Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: libyana on June 28, 2007, 06:56:51 AM
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HI EVERY BODY :
I AM FOOD CHEMIST AND I HAVE A NEW INSTRUMENT FOR PROTIEN DETERMINATION ( Kjeltec™ 2200 Auto Distillation Unit ) FROM FOSS CAMPANY AND I WANT ANY ONE HAS THE SAME INSTUMENT PLEASE CONTANT ME . BECOUSE I HAVE SOME PROPLEMS .
THANX FOR ALL.
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I have the 2300 model, but I´m not an expert. I just prepared the calibration curve and run some measurements of N-NH3 in clean water.
If the problem is simple, perhaps I can help you.
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hi tripton
thank you for your reply and my question is do you work in food samples for example milk, meat, ...etc .? and how can you make calibration for this instrument ?
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Hi Libyana,
I didn´t work with food samples. I just measure some water samples. Probably the conc. in my samples was very low in comparison with food samples. My calibration curve works from 0,5 to 20 mg/L of N-NH3.
I prepared the calibration curve with ammonium chloride stock solution. Then I used about six dilutions to prepare the calibration curve. The equipment give you the HCl ml but you must calculate the concentrations by yourself (or with the PC) using the calibration curve.
I used HCl 0,05N but you can change it depending of the ammonium range (if you expect higer N concentrations you can increase the HCl conc.). Of course, you must know the HCl factor every time you prepare new solution.
I developed my own method to prepare the receiving solution. I used bromocresol green, methyl red and boric acid. Then I add NaOH slowly until reach the final color. The NaOH improves the balnks readings. Probably you will find some procedure in the operation manual. Anyway, I run a new calibration curve with each new batch of receiving solution.
I hope it helps,
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HI tripton
thank you for your information .i use my instrument in food analysis but really your information that you send me very important . i have small quistion here .
the digestion tubes in my instroment only (100 ml ) and when i read manual book the analysis method sys only for (250 ml ) so i can not (do not know ) put the exactly amount for the samples,dlution water ,alkaline,and sulphuric acid .
please if you have idea tell me .and thank you for your cooperatio .
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I haven´t experience using the digestion system. As I measured N-NH3 but not NTK I never used this part of the system.
I don´t know if you must do the method exactly as the procedure (250ml), but perhaps you must adapt it to work with 100ml using less sample and proportional amounts of each reagent. If you must fit the method requeriments, perhaps you must validate the adapted method.
At my laboratory we have the diggestion system but nobody use it nowdays. I remember some time ago, a fellow has some strong reaction with the diggestor and digestion solution was spilled out of the reactors. I don´t know if there was some human mistake or not, but my suggestion is to work carefully with the digestors (glasses, gloves, protection). This person is not working with me nowdays to ask him about. I will try to ask to other person who perhaps used it but it may take me some time, and I´m not sure if I can contact him.
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DEAR tripton
i have some problem with my instrument can you help me . thank you so much