STEP BY STEP, LABCONCO OFFERS NEW SPEED AND NEW SAFETY IN PROTEIN DETERMINATION
1. DISPENSE ACID in complete safety with Labconco Acid and Caustic Dispensing unit. Stored in cabinet at floor level, acid is vacuum-raised to burette with simple push-button controls.
2.
DIGEST SAMPLE
with modern Labconco Kjeldahl Apparatus, shown here installed in optional hood... ideal answer to the problem of excessive heat. Standard Labconco Kjeldahl available today with as many as 48 heaters.
3. A D D
4. ADD CAUSTIC 'at same unit used for dispensing acid. This a t t r a c t i v e unit eliminates the danger of overhead dispensing, likewise corrosion resulting from spilled acids, caustics.
5. DISTILL SAMPLE with same Kjeldahl Apparatus used for digestion. Gas or electric heat, variable heat controls, timers . . . no matter what your needs, Labconco has the right size and model Kjeldahl for you.
WATER
to cool sample in this handy Labconco Kjeldahl Sink. 6' hose has convenient grip valve for adding water to flasks on cart. Sink also ideal for washing and dumping operations.
6. TITRATE
SAMPLE
at this convenient Labconco Titration Unit. Solutions are stored in cabinet and elevated by controlled air pressure
LABCONCO IS THE WORLD'S LEADING MANUFACTURER OF KJELDAHL APPARATUS. WRITE TODAY FOR COMPLETE DETAILS ON THE LABCONCO TEAM FOR PROTEIN DETERMINATION.
LABORATORY CONSTRUCTION CO. 1109 Holmes
Kansas City, Missouri
For further information, circle number 10 A on Readers' Service Card, page 73 A
10 A
REPORT FOR ANALYSTS adsorption on solid granules, and (4) condensation a t low temperatures. E q u i p m e n t for collecting samples of air is of various types, t h e most common being evacuated flasks. T h e main disa d v a n t a g e of this method is t h e small volume of sample which can be obtained and readily transported. Instead of using evacuated flasks, t h e sample can be taken bj* air displacement (purging a sample container), water displacement, and mercury displacement. Consideration m u s t be given t o t h e reactivity of the gas being sampled—for example, water cannot be used if t h e gas is watersoluble. If t h e sample container is closed with stopcocks, substances soluble in stopcock grease cannot be sampled. I n spite of these limitations, the method has proved satisfactory, for example, in collecting mine air samples. T h e collection of samples in liquids has wide application and has the advantage t h a t large samples of air can be scrubbed, t h u s obtaining a sufficient a m o u n t of t h e contaminant for analysis even though present in very low concentrations. T h e absorbing medium m a y lie water for substances readily soluble or it m a y be a solution which reacts with t h e contaminant—for example, alkaline solutions for collection of acid gases, acid solutions for alkaline materials, cadmium chloride for hydrogen sulfide, and iodine solutions for sulfur dioxide. T h e selection of t h e absorbing solution will depend not only on t h e substance to be determined b u t also on possible interfering substances. T h e collection of samples on solid granules such as activated charcoal and silica gel is similar in principle t o absorption in a liquid medium and is used primarily for collection of organic vapors. T h ; s method also has t h e advantage of concentrating on a small volume of adsorbent the material from a large volume of air, t h u s permitting more accurate analysis. T h e use of low temperatures obtained by dry ice and acetone or liquid air or nitrogen t o condense t h e contaminant is frequently resorted to where other methods are not considered applicable or desirable for one reason or another. T h e main advantage of collection by these methods is t h e fact t h a t relatively large a m o u n t s can be obtained and t h u s there is a wide choice of analytical procedures and instrumentation t h a t can be applied in the laboratory. While adaptations and modifications m a y be required, t h e collection of samples and transportation t o t h e laboratory provide potential procedures for virtually any contaminant t h a t is encountered. Continuous Recorders. T h e v a s t majority of analyses t h a t are m a d e t o evaluate workroom exposures are ANALYTICAL
CHEMISTRY
