SPECTROSCOPY
SPECTRAL MEASUREMENTS RAPID, NON-DESTRUCTIVE A new spectrometer is ideal for pharma and more, says Rob Morris T
oday’s compact spectrometers deliver signal to noise ratio (SNR) performance, optical
resolution and acquisition speed comparable to more expensive and less flexible benchtop spectrometers. Here, we explore the absorbance linearity of the new Ocean HR2 spectrometer.
ABSORBANCE OF BOVINE SERUM ALBUMIN To evaluate the Ocean HR2, we measured nearly 30 different concentrations of 503mg bovine serum albumin (BSA) protein samples in distilled water. BSA is often used as a protein concentration standard in biochemical applications. Te setup comprised an Ocean HR2
spectrometer (190-880 nm), a deuterium light source with attenuator, a pair of 400 µm optical fibres, and a quartz cuvette in a cuvette holder. Operating software and
The Ocean HR2 spectrometer
OceanDirect, a device driver platform, completed the system. To ensure best measurement results,
we first warmed up the spectrometer and light source for 30 minutes. Light source output can change slightly until the source is in thermal equilibrium, affecting measurements. Also, as part of the sampling process,
Fig. 1. Bovine serum albumin samples absorb strongly at 280nm
we never removed the quartz cuvette from the cuvette holder, as doing so can introduce errors. Instead, we made our dilutions in the cuvette, using a disposable pipet to remove some of each sample, then mixing in the DI water, and repeating the process for each sample. Our measurements focused on the BSA absorbance peak at 280 nm (Fig. 1), which mapped to absorbance linearity of 0.999, up to 2.5 AU (Fig. 2). Tis level of performance would be beneficial in quantifying other types of protein concentration, as well as for biotechnology applications including
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