Dataset for: A Comparative Evaluation of Analytical Methods for Protein Quantification in Complex Matrices

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This dataset supports the publication "A Comparative Evaluation of Analytical Methods for Protein Quantification in Complex Matrices" by Shadmehri, N., Kayeye, T.N., Venkatesan, K., Wang, Y. and Rodger, A.

The dataset contains raw and processed analytical data from five protein quantification methods applied to commercial UHT oat, almond, soy, and bovine milk samples, as well as protein standards (BSA, γ-globulin, and α-S1-casein). The methods evaluated are: (1) amino acid profiling via UPLC-UV, (2) nitrogen-based elemental (CHNS) analysis, (3) UV-Visible spectrophotometry (A280 nm and Bradford assay), (4) Raman spectroscopy (785 nm excitation, 200–2000 cm⁻¹), and (5) attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy (650–4000 cm⁻¹). Circular dichroism (CD) spectra of protein standards with and without Bradford reagent are also included. All data were collected at the School of Natural Sciences, Macquarie University, Sydney, Australia, with the exception of amino acid profiling, which was performed at the Australian Proteome Analysis Facility (APAF), Macquarie University.

Instrumentation and data collection details are as follows:

UPLC-UV amino acid profiling was performed on a Waters Acquity (Classic) ultra-high-performance liquid chromatography system equipped with a photodiode array (PDA) detector (Waters Corporation, Milford, MA, USA). Derivatised amino acids were detected at 264 nm.

Elemental (CHNS) analysis was conducted on a vario EL cube analyser (Elementar, Langenselbold, Germany) at the Macquarie Analytical and Fabrication Facility (MAFF), Macquarie University. Samples were combusted at 970 °C in a quartz reactor and gas concentrations were quantified using frontal gas chromatography.

UV-Visible spectrophotometry (A280 nm and Bradford assay measurements) was performed on a Jasco V760 UV-Visible spectrophotometer (Jasco Corporation, Hachioji, Tokyo, Japan). Spectra were collected between 240–700 nm at 0.2 nm intervals.

Circular dichroism (CD) spectra were collected on a Jasco J-1500 CD spectropolarimeter (Jasco Corporation, Hachioji, Tokyo, Japan) in 1 mm path length quartz cuvettes, with 8 scans of 2 s digital integration time per measurement.

Raman spectra were acquired using a Snowy Range Raman system (Snowy Range Instruments, Laramie, WY, USA) with 785 nm laser excitation over the range 200–2000 cm⁻¹. Each spectrum was the average of eight scans with 10-second acquisition time.

Fourier-transform infrared (FTIR) spectroscopy was performed using two instruments: a Thermo Scientific Nicolet iS5 FT-IR Spectrometer equipped with an iD5 Attenuated Total Reflectance (ATR) accessory featuring a diamond crystal with a ZnSe lens (Thermo Fisher Scientific, Waltham, MA, USA), and a Jasco FT/IR-4700 equipped with a Jasco Single Reflection ATR (Jasco Corporation, Hachioji, Tokyo, Japan). Spectra were collected in absorbance mode from 650–4000 cm⁻¹ at 4 cm⁻¹ spectral resolution, averaging 64 scans per spectrum.