pH indicator solutions

[ChemGrrl]

SWIC has been having a difficult time of acid/base purifications.  Seems that SWIC's pH paper is insufficiently clear about when the pH is around 7 and thus is of very little use until the solution has been too acidified.  I suggested to SWIC that she investigate using some pH indicator solution in her water layer so that she would have a visual cue as to when she reached the right point.

From my old Analytical text it lloks like Bromthymol blue should work, but I wasn't about to suggest it to SWIC until I knew something about its toxicity or reactivity.  Strangely enough, I couldn't find either bit of info in the Merck Index, and the analytical text I have is not geared to clandestine drug chemists (imagine that!)

Do any bees have any more information on this, or an idea on a better pH indicator for the range 7.0-7.6?  Also, if SWIC were to use bromthymol blue in the acid/base claen-up of pseudo would any residual indicator react with the rp?I₂ or otherwise mess up the reaction (aside from the added mass when weighing the reactant.)

Any help is appreciated by SWIC.
ChemGrrl

"All I wanted was a Pepsi..."

[Rhodium]

BTB (Bromothymol blue) switches from yellow (acid) to blue (basic) in the range you describe, and is greenish in that range, as part of the indicator molecules are blue and the other part yellow at that pH.

[fierceness]

I'm not sure if you are asking this or not, but in case you arent:  Can you put some of the indicator solution into the actual solution with your E or honey without it harming your product?  And can the stuff be cleansed out later with acetone?  I was thinking of using some of the pH indicator that is found in fish/aquarium stores; I am not sure of the actual ingredient though.

[Osmium]

It's not the pH paper that isn't working. It's just that pH is -log H⁺, therefore it's nearly impossible to exactly hit 7.0, or anything close when working with small amounts.
And what is this fascination for pH 7 people have?
Strong acid + weak base will not produce a salt with pH7

[wareami]

bromthymol blue   Organic Chemistry. C₂₇H₂₈Br₂O₅S, white to yellow crystals that are soluble in alcohol and alkaline solutions and slightly soluble in water; used as an acid-base indicator (pH 6.0, yellow; pH 7.6, blue).
bromphenol blue   Organic Chemistry. C₁₉H₁₀Br₄O₅S, prisms or crystals that are slightly soluble in alcohol and benzene and slightly soluble in water; used as an acid-base indicator (pH 3.0, yellow; pH 4.6, purple

