Stability of i-Stat EC6+ cartridges: effect of storage temperature on shelf life.

separate alanine and arginine clearly. This problem was solved by the addition of 2 g/L potassium perchlorate as a chaotropic agent. The detection limits for all of the dabsyl derivatives, the data for regression analysis, and other statistics are listed in Table 2 in the Data Supplement that accompanies the online version of this Technical Brief at http://www. clinchem.org/content/vol50/issue2/. The mean within-day reproducibility was 7.4%, and the mean between-day reproducibility was 5.4%. The dabsylated samples in the dilution buffer were stable for up to 48 h when stored at room temperature protected from light and remained stable for up to 1 week when stored at 4 °C. In conclusion, by adding a nonionic surfactant we were able to use precolumn derivatization of amino acids with dabsyl chloride to aid in the analysis of various amino acids and other compounds of interest in a small amount of CSF without the need for deproteination. Because our method is able to detect all of the amino acids, including the well-known NO-related compound citrulline, we believe that our method could be very useful for studying different types of pain conditions and other central nervous system diseases. Because the analysis of amino acids in CSF is not yet standardized, especially the sample collection, pretreatment, storage, and analysis steps (11, 12, 18), we hope that our report helps to improve and simplify the sample pretreatment protocols. analysis of excitatory amino acids, nitric oxide and prostaglandin E 2 in the cerebrospinal fluid of pregnant women: the effect on labor pain. Changes in the concentrations of amino acids in the cerebrospinal fluid that correlate with pain in patients with fibromyalgia: implications for nitric oxide pathways. nitric oxide pathway in chronic daily headache: evidence from cerebrospinal fluid. Appraisal of four pre-column derivatization methods for the high-performance liquid chromato-graphic determination of free amino acids in biological materials. Evaluation of liquid chromatographic analysis of nutritionally important amino acids in food and physiological samples. A fast and sensitive method for measuring picomole levels of total free amino acids in very small amounts of biological tissues. Analysis of aspartate and glutamate in human cerebrospinal fluid by high-performance liquid chromatography with automated precolumn derivatization. Measurement of glutamate, aspartate and glycine and its potential precursors in human brain using high-performance liquid chromatography by pre-column derivatization with diethylaminoazobenzene sulphonylchloride [Short Communication]. J, et al. Neurotransmitter amino acids in cerebrospinal fluid of patients with Parkinson's disease. Reference …