A near-infrared spectroscopy method to determine aminoglycosides in pharmaceutical formulations

The analytical determination of aminoglycosides in pharmaceutical formulations is very difficult due to the lack of chromophores or fluorophores. Several analytical methods have been developed along the years mainly based on derivatization reactions. The European Pharmacopeia (EP) and the United States Pharmacopeia (USP) describe a microbiological assay to the quantification of aminoglycosides. Near infrared spectroscopy (NIRS) can be used alternatively to analyse aminoglycosides without the need of derivatization reactions or other type of sample processing. A new NIRS based method was developed for the analysis of the aminoglycoside antibiotic neomycin. The method was developed with samples based on a commercial formulation containing neomycin sulphate and three excipients: lactose, talc and magnesium stearate. Synthetic and doped samples were manufactured for this purpose. Three lots of a commercial solid formulation were also used to assess the validity of the method to quantify neomycin sulphate in the industrial pharmaceutical product. The method proposes measurements in reflectance mode using a Fourier-transform near infrared (FT-NIR) spectrometer. Partial least squares regression was the multivariate method adopted to calibrate the NIR spectra with the neomycin sulphate mass fraction. The concentration of neomycin sulphate present in the commercial samples was confirmed by HPLC with pre-column derivatization with phenylisocyanate. Results show that neomycin sulphate was determined successfully in the commercial samples using the method calibrated with the doped samples (mass fraction error of 6.6%). Moreover, the synthetic samples were found to be unqualified to develop the method, producing a biased calibration.     

Determination of ascorbic acid in pharmaceutical preparations by near infrared reflectance spectroscopy

We developed a method for determination of ascorbic acid in pharmaceutical preparations containing various excipients by using near infrared diffuse reflectance spectroscopy and two different calibration methods, viz. stepwise multiple linear regression (SMLR) and partial least-squares (PLS) regression, which provided comparable results and resulted in prediction errors of 1-2%. However, the PLS method provided somewhat better results with the more complex samples.     

Qualitative Discrimination Between Paracetamol Tablets Made by Near Infrared Spectroscopy and Chemometrics With Regard to Polymorphism

Polymorphism is an important characteristic of pharmaceutical products because different polymorphs exhibit different physicochemical stabilities, dissolution rates, etc., which makes them different in therapeutic efficiency. Thus, it is important to control the polymorphic structure of pharmaceutical products. A spectroscopy method based on Fourier transform near infrared (FT-NIR) spectroscopy and chemometric techniques is introduced to classify paracetamol preparations according to polymorphic changes. X-ray diffraction (XRD) and FT-NIR studies were carried out on standard samples, paracetamol preparations (acetaminophen tablet), and also the additives. A direct comparison was performed between the spectroscopic data and those obtained by XRD. The NIR and XRD analyses of paracetamol preparations show some distinct differences, particularly in the Iranian tablet. These differences are found to be related to polymorphism and paracetamol purity. The cluster analysis (CA) and principal component analysis (PCA) were utilized to classify the paracetamol preparations. FT-NIR spectroscopy provides a simple, rapid and accurate qualitative analysis method for the identification of paracetamol polymorphs.     

有指导的正交投影技术结合斜率/截距校正法实现小试水分近红外定量模型向中试传递

针对小试制剂过程建立的近红外定量模型难以直接应用于中试或大生产过程中的问题,该文以小试和中试条件下多批次药用糊精流化床制粒过程为载体,在线采集其近红外光谱数据并测定水分含量,建立小试过程水分近红外定量模型,提出并应用有指导的正交投影技术结合斜率/截距校正的模型传递方法跨尺度预测中试样本,使中试两个测试集A和B的水分相对预测误差分别由51.04%和26.64%降至4.90%和3.99%,显著提高了模型预测的准确度。将该结果与无指导的正交投影技术结合斜率/截距校正法以及模型更新相比较,该方法能更加有效地去除待测样本光谱中的干扰信息,适用范围广,为小试建立的模型放大应用到中试甚至大生产过程提供了新方案。     

NIR analysis of pharmaceutical samples without reference data: improving the calibration

