Investigation of spermatozoa and seminal plasma by fourier transform infrared spectroscopy

Fourier transform infrared (FT-IR) spectra of human spermatozoa and seminal plasma were recorded and analyzed. The procedure that was established for sample preparation enabled acquisition of reproducible spectra. The parameter I(1087)/I(966) for controlling spectra reproducibility was defined. The assignment of bands was carried out using an empirical approach and the origin of the "sperm specific doublet", the bands at 968 cm(-1) and 981 cm(-1), was determined. The principal component regression (PCR) algorithm was used to define the specific spectral regions correlating to characteristics of spermatozoa, such as concentration, straight-line velocity (VSL), and beat cross frequency (BCF). Then, simple spectral parameters, such as band intensities and band ratios, were tested to determine which one best correlates to characteristics of spermatozoa. The region of the amide I band, between 1700 cm(-1) and 1590 cm(-1), was defined as a specific spectral region that correlates to the concentration of spermatozoa. The parameter that gave the linear dependence to the concentration of spermatozoa was the intensity of the amide I band. For VSL, the bands between 1119 cm(-1) and 943 cm(-1) were defined as the specific spectral region. The relative amount of nucleic acids with respect to proteins showed linear dependence on the straight-line velocity of spermatozoa. BCF showed the best correlation to the bands between 3678 cm(-1) and 2749 cm(-1), which largely represent lipids and proteins. These results suggest that FT-IR spectroscopy can serve as an adjunct to conventional histopathology studies.     

傅立叶变换红外光谱法分析市售食品中反式脂肪酸

建立了一种快速测定食品中反式脂肪酸含量的方法,用索氏提取法或氯仿—甲醇提取法提取食品中脂肪,经甲醇-BF3快速甲酯化后,采用Avatar 370傅立叶变换红外光谱对反式脂肪酸进行定性定量分析,回收率为89.5%~103.3%,相对标准偏差为1.80%,重复性好,准确度高,适用于一般食品营养标签的测定。对我国市场上的涂抹奶油、派和蛋糕、饼干、巧克力、冰淇淋、薯片和薯条等6大类食品中20种样品中反式脂肪酸进行测定。结果表明,16种检出样品中反式脂肪酸含量在0.18%~10.34%之间,反式脂肪酸含量随食品种类不同存在显著差异,涂抹奶油、蛋黄派、威化饼干是反式脂肪酸含量较高的食品类别。     

Differentiation of mesophilic and thermophilic bacteria with fourier transform infrared spectroscopy

In the present study the characterization and differentiation of mesophilic and thermophilic bacteria were investigated by using Fourier transform infrared (FT-IR) spectroscopy. Our results showed significant differences between the FT-IR spectra of mesophilic and thermophilic bacteria. The protein-to-lipid ratio was significantly higher for thermophiles compared to mesophiles. The absorption intensity of the CH(3) asymmetric stretching vibration was higher in thermophilic bacteria, indicating a change in the composition of the acyl chains. The higher intensity/area observed in the CH(2) symmetric stretching mode at 2857 cm(-1), and the CH(2) bending vibration band at 1452 cm(-1), indicated a higher amount of saturated lipids in thermophilic bacteria. The lipid C=O stretching vibration at 1739 cm(-1), which was observed in the mesophilic group, was not observed clearly in the thermophilic group, indicating a difference in packing that is presumably due to the decreased proportion of unsaturated acyl chains in thermophilic bacteria. In addition, the carbonyl groups become hydrogen bonded and the cellular DNA content was lower in thermophilic bacteria. Moreover, in the 1000-400 cm(-1) frequency region, the spectra of each bacterial species belonging to both the mesophilic and thermophilic bacterial groups, showed characteristic differences that were discriminated via dendrogram using cluster analysis. The current study implies that FT-IR spectroscopy could be successfully applied for the rapid comparison of bacterial groups and species to establish either similarities or discrepancies, as well as to confirm biochemical or physiological characteristics.     

