Newborn screening - Bad injections

<p>Hello</p><p></p><p> We work in newborn screening, studying profiles of Amino acid and acylcarnitines.</p><p>Our conditions are:</p><p>Plate 96 well with disc of paper impregnated with blood (3.2 ul), it is added with 100 ul methanol + std internal, shaking and injection 20 ul (We are not working with chromatography column).</p><p></p><p>Time(min) Flow Rate %B     %B Curve</p><p> 1. Initial       0.080     100.0    0.0      120 psi</p><p> 2. 0.15         0.020 100.0        0.0 11   50 psi</p><p> 3. 1.20         0.020 100.0       0.0 6</p><p> 4. 1.30         0.600 100.0       0.0 11</p><p> 5. 2.10         0.600 100.0       0.0 11</p><p> 6. 2.20         0.080 100.0       0.0 11</p><p> 7. 2.40         0.080 100.0      0.0 11</p><p>A: Acetonitrile + water (80/20) + 0.1 % acid formic</p><p> Injection volume: 20 ul</p><p>MRM, Mode ESI + (UPLC-TQD)</p><p> A profile is obtanined and the information was processed by Neolynx (Figure A)</p><p></p><p>In the last time, we had <strong>problems of injection</strong>. (Increasingly frecuent with time). (figure B).</p><p>The tests of the sample manager were ok but the Wash syringe static (pump A) not pass. So the Water’s technician changed the Valve manifold assembly and all sample manager’s test were ok. But today we are <strong>wrong injection</strong> (CV > 35 %) and the worse thing of all is that The <strong>quality controls</strong> <strong>went down</strong> significantly</p><p></p><p></p><p>Information:</p><p></p><p>-          Changes:  Sample needle and probe´s capillary.</p><p>-          All test is ok, Except static decay test (pump A).</p><p>-          Attached:  the profile of pressure too.</p><p>-          The method was excellent (CV < 5%) QC, ok  but today not.</p><p>-          17000 injections</p><p></p><p>Thanks Manuel</p>