A solution-based inductively coupled plasma optical emission spectrometric (ICP-OES) method is described for elemental analysis with relative expanded uncertainties on the order of 0.1% relative. The single-element determinations of 64 different elements are presented, with aggregate performance results for the method and parameters for the determination of each element. The performance observed is superior to that previously reported for ICP-OES, resulting from a suite of technical strategies that exploit the strengths of contemporary spectrometers, address measurement and sample handling noise sources, and permit rugged operation with small uncertainty. Taken together, these strategies constitute high-performance ICP-OES.
BackgroundValuable information on the determinants of non-fatal stroke can be obtained from longitudinal observational cohort studies. Such studies often rely on self-reported stroke events, which are best validated with external medical evidence. The aim of this paper is to compare the information on incident non-fatal stroke events arising from different sources.MethodsWe carried out a validation of self-reported stoke events among participants in the Whitehall II Study, a large UK based cohort study (baseline sample size 10,308 men and women).Results106 stroke events were self-reported in three self-administered questionnaires between 2002 and 2009. Eight (7.5%) of these events were discarded as false positives after medical review, 66 were validated by information from the NHS Hospital Episode Statistics (HES) database in England, 16 by manual searches of hospital records alone, and 12 by letters from general practitioners alone. HES provided information on an additional (i.e. not self-reported) 47 events coded as stroke during the period 2002 to 2009 in hospitals in England among the original baseline participants. Of these, 43 participants were no longer active in the study and 4 had completed questionnaires but not reported a stroke event.ConclusionsValidating self-reported strokes in cohort studies with information from the NHS HES database was efficient and provided information on probable non-fatal stroke events among cohort members no longer in active follow-up. Manual extraction from hospital notes can provide supplementary information beyond that available in the HES discharge summary and was used to sub-type some strokes. However, the process was labour intensive. Multiple sources are needed to capture maximum information on stroke events but increasingly with hospitalisation in the acute phase of stroke, HES has an important role. Further development of HES is required to assure validity and coverage.
Background: Cyanide (CN) is a lethal toxin. Quantification in blood is necessary to indicate exposure from many sources, including food, combustion byproducts, and terrorist activity. We describe an automated procedure based on isotope-dilution gas chromatographymass spectrometry (ID GC/MS) for the accurate and rapid determination of CN in whole blood. Methods: A known amount of isotopically labeled potassium cyanide (K 13 C 15 N) was added to 0.5 g of whole blood in a headspace vial. Hydrogen cyanide was generated through the addition of phosphoric acid, and after a 5-min incubation, 0.5 mL of the headspace was injected into the GC/MS at an oven temperature of
A gravimetric method for the determination of sulfate in a sulfate solution standard by the precipitation of barium sulfate is coupled with the instrumental determination of trace sulfate and precipitate contaminants to improve the accuracy and precision of the analysis. Sulfate in a solution of potassium sulfate is separated by a reverse precipitation with barium chloride in very dilute hydrochloric acid. Coulometry, ICP-MS, and flame atomic emission spectrometry (FAES) are used to quantify the level of the contamination in the barium sulfate precipitate and the solubility loss of sulfate in the filtrate, from which correction factors are calculated.Coprecipitating contaminants contribute about 0.3% to the total precipitate mass, while the analyte lost to the filtrate contributes 0.4%. Despite the poorer precision and accuracy of instrumental methods, the over-all precision and accuracy of the sulfate determination is actually improved, since the instrumental methods are used to determine only a very small part of the analyte. The expanded uncertainty (k = 2) of the method is below 0.2% relative to the precipitate mass.
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