API Publ 4670:1998 pdf download

API Publ 4670:1998 pdf download.SELECTING FIELD ANALYTICAL METHODS ADECISION-TREE APPROACH.
Product Types and Regulated Compounds
Although in the majority of spill scenarios a point source hydrocarbon product release represents the origin of contaminated soil or groundwater, it is the water-soluble hydrocarbon fraction transported in groundwater that poses the greatest risk to the environment and human health. Of the water-soluble fraction, those compounds with the highest confirmed or suspected toxicity require the highest degree of attention and more precise and sophisticated analytical tools. Standards for these compounds are in the ppb to sub-ppb range. In Table 2-1 commonly regulated constituents of several product types are summarized.
Gasoline
Chemically, gasoline is predominantly a mixture of hydrocarbons containing 4 to 10 carbon atoms. Gasoline has a boiling point range of 40° to 180°C. Analytically, the total gasoline range concentration of an environmental sample is most commonly determined by its content of hydrocarbons from C to C (GRO methods—Gasoline-Range Organics) inclusive. Constituents of concern in gasoline include benzene, toluene, cthylbenzene and xylcnes, commonly reported as BTEX, and methyl-tertiary butyl ether (MTBE). Several field analytical instruments can be used to detect and quantify gasoline-derived hydrocarbons in environmental samples as summarized in Table 2-2.
DiesdfFuel Oil
Chemically, the average composition of commercial diesel or No. 2 fuel oil consists of a mixture of petroleum hydrocarbons having 13 to 25 carbon atoms. Diesel fuel has a boiling point range of 220° to 350°C. Analytically, the total diesel-range organics (DRO) concentration of an environmental sample is most commonly determined by its content of hydrocarbons from C,4, to C21, inclusive. Constituents of concern of diesel and fuel oil origin include naphthalene and lower molecular weight polynuclear aromatic hydrocarbons (PAils).
By this point in the Decision Tree process, the user has determined within Flow Chart Step Two whether he/she will be selecting constituent-specific, or non-constituent specific field analytical methods. However, within these broad classes of field analytical methods there exists a wide variety of specific methodologies, with varying degrees of precision and accuracy (data quality). In Step Five, the broad classes of constituent-specific and non-constituent specific analytical methods are further refined into four categories, called Levels of Data Quality (LDQs).
LDQ is defined as the degree of sophistication of analytical data. LDQ components are:
1. The method of analysis;
2. The selected analytical instrument; and
3. The QAJQC protocol employed to validate the desired data quality.
In any given LDQ, field analytical methods and instruments are designed for similar field applications and posses comparable analytical capabilities. Factors determining the quality of analytical data for a given LDQ include the method design, the intrinsic instrument capabilities.