Using an appropriate set of samples to construct the calibration set is crucial with a view to ensuring accurate multivariate calibration of NIR spectroscopic data. In this work, we developed and optimized a new methodology for incorporating physical variability in pharmaceutical production based on the NIR spectrum for the process. Such a spectrum contains the spectral changes caused by each treatment applied to the component mixture during the production process. The proposed methodology involves adding a set of process spectra (viz. difference spectra between those for production tablets and a laboratory mixture of identical nominal composition) to the set of laboratory samples, which span the wanted concentration range, in order to construct a calibration set incorporating all physical changes undergone by the samples in each step of the production process. The best calibration model among those tested was selected by establishing the influence of spectral pretreatments used to obtain the process spectrum and construct the calibration models, and also by determining the multiplying factor m to be applied to the process spectra in order to ensure incorporation of all variability sources into the calibration model. The specific samples to be included in the calibration set were selected by principal component analysis (PCA). To this end, the new methodology for constructing calibration sets for determining the Active Principle Ingredients (API) and excipients was applied to Irbesartan tablets and validated by application to the API and excipients of paracetamol tablets. The proposed methodology provides simple, robust calibration models for determining the different components of a pharmaceutical formulation.     

Development and validation of methods for the determination of miokamycin in various pharmaceutical preparations by use of near infrared reflectance spectroscopy

New methods for the determination of the nominal content of miokamycin in three commercial pharmaceutical preparations available in many different forms are proposed. Solid samples, grinding of which is the sole pretreatment required, are analysed by near infrared (NIR) spectroscopy, using a fibre-optic probe. The active principle is quantified by partial least-squares regression (PLSR). The three proposed methods were validated with a view to their use as control methods; the selectivity of the method, and the repeatability, intermediate precision, accuracy, linearity and robustness of each PLSR calibration model used were determined. The relative standard error of prediction (RSEP) was < 1.5% and the validation results testify to the suitability of the proposed methods.     

Quality control of pharmaceuticals with NIR: From lab to process line

This work describes a general framework for assessing the active pharmaceutical ingredient (API) and excipient concentrations simultaneously in pharmaceutical dosage forms based on laboratory-scale measurements. The work explores the comprehensive development of a near infrared (NIR) analytical protocol for the quantification of the API and excipients of a pharmaceutical formulation. The samples were based on a paracetamol (API) formulation with three excipients: microcrystalline cellulose, talc, and magnesium stearate. The developed method was based on laboratory-scale samples as calibration samples and pilot-scale samples (powders and tablets) as model test samples. Both types of samples were produced according to an experimental design. The samples were measured in reflectance mode in a Fourier-transform NIR spectrometer. Additionally, a new method for determining the minimum number of calibration samples was proposed. It was concluded that the use of laboratory-scale samples to construct the calibration set is an effective way to ensure the concentration variability in the development of calibration models for industrial applications. With this method, both API and excipients can be determined in high-throughput applications in the pharmaceutical industry.     

Quantitative analysis of diphenhydramine hydrochloride in pharmaceutical wafers using near infrared and Raman spectroscopy

Wafers with varying concentrations of diphenhydramine hydrochloride (DPH-HCl) as active pharmaceutical ingredient (API) were prepared and their near infrared (NIR) and Raman spectra recorded. The purpose of this study was to compare the suitability of these two vibrational spectroscopic techniques for the quantification of DPH-HCl in pharmaceutical wafers. Partial least squares (PLS1) calibration models with different data pretreatments were tested. Both NIR and Raman spectroscopy proved to be suitable to predict DPH-HCl contents at lower concentration ranges. At higher concentrations, interference by crystallization processes was observed. For investigating the general applicability of the quantification methods, two commercially available products were examined.     

Optical properties of lanthanide-doped lamellar nanohybrids.

In this article a detailed study of the optical properties of lanthanide doped lamellar nanohybrids synthesized by the "benzyl alcohol route" is presented. The synthetic approach results in the formation of a highly ordered lamellar nanocomposite consisting of yttrium or gadolinium oxide crystalline layers with a confined thickness of about 0.6 nm, separated from each other by organic layers of intercalated benzoate molecules. When the inorganic layers are doped with optically-active lanthanide ions they show outstanding emission properties in the green (Tb(3+)), red (Eu(3+)) and near infrared (Nd(3+)). The local environment of the emitting ions and the energy transfer processes involving the phenyl ring of the benzoate complexes and the lanthanide ions are presented, as well as radiance and lifetime measurements. The radiance values are comparable and in some cases even larger than those of standard phosphors, proving that these nanohybrids can compete, from an emission efficiency point of view, with commercial phosphors. Furthermore, in these nanohybrids it is possible by simply changing the excitation wavelength, to tune the emission colour chromaticity without loosing the radiance.     

