DEPOSITION PRINTER WITH GRAVIMETRIC CALIBRATION

AMENDMENT I: The purpose of this amendment is to provide answers to questions received regarding Acceptance testing and Installation as follows: Question on Acceptance Test no.1: 1. Using a 1 M solution of nitric acid in water, average drop mass will be measured using the burst-mode gravimetric method (Anal. Chem. (2009) 81,8577) under a stable waveform and reservoir pressure. For each nozzle, this test will be repeated five times within 30 minutes using a script. The mass of the liquid deposited from each nozzle must be between 1 and 5 mL, with a relative standard deviation of less than one percent in the mass measurement of a particular deposition. The test will be repeated up to five times, modifying waveforms and reservoir pressures as appropriate, until the test is passed. As written, the test has a few logistical problems. 1. Total mass 1-5 g corresponding to 1-5 mL of water: The weight limit for ultra-micro balances is 2.1 g, so the full requested range is not accessible. This applies to all vendors of ultra-micro balances that we are aware of. In addition, it is necessary for systematic control of evaporation effects to start each measurement with a filling of the weighing boat that fully covers the bottom surface. Thus we estimate that at best the range 1-1.5 mL would be accessible. 2. Assuming the largest requested droplet size of 150 µm, which corresponds to 1.77 nL of water, requires 565,000 droplets to accumulate 1 mL of volume. Allocating 1 minute to measurement overhead (setup, evaporation measurement before and after dispensing the target volume) and 2 minutes dispensing droplets at 5 kHz would fit 5 measurements into 15 minutes net. The problem is that after each measurement an operator intervention is necessary to empty out the weighing boat and reapply the base fill covering the bottom of the boat. This is due to the capacity limit of the balance pointed out in problem 1. We note that in Anal. Chem. (2009) 81, 8577 a minimum volume of 72 µg or 1490 droplets of isobutanol were found to be sufficient for a 1% measurement, and similarly in Measurement (2017) 100, 72 a minimum volume of 470 µg (470 nL) or 3670 droplets of water (at 128 ng/droplet, or 63 µm diameter) were found to be sufficient for a measurement with k=2 extended uncertainty of 1%. Accordingly, the objective of proving a 1% measurement capability can be achieved with microliter volumes rather than milliliter volumes. Working in the microliter range, e.g., 10-50 µL, will then allow to run 5 or more tests in a script without interruption and operator interference comfortably inside of half an hour. Answer: The Government shall update the acceptance test to reflect the following change: FROM: "between 1 and 5 mL" To: "between 1 and 5 microliters Question: Installation will need local help to place the machine into the desired room and onto the desired table. The machine size will require probably six to eight people to lift the machine off of the base of the crate and onto the table. Can this be provided? Answer: The Government shall provide the necessary help with installation All other terms and conditions remain unchanged.