Granted Patent B2

US 12,372,539 · App. 17/408,109 · Granted Jul 29, 2025

Inventors: Zhaohui Chen (Las Flores, CA); Nigel Clarke (Vista, CA)

Assignee: Quest Diagnostics Investments LLC

G01N33/74G01N33/49G01N33/6848G01N2333/62H01J49/004

Abstract

Claims (11)

1. A method for determining the amount of insulin in a human plasma or serum sample by high resolution/high accuracy mass spectrometry, the method comprising:

(a) subjecting the sample to solid phase extraction, to form an extracted insulin sample;

(b) purifying the extracted insulin sample by high performance liquid chromatography to form a purified insulin sample;

(c) subjecting the purified insulin sample to an ionization source under acidic conditions suitable to generate a multiply charged insulin ion, wherein the multiply charged insulin ion is detectable by mass spectrometry;

(d) determining the amount of the one or more multiply charged insulin ion by high resolution/high accuracy mass spectrometry conducted at a FWHM of 10,000 or higher, and a mass accuracy of 50 ppm or less; wherein the multiply charged insulin ion is a 6+ charged insulin ion with a mass to charge ratio (m/z) of about 968.8±1.5; and

(e) using the amount of the 6+charged insulin ion to determine the amount of insulin in the sample.

2. The method of claim 1 , wherein the high resolution/high accuracy mass spectrometry is conducted at a FWHM of 15,000 or higher, and a mass accuracy of 20 ppm or less.

3. The method of claim 1 , wherein the high resolution/high accuracy mass spectrometry is conducted at a FWHM of 20,000 or higher, and a mass accuracy of 5 ppm or less.

4. The method of claim 1 , wherein the high resolution/high accuracy mass spectrometry is conducted with a high resolution/high accuracy time-of-flight (TOF) mass spectrometer.

5. The method of claim 1 , wherein the ionization source is an electrospray (ESI) ionization source.

6. The method of claim 1 , wherein the acidic conditions comprise treatment of the sample with formic acid prior to ionization.

Assignments (1)

Continuity (4)

References Cited (137)