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Selected papers from the latest issue:Enhancing sensitivity and precision on NIR reflectance determination of an API at low concentration: application to an hormonal preparation
29 October 2011, 20:44:55
Publication year: 2011
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 29 October 2011
J. Arruabarrena, J. Coello, S. Maspoch
The use of a mixed calibration sample set (intact production tablets and powdered doped samples used to enlarge calibration range) is a usual procedure for the NIR reflectance determination of the API content of a pharmaceutical solid preparation. However, the high difference in scattering properties and the intrinsic low sensitivity of NIR make difficult the achievement of a good precision when API is at a low mass proportion (≈1% w/w). The compression of the calibration powdered samples has been studied as a very simple procedure to enhance the sensitivity of NIR reflectance measurements and, consequently, to improve precision. Different pretreatments (SNV, 1D, 2D and their combinations) have been applied to reduce the spectral difference between powdered and compressed samples. Although none eliminates completely this difference, the combined pretreatment SNV + 2D has proved to be the one with a better performance. Results obtained by using both calibration sample sets (powdered and compacted) in the quantification of estradiol valerate (VE, 2 mg/tablet, ≈1.6% w/w) and medroxyprogesterone (MPA, 10 mg ≈ 8% w/w) in intact tablets of the hormonal preparation show that a slight but significant improvement in precision is obtained when using compacted samples for calibration. A HPLC procedure was developed to be used as reference method.
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 29 October 2011
J. Arruabarrena, J. Coello, S. Maspoch
The use of a mixed calibration sample set (intact production tablets and powdered doped samples used to enlarge calibration range) is a usual procedure for the NIR reflectance determination of the API content of a pharmaceutical solid preparation. However, the high difference in scattering properties and the intrinsic low sensitivity of NIR make difficult the achievement of a good precision when API is at a low mass proportion (≈1% w/w). The compression of the calibration powdered samples has been studied as a very simple procedure to enhance the sensitivity of NIR reflectance measurements and, consequently, to improve precision. Different pretreatments (SNV, 1D, 2D and their combinations) have been applied to reduce the spectral difference between powdered and compressed samples. Although none eliminates completely this difference, the combined pretreatment SNV + 2D has proved to be the one with a better performance. Results obtained by using both calibration sample sets (powdered and compacted) in the quantification of estradiol valerate (VE, 2 mg/tablet, ≈1.6% w/w) and medroxyprogesterone (MPA, 10 mg ≈ 8% w/w) in intact tablets of the hormonal preparation show that a slight but significant improvement in precision is obtained when using compacted samples for calibration. A HPLC procedure was developed to be used as reference method.
Highlights
► A NIR procedure for the determination of two APIs in an hormone preparation is reported ► A novel procedure to prepare the calibration samples is proposed ► compaction of powdered calibration samples reduce scattering effect ► Compression increases effective optical pathlength and improves precision.Comparisons of different regressions tools in measurement of antioxidant activity in green tea using near infrared spectroscopy
26 October 2011, 20:40:55
Publication year: 2011
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 25 October 2011
Quansheng Chen, Zhiming Guo, Jiewen Zhao, Qin Ouyang
To rapidly and efficiently measure antioxidant activity (AA) in green tea, near infrared (NIR) spectroscopy was employed with the help of a regression tool in this work. Three different linear and nonlinear regressions tools (i.e. partial least squares (PLS), back propagation artificial neural network (BP-ANN), and support vector machine regression (SVMR)), were systemically studied and compared in developing the model. The model was optimized by a leave-one-out cross-validation, and its performance was tested according to root mean square error of prediction (RMSEP) and correlation coefficient (Rp) in the prediction set. Experimental results showed that the performance of SVMR model was superior to the others, and the optimum results of the SVMR model were achieved as follow:RMSEP= 0.02161 andRp = 0.9691 in the prediction set. The overall results sufficiently demonstrate that the spectroscopy coupled with the SVMR regression tool has the potential to measure AA in green tea.
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 25 October 2011
Quansheng Chen, Zhiming Guo, Jiewen Zhao, Qin Ouyang
To rapidly and efficiently measure antioxidant activity (AA) in green tea, near infrared (NIR) spectroscopy was employed with the help of a regression tool in this work. Three different linear and nonlinear regressions tools (i.e. partial least squares (PLS), back propagation artificial neural network (BP-ANN), and support vector machine regression (SVMR)), were systemically studied and compared in developing the model. The model was optimized by a leave-one-out cross-validation, and its performance was tested according to root mean square error of prediction (RMSEP) and correlation coefficient (Rp) in the prediction set. Experimental results showed that the performance of SVMR model was superior to the others, and the optimum results of the SVMR model were achieved as follow:RMSEP= 0.02161 andRp = 0.9691 in the prediction set. The overall results sufficiently demonstrate that the spectroscopy coupled with the SVMR regression tool has the potential to measure AA in green tea.
