Using the Zambelli Method to Determine Nitrite Concentration

In a recent study published in Spectrochimica Acta Part B: Atomic Spectroscopy, researchers presented a method for the determination of nitrite within a non-linear range (1). This method overcomes some of the limitations of previously reported methods by offering improved accuracy and an expanded range.

Isoamyl nitrite molecular structure isolated on white | Image Credit: © vitanovski - stock.adobe.com

Detecting nitrite is important for many reasons. As a compound often found in various industrial and environmental contexts, nitrite is known for its toxicity to both human health and environmental ecosystems. Traditionally, techniques for quantifying nitrite concentrations were confined to the linear range, limiting their effectiveness in accurately representing a wider spectrum of values (1).

In this study, the researchers used what they termed the Zambelli method and combined it with UV-visible (UV-vis) absorption spectra and correlated component regression (CCR) to expand the range of accurate nitrite concentration determination. This method covered a range of 0.27–11.34 ppm, which far exceeded the ranges of other methods (1). The researchers also employed a wavelength selection strategy in conjunction with partial least squares (PLS) before implementing CCR to enhance the accuracy of their model (1).

The experimentation of this method involved preprocessing the spectral data using standard normal variant (SNV) and Savitzky-Golay (SG) techniques. Employing a backward selection (BS) strategy alongside PLS, the researchers identified the 15 most sensitive wavelengths (1).

Subsequently, a CCR model was established utilizing the 15 selected wavelengths and the actual nitrite concentrations (1). The outcomes displayed a strong correlation between predicted and measured nitrite values with an R²_C of 0.9996, RMSE_C of 4.7491E-15, RMSE_CV of 0.0004, and a minimal mean absolute percentage error (MAPE) of 0.68% (1).

The researchers validated the accuracy of their method through an exhaustive accuracy profile. Notably, the profile demonstrated that 80% of future results will fall within the stringent 10% acceptability limit, signifying the method's reliability (1). This validation range spanned from 1.30 to 8.83 mg/L, further underscoring the versatility and precision of the proposed method (1).

This study opens new avenues for accurately determining nitrite concentration. Because this new approach offers improved accuracy and expanded range, it can enable more comprehensive assessments of nitrite-related risks and impacts across various industries and environmental settings.

Reference

(1) Nini, M.; Khoumri, E.-M.; Layachi, O. A.; Nohair, M. Utilization of ultraviolet-visible spectrophotometry in conjunction with wrapper method and correlated component regression for nitrite prediction outside the Beer–Lambert domain. J. Chemom. 2023, ASAP. DOI: 10.1002/cem.3502