Direct determination of niflumic acid in a pharmaceutical gel by ATR/FTIR spectroscopy and PLS calibration

Rapid diagnosis of rheumatoid arthritis and ankylosing spondylitis based on Fourier transform infrared spectroscopy and deep learning

OBJECTIVE

Rheumatoid arthritis and Ankylosing spondylitis are two common autoimmune inflammatory rheumatic diseases that negatively affect activities of daily living and can lead to structural and functional disability, reduced quality of life. Here, this study utilized Fourier transform infrared (FTIR) spectroscopy on dried serum samples and achieved early diagnosis of rheumatoid arthritis and ankylosing spondylitis based on deep learning models.

METHOD

A total of 243 dried serum samples were collected in this study, including 81 samples each from ankylosing spondylitis, rheumatoid arthritis, and healthy controls. Three multi-scale convolutional modules with different specifications were designed based on the multi-scale convolutional neural network (MSCNN) to effectively fuse the local features to enhance the generalization ability of the model. The FTIR was then combined with the MSCNN model to achieve a non-invasive, fast, and accurate diagnosis of ankylosing spondylitis, rheumatoid arthritis, and healthy controls.

RESULTS

Spectral analysis shows that the curves and waveforms of the three spectral graphs are similar. The main differences are distributed in the spectral regions of 3300-3250 cm-1, 3000-2800 cm-1, 1750-1500 cm-1, and 1500-1300 cm-1, which represent: Amides, fatty acids, cholesterol, proteins with a carboxyl group, amide II, free amino acids, and polysaccharides. Four classification models, namely artificial neural network (ANN), convolutional neural network (CNN), improved AlexNet model, and multi-scale convolutional neural network (MSCNN) were established. Through comparison, it was found that the diagnostic AUC value of the MSCNN model was 0.99, and the accuracy rate was as high as 0.93, which was much higher than the other three models.

CONCLUSION

The study demonstrated the superiority of MSCNN in distinguishing ankylosing spondylitis from rheumatoid arthritis and healthy controls. FTIR may become a rapid, sensitive, and non-invasive means of diagnosing rheumatism.

Microwave synthesis of blue emissive carbon dots from 5-sulpho anthranilic acid and 1,5-diphenyl carbazide for sensing of levocetirizine and niflumic acid

In this work, water soluble carbon dots (CDs) were synthesized by using 5- sulpho anthranilic acid (SAA) and 1,5-diphenylycarbazide (DPC) as precursors via microwave-assisted method and named as "SD-CDs". We studied the effect of SAA and DPC molar ratio (1:3, 2:2 and 3:1) for the preparation of blue fluorescent CDs, showing the best emission properties at molar 3:1 ratio of SAA and DPC. The as-prepared SD-CDs emit bright blue color under UV light at 365 nm, and exhibit emission peak at 392 nm when excited at 319 nm. The as-synthesized SD-CDs act as a fluorescent sensor for detection of levocetirizine and niflumic acid through the fluorescence "turn-on-off" mechanism. The developed probe exhibited good linearity in the concentrations (levocetirizine - 1.0-100 µM and niflumic acid - 0.5-100 µM) with detection limits of 3.92 nM and 0.19 µM for levocetirizine and niflumic acid, respectively. Importantly, the developed analytical method was successfully used for the detection of levocetirizine in tablets and niflumic acid in biofluids of human (serum, plasma and urine), showing good recoveries from 97 to 99 %. Thus, this SD-CDs-based fluorescence method has the potential for levocetirizine and niflumic acid assays in biological and pharmaceutical samples.

