# US 5,346,622 A · Hydrocarbon class separation and quantitation by split column effluent analysis > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,346,622 A - Document ID: US5346622A - Status: Granted - Kind: A - Application number: 08/026,385 - Filed: 1993-03-04 - Granted: 1994-09-13 - Earliest claimed: 1993-03-04 - Assignees: Hewlett-Packard Company - Inventors: Matthew S. Klee; Mu Z. Wang - Web page: https://patentgrep.com/patent/US5346622A ## CPC - B01D 15/08: Selective adsorption, e.g. chromatography - B01D 15/10: characterised by constructional or operational features - G01N 30/32: of pressure or speed (G01N30/36 takes precedence) - F02B 3/06: with compression ignition (compression ignition engines using air or gas for blowing fuel into compressed air in cylinder F02B13/02) - G01N 30/02: Column chromatography - G01N 30/68: Flame ionisation detectors - G01N 30/74: Optical detectors {(measurement of intensity, velocity, spectral content, polarisation, or phase of infrared, visible or ultraviolet light G01J)} - G01N 30/78: using more than one detector - G01N 33/28: Oils {, i.e. hydrocarbon liquids} (edible oils or edible fats G01N33/03) - G01N 2030/324: {speed, flow rate} - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - G01N: INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES (measuring or testing apparatus or processes other than immunoassay, involving enzymes or microorganisms C12M, C12Q) - F02B: INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL (gas-turbine plants F02C; hot-gas or combustion-product positive-displacement engine plants F02G) ## Abstract Methods of separating and classifying the relative amounts of two or more classes of hydrocarbon molecules in a sample are disclosed wherein an input stream comprising a mobile phase and the sample is injected into a chromatographic column, and an effluent stream exiting a chromatographic column is split into a first effluent stream and a second effluent stream. The mass of carbon in each of the classes of hydrocarbons in the first effluent stream is determined, preferably using a flame ionization detector, and the second effluent stream is directed through a variable restrictor, allowing the pressure and mass flow rate of the input stream to be independently controlled and improved results obtained. In a preferred embodiment the present invention also includes identifying the hydrocarbon molecules in the second effluent stream in order to verify the analysis or provide additional data, preferably by using an ultraviolet detector. The present invention is most preferably used to analyze the aromatic hydrocarbons in a sample of diesel fuel. ## Claims ### Claim 1 A method of separating and classifying the relative amounts of two or more classes of hydrocarbon molecules in a sample, comprising the steps of: injecting an input stream comprising a mobile phase and the sample into a chromatograph at predetermined conditions of pressure, temperature and flow rate; splitting an effluent stream exiting the chromatograph into a first effluent stream and a second effluent stream; determining the mass of carbon in each of the classes of hydrocarbons in the first effluent stream; directing the second effluent stream through a variable restrictor; and adjusting the variable restrictor to independently control the pressure and flow rate of the input stream. ### Claim 2 (depends on 1) The method of claim 1, wherein the mobile phase comprises a supercritical fluid. ### Claim 3 (depends on 1) The method of claim 1, wherein the step of determining the mass of carbon comprises directing the first effluent stream into a flame ionization detector. ### Claim 4 (depends on 1) The method of claim 1, further comprising the step of identifying the hydrocarbon molecules in the second effluent stream. ### Claim 5 (depends on 4) The method of claim 4, wherein the step of identifying the hydrocarbon molecules comprises directing the second effluent stream into an ultraviolet detector. ### Claim 6 (depends on 1) The method of claim 1, wherein the step of adjusting the variable restrictor comprises axially moving a pin to restrict mass flow by varying the size of an orifice. ### Claim 7 (depends on 1) The method of claim 1, wherein the step of adjusting the variable restrictor comprises selecting an orifice plate comprising a fixed orifice and inserting the orifice plate into the variable restrictor. ### Claim 8 (depends on 7) The method of claim 7, wherein the first effluent stream comprises less than 5% of the input stream. ### Claim 9 (depends on 1) The method of claim 1, wherein the step of splitting the effluent stream exiting the column creates a first effluent stream having a substantially smaller mass flow rate than the second effluent stream. ### Claim 10 (depends on 1) The method of claim 1, wherein the sample comprises diesel fuel and the classes of hydrocarbons comprise saturated and aromatic hydrocarbons.