RESUMEN
Lithium carbonate (Li2CO3) is a critical raw material in cathode material production, a core of Li-ion battery manufacturing. The quality of this material significantly influences its market value, with impurities potentially affecting Li-ion battery performance and longevity. While the importance of impurity analysis is acknowledged by suppliers and manufacturers of battery materials, reports on elemental analysis of trace impurities in Li2CO3 salt are scarce. This study aims to establish and validate an analytical methodology for detecting and quantifying trace impurities in Li2CO3 salt. Various analytical techniques, including X-ray diffraction (XRD), scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDX), X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma optical emission spectroscopy (ICP-OES), were employed to analyze synthetic and processed lithium salt. X-ray diffraction patterns of Li2CO3 were collected via step-scanning mode in the 5-80° 2θ range. SEM-EDX was utilized for particle morphology and quantitative impurity analysis, with samples localized on copper tape. XPS equipped with a hemispherical electron analyzer was employed to analyze the surface composition of the salt. For ICP-OES analysis, a known amount of lithium salt was subjected to acid digestion and dilution with ultrapure water. Multielemental standard solutions were prepared, including elements such as Al, Cd, Cu, Fe, Mn, Ni, Pb, Si, Zn, Ca, K, Mg, Na, and S. Results confirmed the presence of the zabuyelite phase in XRD analysis, corresponding to the natural form of lithium carbonate. SEM-EDX mapping revealed impurities of Si and Al, with low relative quantification values of 0.12% and 0.14%, respectively. XPS identified eight potential impurity elements, including S, Cr, Fe, Cl, F, Zn, Mg, and Na, alongside Li, O, and C. Regarding ICP-OES analysis, performance parameters such as linearity, limit of detection (LOD), and quantification (LOQ), variance, and recovery were evaluated for analytical validation. ICP-OES results demonstrated high linearity (>0.99), with LOD and LOQ values ranging from 0.001 to 0.800 ppm and 0.003 to 1.1 ppm, respectively, for different elements. The recovery rate exceeded 90%. In conclusion, the precision of the new ICP-OES methodology renders it suitable for identifying and characterizing Li2CO3 impurities. It can effectively complement solid-state techniques such as XRD, SEM-EDX, and XPS.
RESUMEN
OBJECTIVES: The primary objective of this study was to compare the use of opioid infusions to that proposed in guidelines published in an in-house medication handbook. Secondary objectives were to assess the documented use of a standardized neonatal pain assessment tool and to describe the supplemental use of opioids concurrent with an opioid infusion. METHODS: A retrospective chart review was performed for all patients in the NICU who received opioid infusions between November 1, 2005, and November 30, 2006. Data collected included patient characteristics, opioid infusion dosing and duration, supplemental opioid use, and pain assessment documentation. RESULTS: Of the110 neonates who received morphine or fentanyl during the study period, 65 patients met inclusion criteria. Reasons for starting an opioid infusion included nonsurgical sedation and/or analgesia (51%), postoperative pain (17%), and procedural pain (1%). No reason was documented for 31% of patients. Thirtyeight percent of neonates received a loading dose of opioid before initiation of the infusion. The median dose was 100 mcg/kg (IQR=48.2) for morphine and and 1 mcg/kg (IQR=0.8) for fentanyl. The mean ± SD starting rates of morphine and fentanyl infusions were 12.3 ± 4.7 mcg/kg/hr and 1.5 ± 1.7 mcg/kg/hr, respectively. Supplemental opioid doses were given to 46% of neonates during the infusion period. Supplemental doses were given for procedures (69%) and pain/agitation/sedation (26%). No reason was documented for 5% of patients. The Neonatal Pain, Agitation and Sedation Scale scores were only documented 9% of the time for each day that the patient received an opioid infusion. CONCLUSIONS: Dosing of opioids generally was within the recommendations that are described in the in-house medication handbook. A substantial percentage of neonates received supplemental opioid doses while on opioid infusions, mostly for procedural pain management. Documentation of the reason for using opioid infusions and the assessment of neonatal pain was poor.
