Bisirat Araya

Infrared spectra were collected on an FT-IR spectrometer equipped with the Harrick DiaMaxATR™ single-reflection high-throughput diamond ATR accessory (see Figure 1). The system was purged to remove water vapor and CO

 resolution and the signal was averaged over 16 scans. The spectra were referenced to the clean ATR crystal.


The sample used here was Easy-Off™ Heavy Duty Oven Cleaner (Reckitt Benckiser). Two drops of the oven cleaner were placed on the center of the ATR crystal and spectra were collected at 20 scans per s over a period of 60 min.


Figure 2 shows the series of FT-IR spectra acquired over the period of 60 min, showing water evaporating from the oven cleaner and concentrating the remaining ingredients. The MSDS for the oven cleaner indicates that it is composed of 2-(2-Butoxyethoxy)ethanol, 2-amino-ethanol, sodium hydroxide, and liquefied petroleum gases. As it dries, the OH stretching and bending vibrations around 3300 and 1645 cm

 respectively decrease, showing the evaporation of water present with sodium hydroxide. The bands at 2958, 2930, 2862, and 2800 cm

, due to CH stretches, increase as the oven cleaner becomes more concentrated, as do the amine bands at 1658 and 1590 cm

. Presumably the volatile petroleum components are also evaporating. But the decrease in the volatile organics is more difficult to discern, due to the increased concentration of the nonvolatile compounds. Note that the rate at which the oven cleaner concentrates could be measured by looking at peak areas, as demonstrated by the inset graph for the C=C transition at 1000 cm

 ATR spectra of oven cleaner over time. The arrow indicates increasing time, and the inset shows the change in concentration of C=C species with time.

Because diamond is a more chemically durable material, it can be effectively used as an ATR crystal for some corrosive samples. This has been demonstrated here using the Harrick DiaMaxATR to measure the ATR spectra of oven cleaner, as it becomes increasingly concentrated due to evaporation of the solvent therein.


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Articles

Because of their corrosive properties, corrosive lipids are challenging to analyze by ATR-FT-IR. Repeated and prolonged analysis can damage many ATR crystals. Diamond ATR is a better choice for such applications than other ATR crystal materials like ZnSe and Ge. This application note examines a corrosive liquid as it becomes progressively more concentrated using diamond ATR.


Bisirat Araya

Articles

A Corrosive Liquid Investigated by Diamond ATR Infrared Spectroscopy