An in-depth mechanistic study of the p-hydroxyphenylglycine synthetic process using in situ ATR-IR spectroscopy

In this study, an in situ ATR-IR technique was used as a powerful tool to gain insight into the synthetic process of p-hydroxyphenylglycine (p-HPG) by the sulfamic acid-glyoxylic acid-phenol method. Combined with other chemical and instrumental analysis technologies, the reaction sequence and key intermediates of this one-pot reaction were determined, and two concomitant reaction paths have been put forward for the first time. The possible reaction mechanism has been suggested, and the reaction efficiency of each path is discussed in detail. Through the optimization of the experimental parameters, an approximately 40% increase in the final product yield was achieved compared with previous reports. We believe that this study will without a doubt trigger research interest in understanding the industrial production process of important chemicals and pharmaceuticals and as a result will promote the sustainable development and application of novel, efficient chemical reaction routes.

Quantification and Classification of Diclofenac Sodium Content in Dispersed Commercially Available Tablets by Attenuated Total Reflection Infrared Spectroscopy and Multivariate Data Analysis

A new methodology, based on Fourier transform infrared spectroscopy equipped with an attenuated total reflectance accessory (ATR FT-IR), was developed for the determination of diclofenac sodium (DS) in dispersed commercially available tablets using chemometric tools such as partial least squares (PLS) coupled with discriminant analysis (PLS-DA). The results of PLS-DA depicted a perfect classification of the tablets into three different groups based on their DS concentrations, while the developed model with PLS had a sufficiently low root mean square error (RMSE) for the prediction of the samples’ concentration (~5%) and therefore can be practically used for any tablet with an unknown concentration of DS. Comparison with ultraviolet/visible (UV/Vis) spectrophotometry as the reference method revealed no significant difference between the two methods. The proposed methodology exhibited satisfactory results in terms of both accuracy and precision while being rapid, simple and of low cost.

Comparison and evaluation of the quick purification methods of methamphetamine hydrochloride from dimethyl sulfone for spectroscopic identification

Methods to quickly purify methamphetamine hydrochloride from the cutting agent dimethyl sulfone for subsequent identification of confiscated crystalline samples using infrared absorption spectroscopy were compared and evaluated. Although sequential solvation and reprecipitation methods were simple, spectral contamination from dimethyl sulfone was inevitable and might affect the interpretation of the spectra. In addition, methamphetamine hydrochloride and dimethyl sulfone could form a solid solution because of solvation of both crystals into a single solution layer. By contrast, sublimation was an effective method for separation of methamphetamine hydrochloride and dimethyl sulfone. Sublimation combined with infrared absorption spectroscopy enabled rapid identification of crystalline methamphetamine hydrochloride.

Green method by diffuse reflectance infrared spectroscopy and spectral region selection for the quantification of sulphamethoxazole and trimethoprim in pharmaceutical formulations

An alternative method for the quantification of sulphametoxazole (SMZ) and trimethoprim (TMP) using diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) and partial least square regression (PLS) was developed. Interval Partial Least Square (iPLS) and Synergy Partial Least Square (siPLS) were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. Fifteen commercial tablet formulations and forty-nine synthetic samples were used. The ranges of concentration considered were 400 to 900 mg g-1SMZ and 80 to 240 mg g-1 TMP. Spectral data were recorded between 600 and 4000 cm-1 with a 4 cm-1 resolution by Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS). The proposed procedure was compared to high performance liquid chromatography (HPLC). The results obtained from the root mean square error of prediction (RMSEP), during the validation of the models for samples of sulphamethoxazole (SMZ) and trimethoprim (TMP) using siPLS, demonstrate that this approach is a valid technique for use in quantitative analysis of pharmaceutical formulations. The selected interval algorithm allowed building regression models with minor errors when compared to the full spectrum PLS model. A RMSEP of 13.03 mg g-1for SMZ and 4.88 mg g-1 for TMP was obtained after the selection the best spectral regions by siPLS.