Using fourier transform infrared spectroscopy to examine structure in bisurea organogels

The structure of two bisurea organogels was examined by Fourier-transform infrared (FT-IR) spectroscopy. Organogels were prepared in benzene at different concentrations of gelator in order to determine the effect of concentration on the assembly of organogelator molecules. This work examined two types of bisurea organogelators, both with dodecyl alkyl tail groups. The two molecules differ only in the length of an alkyl chain separating their two urea groups: 6 carbons in the C6C12 organogelator (1,6-bis(3(3,5-didodecoxybinzyl)-urea-hexane) and 12 carbons in the C12C12 organogelator (1,12-bis(3(3,5-didodecoxybinzyl)-urea-dodecane). The degree of urea hydrogen bonding was determined from the position of the amide II band, and the conformational order of the alkyl chains in the organogelator was determined in the methylene bending region. Both gels showed a general trend of less hydrogen bonding and greater conformational disorder in the alkyl chains as the concentration of organogelator increased; however, the changes were smaller in the C12C12 gels. This decrease in structural order with increasing organogelator concentration is explained by the kinetics of gel formation; more concentrated gels solidify too quickly to assemble perfectly. The observed differences between the two organogelators are caused by the different structures into which these two similar molecules assemble. The C6C12 organogelator only assembles linearly, while the C12C12 organogelator can form sheets through brick-like packing, and these packing motifs were confirmed by scanning electron microscopy.     

Discrimination of soil-borne fungi using fourier transform infrared attenuated total reflection spectroscopy

Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy was used to discriminate five commonly encountered soil-borne fungi that cause severe economic damage to agriculture: Colletotrichum, Fusarium, Pythium, Rhizoctonia, and Verticillium. Contrary to previous studies related to microorganism discrimination using FT-IR-ATR spectroscopy, the pathogen samples were not dried on the ATR crystal, which is a time-consuming operation. Rather, after removing some pathogen filaments from the solution using tweezers, these were placed directly on a flat ATR crystal and pressure was applied using a pressure clamp. Following water subtraction, baseline correction, and normalization of the spectra, principal component analysis was used as a data-reduction step and canonical variate analysis was used for discrimination. Discrimination was performed at the genus level and at the strain level for Colletotrichum. For discrimination between the five fungi at the genus level, the success rate for the validation samples ranged from 75% to 89%. For discrimination between the two Colletotrichum strains, the success rate was 78%. Comparison with spectra of similar fungi dried on the ATR crystal showed that both types of spectra were very similar, indicating that drying the samples on the ATR crystal is not required and can be replaced by mathematical post-processing of the spectra. For routine analyses that involve rapid screening of very large amounts of samples, this approach allows for increasing significantly the number of samples that can be analyzed daily.     

Rapid nondestructive on-site screening of methylamphetamine seizures by attenuated total reflection fourier transform infrared spectroscopy

The identification and quantification of illicit substances in the field is often desirable. Fourier transform infrared spectroscopy (FT-IR) has both qualitative and quantitative capabilities and field portable instruments are commercially available. Transmission infrared spectra of mixtures containing ephedrine hydrochloride, glucose, and caffeine and attenuated total reflection (ATR) infrared spectra of mixtures composed of methylamphetamine hydrochloride, glucose, and caffeine were used to develop principal component regression (PCR) calibration models. The root mean sum of errors of predictions (RMSEP) of all individual components in a mixture from a single measurement was <6% w/w, which reduced to approximately 3% w/w when triplicates were averaged. Sample mixing and grinding are essential to minimize the effect of heterogeneity, as deviations of up to 20% w/w were observed for single measurements of unground samples. Poor predictions of the components in a mixture occurred when samples were "contaminated" with substances not present in the calibration set, as would be expected. When only a single analyte (drug) was targeted, using a calibration set that contained both contaminated and uncontaminated samples, an RMSEP of approximately 4% w/w was achieved. The results demonstrate that ATR-FT-IR has the potential to quantify methylamphetamine samples, and possibly other licit or illicit substances, in at-seizure and on-site scenarios.     

Artificial diamond as a broadband infrared beam splitter for fourier transform spectroscopy

We show that an artificially grown diamond plate serves as a very broadband beam splitter from approximately 7 mum, where the intrinsic diamond absorption becomes important, to the submillimeter region (a 250-mum wavelength or longer).     

Characterization and quantitation of aprepitant drug substance polymorphs by attenuated total reflectance fourier transform infrared spectroscopy

In this study, we report the use of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FT-IR) for the identification and quantitation of two polymorphs of Aprepitant, a substance P antagonist for chemotherapy-induced emesis. Mixtures of the polymorph pair were prepared by weight and ATR-FT-IR spectra of the powdered samples were obtained over the wavelength range of 700-1500 cm(-1). Significant spectral differences between the two polymorphs at 1140 cm(-1) show that ATR-FT-IR can provide definitive identification of the polymorphs. To investigate the feasibility of ATR-FT-IR for quantitation of polymorphic forms of Aprepitant, a calibration plot was constructed with known mixtures of the two polymorphs by plotting the peak ratio of the second derivative of absorbance spectra against the weight percent of form II in the polymorphic mixture. Using this novel approach, 3 wt % of one crystal form could be detected in mixtures of the two polymorphs. The accuracy of ATR-FT-IR in determining polymorph purity of the drug substance was tested by comparing the results with those obtained by X-ray powder diffractometry (XRPD). Indeed, polymorphic purity results obtained by ATR-FT-IR were found to be in good agreement with the predictions made by XRPD and compared favorably with actual values in the known mixtures. The present study clearly demonstrates the potential of ATR-FT-IR as a quick, easy, and inexpensive alternative to XRPD for the determination of polymorphic identity and purity of solid drug substances. The technique is ideally suited for polymorph analysis, because it is precise, accurate, and requires minimal sample preparation.     