Inaccurate data can not be used as standards in pharmaceutical and biomedical analysis
26 October 2011, 20:40:55
Publication year: 2011
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 25 October 2011
Tadeusz Aniszewski
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 25 October 2011
Tadeusz Aniszewski
Comprehensive investigation of the influence of acidic, basic, and organic mobile phase compositions on bioanalytical assay sensitivity in positive ESI mode LC/MS/MS
26 October 2011, 20:40:55
Publication year: 2011
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 25 October 2011
Paul D. Rainville, Norman W. Smith, David Cowan, Robert S. Plumb
The sensitivity and accuracy of a bioanalytical method is critical in defining the pharmacokinetic (PK) parameters of a potential new chemical entity (NCE). Inhaled therapeutics and low dose NCEs present one of the most significant analytical challenges to the bioanalyst, due to their low systemic concentration. The sensitivity of a bioanalytical LC/MS/MS based assay can be influenced by multiple parameters, including: mobile phase composition, extraction efficiency and chromatographic performance. In this work, we discuss the influence of acidic (pH 3), and basic (pH 10) aqueous mobile phases in conjunction with the two most common organic modifiers used in HPLC, acetonitrile and methanol, on the assay sensitivity of twenty-four probe pharmaceuticals in solvent and biological fluid extract. The study showed that when the test probe pharmaceuticals were analyzed with basic aqueous mobile phases compared to standard acidic conditions the following results were observed: increases in chromatographic peak area ranging from 1.2 to 9.6 fold for twenty-one of the test compounds as well as increased signal-to-noise for greater than seventy percent of the compounds. This observed increase in the MS response was not necessarily related to the later elution of the analyte in a higher organic composition under basic conditions. This was demonstrated as seven out of the twenty-four (approximately thirty percent) of the probe pharmaceuticals tested, eluted earlier, or with the same retention time, under basic conditions, and still produced a greater signal-to-noise when analyzed under these basic conditions. Also observed were decreases in chromatographic peak width, and increases in the retention time of very hydrophilic pharmaceutical compounds. The effect of the mobile phase combinations on the retention and MS response of the choline-containing phospholipids present in precipitated plasma was also investigated, as these analytes are a major source of interference when developing a bioanalytical assay.
Source: Journal of Pharmaceutical and Biomedical Analysis, Available online 25 October 2011
Paul D. Rainville, Norman W. Smith, David Cowan, Robert S. Plumb
The sensitivity and accuracy of a bioanalytical method is critical in defining the pharmacokinetic (PK) parameters of a potential new chemical entity (NCE). Inhaled therapeutics and low dose NCEs present one of the most significant analytical challenges to the bioanalyst, due to their low systemic concentration. The sensitivity of a bioanalytical LC/MS/MS based assay can be influenced by multiple parameters, including: mobile phase composition, extraction efficiency and chromatographic performance. In this work, we discuss the influence of acidic (pH 3), and basic (pH 10) aqueous mobile phases in conjunction with the two most common organic modifiers used in HPLC, acetonitrile and methanol, on the assay sensitivity of twenty-four probe pharmaceuticals in solvent and biological fluid extract. The study showed that when the test probe pharmaceuticals were analyzed with basic aqueous mobile phases compared to standard acidic conditions the following results were observed: increases in chromatographic peak area ranging from 1.2 to 9.6 fold for twenty-one of the test compounds as well as increased signal-to-noise for greater than seventy percent of the compounds. This observed increase in the MS response was not necessarily related to the later elution of the analyte in a higher organic composition under basic conditions. This was demonstrated as seven out of the twenty-four (approximately thirty percent) of the probe pharmaceuticals tested, eluted earlier, or with the same retention time, under basic conditions, and still produced a greater signal-to-noise when analyzed under these basic conditions. Also observed were decreases in chromatographic peak width, and increases in the retention time of very hydrophilic pharmaceutical compounds. The effect of the mobile phase combinations on the retention and MS response of the choline-containing phospholipids present in precipitated plasma was also investigated, as these analytes are a major source of interference when developing a bioanalytical assay.
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