Problem in analyzing cystine stones using FTIR spectroscopy

Abstract

Cystine stones are produced by an inherited disorder of the transport of amino acid cystine that results in excess of cystine in the urine (cystinuria). Cystine calculi in urinary tract present a significant problem in patients. We have recorded that cystine calculi are very uncommon in our region. Cystine crystals are unusually identified in the urinary deposits. The problem of recognizing cystine by FTIR as a component in mixture of stones is significant. The problem is compounded by the similarity of wavelengths of cystine with that of whewellite and uric acid. The objective of this paper is to elucidate the problems of identifying cystine in stone analysis and identifying a solution to get over this deficiency. Out of 1,300 urinary stones analysed by ordinary wet chemical methods and infrared spectroscopy, 30 stone samples, which were reported to have cystine peaks in significant numbers, were selected. These samples were powdered, mixed with potassium bromide, pelletized and taken up for FTIR analysis. The wavelength patterns were scrutinized by comparing with the peaks obtained by the reference standards of cystine. Spectra were also obtained from pure cystine. Comparison of spectra with those of whewellite and uric acid was performed. Then the samples were taken for Scanning electron microscopy with elemental distribution analysis X-ray (SEM-EDAX). The samples were made conductive by gold sputtering and were fed into JEOL JSM 35 C SEM machine. Morphology was recorded by taking photographs. Further elemental distribution analysis (EDAX) was carried out to identify the elemental composition. Of the 30 samples taken up for FTIR analysis, all showed spectra identifiable with the reference peaks for cystine. However, when these peaks were compared with those of whewellite and uric acid, all the stone samples showed duplication of peaks for whewellite and uric acid and whewellite. The pure cystine spectra showed identifiable peaks are in the range of 3026, 1618.28, 1485, 846.75 cm(-1), etc. (from the standard spectrum of pure cystine). All the analysis findings were correlated with EDAX findings. On doing EDAX, we could separately find out the components present in a mixture. Three stones contained elemental pattern to fit with those of cystine. Even though it is difficult to find out the presence of cystine molecule in FTIR, it is possible to recognize it through EDAX and will be possible to confirm the presence of cystine in mixed urinary stones.

Characterization of Gallbladder Stones From Cholelithiasis Patients of Northern Greece, Using Complementary Techniques

“…[6] Such analytical studies, incorporating both nondestructive and destructive analytical methodologies, have been conducted worldwide, providing significant information on the formation and composition of gallbladder stones and helping physicians to take prophylactic measures for the patients. [2,3,5] Following the classification of gallbladder stones by Grunhage and Lammert, [5] there exist yellowcolored pure cholesterol stones, black pigment stones, and brown pigment stones, while Jayalakshmi et al [7] refer to three morphological classes: cholesterol, pigment, and mixed stones. Considering the above-mentioned categorization, this study focuses on characteristic bladder calculi with distinctive morphology and structure.…”

“…Urinary stones are generally composed of organic materials and inorganic crystals (mainly of calcium, phosphate, magnesium salts, oxalate, and=or uric acid). [1][2][3][4] Gallbladder stones form when the concentration of cholesterol or bilirubin exceeds the solubility in the bile salt and phospholipid-rich bile and may develop a single, often large stone or many smaller ones, even several thousands. [2,3,5] Human gallstones occur in a variety of shapes, sizes, and crystalline to amorphous structures and range in color from creamy white and yellow to black and brown.…”

Nanouric acid or nanocalcium phosphate as central nidus to induce calcium oxalate stone formation: a high-resolution transmission electron microscopy study on urinary nanocrystallites

“…13 In addition, the prominent peaks of S, C, O, and Ca were observed by EDS for cystine calculi. 12 These findings, combined with the results from FT-IR, showed that the sample contained COM and cystine.…”

“…[10][11][12][13] For instance, SEM-energy dispersive X-ray spectroscopy (EDS) was used to analyze the chemical element distribution in the surface and interior layers of CaOx stones.…”

TOF‐SIMS study of cystine and cholesterol stones

“…However, it is inadequate to analyze cystine in compounds with a mixture of calcium oxalate and uric acid because of the overlapping of characteristic absorption bands; this technique often requires the confirmation by some other complementary methods. When chemical analysis is used as a complementary technique with FTIR for cystine containing stone identification, surprisingly very low success rate (10%) was confirmed by scanning electron microscopy with energy‐dispersive X‐ray spectroscopy (SEM‐EDAX) . The confirmation with SEM‐EDAX resulting in an unanticipated cystine stone occurrence rate of 0.2% (3 out of 1300 stones), which is 5–10 times lower than the worldwide statistical data (1–2%).…”