Cary 60 - high zero value at initialisation

Hello Guys, i hope you are doing well.

I have a question regarding a Cary 60. This instrument is 6 years old and it is used routinely in the lab. I see this instrument have a high value for the zero when it is initialized; once it is turned on, and finish the sequence, there is a value -1.1 Abs in the upper left corner (which is inusually high in my opinion). If i press the "Zero" button within the app Concentration, the instrument corrects this and i can "work" with it but i know this is not correct for example for low readings measurements or high absorbing samples.

In the other hand, i tried to optimize the lamp, and i cannot get more than 3.5%T with this lamp. Also, i have a spare one (new) and the results are the same. I think the light is missing somewhere between the Lamp exit and the entrance slit but i have not tested yet. With zero order, i can see the white light spot coming into the sample compartment just in the middle of the cell as should. so i think the light is reaching both reference and sample detectors. 

I´m concerned about the high absorbance reading at the initialisation. I just though about the beamsplitter but not sure because this part is fixed. maybe the beam is not 50/50 reaching the Ref/sample and causing what i describe.

Another thing i see is that when doing IPT, the flatness baseline is "jumping" and making the test to fail. I have checked the Gear Segment and looks ok and no gap between this and the Motor Pinion.

I´m looking for some suggestions about this issue. I know this instrument is simple and reliable but this is the first time this happens with this kind of instrument.

I think that performing "Optical Alignment" from Diagnostics software will help. 

Any comment is welcome. If you need any image related, i can post it. 

  • Hi,

    Thank you for question. You are observing a high negative Abs value. This indicates that there is more light reaching the detector since you last zeroed the instrument.  This may be expected if you zero using a cuvette and matrix that is at 1 Abs. Then, when you turn the instrument on it is still subtracting the previous zero value despite there being no sample in the beam path.

    However, if you are still concerned that there might be an issue with your optical path that is causing the issue, please contact your local Technical Support team (Contact Us | Agilent).

    Best Regards,

    Andrew Coukouma

  • Hi Andrew, Thanks for the reply. Once the instrument is zeroed (with anything within sample compartment), If I read "air" or water or a reagent blank, the result is a High negative value.

    Please, see the attached picture.

    I Will take some actions to troubleshoot this and let you know how it is going.

    Thanks, 

Was this helpful?