ABSTRACT
Objective To establish an HPLC method to determine the related substances of metolazone and valsartan in com?pound metolazone tablets. Methods An Agilent Eclipse SB-C18 column (4.6 mm × 250 mm,5 μm) was used with 0.01 mol/L KH2PO4 buffer(pH=3.5)-acetonitrile as the mobile phase with gradient elution at a flow rate of 1.0 ml/min. The column temperature was 30℃ and the detection wavelength was 237 nm. Injection volume was 20 μl. Results Metolazone,valsartan and related sub?stance B of valsartan were separated completely. The calibration curves were linear within the range of 3-30μg/ml for metolazone, 0.1-2.0μg/ml for valsartan and 0.08-2.0μg/ml for related substane B of valsartan. The average recoveries were 102.97%,100.81%and 100.44%,respectively. The repeatability and intermediate precision met with requirements. The test solution was stable within 24 h. Conclusion The method is specific,sensitive,accurate and reliable,thereby can be used for the determination of metolazone and valsartan related substances in compound metolazone tablets.
ABSTRACT
Objective To develop an LC-MS/MS method for simultaneous determination of metolazone and valsartan in beagle dog plasma.Methods The chromatographic separation was achieved on an Agilent Poroshell 120(2.1 mm ×30 mm × 2.7 μm)analytical column.The multiple reaction monitoring mode operating in positive ion was adopted in MS detection, and precursors to the product ion transitions of m/z 366.2/259, 436.2/291 and 423.4/207 were used to measure metola-zone, valsartan and internal standard ( losartan potassium) .Results The method was linear over the concentration range of 0.5 ng/ml-100 ng/ml for metolazone and 5-5000 ng/ml for valsartan, with the correlation coefficients ( r2 ) of 0.9937 and 0.9939, respectively.The average intra-day precision values ( RSD) were 2.09% -8.85% for metolazone and 2.36%-13.12%for valsartan.The matrix effect values were 87.73%-98.62%for metolazone and 99.03%-137.35%for valsartan.The average recovery was 75.74%-81.82%for metolazone and 83.89%-95.64%for valsartan.Conclu-sion This analytical method for metolazone and valsartan is simple, accurate and sensitive, so it can be used for pharma-cokinetic research of metolazone and valsartan immediate release tablets in beagle dogs.
ABSTRACT
Objective To develop an LC-MS/MS method for the determination of ropivacaine in rat plasma. Methods The chromatographic separation was achieved on an Agela MP C18(2.1 mm×50 mm,3μm)analytical column. The multiple reaction monitor?ing(MRM)mode of the positive ion was adopted in the MS detection,and the precursors to the product ion transitions of m/z 275.2/126.1 and 326.0/291 were used to measure ropivacaine and internal standard(midazolam). Results The method was linear over the ropiva?caine concentration range of 0.5-250 ng/ml with the correlation coefficients r of 0.9946. The average inter-day precision values(RSD) were 1.32%-6.74%,the matrix effect values were 95.5%-102.6% and the average recovery values were 89.8%-104.7%. Conclu?sion The analysis methods for ropivacaine are simple,accurate and sensitive,thus can be used for the pharmacokinetic research of ropivacaine incorporated cubic liquid crystal in rat.