A method combining capillary electrophoresis (CE) and capacitively coupled contactless conductivity detection (C4D) was developed for the determination of melamine and metal ions, namely, potassium, calcium and sodium in milk. The milk samples (original samples were employed for metal ion determination and the fortified ones were used for melamine assaying) were first extracted with trichloroacetic acid and acetonitrile, and then the extracts were centrifuged. The supernatants from the melamine-fortified samples were further treated with solid phase extraction before CE assay. CE separation was carried out in a 50 m50 cm capillary with 20 mmol/L lactic acid as background electrolyte, the detection limits of K+, Ca2+, Na+ were in the range of 0.009-0.040 g/g and those of melanine were in the range of 0.10-0.20 g/g for the standard solution and milk sample, respectively

What is contactless conductivity and why is it used in this analysis?

0 mL of milk is extracted by adding 5.0 mL of acetic acid and acetonitrile and 8mL of supernatant is removed following centrifugation to separate out the cream. Then the 8mL supernatant is extracted by SPE and eluted with 2mL of 20% methanol water. The extraction produces 90% recovery. 100uL is injected on the CE producing a peak of 200mVs. A 100uL sample of melamine standard injected by CE of 12 ug/g produced a peak of 150mVs. What is the concentration of the sample?

I think its supposed to maybe say 10 mL extracted, but not sure, bc its written as 0 on the orginal document