# US 2021/0280403 A1 · Mass spectrometric determination of fatty acids

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- Number: US 2021/0280403 A1
- Document ID: US20210280403A1
- Status: Published application
- Kind: A1
- Application number: 17/328,059
- Filed: 2021-05-24
- Published: 2021-09-09
- Earliest claimed: 2011-06-22
- Assignees: Quest Diagnostics Investments Incorporated
- Applicants: Quest Diagnostics Investments Incorporated
- Inventors: Scott GOLDMAN
- Web page: https://patentgrep.com/patent/US20210280403A1

## CPC

- H01J 49/0036: {Step by step routines describing the handling of the data generated during a measurement}
- G01N 33/92: involving lipids, e.g. cholesterol {, lipoproteins, or their receptors (steroid hormones G01N33/743)}
- H01J 49/0027: {Methods for using particle spectrometers}
- H01J 49/10: Ion sources; Ion guns
- H01J 49/426: {Methods for controlling ions}
- G01N 2560/00: Chemical aspects of mass spectrometric analysis of biological material
- Y10T 436/20: Oxygen containing
- Y10T 436/200833: Carbonyl, ether, aldehyde or ketone containing
- Y10T 436/201666: Carboxylic acid
- H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H)
- 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)
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

The invention relates to the detection of fatty acids. In a particular aspect, the invention relates to methods for detecting very long chain fatty acids and branched chain fatty acids by mass spectrometry.

## Claims

### Claim 1

A method for determining an amount of one or more underivatized pristanic acid and/or phytanic acid in a sample by mass spectrometry, the method comprising:
(a) subjecting the sample containing an amount of one or more underivatized pristanic acid and/or phytanic acid to an ionization source to generate one or more underivatized pristanic acid and/or phytanic acid ions detectable by mass spectrometry;
(b) determining an amount of the one or more underivatized pristanic acid and/or phytanic acid ions by mass spectrometry; and
(c) determining the amount of the one or more underivatized pristanic acid and/or phytanic acid in the sample from the amount of the one or more underivatized pristanic acid and/or phytanic acid ions determined in step (b).

### Claim 2 (depends on 1)

The method of claim 1, further comprising determining an amount of tetracosanoic acid.

### Claim 3 (depends on 1)

The method of claim 1, further comprising determining an amount of hexacosanoic acid.

### Claim 4 (depends on 1)

The method of claim 1, wherein the ionization source is electron ionization, chemical ionization, electrospray ionization (ESI), photon ionization, photoionization, atmospheric pressure photoionization (APPI), laser diode thermal desorption (LDTD), fast atom bombardment (FAB), liquid secondary ionization (LSI), matrix assisted laser desorption ionization (MALDI), field ionization, field desorption, thermospray ionization, plasmaspray ionization, surface enhanced laser desorption ionization (SELDI), inductively coupled plasma (ICP), or particle beam ionization.

### Claim 5 (depends on 1)

The method of claim 1, wherein the sample is subjected to liquid/liquid extraction prior to ionization.

### Claim 6 (depends on 1)

The method of claim 1, wherein the one or more fatty acids are subjected to a liquid chromatography column prior to ionization.

### Claim 7 (depends on 6)

The method of claim 6, wherein the liquid chromatography column comprises a high performance liquid chromatography (HPLC), reverse phase liquid chromatography (RPLC), turbulent flow liquid chromatography (TFLC), or high turbulence liquid chromatography (HTLC).

### Claim 8 (depends on 1)

The method of claim 1, wherein the method further comprises determining an amount of the one or more internal standards added prior to step (a).

### Claim 9 (depends on 8)

The method of claim 8, wherein the internal standard is pristanic acid-2H3 phytanic acid-2H3, docosanoic acid-2H3, tetracosanoic acid-2H3, or hexacosanoic acid-2H3.

### Claim 10 (depends on 1)

A method of diagnosing or monitoring a peroxisomal disorder comprising determining an amount of one or more fatty acids in a patient sample by steps of claim 1.

### Claim 11 (depends on 10)

The method of claim 10, wherein an abnormal level of fatty acids is indicative of the peroxisomal disorder.

### Claim 12 (depends on 11)

The method of claim 11, wherein the peroxisomal disorder is Zellweger syndrome, pseudo-Zellweger syndrome, infantile and adult Refsum disease, adrenoleukodystrophy, rhizomelic chondrodysplasia punctata type 1 (RCDP-1), D-bifunctional protein deficiency, or acyl-coA oxidase deficiency.

### Claim 13 (depends on 1)

The method of claim 1, subjecting the sample to a hexane extraction.

### Claim 14 (depends on 13)

The method of claim 13, wherein the sample is subjected to an acid hydrolysis prior to ionization.