Evaluation of X-ray fluorescence spectroscopy as a method for the rapid and direct determination of sodium in cheese

Abstract

Cheese manufacturers indirectly determine Na in cheese by analysis of Cl using the Volhard method, assuming that all Cl came from NaCl. This method overestimates the actual Na content in cheeses when Na replacers (e.g., KCl) are used. A direct and rapid method for Na detection is needed. X-ray fluorescence spectroscopy (XRF), a mineral analysis technique used in the mining industry, was investigated as an alternative method of Na detection in cheese. An XRF method for the detection of Na in cheese was developed and compared with inductively coupled plasma optical emission spectroscopy (ICP-OES; the reference method for Na in cheese) and Cl analyzer. Sodium quantification was performed by multi-point calibration with cheese standards spiked with NaCl ranging from 0 to 4% Na (wt/wt). The Na concentration of each of the cheese standards (discs: 30mm×7mm) was quantified by the 3 methods. A single laboratory method validation was performed; linearity, precision, limit of detection, and limit of quantification were determined. An additional calibration graph was created using cheese standards made from natural or process cheeses manufactured with different ratios of Na:K. Both Na and K calibration curves were linear for the cheese standards. Sodium was quantified in a variety of commercial cheese samples. The Na data obtained by XRF were in agreement with those from ICP-OES and Cl analyzer for most commercial natural cheeses. The XRF method did not accurately determine Na concentration for several process cheese samples, compared with ICP-OES, likely due to the use of unknown types of Na-based emulsifying salts (ES). When a calibration curve was created for process cheese with the specific types of ES used for this cheese, Na content was successfully predicted in the samples. For natural cheeses, the limit of detection and limit of quantification for Na that can be determined with an acceptable level of repeatability, precision, and trueness was 82 and 246mg/100g of cheese, respectively. Calibration graphs should be created with standards that reflect the concentration range, ratio, and salt type present in the cheeses. This XRF method can be successfully used for the rapid and direct measurement of Na content in a wide variety of natural cheeses. Commercial process cheese manufacturers use proprietary blends of ES. We did find that the XRF technique worked for process cheese when the calibration graphs were created with the specific types of ES actually used.

Rapid analysis of Na, Mg, Ca, Fe, and Zn in breakfast cereals (granola type) by energy dispersive‐X‐ray fluorescence

“…The sample preparation is similar to those used in previous studies . Pellets (32‐mm diameter) were prepared using 6 g +/−0.1 g of homogenized powder pressed with under 10 to 17 tons, using a benchtop electro hydraulic press (max.…”

“…The technique of X‐ray fluorescence analysis (XRF) has been previously shown as fit for purpose for elemental analysis of a wide range of organic and inorganic samples. Although initial applications for the technique were predominately in geology, mining, and manufacturing, Energy dispersive‐X‐ray fluorescence (ED‐XRF) is now a well spread in food industry for easy and rapid measurement of major elements and/or trace elements in many different matrices such as infant cereals, milk based powders, cocoa powder drinks, cheese, pet food, and rice . Contrary to reference methods like atomic absorption spectrophotometry (AAS) and inductively coupled plasma‐atomic emission spectrometry (ICP‐AES), ED‐XRF technique is not destructive.…”

Cancer Salt Nostalgia

“…All these methods report data from wet tissue or dry tissue measurement with varying levels of repeatability and reproducibility. However, all these methods require a significantly large tissue sample, of either approximately 0.5 cm in diameter or a tumor tissue volume of around 50–70 μL [ 79 , 80 , 81 , 82 , 83 ]. Further, these techniques cannot differentiate between extracellular versus intracellular sodium concentrations.…”

Energy-Dispersive X-ray (EDX) fluorescence based analysis of heavy metals in marble powder, paddy soil and rice (Oryza sativa L.) with potential health risks in District Malakand, Khyber Pakhtunkhwa, Pakistan

“…The instrumental analysis worked on the principle that each element emits secondary 'fluorescent' X-rays of typical energy when exposed to X-rays of appropriately high quanta from an X-ray tube. The energy with the intensity of these emitted X-rays is measured and used for the determination of elemental composition and its concentration in the sample through the detection system [26,27]. Generally, elements with higher atomic weight required higher energy for fluorescence emission and subsequently higher energy of fluorescence easily detects fluorescence.…”