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Use of Raman Spectroscopy, Scanning Electron Microscopy and Energy Dispersive X-ray Spectroscopy in a Multi-Technique Approach for Physical Characterization of Purple Urine Bag Syndrome

https://doi.org/10.3390/app12084034

“Purple urine bag syndrome (PUBS) is a rare condition characterized by purple discoloration of urine and urine bags. Although it is benign, it represents an alarming symptom to the patients and their relatives because of purple discoloration. We have physically characterized urine and urine bags belonging to a patient suffering from PUBS using an approach that combines Raman spectroscopy (RS) and scanning electron microscopy (SEM) coupled with energy dispersive X-ray (EDX). Five “blue” discolored bags and one sterile urine bag, representing the control, were cut into 1 cm2 square samples and analyzed by using RS and SEM + EDX technique. RS enabled us to identify the presence of indigo, a metabolite of tryptophan, while SEM analysis showed the biofilm deposit, probably due to the presence of microorganisms, and the EDX measurements exhibited the elemental composition of the bags. In particular, urine bags before and after the presence of PUBS urine showed an increase of ~32% of Cl, ~33% of O, ~667% of Ca, ~65% of Al and Mg, while C decreased by about 41%. Our results, to be taken as a proof-of-principle study, are promising for the aim to characterizing the urine bags in a flexible, inexpensive, and comprehensive manner.”

“The elemental analysis of the drainage bag was performed by the EDX of the FEI Quanta 450 FEG. As a result, an X-ray spectrum was obtained and the instrumentation gave us the elemental composition, with relative errors, in percentages as a table. In the spectrum, the peak position identifies the different elements in the sample surface, whereas its intensity allows quantitative characterization of each detected element. The analysis results were carried out according to the reference energy spectrum of the calibration included in the instrument library. Both qualitative and quantitative elemental analyses were conducted at four different points on each sample surface. The obtained results represent the mean value of four different measurements effectuated on every target sample.”

The EDX analysis was applied to detect the elemental composition of the bag both before (control) and after the use by the patient (“blue bags”). The results of the EDX analysis are reported in Table 2. EDX provides elemental data in both atomic and weight percentages automatically through the built-in software. The major components of the control bag and samples were Cl, C and O. In the sample bags Ca and P, and small traces of K, were also detected. In the “blue bag” sample, it is possible to notice an increase in the amount of chlorine, oxygen, magnesium and calcium, compared to the control one.
Table 2. Results of EDX analysis.
Element Control (abs) “Blue Bags” (abs) Control Wt [Error] (%) “Blue Bag” Wt [Error] (%)
Chlorine 25.25 33.34 16.63 [2.64] 25.17 [3.47]
Carbon 97.15 57.12 63.98 [32.64] 43.13 [20.96]
Oxygen 28.01 37.32 18.45 [10.09] 28.18 [13.12]
Sodium 1.91 1.44 [0.46]
Calcium 0.03 0.23 0.02 [0.08] 0.18 [0.10]
Potassium 0.08 0.06 [0.08]
Nickel 0.02 0.03 0.02 [0.08] 0.02 [0.08]
Aluminum 0.43 0.71 0.28 [0.14] 0.54 [0.18]
Magnesium 0.66 1.09 0.44 [0.19] 0.82 [0.26]
Phosphorus 0.19 0.14 [0.10]
Silicon 0.16 0.30 0.10 [0.10] 0.13 [0.12]
Neodymium 0.13 0.12 0.08 [0.09] 0.09 [0.09]
In particular, SEM + EDX analysis, performed on urine bags, before and after the presence of urine, showed an increase of ~32% of Cl, ~33% of O, ~667% of Ca, ~65% of Al and Mg, while C decreased by about 41%. Traces of P, Na, and K were found in the analyzed urine bag. They were probably present in the urine and deposited on the square sample of the “blue” bag surface. No variation was observed for Ni and Silicon.

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