Synthesis and antimicrobial activity of CuO@BaO/CaO nanocomposites using precipitation method

In this study, copper oxide doped barium and calcium oxide were prepared by a simple precipitation method. Using the similar synthetic procedure, to alter the molar radio of metal precursor to prepared four different composites viz., CuO@BaO/CaO (0.5:0.4:0.1), CuO@BaO/CaO (0.5:0.3:0.2), CuO@BaO/CaO (0.5:0.2:0.3) and CuO@BaO/CaO (0.5:0.1:0.4). The prepared composites were evaluating the X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR), Scanning Electron Microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDAX) analysis. Antibacterial tests were carried out on the composite produced. The results show that the composite materials exhibit high antibacterial activity with CuO@BaO/CaO(0.5:0.3:0.2) exhibiting stronger activity than CuO@BaO/CaO (0.5:0.4:0.1) because barium concentration decreases and calcium concentration increases.     

An HPTLC Method for the Evaluation of Two Medicinal Plants Commercially Available in the Indian Market Under the Common Trade Name Brahmadandi

Brahmadandi is an important medicinal plant used in the Indian system of medicine (Ayurveda) for the treatment of numerous diseases. A literature search revealed that different plants are available on the market under the trade name Brahmadandi viz., roots of Echinops echinatus Roxb, and the aerial parts of Tricholepis glaberrima DC which are sold either in their crude or in powdered form. Currently, no analytical procedures appear to be available for quality control purposes. In the present communication, we report a simple HPTLC method for the quantification of the lupeol content in the aforementioned plant species. The method was validated for precision, repeatability and accuracy. Instrument precision and repeatability of the method were found to be 0.56 and 2.87 %RSD, respectively. Intra-day and inter-day precision of the method was determined to be in the ranges of 0.71–2.02 and 1.03–2.02 %RSD, respectively. Accuracy of the method was evaluated by a recovery study conducted at three different levels. The mean percentage recovery was found to be 100.85%. The developed HPTLC method for estimation of lupeol was found to be simple, precise and accurate and may be useful for routine quality control of the commercial samples of Brahmadandi.     

煤基费托合成油中微量总铁的测定

铁系催化剂的残留污染一直是煤间接液化技术生产费托合成油工艺生产和产品质量控制的重点关注问题之一。准确分析合成油中微量残留铁的含量已成为工艺开发过程中至关重要的手段。该文对不同检测方法进行了对比,以燃烧灰化样品等离子体发射光谱检测铁含量的方法对不同沸点的合成油样品进行了验证,并通过实验数据优化了检测方法中的关键步骤。经验证费托合成油样品前处理最优条件为称样量5 g,马弗炉于500℃灰化1 h。该法对铁含量测定的回收率大于95%,相对标准偏差(RSD)不大于5.7%,检出限及定量下限分别为0.15 mg/kg和0.50 mg/kg。     

温度限制串联相关网络-近红外光谱法用于药物甲硝唑的质量控制

近红外漫反射光谱是一种简便、快速的有机物分析方法,样品不需处理即可直接测量,易于实现固态样非破坏测定.近红外漫反射光谱分析技术广泛应用于农业、食品、化妆品、烟草和石油等方面的组分分用近红外漫反射光谱法进行药品的非破坏性分析正成为国际热门课题.但近红外漫反射光谱的光谱范宽,吸收强度很弱,且组分间光谱严重重叠,给非破坏性分析带来了困难.而近红外漫反射光谱法与化量学相结合,能有效地解决光谱重叠带来的问题[1～3].     

Quantification of lysine clonixinate in intravenous injections by NIR spectroscopy

Migraine is a very painful and somewhat unpredictable ache that affects millions of people worldwide and for which no definite medicine exists, yet. New drugs and/or pharmaceutical forms are being developed, for which new quantitation methods are required. Lysine clonixinate (LC) has proved very advantageous to alleviate migraine episodes although, so far, no analytical procedures have been reported to quantify it in pharmaceutical dosage forms usually employed by physicians, i.e., injectable solutions. In this paper a NIR spectral method was developed and validated against international pharmaceutical standard guidelines and a new UV-based method to quantify LC in intravenous injection solutions. Both methods are almost inexpensive, fast, simple and suitable for LC routine determination. In addition, they provide analytical protocols less time-consuming than other reported HPLC methods (developed for other matrices), proved to be specific, accurate, precise and linear within the typical working range, according to the Harmonized Tripartite Guideline of Validation of Analytical Procedures from the International Conference on Harmonization. Both methods yield equivalent results and they are useful to monitor the concentration of LC in injectable solutions in routine analysis.     

