# US 12,761,193 B2 · Analysis method of carboxylic acid anhydride

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- Number: US 12,761,193 B2
- Document ID: US12761193B2
- Status: Granted
- Kind: B2
- Application number: 18/437,259
- Filed: 2024-02-09
- Published: 2024-08-22
- Granted: 2026-10-13
- Earliest claimed: 2023-02-10
- Assignees: Shimadzu Corporation
- Applicants: Shimadzu Corporation
- Inventors: Yusuke Masuda; Hidetoshi Terada
- Web page: https://patentgrep.com/patent/US12761193B2

## CPC

- G01N 30/88: Integrated analysis systems specially adapted therefor, not covered by a single one of the groups G01N30/04 - G01N30/86
- B01D 15/40: using supercritical fluid as mobile phase or eluent
- G01N 2030/027: {Liquid chromatography}
- G01N 2030/884: {organic compounds}
- 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)
- 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)

## Abstract

A method for analyzing a sample containing a carboxylic acid anhydride includes, in a stated order, a first step of causing the sample to pass through a column together with a first mobile phase to detect a carboxylic acid anhydride eluted from the column in supercritical fluid chromatography, and a second step of causing a second mobile phase to pass through the column by switching the mobile phase from the first mobile phase to the second mobile phase after a lapse of a retention time of the carboxylic acid anhydride to detect at least one of a carboxylic acid ester and a carboxylic acid eluted from the column. The first mobile phase is a mixture of carbon dioxide and an organic solvent having no hydroxyl group, and the second mobile phase is a mixture of carbon dioxide, an acid, and an organic solvent having a hydroxyl group.

## Claims

### Claim 1

A method for analyzing a sample containing a carboxylic acid anhydride, the method comprising, in a stated order:
a first step of causing the sample to pass through a column together with a first mobile phase to detect a carboxylic acid anhydride eluted from the column in supercritical fluid chromatography; and
a second step of causing a second mobile phase to pass through the column by switching the mobile phase from the first mobile phase to the second mobile phase after a lapse of a retention time of the carboxylic acid anhydride to detect at least one of a carboxylic acid ester and a carboxylic acid eluted from the column,
wherein
the first mobile phase is a mixture of carbon dioxide and an organic solvent having no hydroxyl group, and
the second mobile phase is a mixture of carbon dioxide, an acid, and an organic solvent having a hydroxyl group.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the acid is phosphoric acid or formic acid.

### Claim 3 (depends on 1)

The method according to claim 1, wherein
the organic solvent having no hydroxyl group is acetonitrile, and
the organic solvent having a hydroxyl group is methanol or ethanol.