Nontoxic and chemically stable hollow optical fiber probe for fourier transform infrared spectroscopy

Remote spectroscopy systems based on hollow optical fiber probes are proposed and experimental results using a Fourier transform spectroscope are presented. A hollow optical-fiber probe with a silver and polymer inner coating is used to deliver incoherent light to a target and another separate hollow fiber is used to collect the reflected light. The reflectance spectra of teeth, skin, and oral mucosa were successfully measured with the probe even from surfaces with reflectances lower than 0.5%. The preliminary results obtained using attenuated total reflection spectroscopy are also presented. This remote infrared spectroscope is useful for endoscopic measurements inside the body because it is flexible, durable, nontoxic, and has the low transmission losses associated with hollow-fiber-based probes.     

傅里叶变换衰减全反射红外光谱法化学试剂定性鉴别数据库的建立

使用傅里叶变换衰减全反射红外光谱法(ATR-FTIR)进行了近200种有机化学试剂的定性鉴别试验,建立了傅里叶变换衰减全反射红外光谱数据库。使用该方法能够鉴别大多数常见的有机化合物,并具有分辨力高、检验简便的特点。     

人血清中血糖的近红外光谱快速检测

应用傅利叶变换近红外光谱透射技术结合偏最小二乘法 ( PLS) ,快速定量分析了人血清中血糖含量 .利用内部交叉验证和自动优化功能对预测模型进行了优化 ,确定了最优建模参数 .模型对人血清中葡萄糖定标样品集的实测含量与预测含量的相关系数 r=0 .91 48,内部校正均方差 RMSECV=0 .487mmol/L.     

Quantification of volatile organics in soil aging experiments using fourier transform infrared spectroscopy

On-line Fourier transform infrared (FT-IR) spectroscopy was applied to monitor the concentration of halogenated volatile organic compounds in a sample-preparation process that simulates long-term, slow accumulation of contaminants in soils (i.e., aging). Artificial aging is conducted by circulating a supercritical fluid solution containing the contaminant(s) of interest through a packed soil column. Mid-infrared spectra of several volatile halocarbons were measured in supercritical Xe and CO(2) to evaluate possible interferences from the strong absorption of CO(2). Although some of the C-X bands were partially masked in supercritical CO(2), all of the compounds studied had distinct spectral features in the region 1400-700 cm(-1) and could be monitored in either solvent. Quantitative measurements of halogenated volatile organics in supercritical CO(2) were demonstrated with CCl(4). Excellent results were obtained over the range 7-280 mM. Representative artificial aging experiments were conducted on two test soils using CCl(4) as the contaminant. On-line (FT-IR) estimates of the aged soil concentrations were 1.3-4.4 times higher than off-line concentrations obtained by gas chromatography/mass spectrometry. The discrepancies were primarily ascribed to post-aging losses that occurred during depressurization and subsequent sample handling. FT-IR spectroscopy is shown to be a powerful tool for monitoring soil loading behavior and for developing artificial aging protocols.     

Postoperative plasma metabolic consequences of an osseous substitute implantation: analysis by fourier transform infrared spectroscopy

In this study, we have investigated the postoperative plasma consequences of coral implantation into femoral condyle of rabbits. Analyses were performed using Fourier transform infrared (FT-IR) spectroscopy, a sensitive and nondestructive method, to evaluate plasma modifications one day, one week, one month, and three months after surgery. This technique showed that both surgery and implantation induced important changes of lipidic compounds one day after surgery, with a body lipolysis. Major modifications appeared one week after surgery, with a decrease of protein and saccharide contents, and an increase of amino acids accompanied by a noticeable inflammatory process. These last changes were revealed by a hierarchical classification in the 1430-1295 and 1137-1092 cm(-1) spectral regions, leading to two well-separated groups, before and one week after surgery. After a delayed time of three months and despite a substantial recovery for biomolecules such as proteins and fatty acids, some alterations are always observed, such as for amino acids, triglycerides, and glycerol. Moreover, molecules implicated in the inflammatory process had not reached their initial level.     