Automated interface for hyphenation of planar chromatography with mass spectrometry

A fully automated interface to couple high-performance thin-layer chromatography (HPTLC) with mass spectrometry (MS) is described. This universal hands-free interface connects intact normal-phase plates to any liquid chromatography/mass spectrometry (LC/MS) system without any adjustments or modifications to the mass spectrometer. The interface extracts the complete substance band with its depth profile and thus allows detections in the pg/band range. The high performance of the automated interface was evaluated through caffeine quantification in real samples, viz., energy drinks and pharmaceutical tablets, without internal standard. Following chromatographic separation on silica gel 60 F(254) HPTLC plates, caffeine bands were eluted from the plate by means of the automated interface to the electrospray ionization (ESI) source of a triple-quadrupole mass spectrometer. Since in full scan mode only the protonated molecule [M+H](+) was observed, caffeine quantification was performed using the selected-ion monitoring (SIM) mode at m/z 195. The validation showed highly reliable results for the linear range (R(2) = 0.9973), repeatability (RSD = 5.6%, n = 6) and intermediate precision (RSD = 1.5%, n = 3). Regarding accuracy the results obtained by HPTLC/MS were not statistically different (F-test, t-test) from those obtained by validated HPTLC/UV methods. Hence, this interface proved to be one of the most reliable and universal interfaces for HPTLC/MS.     

PLS and first derivative of ratio spectra methods for determination of hydrochlorothiazide and propranolol hydrochloride in tablets

Two new analytical methods have been developed as convenient and useful alternatives for simultaneous determination of hydrochlorothiazide (HCT) and propranolol hydrochloride (PRO) in pharmaceutical formulations. The methods are based on the first derivative of ratio spectra (DRS) and on partial least squares (PLS) analysis of the ultraviolet absorption spectra of the samples in the 250–350-nm region. The methods were calibrated between 8.7 and 16.0 mg L⁻¹ for HCT and between 14.0 and 51.5 mg L⁻¹ for PRO. An asymmetric full-factorial design and wavelength selection (277–294 nm for HCT and 297–319 for PRO) were used for the PLS method and signal intensities at 276 and 322 nm were used in the DRS method for HCT and PRO, respectively. Performance characteristics of the analytical methods were evaluated by use of validation samples and both methods showed to be accurate and precise, furnishing near quantitative analyte recoveries (100.4 and 99.3% for HCT and PRO by use of PLS) and relative standard deviations below 2%. For PLS the lower limits of quantification were 0.37 and 0.66 mg L⁻¹ for HCT and PRO, respectively, whereas for DRS they were 1.15 and 3.05 mg L⁻¹ for HCT and PRO, respectively. The methods were used for quantification of HCT and PRO in synthetic mixtures and in two commercial tablet preparations containing different proportions of the analytes. The results of the drug content assay and the tablet dissolution test were in statistical agreement (p < 0.05) with those furnished by the official procedures of the USP 29. Preparation of dissolution profiles of the combined tablet formulations was also performed with the aid of the proposed methods. The methods are easy to apply, use relatively simple equipment, require minimum sample pre-treatment, enable high sample throughput, and generate less solvent waste than other procedures. Electronic supplementary material Supplementary material is available in the online version of this article at and is accessible for authorized users.     

Quantification of lysine clonixinate in intravenous injections by NIR spectroscopy

Migraine is a very painful and somewhat unpredictable ache that affects millions of people worldwide and for which no definite medicine exists, yet. New drugs and/or pharmaceutical forms are being developed, for which new quantitation methods are required. Lysine clonixinate (LC) has proved very advantageous to alleviate migraine episodes although, so far, no analytical procedures have been reported to quantify it in pharmaceutical dosage forms usually employed by physicians, i.e., injectable solutions. In this paper a NIR spectral method was developed and validated against international pharmaceutical standard guidelines and a new UV-based method to quantify LC in intravenous injection solutions. Both methods are almost inexpensive, fast, simple and suitable for LC routine determination. In addition, they provide analytical protocols less time-consuming than other reported HPLC methods (developed for other matrices), proved to be specific, accurate, precise and linear within the typical working range, according to the Harmonized Tripartite Guideline of Validation of Analytical Procedures from the International Conference on Harmonization. Both methods yield equivalent results and they are useful to monitor the concentration of LC in injectable solutions in routine analysis.     

