# US 5,344,637 A · Use of saturated, ring-containing compounds as clearing solvents in histologic procedures

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- Number: US 5,344,637 A
- Document ID: US5344637A
- Status: Granted
- Kind: A
- Application number: 08/069,718
- Filed: 1993-06-01
- Granted: 1994-09-06
- Earliest claimed: 1993-06-01
- Inventors: Gerald W. Camiener
- Web page: https://patentgrep.com/patent/US5344637A

## CPC

- G01N 1/34: Purifying; Cleaning {(processes or apparatus for extracting or separating nucleic acids from biological samples C12N15/1003)}
- G01N 1/36: Embedding or analogous mounting of samples
- G01N 2001/4061: {Solvent extraction}
- 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)

## Abstract

A method of using saturated organic ring-containing compounds as clearing solvents for biological materials is described. The clearing solvents are equally effective or superior to conventional clearing solvents but they lack the toxic and noxious characteristics of conventional clearing solvents. The clearing solvents are used to replace the alcohol and/or other dehydrants in fixed biological materials and to remove wax from wax-imbedded biological materials.

## Claims

### Claim 1

A method of preparing biological material for microscopic examination, comprising contacting said biological material with a clearing solvent to remove alcohol and/or other dehydrants contained in the biological material or to remove wax contained in the biological material, wherein the clearing solvent consists essentially of from 5% to 100% by weight of a compound or combination of compounds having a higher flashpoint than xylene which is selected from the group consisting of unsubstituted and substituted saturated, organic ring-containing compounds, hydrogenated aromatic petroleum distillates, and combinations thereof.

### Claim 2 (depends on 1)

The method of claim 1 wherein the clearing solvent is an organic ring-containing compound selected from the group consisting of unsubstituted and substituted cyclopentane, cyclopentene, cyclohexane and cyclohexene.

### Claim 3 (depends on 2)

The method of claim 2 wherein the substituents are selected from the group consisting of straight and branched chain alkyl and alkenyl groups having 1 to 10 carbon atoms and halogen groups.

### Claim 4 (depends on 1)

The method of claim 1 wherein the clearing solvent is an organic ring-containing compound selected from the group consisting of cyclopentane, cyclopentene, cyclohexane and cyclohexene which is itself substituted with an organic ring-containing compound selected from the group consisting of unsubstituted and substituted cyclopentane, cyclopentene, cyclohexane and cyclohexene.

### Claim 5 (depends on 1)

The method of claim 1 wherein the clearing solvent is an organic ring-containing compound selected from the group consisting of unsubstituted and substituted saturated forms of biphenyl, naphthalene, quinoline, isoquinoline, acenaphthene, and cyclopentadiene.

### Claim 6 (depends on 1)

The method of claim 1 wherein the dewaxing agent is an organic ring-containing compound selected from the group consisting of unsubstituted and substituted saturated forms of fluorene, phenanthrene, anthracene, p-terphenyl fluoranthene, pyrene and chrysene.

### Claim 7 (depends on 1, 2)

The method of claim 1 wherein the dewaxing agent is an organic ring-containing compound selected from the group consisting of acids derived from the compounds listed in claim 2.

### Claim 8 (depends on 7)

The method of claim 7 wherein the dewaxing agent is selected from the group consisting of cyclopentanecarboxylic acid, cyclopentylacetic acid, alkyl-substituted cyclopentyl formic acid, alkyl-substituted cyclopentenyl formic acid, alkyl-substituted cyclohexyl formic acid, alkyl-substituted cyclohexenyl formic acid, alkenyl-substituted cyclopentyl formic acid, alkenyl-substituted cyclopentenyl formic acid, alkenyl-substituted cyclohexyl formic acid, alkenyl-substituted cyclohexenyl formic acid, alkyl-substituted cyclopentyl acetic acid, alkyl-substituted cyclopentenyl acetic acid, alkenyl-substituted cyclohexyl acetic acid, alkyl-substituted cyclohexenyl acetic acid, alkenyl-substituted cyclopentyl acetic acid, alkenyl-substituted acid, and alkenyl-substituted cyclohexenyl acetic acid.

### Claim 9 (depends on 1)

The method of claim 1 wherein the dewaxing agent is an organic ring-containing compound selected from the group consisting of nitrogen and/or sulfur containing ring compounds.

### Claim 10 (depends on 9)

The method of claim 9 wherein the dewaxing agent is selected from the group consisting of unsubstituted and substituted saturated or partially-saturated quinoline, isoquinoline, pyridine, indole, acridine, carbazole, tetramethylene and pentamethylene sulfides.

### Claim 11 (depends on 1)

The method of claim 1 wherein the clearing solvent is prepared by distilling a mixture of saturated and unsaturated organic ring-containing compounds and selecting distillation fractions that have higher percentages by weight of saturated organic ring-containing compounds compared to the starting mixture.