Crystallization of polylactide and its stereocomplex investigated by two-dimensional fourier transform infrared correlation spectroscopy employing carbonyl overtones

The band origins and transitions of weak vibrational modes developed in the 3500 cm(-1) region of polylactide (PLA) spectra during crystallization are investigated. The band assignment to the OH stretching mode of terminal hydroxyls is unlikely because the trace amount of chain-ends is negligible considering the long chain of high molecular weight polymer. The band intensity can be enhanced for quantitative study by increasing the sample film thickness. The results show that the transition patterns of these bands mimic those of C=O stretching modes. Therefore, these are assigned to C=O overtones. Two bands associated with crystalline and amorphous characteristics are revealed during cold crystallization. The crystalline C=O bands of PDLA and its stereocomplex counterpart are located at 3510 cm(-1) and 3482 cm(-1), respectively, indicating a weaker C=O bond in the latter crystal structure. Two-dimensional Fourier transform infrared (2D-FT-IR) correlation spectroscopy is then applied to study the correlation between C=O overtones and the crystalline characteristic band located near 900 cm(-1). The transitions of the two vibrational modes observed in crystallization of the stereocomplex are in-phase with each other. This reflects an involvement of short-range hydrogen bonding in the stereocomplex crystal structure. In contrast, crystallization of PDLA shows that the C=O overtone varies prior to that of the C-H character, indicating that dipole-dipole force is a crystal-induced interaction.     

Anisotropy studied by polarization-modulated fourier transform infrared reflection difference microspectroscopy

We investigated anisotropic optical behavior in solid-state materials using Fourier transform infrared reflection microspectroscopy in combination with polarization modulation. For a Ca1.8Sr0.2RuO4 crystal with an isotropic optical surface, we found the reflection difference to be very close to zero, independent of the azimuthal angle of the sample. A Ca1.4Sr0.6RuO4 crystal with an anisotropic optical surface, however, exhibited a large anisotropic optical response with a strong angular dependence following a sinusoidal behavior. Furthermore, we examined the spatial distribution of the reflection difference in Bi0.17Ca0.83MnO3+delta using infrared synchrotron radiation and could clearly distinguish microscopic anisotropic domains having different optical axes. These results demonstrate that our experimental scheme can be used as a powerful tool to spectrally and spatially resolve anisotropy of solid-state materials in the mid-infrared region.     

Differentiation of neotropical fish species with statistical analysis of fourier transform infrared photoacoustic spectroscopy data

Fourier transform infrared photoacoustic spectroscopy (FTIR-PAS) was applied to nineteen fish species in Brazil's Upper Paraná River basin to identify differences in the structural composition of their scales. To differentiate the species, a canonical discriminant analysis was used to indicate the most important absorption peaks in the mid-infrared region. Significant differences were found in the chemical composition of scales among the studied fish species, with Wilk's lambda = 5.2 × 10(-6), F((13,18,394)) = 37.57, and P < 0.001, indicating that O-CH(2) wag at 1396 cm(-1) can be used as a biomarker of this species group. The species could be categorized into four groups according to phylogenetic similarity, suggesting that the O-CH(2) 1396 cm(-1) absorbance is related to the biological traits of each species. This procedure can also be used to complement evolutionary studies.     

On-line fourier transform infrared detection in capillary electrophoresis

The coupling of Fourier transform infrared (FT-IR) spectroscopy as a new on-line detection principle in capillary electrophoresis (CE) is presented. To overcome the problem of total IR absorption by the fused-silica capillaries that are normally employed in CE separations, a micromachined IR-transparent flow cell was constructed. The cell consists of two IR-transparent CaF2 plates separated by a polymer coating and a titanium layer producing an IR detection window, 150 microm wide and 2 mm long, with a path length of 15 microm. The IR beam was focused on the detection window using an off-axis parabolic mirror in an optical device (made in-house) attached to an external optical port of the spectrometer. The connections between the fused-silica capillaries and the flow cell were made by a small O-ring of UV-curing epoxy adhesive on the sharply cut ends of the capillaries, allowing the capillaries to be easily replaced. Aqueous solutions comprising mixtures of adenosine, guanosine, and adenosine monophosphate were used to test the system's performance. Conventional on-line UV detection was employed to obtain reference measurements of analytes after the IR detection flow cell. The limit of FT-IR detection for all analytes (in absolute amounts) was in the nano- to picogram range corresponding to concentrations in the low-millimolar range.     

Artificial diamond as a broadband infrared beam splitter for fourier transform spectroscopy: improved results

We show that an artificially grown diamond plate with an improved surface flatness serves as an infrared beam splitter to wavelengths as short as 2.2 mum (4500 cm(-1)).