The WingNutz have always used universal indicator solution....if you can get you hands on it, it works well with one drop added to aqueous solution. The slightest pinkness indicates good to go. Since runningout of that they went to the market and picked up 4-way dip sticks that only read in the 6.8-8.0 ph range.
As for toxicity of the bromthymol solution....from the fish store.....you asked for it!
****** ANAYLTICAL SYSTEMS -- BROMTHYMOL BLUE INDICATOR SOLN, 170-S
MATERIAL SAFETY DATA SHEET
NSN: 650500N036198
Manufacturer's CAGE: 90767
Part No. Indicator: A
Part Number/Trade Name: BROMTHYMOL BLUE INDICATOR SOLN, 170-S
===========================================================================
                            General Information
===========================================================================
MSDS Serial Number: BQMQL
Hazard Characteristic Code: F5
===========================================================================
                     Ingredients/Identity Information
===========================================================================
Proprietary: NO
Ingredient: 4,4'-(3H-2,1-BENZOXATHIOL-3-YLIDENE) BIS(2-BROMO-3-METHYL-6-
(1-METHYLETHYL)-, S,S-DIOXIDE; (BROMTHYMOL BLUE)
Ingredient Sequence Number: 01
Percent: 0.1
NIOSH (RTECS) Number: SJ7450000
CAS Number: 76-59-5
OSHA PEL: NOT APPLICABLE
ACGIH TLV: NOT APPLICABLE
-------------------------------------
Proprietary: NO
Ingredient: METHANOL
Ingredient Sequence Number: 02
Percent: 20
NIOSH (RTECS) Number: PC1400000
CAS Number: 67-56-1
OSHA PEL: S,200PPM/250STEL
ACGIH TLV: S,200PPM/250STEL; 93
===========================================================================
                     Physical/Chemical Characteristics
===========================================================================
Appearance And Odor: DARK GREEN
Boiling Point: 141F,61C
Vapor Pressure (MM Hg/70 F): 97
Solubility In Water: VERY SOLUBLE
===========================================================================
                      Fire and Explosion Hazard Data
===========================================================================
Extinguishing Media: CARBON DIOXIDE OR DRY CHEMICAL FOR SMALL FIRES.
ALCOHOL OR POLYMER FOAM FOR LARGE FIRES.
Special Fire Fighting Proc: WEAR NIOSH/MSHA APPROVED SCBA AND FULL
PROTECTIVE EQUIPMENT (FP N). ADDITION OF WATER REDUCES INTENSITY OF FLAME.
Unusual Fire And Expl Hazrds: NONE SPECIFIED BY MANUFACTURER.
===========================================================================
                              Reactivity Data
===========================================================================
Stability: YES
Cond To Avoid (Stability): HEAT, SPARKS, FIRES.
Materials To Avoid: NONE SPECIFIED BY MANUFACTURER.
Hazardous Decomp Products: NONE SPECIFIED BY MANUFACTURER.
Hazardous Poly Occur: NO
Conditions To Avoid (Poly): NOT RELEVANT
===========================================================================
                            Health Hazard Data
===========================================================================
LD50-LC50 Mixture: NONE SPECIFIED BY MANUFACTURER.
Route Of Entry - Inhalation: YES
Route Of Entry - Skin: YES
Route Of Entry - Ingestion: YES
Health Haz Acute And Chronic: SWALLOWING THE LIQUID CAUSES INEBRIATION,
HEADACHE, NAUSEA AND VOMITING LEADING TO SEVERE ILLNESS, BLINDNESS AND
PERHAPS DEATH. LIQUID CAUSES EYE IRRITATION. MAY BE FATAL OR CAUSE
BLINDNESS IF SWALLOWED.
Carcinogenicity - NTP: NO
Carcinogenicity - IARC: NO
Carcinogenicity - OSHA: NO
Explanation Carcinogenicity: NOT RELEVANT
Signs/Symptoms Of Overexp: SEE HEALTH HAZARDS.
Med Cond Aggravated By Exp: NONE SPECIFIED BY MANUFACTURER.
Emergency/First Aid Proc: SKIN: FLUSH WITH PLENTY OF WATER. EYES: FLUSH
WITH PLENTY OF WATER FOR AT LEAST 15 MINUTES. GET MEDICAL CARE FOR EYES.
INGEST: INDUCE VOMITING @ ONCE. THEN GIVE 2 TABLESPOONS OF BAKING SODA & A
GLASS OF WATER. CALL A PHYSICIAN @ ONCE. INHAL: REMOVE TO FRESH AIR.
SUPPORT BRTHG (GIVE O*2/ARTF RESP) (FP N).
===========================================================================
                   Precautions for Safe Handling and Use
===========================================================================
Steps If Matl Released/Spill: FLUSH SPILLED MATERIAL WITH LARGE VOLUME OF
WATER.
Neutralizing Agent: NONE SPECIFIED BY MANUFACTURER.
Waste Disposal Method: WASH WITH WATER DOWN THE DRAIN. DISPOSE OF I/A/W
FEDERAL, STATE & LOCAL REGULATIONS (FP N).
Precautions-Handling/Storing: DO NOT LEAVE CONTAINER OPEN. AVOID PROLONGED
OR REPEATED CONTACT WITH SKIN.
Other Precautions: NONE SPECIFIED BY MANUFACTURER.
===========================================================================
                             Control Measures
===========================================================================
Respiratory Protection: USE NIOSH/MSHA APPROVED RESPIRATOR APPROPRIATE FOR
EXPOSURE OF CONCERN (FP N).
Ventilation: GEN(MECH): ACCEPTABLE. LOCAL EXHAUST: PREFERABLE.
Protective Gloves: PLASTIC GLOVES.
Eye Protection: CHEMICAL WORKERS GOGGLES (FP N).
Other Protective Equipment: IMPERVIOUS APRON & BOOTS, EYE BATH, SHOWER.
Work Hygienic Practices: NONE SPECIFIED BY MANUFACTURER.
Suppl. Safety & Health Data: NONE SPECIFIED BY MANUFACTURER.
===========================================================================
                            Transportation Data
===========================================================================
Trans Data Review Date:   93125
DOT PSN Code: JEZ
DOT Proper Shipping Name: METHANOL, OR METHYL ALCOHOL
DOT Class: 3
DOT ID Number: UN1230
DOT Pack Group: II
DOT Label: FLAMMABLE LIQUID, POISON
IMO PSN Code: JPB
IMO Proper Shipping Name: METHANOL
IMO Regulations Page Number: 3251
IMO UN Number: 1230
IMO UN Class: 3.2
IMO Subsidiary Risk Label: TOXIC
IATA PSN Code: QHQ
IATA UN ID Number: 1230
IATA Proper Shipping Name: METHANOL
IATA UN Class: 3
IATA Subsidiary Risk Class: 6.1
IATA Label: FLAMMABLE LIQUID
AFI PSN Code: QHQ
AFI Prop. Shipping Name: METHANOL OR METHYL ALCOHOL
AFI Class: 3
AFI ID Number: UN1230
AFI Pack Group: II
AFI Label: 6.1
AFI Basic Pac Ref: 7-7
===========================================================================
                               Disposal Data
===========================================================================
===========================================================================
                                Label Data
===========================================================================
Label Required: YES
Technical Review Date: 05NOV92
Label Date: 05NOV92
Label Status: G
Common Name: BROMTHYMOL BLUE INDICATOR SOLN, 170-S
Chronic Hazard: NO
Signal Word: DANGER!
Acute Health Hazard-Severe: X
Contact Hazard-Slight: X
Fire Hazard-Severe: X
Reactivity Hazard-None: X
Special Hazard Precautions: FLAMMABLE! KEEP AWAY FROM HEAT, SPARKS, OPEN
FLAME. ACUTE: LIQUID CAUSES EYE IRRITATION. INGESTION CAUSES INEBRIATION,
HEADACHE, NAUSEA, & VOMITING LEADING TO SEVERE ILLNESS, BLINDNESS, AND
DEATH. CHRONIC: NONE SPECIFIED BY MANUFACTURER.
Protect Eye: Y
Protect Skin: Y
Protect Respiratory: Y

~ß~Just Wing It!~ß~
ô¿ôWareami or «¤¿¤»Wireami

[SnoHoe]

FYI, don't dwell too much on PH (I don't measure, just throw acid in, so what if it drops super low) then recrystalize using only hot IPO and stick in freezer.  It will come out like mine!!