Reference chemical

Adopting the enantiomers of glyceraldehyde as stereo chemical reference com pounds originated with proposals made in 1906 by M A Rosanoff a chemist at New York University... 

Crop Protection Chemicals Reference (CPCR), 6th ed.. Chemical and Pharmaceutical Press, John Wiley Sons, Inc., New York, 1990. Includes brand names and product labels. 

Information about this splendid compilation came to me from a chemist, Robert Weast (1985), who was editor from 1952 until 1988... 37 years He also informed me that the creation (jointly by the American Chemical Society and the American Institute of Physics) of the Journal of Physical and Chemical Reference Data, which began publication in 1972, was encouraged by the results of a survey which indicated how widely the Rubber Bible was used. Weast describes this journal as a truly outstanding source of critically evaluated data . In saying this, he underlined the crucial role of editors and contributors critical judgment in selecting data for such compilations. David Tide, the editor of the journal, in 1989 succeeded Robert... 

Under this provision, facilities should notify the LEPC and consequently the SERC of any possible environmental release of specific chemicals. The specific chemicals referred to in SARA Title III are found on the Extremely Hazardous Substance List (40 CER 355) and the Reportable Quantity List (the Comprehensive Environmental Response, Compensation, and Liability Act [CERCLA] Section 103 [a]). 

For Threshold Limit Values (TLV) of other chemicals, refer to the American Conference of Industrial Hygienist Handbook. 

Endosulfan is sold as a mixture of two different forms of the same chemical (referred to as a- and P-endosulfan). It is a cream- to brown-colored solid that may appear crystalline or in flakes. It has a distinct odor similar to turpentine. Endosulfan does not bum. 

Sodium hydroxide is an important chemical raw material because it readily forms other chemicals (salts), that are soluble in water. It is a type of chemical referred to as a base. Bases are compounds, that react with acids to form water and a salt. 

The term fine chemicals is widely used (abused ) as a descriptor for an enormous array of chemicals produced at small scale and is frequently assumed to infer a significant added value of the product derived from the degree of complexity (number of functional groups, geometric isomers, and enantiomers) and precision in their manufacture. Whether the term fine chemicals refers to the finesse of the chemistry or to the small scale of manufacture is far from clear. However, in order to assist our discussion the following division can be adopted [2] ... 

Undesirable emissions of toxic gases may occur as a result of mixing relatively common chemicals. Refer to Table 6.4. Chemicals which are incompatible in this way must be brought into contact only under strictly controlled conditions. 

Hotop, H. and Lineberger, W.C. (1975) Binding energies in atomic negative ions. II. Journal of Physical and Chemical Reference Data, 14, 731—750. 

In 1975 the World Health Organization produced a guideline for the establishment, maintenance and distribution of chemical reference substances (WHO 1975). This document was intended to foster collaboration and harmonization of approval for the provision of reference substances by national authorities and organizations responsible for reference substances collections. This guideline was revised in 1982 (WHO 1982) and a further revision was completed more recently (WHO 1999) to take into account progress in pharmaceutical analysis. The latest guidehne defines both primary chemical reference substance and secondary chemical reference substance as follows ... 

A designated primary chemical reference substance is widely acknowledged as having appropriate qualities within a specified context, and whose value is accepted without reliance on comparison to another chemical substance. 

A secondary chemical reference substance is a substance whose characteristics are assigned and/or calibrated by comparison with a primary chemical reference substance. The extent of characterization and testing of a secondary chemical reference substance may be less extensive than for a primary chemical reference substance. This definition may apply to some substances termed Working Standards . 

It is policy of the Commission of the European Pharmacopoeia to minimize the use of reference substances/preparations since the production, maintenance and distribution of chemical reference substances is a costly and time-consuming undertaking. Therefore the decision to establish a reference substance shoidd not be taken lightly and consideration should be given to other approaches which could be adopted to avoid the use of reference substances. A number of strategies can be employed to reduce the need for reference substances. 

The procedure employed for the establishment of the chemical reference substances used in these assays has been previously published (Sandrin et al. 1997). The CRSs for the microbiological assays of antibiotics are first submitted to the chemical tests of the monograph. If the results are satisfactory, a collaborative microbiological assay is carried out, using the International Standard as calibrator. Thus, these reference substances are considered to be secondary reference substances since they are calibrated against existing standards. Potency is expressed in International Units. If an International Standard does not exist, European Pharmacopoeia Units are used. 

Fig. 5-9 Decision tree used to accept or reject results from collaborative trials to establish the potencies of antibiotics to be used as chemical reference substances for microbiological assay standards.

Implementation of this procedure precludes the necessity of giving expiry dates for these substances. However, no studies are undertaken to test the stability of the substance in opened vials or ampoules nor the substances in solution. Users of reference substances should not store solutions of chemical reference substances or opened vials. 

Since the CRSs and BRPs are officially certified by the European Pharmacopoeia Commission, which adopts the reports establishing their suitability for the intended use, it should be noted that neither certificates of analysis nor data which are not relevant to the use of the substances as defined by the Ph. Eur. monograph, are provided with the reference products or substances. Information required for the correct use of the chemical reference substance or biological reference preparation is provided. The label on the vials or ampoules gives ... 

A catalogue is issued three times a year, after each session of the European Pharmacopoeia Commission, where new and replacement batches of chemical reference substances or biological reference preparations are adopted. This catalogue indicates for each substance or preparation ... 

IPCRSs International Pharmacopoeia Chemical Reference Substances... 

European Pharmacopoeia Chemical Reference Substances Physikalisch-Technische Bundesanstalt, Germany National Task Force on RMs, India... 

Figure 2. Chemical structures of several chemicals referred to in the text ...

Test 2 Examine by infrared absorption spectrophotometry, according to the general procedure (2.2.24), comparing with spectrum obtained with primaquine diphosphate Chemical Reference Substance (CRS). Examine the substance as discs prepared as follows dissolve separately 0.1 g of primaquine diphosphate and the reference substance in 5 mL of water R, add 2 mL of dilute ammonia R and 5 mL of chloroform R and shake dry the chloroform layer over 0.5 g of anhydrous sodium sulfate R prepare a blank disc using about 0.3 g of potassium bromide R, apply dropwise to the disc 0.1 mL of the chloroform layer, allowing the chloroform to evaporate between applications dry the disc at 50 °C for 2 min. 

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