DHA ‘Front End’ Analysis
High temperature simulated distillation methods for crude oils (ex.
ASTM D7169 *
Additionally, carbon disulfide quenches the flame ionization detector’s response while it is eluting resulting in unreliable quantitative analysis of the boiling distribution in the C4-C8 region.
If the C4-C8 region is important to you, a separate analysis of the light end portion of the crude oil sample via ultra-high resolution capillary gas chromatography (using a DHA test method) is necessary to obtain a much better representation of the boiling point curve in the interval in question. The boiling point distribution obtained from this analysis is ‘merged’ with the data produced via the high temp crude oil test method to yield a much more accurate boiling point curve for the boiling point interval in question. This is commonly referred to as ‘DHA Front End’ analysis.
Although DHA methods are used, care must be taken to eliminate the possibility of higher boiling components contained in the crude oil sample contaminating the ultra-high resolution columns used. This is accomplished through the use of a pre-fractionating inlet system*
Brochure Download
)
specify the use capillary columns with a very thin stationary phase. Unfortunately, such columns are unable to fully
separate C4-C8 components in the sample because of the effect of the carbon disulfide diluent. This results in an
unreliable boiling point distribution corresponding to the elution interval.Additionally, carbon disulfide quenches the flame ionization detector’s response while it is eluting resulting in unreliable quantitative analysis of the boiling distribution in the C4-C8 region.
If the C4-C8 region is important to you, a separate analysis of the light end portion of the crude oil sample via ultra-high resolution capillary gas chromatography (using a DHA test method) is necessary to obtain a much better representation of the boiling point curve in the interval in question. The boiling point distribution obtained from this analysis is ‘merged’ with the data produced via the high temp crude oil test method to yield a much more accurate boiling point curve for the boiling point interval in question. This is commonly referred to as ‘DHA Front End’ analysis.
Although DHA methods are used, care must be taken to eliminate the possibility of higher boiling components contained in the crude oil sample contaminating the ultra-high resolution columns used. This is accomplished through the use of a pre-fractionating inlet system*
Brochure Download
.