Reduction in positive bias in wet assays due to splashing

• US 5,958,789 A
• Filed: 07/29/1997
• Issued: 09/28/1999
• Est. Priority Date: 07/29/1997
• Status: Expired due to Term

• Current Assignee: Johnson & Johnson Clinical Diagnostics Inc. (Johnson & Johnson)
• Original Assignee: Johnson & Johnson Clinical Diagnostics Inc. (Johnson & Johnson)
• Inventors: Riall, James Daniel, Hyde, David Donald, Jacobs, Merrit Nyles
• Primary Examiner(s): Chin, Christopher L.
• Application Number:
  US08/902,463
• Time in Patent Office: 791 Days
• Field of Search: 422/63, 422/67, 422/100, 436/500, 436/510, 436/43, 436/47, 436/65, 436/815, 436/817, 436/818
• US Class Current: 436/500
• CPC Class Codes: G01N 2035/102 Preventing or detecting loss of fluid by dripping
• CPC Class Codes: G01N 2035/1034 Transferring microquantities of liquid
• CPC Class Codes: G01N 2333/59 Follicle-stimulating hormone [FSH]; Chorionic gonadotropins, e.g. HCG; Luteinising hormone [LH]; Thyroid-stimulating hormone [TSH]
• CPC Class Codes: G01N 33/5302 Apparatus specially adapted for immunological test procedures
• CPC Class Codes: G01N 33/5306 Improving reaction conditions, e.g. reduction of non-specific binding, promotion of specific binding
• CPC Class Codes: G01N 33/54366 Apparatus specially adapted for solid-phase testing
• CPC Class Codes: G01N 33/54393 Improving reaction conditions or stability, e.g. by coating or irradiation of surface, by reduction of non-specific binding, by promotion of specific binding
• CPC Class Codes: Y10S 436/815 Test for named compound or class of compounds
• CPC Class Codes: Y10S 436/817 Steroids or hormones
• CPC Class Codes: Y10S 436/818 Human chorionic gonadotropin
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/113332 with conveyance of sample along a test line in a container or rack

Abstract

A method of preventing false detection of signal due to splashing of reagent liquid used to produce such signal, when dispensing at least one such liquid from a metering tip into a second liquid, comprising the steps of: a) positioning the metering tip a predetermined distance above the upper level of the second liquid prior to dispensing the one liquid; and

b) while maintaining the distance throughout the dispensing of the one liquid, dispensing the one liquid;

wherein the predetermined distance is between about 1.0 mm and about 2.0 mm so that splashing during dispensing is reduced.

Claims

1. A method of preventing false detection of signal due to splashing of reagent liquid used to produce such signal, when dispensing at least one such liquid from a metering tip into a second liquid having an exposed upper level, comprising the steps of:

a) positioning the metering tip a predetermined distance above the upper level of the second liquid prior to dispensing the one liquid; and

b) while maintaining said distance throughout the dispensing of the one liquid, dispensing said one liquid;

wherein said predetermined distance is between about 1.0 mm and about 2.0 mm so that splashing during dispensing is reduced.

2. A method as defined in claim 1, wherein all additional liquids are dispensed into liquids already present, using said predetermined distance.

3. A method as defined in claim 1, wherein said step b) comprises dispensing said one liquid out of an orifice of about 0.5 mm diameter at a rate of about 380 μ

L per sec to further reduce splashing.

4. A method as defined in claim 1, wherein said reagent liquid is a labeled analyte-specific reagent used in a wet immunoassay.

5. A method as defined in claim 4, wherein said immunoassay is selected from the group consisting of TSH and hCG.