Near‐Infrared Croconaine Rotaxanes and Doped Nanoparticles for Enhanced Aqueous Photothermal Heating

The photothermal effect is the generation of heat by molecules or particles upon high‐energy laser irradiation, and near‐infrared absorbers such as gold nanoparticles and organic dyes have a range of potential photothermal applications. The favourable photothermal properties of thiophene‐functionalised croconaine dyes were recently discovered. The synthesis and properties of novel croconaine rotaxane and pseudorotaxane architectures capable of efficient photothermal performance in both organic and aqueous environments are reported. The versatility of this dye‐encapsulation strategy was demonstrated by the preparation of two organic croconaine rotaxanes using different synthetic methods: the formation of an aqueous pseudorotaxane association complex, and the synthesis of water‐soluble, croconaine‐doped silicated micelle nanoparticles. All of these near‐infrared‐absorbing systems exhibit excellent photothermal behaviour, with pseudorotaxane and rotaxane formation vital for effective aqueous heat generation. Dye encapsulation provides steric protection to enhance the stability of a water‐sensitive croconaine dye, while rotaxane‐doped nanoparticles avoid detrimental band broadening caused by chromophore coupling.     

Quantification of pharmaceutical compounds in tissue and plasma samples using selective ion accumulation with multiple mass isolation windows

Quantification of pharmaceutical compounds using matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is an alternative to traditional liquid chromatography (LC)-MS techniques. Benefits of MALDI-based approaches include rapid analysis times for liquid samples and imaging mass spectrometry capabilities for tissue samples. As in most quantification experiments, the use of internal standards can compensate for spot-to-spot and shot-to-shot variability associated with MALDI sampling. However, the lack of chromatographic separation in traditional MALDI analyses results in diminished peak capacity due to the chemical noise background, which can be detrimental to the dynamic range and limit of detection of these approaches. These issues can be mitigated by using a hybrid mass spectrometer equipped with a quadrupole mass filter (QMF) that can be used to fractionate ions based on their mass-to-charge ratios. When the masses of the analytes and internal standards are sufficiently disparate in mass, it can be beneficial to effect multiple narrow mass isolation windows using the QMF, as opposed to a single wide mass isolation window, to minimize chemical noise while allowing for internal standard normalization. Herein, we demonstrate a MALDI MS quantification workflow incorporating multiple sequential mass isolation windows enabled on a QMF, which divides the total number of MALDI laser shots into multiple segments (i.e., one segment for each mass isolation window). This approach is illustrated through the quantitative analysis of the pharmaceutical compound enalapril in human plasma samples as well as the simultaneous quantification of three pharmaceutical compounds (enalapril, ramipril, and verapamil). Results show a decrease in the limit of detection, relative standard deviations below 10%, and accuracy above 85% for drug quantification using multiple mass isolation windows. This approach has also been applied to the quantification of enalapril in brain tissue from a rat dosed in vitro. The average concentration of enalapril determined by imaging mass spectrometry is in agreement with the concentration determined by LC–MS, giving an accuracy of 104%.     

Multivariate curve resolution of pH gradient flow injection mixture analysis with correction of the Schlieren effect

Multivariate curve resolution using alternating least squares (MCR-ALS) was used to quantify ascorbic (AA) and acetylsalicylic (ASA) acids in four pharmaceutical samples using a flow injection analysis (FIA) system with pH gradient and a diode array (DAD) spectrometer as a detector. Four different pharmaceutical drugs were analyzed, giving a data array of dimensions 51 x 291 x 61, corresponding respectively to number of samples, FIA times and spectral wavelengths. MCR-ALS was applied to these large data sets using different constraints to have optimal resolution and optimal quantitative estimations of the two analytes (AA and ASA). Since both analytes give an acid-basic pair of species contributing to the UV recorded signal, at least four components sholuld be proposed to model AA and ASA in synthetic mixture samples. Moreover, one additional component was needed to resolve accurately the Schlieren effect and another additional component was also needed to model the presence of possible interferences (like caffeine) in the commercial drugs tablets, giving therefore a total number of 6 independent components needed. The best quantification relative errors were around 2% compared to the reference values obtained by HPLC and by the oxidation-reduction titrimetric method, for ASA and AA respectively. In this work, the application of MCR-ALS allowed for the first time the full resolution of the FIA diffusion profile due to the Schlieren effect as an independent signal contribution, suggesting that the proposed MCR-ALS method allows for its accurate correction in FIA-DAD systems.