Jim,

I must have 6 or 7 meters. There is no getting around the calibrating every now and then. It's no big deal.

Still interested?

jt

Yep. Still interested. Tell me more.

Jim

Well, well, you guys beat me to it. I was thinking all this morning "gotta get a new pH meter" as I'm not sure if the one I borrowed from my son is working right or not. I had no directions on its use.

However, now that you opened the door ----

I have a few questions.

Of course, the recent posts about pH in making sourdough starter comes to mind alright, but also other factors concerning foods and pH have sprung up since being introduced to this forum.

A short while ago, when I was trying to extract the pectin from some lime peelings, I inadvertently allowed the squeezing sac come into contact with a strainer, that apparently wasn't stainless steel. The acidity of the brew reacted on the metal, thereby making the pectin unuseable. Solution of course - buy stainless steel nonreactive strainer.

Also, this a.m., while trying to take a pH of my sourdough starter, I noted that the probe of the instrument also produced the same acidic black mark on a towel - it apparently was not a nonreactive probe on the pH meter.

I don't know how this would affect my starter but it didn't taste "off." Still from time to time, I find this acid/nonreactive sort of conflict. It also leads me on to things like cooking tomatoes in my old cast aluminum kettles (previously), and the acidic taste of the finished product.

This in turn leads me to tomatoes and the need for bottled lemon juice in order to make them acidic enough to be "safe" for canning.

I know it all sounds like it doesn't have any connection - but is it possible that we may wind up cooking and canning by a safer method - call it measuring the acidity in home canned foods with a pH meter prior to canning them.

Apparently, someone has done this when making recipes safe for home canning, hence recipes that are provided to us.

Sorry if this is rambling some, but I've been mulling this about for awhile.

I'm glad you brought up the meter posting - I'm here lurking.

Just my 2 c's.

Bejay

"...I was thinking all this morning "gotta get a new pH meter""

It's called ESP. :-)

Jim

My recommendations:

Meter

pH 4.01 buffer solution

pH 7.01 buffer solution

jt

Thanks, John. I took your advice and ordered those items. The meter includes pH 7.01 buffer solution, but it didn't say how much, so I ordered more to avoid hassles and shipping expense later.

Soon I will be able to tell you the pH of my starter.

Jim

Jim,

I'm glad you ordered. When I first started recommending this meter and online store they had I think 60+ to sell. Now with your purchase must be down to 3.

The pH buffer solutions will last you at least 2 years by expiration date & I wouldn't hesitate using for an additional year. They do go bad. I have a bottle issued to me in '93 or '94 that is way off.

When you get your meter I suggest you make a bottle/vial of salt solution to wet the meter electrode after use and before capping. This will make sense after you get I think. Just some salt and some distilled water. I don't think the concentration means all that much up to a point.

jt

I think the black stain on the towel may have been traces of nickle. Nickle reacts and will produce a black color. Aluminium usually will produce a gray color, while copper will produce a greenish blue. The pH meters I have seen usually have all glass probes, whch tend to be less reactive than any metal types. Usually a quick taste of the cutrure for an acidic/sour flavor can be done easily as your tongue knows for sure, but its not going to tell you how acidic it is in pH.

Jim,

You did the right thing in ordering the extra 3 packets. The expiration dates on the ones I got are for various months in 2011. I poured the contents of a 20 ml buffer solution packet into glass vials for storage. Just a very small amt poured into another vial is all that is needed for calibration. And I'm using that small amt twice before dumping out and pouring in fresh.

The 10 ml glass vials from American Science and Surplus are just the right size for the probe.

jt

"When you get your meter I suggest you make a bottle/vial of salt solution to wet the meter electrode after use and before capping. This will make sense after you get I think. Just some salt and some distilled water."

Meter arrived today. I think I understand. HI 70300 Storage Solution is just salty water. Right?

Jim

Jim writes: > Meter arrived today. I think I understand. HI 70300 Storage Solution is just salty water. Right?

Jim,

Yes, that is all it is.

jt

I have that exact meter. It's great. But lately the numbers have been really jumpy on the meter and it seems to lose calibration very quickly. Anyone have problems with that? I wonder if the electrode is going bad or something. Last night we were testing hot sauces and the numbers would stabilize to a certain reading but if the meter was jostled or raised out of solution and then put back in the ph would dramatically change. Also I calibrated right before we started and after testing 2 or 3 hot sauces, I decided to check the calibration solutions and the numbers were way off.
Sometimes just moving the ph meter wand in the solution will cause dramatic changes in the ph reading.
Any ideas?

kendra

On another site, in a thread about digital guitar/ukulele tuners, someone said they behaved that way when the battery started to go. It would be nice if that's the problem because the fix is easy.

