Evolution of the structural polymorphs of poly(l-lactic acid) during the in vitro mineralization of its hydroxyapatite nanocomposites by attenuated total reflection fourier transform infrared mapping coupled with principal component analysis

Polymer ◽  
2021 ◽  
pp. 124318
Author(s):  
Tongtong Dou ◽  
Bingyao Zhou ◽  
Shui Hu ◽  
Pudun Zhang
2020 ◽  
pp. 000370282096971
Author(s):  
Nataša Radosavljević Stevanović ◽  
Milena Jovanović ◽  
Federico Marini ◽  
Slavica Ražić

Heroin is one of the most frequently seized drugs in Southeastern Europe. Due to the position in the Balkan route, the Republic of Serbia keeps important role in suppression of the trafficking of heroin for domestic and foreign illegal market. This research is aimed to provide a good scientific approach in the field of seized heroin analysis. Two different forms of heroin are present in the illegal market, mostly in mixtures with typical “cutting” agents: caffeine, paracetamol, and sugars. It was observed that the quantity of pure heroin in seized samples slightly increases from year to year. The aim of this study was to produce a reliable and fast procedure for classification of illicit heroin samples and determination of the concentration range of heroin in the samples. For that purpose, the attenuated total reflection Fourier transform infrared spectroscopy (ATR FT-IR) technique was used and combined with such chemometric methods as principal component analysis, cluster analysis, and partial least squares. Principal component analysis (PCA) as an unsupervised model was used for exploratory purposes to identify trends, similarities, and differences between samples by reducing the dimensionality of the data. The cluster classification of examined samples turned out to be extremely useful to evaluate the possibilities of the ATR FT-IR technique to classify the samples appropriately into the patterns, the constituted clusters. Additionally, partial least square was the suitable method for the purpose of determination of the heroin hydrochloride concentration range in examined samples. It is proved that the joined application of spectroscopy and chemometrics can be extremely convenient and useful for forensic and drugs control laboratories.


2021 ◽  
Vol 6 (1) ◽  
pp. 26
Author(s):  
Ivan Andriansyah ◽  
Hilman Nur Mukhlis Wijaya ◽  
Purwaniati Purwaniati

Kopi merupakan bahan minuman yang sangat terkenal bukan hanya di Indonesia melainkan di seluruh dunia, jenis yang sering dijumpai yaitu arabika dan robusta. Tingginya harga dan permintaan kopi banyak produsen memalsukan atau mencampur kopi dengan bahan lain. Adulterasi adalah upaya menambah atau mengganti bahan makanan dengan tujuan memperoleh, sehingga memberikan dampak buruk pada konsumen. Tujuan dari jurnal ini adalah untuk mengetahui ada atau tidaknya adulteran pada kopi luwak yang beredar dipasaran. Metode analisis FTIR digunakan untuk membuat pola sidik jari dari ekstrak kopi melalui analisis kemometrik dengan metode Principal Component Analysis (PCA). Ekstraksi dilakukan dengan cara maserasi menggunakan pelarut etanol 96%. Pengukuran spektrum inframerah menggunakan alat FT-IR, pada bilangan gelombang 4000-650cm-1 dan resolusi 4 cm-1. Klasifikasi dari kopi yang diadulteran dengan arabika dan kopi luwak menggunakan data PC-1 dan PC-2 dengan nilai berturut-turut 82% dan 14%. Hasil menunjukkan nilai scores menggunakan PC-1 dan PC-2 sampel kopi A berada dekat kuadran kopi luwak, sampel kopi B berada di antara kuadran kopi arabika (adulteran) dan luwak, dan kopi sampel C berada dekat kuadran arabika (adulteran). Metode FTIR dapat mendeteksi dengan batas deteksi 15% (b/b)


1987 ◽  
Vol 41 (3) ◽  
pp. 449-453 ◽  
Author(s):  
P. B. Harrington ◽  
T. L. Isenhour

Different methods of data preprocessing were evaluated for the compression of Fourier transform-infrared spectral libraries by principal component analysis (PCA). The effect of noise on compressed library searches was examined. A PCA compression of an infrared library achieved an 81% reduction in size without any loss in search performance.


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