【求助】新手初级问题：样品的取样问题。

你在操作的时候,没有设置好工作曲线的单位,浓度设置为ug/l或ng/mL等．你可以将ＰＰＭ换成ug/l或ng/mL后在计算．用测定结果乘试液体积除以样品质量就可以了．计算过程中注意单位！

PPM最好不用,液体用mg/L,ug/ml,ng/L等,固体用质量百分数或每百万份含多少.

哇，你们的口服液的As含量控制在2ppm？那还是少喝你们的口服液为好啊。什么牌子的？
Never try to convert units in soil from mg/kg into mg/L。的意思估计是叫你用质量浓度来表示控制物质的含量。要求你用mg/kg来表示，而不要用mg/L来表示。
那就是说你应该先抽取100mLaliquot of well-mixed sample的样品，然后从中取样液2g，再用1-3 ml 的酸（HNO3+/HCL+HNO3/+H2SO4）来消解。在定容。
最后转换样液浓度为样品的质量浓度。即由mg/L转为mg/kg
你按公式：r=(Co*V)*d/M来算出浓度
Co:样液浓度
V:定容体积
d:稀释倍数
M:称样的质量

說不定是單位弄錯誤了啦。。

暴露了卫生内控指标啊。

Thanks for all the replies.
Just want to clarify why high metal concentration: By FDA regulation, the Arsenic/Lead/Mercury concentration in all our the finished products should be NO More Than 1-2 ppm. We are the official vendors for the petsmart. So Do not worry about our company's product.

This afternoon, I used the vapor generation technique to detect the final Arsenic concentration in the preblend products by using following parameters:
Wavelength 193.7 nm
SBW 0.2 nm
Lamp Current 10mA
Acid Channel 10 M HCI
NaBH4 Channel 0.6% NaBH4; 0.5% NaOH,10% KI

The final concentration is 73 ug/L ( should be 73 ppb, am I right?)

But in fact, in the lab for the routine testing, we just use the AAS as a method of quality control by detecting the heavy metals: if NMT (No more than) 1-2 ppm, pass. if lager than 1-2 PPM, need to re-sample and re-package our product. The lab needs to develop a fast method to meet the requirement of manufacture section. That maybe a compromise for production of pets food.

Thanks for your reply. according SOPs, I should use the units: mg/kg , mg/L,g/kg ,g/L, not the ppm,ppb in solid sample.
Best

哇塞，楼上都是高手啊。。。呵呵

是啊，都是高手，学习了

是的啊，换算起来很不方便啊