Chemical Analysis

DO

• Wear an approved face shield. Because good vision is essential, take great care to keep your face shield clean and free from scratches.
• Wear chemically resistant gloves that protect the hands and forearms.
• Wear a lab coat that protects the arms, torso, upper legs and clothing.
• Keep all analysis tools and chemicals in a clean, safe place.
• Keep all tools clean and in good working order.
• Read the Product Safety Data sheets for all of the chemicals that you use in your shop and the warning labels affixed to the sides of the reagent containers found in the chemical analysis kit.
• Keep the name and phone number of an emergency physician and your local emergency poison response center in a convenient location next to the shop phone.

DON'T

• Handle food or smoking materials with the protective gloves. Actually, you should NEVER eat or drink when operating PCB fabrication equipment. Dissolved copper is a toxin and should be handled with the same caution and respect as sulfuric acid or any other hazardous material.
• Handle the plating or analysis materials in a negligent or careless manner.
• Operate any part of your system until you have thoroughly read and understood all of the instructions that came with it.
• Handle un-rinsed etched or plated objects without gloves.
• Allow untrained personnel access to the shop.

Analysis tools

Automatic Pipettor

Test samples for the techniques presented in this chapter are most easily measured with a 100 uL (0.10 ml) fixed volume "automatic" pipettor. To use this device, place a disposable tip firmly on the end of the pipettor. Depress the plunger until the first stop is felt. Immerse the tip into the liquid to be sampled and slowly release the plunger. To dispense the sample, press the plunger all of the way in (past the first stop) to clear the tip. The disposable tip can be re-used several times, especially if the pipettor is used to consistently measure the same bath.
Digital titrator

Using a digital titrator is far superior to pipette titration in terms of convenience, repeatability, and absolute accuracy. The operating principal behind the titrator is usually well described in the manual from the manufacturer and will not be repeated here. One point that is usually left out however, is that the delivery tubes included with the device can be reused indefinitely if they are rinsed out with forced deionized water and shaken like a thermometer to remove any residual liquid. They may also be blown out if care is taken to use compressed air that has been filtered and dried. Always re-use a delivery tube for the same titrant that it was originally used for. Failure to observe this precaution may cause contamination of the titrant syringes and lead to erroneous results.

Always record the results of these analyses in your dated log book for future reference! This data will allow you to order replenishment chemicals in a timely manner and avoid a possible loss of use of your system.

During any chemical analysis, care should be taken to thoroughly mix all of the ingredients used by swirling the beaker in a vigorous manner. Do not spill any portion of the sample as this could affect your results.