Jim

Kendra,

Sounds like you have a bad electrode, but try a new battery first. Are you putting the electrode tip away wet each time? That is dipping into a salt solution before putting the cap on? I would unscrew the electrode and see if any food or liquid seeped into the connection.

Then call the company.

It's not unusual for the meter to have problems settling on a single 1 hundredth and change up and down from say pH 4.01 and 4.02, but have not experienced any worse than that.

jt

yes, i am going to try a new battery first and see if that helps. I have been putting the electrode battery away wet everytime, but there could be food or liquid seeped in. I will get a new battery tonight though and try that. I think I would have to go to radio shack or order online for the electrode.

kendra

Kendra,

I'll bet WallyWorld has that battery. Was there any warranty on your meter? I don't remember if mine came with one or not.

jt

Here is a link that might be useful: Electrode

I messed up that last post, I meant just the electrode not the electrode battery. I don't thinkthere was a warrenty, I bought off ebay but I don't remember any warrenty paperwork. I will have to look into it. I do know that periodically those electrodes do have to be replaced. I think walgreens might have the battery and I drive right by one tonight on my way home from work.

kendra

So, the battery seemed to fix the jumping numbers problem. Thanks everyone for your help.
However, how often do you calibrate your machines? Just for kicks last night, I replaced the batteries, calibrated the machine, and then tested a few vinegars and sauces. Numbers were very stable with none of the craziness of earlier. However then I thought let me check my reference solutions that I calibrated with. The 7.01 solution was reading a 6.65. I had just calibrated it 10 minutes earlier. Any ideas? Maybe bad solution?

kendra

Kendra,

Thats a pretty big difference and not one I could live with. I try to check calibration almost every time I use the meter, but only once before I start testing a batch of whatever. Sometimes I skip testing with the 7.01 solution because what I test is always 4.01 or lower. Did you get 4.01 solution?

The buffer solutions do go bad. I have a bottle that is over 10 years old and is way off. One of my old meters (exact same as the new one) can't be calibrated because I wore out the calibrating screw. The electrode is still perfect except I know reads a couple tenths high. Back to the buffer solution. Do you rinse the electrode tip after using every time? Yes. Has your buffer solution been contaminated and or diluted? I took a 20 ML packet of solution and poured equally into three 10 ML glass vials. When I calibrate I pour a very small amt into a 4th glass vial. I use this small amt for only a couple of tests and then discard. Our tap water is always very close to 7.0 and has 500 ppm minerals etc in it. Just a little bit of this water on the electrode tip could throw a small amt of solution off in a hurry. Ideally I should swirl in distilled water after rinsing with tap water.

The keeping the electrode tip wet with salt water when stored is very important too from what I remember reading way back when.

And your meter may be a dud.

jt

hmmmm...those are some good things to think about. I just ordered some replacement 7.01 and 4.01 calibration solutions although they are not expired, you never know could be a bad batch.
It is possible I am diluting the test solution but wouldn't that cause the reading to become more alkaline instead of more acidic? I don't know. I am goint to try new test solution if that doesn't work maybe new electrode. And if that doesn't work maybe new meter.
I feel pretty confident that my meter overall is reading correctly since I tested regular vinegar that came out right on and I know my hot sauces are pretty acidic since there is a fair amount of vinegar in them. But you cannot be too careful so I really want to narrow down the problem with the meter.
Thanks for all your guys' help, I really appreciate it..:)
kendra

If your diluting a solution with water, use distilled, as its pH is 7.0 so you will not offset any reading by using tap water which can vary greatly from 6 to more than 8.

I'm going to go with bad electrode. Even diluting the buffer solution should not change the pH significantly. Contaminating just might. But to change that much in 10 minutes... just doesn't compute.

Perhaps your electrode to meter body connection is bad.

I sure hate it when things don't work right.

A couple points that might be of interest. Temperature will affect readings. Since your units don't appear to have a temperature adjustment try to take all your readings at or near room temperature. Even your calibration fluids should be warmed to room temp if you store them refrigerated. Since these solutions are buffered it takes alot of contamination to change their pH.

pH elotrodes rely on ion transfer accross a membrane. If that membrane material becomes blocked you may need to rejuvinate the electrode. There are various recommendations on the web but basically you need to soak the electrode in a stronger acid for a short interval to digest the gunk from the porous membrane. This method works about 50% of the time. If the readings frequently "Drift" or are slow to reach the end reading you should consider rejuvination.

Storing the electrodes dry is one of biggest problems. I never used salt soln but the tip should be kept from drying by either keeping in a tap water vessel or putting tap water in the cover cap before reinserting it onto the electrode tip.

Some units are junk out of the box. We spent a $400 for a stainless steel unit from IQ Scientific Instr that never would give reliable readings. If you check out a source like colepalmer.com you see that they carry hundreds of electrodes for various applications. If you want better results than you can get with litmus paper then you might want to look into a credible unit.