Simultaneous diffuse reflectance infrared determination of clavulanic acid and amoxicillin using multivariate calibration techniques

A method for simultaneous determination of clavulanic acid (CA) and amoxicillin (AMO) in commercial tablets was developed using diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) and multivariate calibration. Twenty-five samples (10 commercial and 15 synthetic) were used as a calibration set and 15 samples (10 commercial and 5 synthetic) were used for a prediction set. Calibration models were developed using partial least squares (PLS), interval PLS (iPLS), and synergy interval PLS (siPLS) algorithms. The best algorithm for CA determination was siPLS model with spectra divided in 30 intervals and combinations of 2 intervals. This model showed a root mean square error of prediction (RMSEP) of 5.1 mg g(-1). For AMO determination, the best siPLS model was obtained with spectra divided in 10 intervals and combinations of 4 intervals. This model showed a RMSEP of 22.3 mg g(-1). The proposed method was considered as a suitable for the simultaneous determination of CA and AMO in commercial pharmaceuticals products.

Simultaneous determination of sulphamethoxazole and trimethoprim in powder mixtures by attenuated total reflection-Fourier transform infrared and multivariate calibration

A partial least-squares calibration (PLS) procedure in combination with infrared spectroscopy has been developed for simultaneous determination of sulphamethoxazole (SMZ) and trimethoprim (TMP) in raw material powder mixtures used for manufacturing commercial pharmaceutical products. Multivariate calibration modeling procedures, interval partial least squares (iPLS) and synergy partial least squares (siPLS), were applied to select a spectral range that provided the lowest prediction error in comparison to the full-spectrum model. The experimental matrix was constructed using 49 synthetic samples and 15 commercial samples. The considered concentration ranges were 400-900 mg g(-1) SMZ and 80-240 mg g(-1) TMP. Spectral data were recorded between 650 and 4000 cm(-1) with a 4 cm(-1) resolution by Fourier transform infrared spectroscopy coupled with attenuated total reflectance (ATR-FTIR) accessory. The proposed procedure was compared with conventional procedure by high performance liquid chromatography (HPLC) using 15 commercial samples containing SMZ and TMP. The results showed that PLS regression model combined to ATR-FTIR is a relatively simple, rapid and accurate procedure that could be applied to the simultaneous determination of SMZ and TMP in routine quality control of powder mixtures. A root mean square error of prediction (RMSEP) of 13.18 mg g(-1) for SMZ and 6.03 mg g(-1) for TMP was obtained after selection of better intervals by siPLS. Using the proposed procedure it is possible to analyze each sample in less than 3 min considering two replicates (excluding the grinding step). Accuracy was checked by comparison to HPLC method and agreement better than 98.8% was achieved.

(19)F NMR spectroscopic characterization of the interaction of niflumic acid with human serum albumin

The interaction of a non-steroidal anti-inflammatory drug, niflumic acid (NFA), with human serum albumin (HSA) has been investigated by (19)F nuclear magnetic resonance (NMR) spectroscopy. A (19)F NMR spectrum of NFA in a buffered (pH 7.4) solution of NaCl (0.1 mol L(-1)) contained a single sharp signal of its CF(3) group 14.33 ppm from the internal reference 2,2,2-trifluoroethanol. Addition of 0.6 mmol L(-1) HSA to the NFA buffer solution caused splitting of the CF(3) signal into two broadened signals, shifted to the lower fields of 14.56 and 15.06 ppm, with an approximate intensity ratio of 1:3. Denaturation of HSA by addition of 3.0 mol L(-1) guanidine hydrochloride (GU) restored a single sharp signal of CF(3) at 14.38 ppm, indicating complete liberation of NFA from HSA as a result of its denaturation. These results suggest that the binding is reversible and occurs in at least two HSA regions. Competitive (19)F NMR experiments using warfarin, dansyl-L: -asparagine, and benzocaine (site I ligands), and L: -tryptophan and ibuprofen (site II ligands) revealed that NFA binds to site I at two different regions, Ia and Ib, in the ratio 1:3. By use of (19)F NMR with NFA as an (19)F NMR probe the nonfluorinated site I-binding drugs sulfobromophthalein and iophenoxic acid were also found to bind sites Ia and Ib, respectively. These results illustrate the usefulness and convenience of (19)F NMR for investigation of the HSA binding of both fluorinated and nonfluorinated drugs.