Reagent water specification

Commission on Laboratory Inspection and Accreditation. Reagent water Specifications. Skokie, IL College of American Pathologists, 1985. 

Reagent grade chemicals, such as conforming to the ACS Specifications shall be used and water conforming to the Specifications for Reagent Water, ASTM Desigoation D1193... 

More than seven replicates may be analyzed however, all of the obtained results must be used in the calculation, unless there is a well-justified reason to discard any of them. MDLs are specific to a given matrix, method, and instrument, and greatly depend on the analyst s technique. The better the analytical precision, the lower the calculated value of the MDL. Laboratories are required to perform MDL studies at least once a year (APHA, 1998 EPA, 1999d). However, the MDLs may be determined more often if there is a change in the laboratory extraction, analysis, or instrumentation. For trace element analyses, the MDL studies are performed in reagent water only, as a metal-free solid matrix that would successfully emulate natural soils does not exist. 

Asymmetric hydrolysis has several specific advantages to offer. First of all it uses water as one of the reagents. Water is cheap, safe, and environmentally benign Second, chiral 1,2 diols are versatile building blocks for complex organic molecules. Finally, asymmetric catalytic epoxidation does not work for alkenes such as propylene. However, by this method a racemic mixture of... 

TABLE 6-6. Laboratory Reagent Grade Water Specifications"... 

In order to determine the number of histidine residues involved in zinc coordination, the L chains of TeTx and BoNT/A, B and E were modified with diethyl pyrocarbonate (DEPC), a reagent that specifically modifies histidine residues. In each case, two additional histidines were modified in the apo-toxin that were not affected in the holo-neurotoxin (Schiavo etal., 1992 b, c). These results indicate that the zinc atom of CNTs is coordinated via two histidines and a Glu-bound water molecule, as in thermolysin. Mutations at the two histidines of the motif inactivate TeTx and suppress its ability to bind radio-labeled Zn " (Yamasaki etal., 1994 b). In addition, mutations of the conserved Glu-271 and Glu-272 of TeTx, predicted to be in an a-helical segment (Lebeda and Olson, 1994), result in decreased zinc binding and loss of activity. Based on these experimental results, it has... 

The preparation of most reagents and solutions used in the clinical laboratory requires pure water. In the distant past, the term distilled has been used to mean pure, because distillation was the principal procedure used to remove the impurities that water contains in its natural state. Now there are alternative, cost effective, methods to produce pure water. In fact single-distilled water fails to meet the specifications for Type I Clmical Laboratory Reagent Water put forward by the NCCLS. ... 

Distillation is the process of vaporizing and condensing a liquid to purify or concentrate a substance or to separate a volatile substance from less volatile substances. It is the oldest method of water purification. Problems with distillation for preparing reagent water include the carryover of volatile impurities and entrapped water droplets that may contain impurities into the purified water. This will result in contamination of the distillate with volatUes, sodium, potassium, manganese, carbonates, and sulfates. As a result, water treated by distillation alone does not meet the specific conductivity requirement of type I water. 

Nitroso-R salt (formula 18.3) is a derivative of l-nitroso-2-naphthol. Both reagents are specific for cobalt. The sulphonate groups in the molecule of nitroso-R salt render this reagent and its cobalt complex soluble in water but insoluble in non-polar solvents. Hence, nitroso-R salt is used to determine cobalt spectrophotometrically in aqueous medium [29]. In acidic solution (pH 4), cobalt(Il) is oxidized to Co(IlI). 

ASTM standard specification for reagent water, designation D 1193-77 (reapproved 1983). American Society for Testing Materials, Philadelphia. 

The reagent station holds all the flasks required for the Enzygnost (R) test, in addition to a further reagent for specific assays. It can hold up to six reagent flasks, of which at least two are for the conjugate an one is for distilled water. 

The horseshoe crab Ldmulus) suffers from a disease caused by the genus Vibrio which causes fatal intravascular clotting. This observation led to the realisation that the amoebocytes collected from the haemolymph of the crab contained a reactive protein (known as LAL), which could be released by lysis in distilled water. The LAL reagent is specific for the endotoxin of Gram-negative bacteria. This endotoxin is the lipopolysaccharide (LPS) fraction, and it is the lipid portion which reacts with LAL. 

Pilot plant and service tests may be more vulnerable to unforeseen difficulties as a consequence of constraints and demands from external technical and nontechnical sources. Laboratory tests avoid some of these difficulties because there is usually more flexibility in the allocation of supplies and equipment and in the scheduling of personnel. Certain common sense practices can improve laboratory, pilot plant, and service tests. Use good quality water for the preparation of aqueous solutions (systems are available at reasonable cost that routinely supply Type 1 water) (see ASTM D 1193, Specification for Reagent Water, part 9). Provide regulated and filter power for operating critical electroitic instruments and computers. Establish a well-defined ground system for test equipment. 

Standard Test Method for Copper Strip Corrosion by Industrial Aromatic Hydrocarbons Standard Test Methods for Nonrigid Vinyl Chloride Polymer Tubing Used for Electrical Insulation Standard Practice for Substitute Ocean Water Standard Specification for Reagent Water... 

ASTM Standard. D1193-91 Standard Specification for Reagent Water, 1997. 

Prior to running a method, an analyst is often required to demonstrate proficiency in analyzing samples using the method. Many of the USEPA methods require this initial demonshation, and often project QAPs require this for a specific analysis. Sometimes special methods are developed in laboratories for several specific compounds that cannot be determined by routine methods and an IDPF is required. In the IDPF the analyst is required to spike four samples in the appropriate matrix (usually water, soil, or air) and analyze them according to the method. Usually the target analytes are spiked into a clean matrix such as laboratory reagent water or sand to minimize matrix effects. Accuracy is monitored by recoveries of the analyte and precision by the RSD. Often acceptance windows for accuracy and precision are defined in the method or the QAP. These studies... 

Purity of Water—Unless otherwise indicated, references to water shall be understood to mean reagent water as defined by Type III of Specification D 1193. 

D 86 Test Method for Distillation of Petroleum Products D1193 Specification for Reagent Water ... 

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