油品润滑脂中不同基团吸收峰检测方案(光谱配件)

IR Spectra of Grease：PearlTM vs QuestTM f GREASES AND LUBRICANTS are important to helpmoving parts and machinery operate smoothly. Overtime， they can degrade and pick up contaminants.Therefore， we need reliable ways to inspect them andliterally keep things running smoothly. Attenuated Total Reflectance (ATR) isanestablished technique used in the IRspectral analysis of many solidand liquid samples， such asorganic polymers1 and solvated This is easy for liquids， but solids need to be pressedonto the crystal. This application note will show that The PearlTMliquid transmission accessory iss perfect formeasuring IR spectra of ‘sticky’ and relativelyimmobile liquid samples like greases and lubricantsas easily， quickly and reliably as a comparable ATRtechnique， such as with the QuestTM. Which of Specac's latest IRaccessories is more suitablefor testing grease samples? AN2 Equipment and Methods A Quest MATRfittedwithan extended rangediamond crystal puck was used to collect ATRspectra. It had an effective pathlength of 4.5 pm. The PearlTMaccessory was used】 to record IRtransmission spectra via its Oyster Cell with wedgedZnSe windows and a 50 pm pathlength (P/NGS31221). DuPont Krytox Gpl205 and Castrol LM greaseswere tested；<1 ml of sample without dilution. The spectra were recorded with a 1 cm1 in an FTIRspectrometer. Their absorbance traces are shown inFigures 1 and 2 respectively. For the QuestM， the samples were spread over adiamondcrystal. For the PearlTM， the greases were spread on thebottom ZnSe window of the Oyster Cell. The sample introduction， spectral data acquisitionand subsequent clean-up were all quick and easydue to the design of both the QuestTM and thePearlTM Results and Discussions Figure 1 shows the IR absorption spectrum from3600 -600 cm-of Castrol LM grease recorded withboth the QuestTM ATR and the PearlTM. The two techniques capture the same peaks but withdifferent resolution. Figure 1： Castrol LM grease spectrum， PearlTM vs QuestTM The clearest difference is the stronger absorption oflight at 2900 cm in the PearlTM. Another key observation is that the signal intensity inthe PearlTM is 10 times stronger than that recorded inthe ATR， reflecting the ~10 times longer pathlength. Figure 2 shows a similar comparison for the Krytoxlubricant. In both figures， the weaker absorption bands， suchas those that lie within the 500 -1500 cm-1fingerprintregion， appear more intense when measured usingthe PearlTM accessory. A Ge puckcan be usedinstead of diamond in theQuestTM ATR to give alesser depth of IR beampenetration. This woulddecrease the effective pathlength Ssuecac Pea in the ATR measurement and the sample absorbance. Figure 2： DuPont Krytox spectrum， PearlTM vs QuestIM Conclusion IR absorption spectra for fairly immobile greases wererecorded using the QuestM ATR and the PearlTM liquidtransmission accessory. The spectral features recorded in the QuestTM werequite weak because the ATR technique provides muchshorter pre-defined effective pathlengths that aredependent on a sample contact effect with the ATRcrystal and the incident angles being used. Conversely， the spectra were amplified using thePearlTM， which offers a longer pathlength. This means that vibrational modes att1largerwavenumber， such as -OH or-NH molecular stretchingvibrations， can be more readily identified by thistransmission technique rather than the ATR alternative. The PearlTM offers greaterspectral resolution.27 Overall the PearlTM offers greater spectral resolution，even for samples which weakly absorb in the IR. There is also no need for a complicated spectralintensity correction with the PearlTM. Furthermore， thepathlength can be easily controlled and determinedin the PearlTM，unlike in the QuestTM. The PearlTM and QuestM are available in various colours. Nevertheless， ATR is a very reliable and fast methodand perfect when only a small amount of sample ispresent and absorbs strongly in the IR. Email sales@specac.com or visit www.specac.com References [1] Blanc， F， Blanc， Chong， S.Y.，McDonald， T.O.， Adams， D.J.，Pawsey，S.， Caporini， M.A.， Cooper， A.l.， Dynamic NuclearPolarization NMR Spectroscopy Allows High-ThroughputCharacterization of Microporous Organic Polymers. J. Am.Chem. Soc. 135， 14，15290-15293(2013). [2] Boulet-Audet， M.， Byrne， B.， Kazarian， S.G.， High-Throughput Themmal Stability Analysis of a MonoclonalAntibody by Attenuated Total Reflection FT-IRSpectroscopic Imaging. Anal. Chem. 86， 9786 (2014). PearlTM Wedged Lower Windows CaF2 ZnSe 25 um GS31326 GS31226 50 pm GS31321 GS31221 100 pm GS31322 GS31222 200 pm GS31323 GS31223 500 pm GS31324 GS31224 1000 pm GS31325 GS31225 Did you know parallel windows are also available? QuestTM ATR Models Diamond i ZnSe Ge Standard GS10800 GS10802 GS10803 Extended Range GS10801 N/A N/A Volatiles Cover Part Number Purge Bellows GS10707 Steel Flat Anvil GS10820 Steel Pellet Anvil GS10821          采用新型pearl 透射液体池与传统的ATR方法检测润滑脂做了比较，采用了杜邦以及嘉实多的润滑脂作为样品进行分析。      pearl 珍珠池采用一滴或注入式方式进行 测试，方便，快捷，特别是在测试油品方面，粘稠物质方面，不需要再组装样品池，添加氟油等繁琐工作，直接一滴即可测试。原来采用透射方式满足国标。     此次测试的检测结果信号大幅度增强，在高波数范围的振动，如-OH以及-NH 的伸缩振动增强，比传统的ATR衰减全反射的测试结果更加明显，谱图更加清晰。