LABORATORY OF THE IVIOIMTH
Functions of Technical Services Laboratory Focus on Meat and Poultry H E W A S H I N G T O N , D. c , laboratory
T is one of eight
chemical laboratories operated b y the Laboratory Branch of t h e Technical Services Division, Consumer a n d Marketing Service, U. S. D e p a r t m e n t of Agriculture. The laboratory is located on the sixth floor of t h e Agriculture Annex Building, 12th & C Streets, S. W., Washington, D . C. While t h e functions of the laboratory are similar t o the other seven field laboratories in t h e analytical control of meat products and poult r y products, it serves more as a Special Services laboratory. T h e M e a t Inspection Act and Poult r y Products Inspection Act require continuous Federal inspection of all
A USDA chemist performs t h e distillation step t e r m i n i n g the a m o u n t o f nitrate in a meat s a m p l e
in de-
Fat samples are extracted in preparat i o n f o r injection into t h e gas chromatograph f o r determination of origin (animal o r vegetable) by sterol content
160 A
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ANALYTICAL CHEMISTRY
meat a n d meat products a n d poultry and poultry products moving in interstate and foreign commerce. Samples taken b y Federal meat and poultry inspectors are sent t o the laboratory for assurance t h a t t h e product meets t h e requirements of these two laws. F o r instance, analyses are necessary to determine whether or n o t cured meat products contain more t h a n t h e maximum permitted amounts of sodium nitrite ; if hamburger contains excessive fat ; or, whether the cereal, nonfat dry milk, a n d / o r soya flour in sausage is within prescribed limits. Added moisture, phosphate, ascorbic acid, and other meat additives in sausage, cured smoked products, meat loaf, etc.
are also checked in this laboratory. Routine analyses of protein are made by the Kjeldahl method; salt by a modified Volhard procedure; fat by petroleum ether (Soxhlet) extraction; and nitrite b y a modified Griess method. These a n d other methods are described in "Official Methods of Analysis of the A. O. A. C," 10th Edition. I n addition to these routine control procedures, the Washington laboratory serves as a "referee" when a controversy arises concerning the validity of findings reported on a sample by one of the other laboratories. Samples submitted by meat and poultry inspection staff officers, p r e p a r a t o r y to making policy decisions, are also
A meat inspection chemist prepares to inject an extract sample into the gas chromatograph for determination of insecticide residue. Such residues in meat products are limited t o very small amounts
Washington meat inspection laboratory employees perform various analyses in their newly-designed laboratory
handled as are various special projects. Surveys of the background level of such toxic heavy metals as lead, arsenic, mercury, and selenium in animal tissue are currently in progress. M e t h ods for their determination on a routine basis are being studied. The laboratory determines metals in meat and poultry items by use of spectrographic and flame photometric methods. M e a t and poultry products are checked periodically to determine the presence and amount of the radioactive elements, strontium-90 and cesium-137. Determinations of antioxidants in fats and oils are currently being made by various methods, including the use of gas-liquid chromatography techniques. One of the special projects consists of the determination of insecticide residues in meat. This work utilizes both gas-liquid and thin-layer chromatography. Gas-liquid chromatography is also used for determining animal fat in vegetable fat, by identifying and quanti ta ting sterols. Fred B . Hilty is the Chemist-inCharge, and he has a staff of six chemists, two physical science aids, one secretary, and two laboratory helpers. (Continued
on -page 162)
VOL. 39, NO. 2, FEBRUARY 1967
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161 A
LABORATORY
OF
THE
MONTH Meat inspection laboratory employees perform many tests on meat samples, such as salt determination by Volhard method and nitrogen determination by Kjeldahl m e t h o d , supplemented by the Titralizer
Meat product samples f r o m all over the country are received by the Washington meat inspection laboratory. They are sorted and catalogued to expedite rapid processing so t h a t results can be rushed back t o the meat inspection stations
Salt content of the meat product is determined (by Volhard method) in order to calculate the a m o u n t of added substances
The identity of insecticide residues and a m o u n t present in samples are revealed on the gas chromatograph chart 162 A
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ANALYTICAL CHEMISTRY
A chemist takes i n f o r m a t i o n f r o m t h e Titralizer to calculate the a m o u n t of protein in the meat sample
Meat product samples are prepared for analysis by passing twice through the grinder See ACS Laboratory Guide for All Products/Sales OfficeCircle No. 52 on Readers' Service Card -
