properties of beverages, significant factors affecting enamel loss were pH value and concentration of calcium.